diff options
Diffstat (limited to 'Documentation/admin-guide')
39 files changed, 2134 insertions, 472 deletions
diff --git a/Documentation/admin-guide/acpi/fan_performance_states.rst b/Documentation/admin-guide/acpi/fan_performance_states.rst index 98fe5c333121..b9e4b4d146c1 100644 --- a/Documentation/admin-guide/acpi/fan_performance_states.rst +++ b/Documentation/admin-guide/acpi/fan_performance_states.rst @@ -60,3 +60,31 @@ For example:: When a given field is not populated or its value provided by the platform firmware is invalid, the "not-defined" string is shown instead of the value. + +ACPI Fan Fine Grain Control +============================= + +When _FIF object specifies support for fine grain control, then fan speed +can be set from 0 to 100% with the recommended minimum "step size" via +_FSL object. User can adjust fan speed using thermal sysfs cooling device. + +Here use can look at fan performance states for a reference speed (speed_rpm) +and set it by changing cooling device cur_state. If the fine grain control +is supported then user can also adjust to some other speeds which are +not defined in the performance states. + +The support of fine grain control is presented via sysfs attribute +"fine_grain_control". If fine grain control is present, this attribute +will show "1" otherwise "0". + +This sysfs attribute is presented in the same directory as performance states. + +ACPI Fan Performance Feedback +============================= + +The optional _FST object provides status information for the fan device. +This includes field to provide current fan speed in revolutions per minute +at which the fan is rotating. + +This speed is presented in the sysfs using the attribute "fan_speed_rpm", +in the same directory as performance states. diff --git a/Documentation/admin-guide/blockdev/index.rst b/Documentation/admin-guide/blockdev/index.rst index b903cf152091..957ccf617797 100644 --- a/Documentation/admin-guide/blockdev/index.rst +++ b/Documentation/admin-guide/blockdev/index.rst @@ -1,8 +1,8 @@ .. SPDX-License-Identifier: GPL-2.0 -=========================== -The Linux RapidIO Subsystem -=========================== +============= +Block Devices +============= .. toctree:: :maxdepth: 1 diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst index 3e11926a4df9..c73b16930449 100644 --- a/Documentation/admin-guide/blockdev/zram.rst +++ b/Documentation/admin-guide/blockdev/zram.rst @@ -315,8 +315,8 @@ To use the feature, admin should set up backing device via:: echo /dev/sda5 > /sys/block/zramX/backing_dev -before disksize setting. It supports only partition at this moment. -If admin wants to use incompressible page writeback, they could do via:: +before disksize setting. It supports only partitions at this moment. +If admin wants to use incompressible page writeback, they could do it via:: echo huge > /sys/block/zramX/writeback @@ -341,9 +341,14 @@ Admin can request writeback of those idle pages at right timing via:: echo idle > /sys/block/zramX/writeback -With the command, zram writeback idle pages from memory to the storage. +With the command, zram will writeback idle pages from memory to the storage. -If admin want to write a specific page in zram device to backing device, +Additionally, if a user choose to writeback only huge and idle pages +this can be accomplished with:: + + echo huge_idle > /sys/block/zramX/writeback + +If an admin wants to write a specific page in zram device to the backing device, they could write a page index into the interface. echo "page_index=1251" > /sys/block/zramX/writeback @@ -354,7 +359,7 @@ to guarantee storage health for entire product life. To overcome the concern, zram supports "writeback_limit" feature. The "writeback_limit_enable"'s default value is 0 so that it doesn't limit -any writeback. IOW, if admin wants to apply writeback budget, he should +any writeback. IOW, if admin wants to apply writeback budget, they should enable writeback_limit_enable via:: $ echo 1 > /sys/block/zramX/writeback_limit_enable @@ -365,7 +370,7 @@ until admin sets the budget via /sys/block/zramX/writeback_limit. (If admin doesn't enable writeback_limit_enable, writeback_limit's value assigned via /sys/block/zramX/writeback_limit is meaningless.) -If admin want to limit writeback as per-day 400M, he could do it +If admin wants to limit writeback as per-day 400M, they could do it like below:: $ MB_SHIFT=20 @@ -375,16 +380,16 @@ like below:: $ echo 1 > /sys/block/zram0/writeback_limit_enable If admins want to allow further write again once the budget is exhausted, -he could do it like below:: +they could do it like below:: $ echo $((400<<MB_SHIFT>>4K_SHIFT)) > \ /sys/block/zram0/writeback_limit -If admin wants to see remaining writeback budget since last set:: +If an admin wants to see the remaining writeback budget since last set:: $ cat /sys/block/zramX/writeback_limit -If admin want to disable writeback limit, he could do:: +If an admin wants to disable writeback limit, they could do:: $ echo 0 > /sys/block/zramX/writeback_limit_enable @@ -393,7 +398,7 @@ system reboot, echo 1 > /sys/block/zramX/reset) so keeping how many of writeback happened until you reset the zram to allocate extra writeback budget in next setting is user's job. -If admin wants to measure writeback count in a certain period, he could +If admin wants to measure writeback count in a certain period, they could know it via /sys/block/zram0/bd_stat's 3rd column. memory tracking diff --git a/Documentation/admin-guide/bootconfig.rst b/Documentation/admin-guide/bootconfig.rst index a1860fc0ca88..d99994345d41 100644 --- a/Documentation/admin-guide/bootconfig.rst +++ b/Documentation/admin-guide/bootconfig.rst @@ -158,9 +158,15 @@ Each key-value pair is shown in each line with following style:: Boot Kernel With a Boot Config ============================== -Since the boot configuration file is loaded with initrd, it will be added -to the end of the initrd (initramfs) image file with padding, size, -checksum and 12-byte magic word as below. +There are two options to boot the kernel with bootconfig: attaching the +bootconfig to the initrd image or embedding it in the kernel itself. + +Attaching a Boot Config to Initrd +--------------------------------- + +Since the boot configuration file is loaded with initrd by default, +it will be added to the end of the initrd (initramfs) image file with +padding, size, checksum and 12-byte magic word as below. [initrd][bootconfig][padding][size(le32)][checksum(le32)][#BOOTCONFIG\n] @@ -196,6 +202,25 @@ To remove the config from the image, you can use -d option as below:: Then add "bootconfig" on the normal kernel command line to tell the kernel to look for the bootconfig at the end of the initrd file. +Embedding a Boot Config into Kernel +----------------------------------- + +If you can not use initrd, you can also embed the bootconfig file in the +kernel by Kconfig options. In this case, you need to recompile the kernel +with the following configs:: + + CONFIG_BOOT_CONFIG_EMBED=y + CONFIG_BOOT_CONFIG_EMBED_FILE="/PATH/TO/BOOTCONFIG/FILE" + +``CONFIG_BOOT_CONFIG_EMBED_FILE`` requires an absolute path or a relative +path to the bootconfig file from source tree or object tree. +The kernel will embed it as the default bootconfig. + +Just as when attaching the bootconfig to the initrd, you need ``bootconfig`` +option on the kernel command line to enable the embedded bootconfig. + +Note that even if you set this option, you can override the embedded +bootconfig by another bootconfig which attached to the initrd. Kernel parameters via Boot Config ================================= diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst index faac50149a22..2cc502a75ef6 100644 --- a/Documentation/admin-guide/cgroup-v1/memory.rst +++ b/Documentation/admin-guide/cgroup-v1/memory.rst @@ -64,6 +64,7 @@ Brief summary of control files. threads cgroup.procs show list of processes cgroup.event_control an interface for event_fd() + This knob is not available on CONFIG_PREEMPT_RT systems. memory.usage_in_bytes show current usage for memory (See 5.5 for details) memory.memsw.usage_in_bytes show current usage for memory+Swap @@ -75,6 +76,7 @@ Brief summary of control files. memory.max_usage_in_bytes show max memory usage recorded memory.memsw.max_usage_in_bytes show max memory+Swap usage recorded memory.soft_limit_in_bytes set/show soft limit of memory usage + This knob is not available on CONFIG_PREEMPT_RT systems. memory.stat show various statistics memory.use_hierarchy set/show hierarchical account enabled This knob is deprecated and shouldn't be diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 5aa368d165da..176298f2f4de 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -1208,6 +1208,34 @@ PAGE_SIZE multiple when read back. high limit is used and monitored properly, this limit's utility is limited to providing the final safety net. + memory.reclaim + A write-only nested-keyed file which exists for all cgroups. + + This is a simple interface to trigger memory reclaim in the + target cgroup. + + This file accepts a single key, the number of bytes to reclaim. + No nested keys are currently supported. + + Example:: + + echo "1G" > memory.reclaim + + The interface can be later extended with nested keys to + configure the reclaim behavior. For example, specify the + type of memory to reclaim from (anon, file, ..). + + Please note that the kernel can over or under reclaim from + the target cgroup. If less bytes are reclaimed than the + specified amount, -EAGAIN is returned. + + memory.peak + A read-only single value file which exists on non-root + cgroups. + + The max memory usage recorded for the cgroup and its + descendants since the creation of the cgroup. + memory.oom.group A read-write single value file which exists on non-root cgroups. The default value is "0". @@ -1301,6 +1329,11 @@ PAGE_SIZE multiple when read back. Amount of memory used to cache filesystem data, including tmpfs and shared memory. + kernel (npn) + Amount of total kernel memory, including + (kernel_stack, pagetables, percpu, vmalloc, slab) in + addition to other kernel memory use cases. + kernel_stack Amount of memory allocated to kernel stacks. @@ -1321,6 +1354,12 @@ PAGE_SIZE multiple when read back. Amount of cached filesystem data that is swap-backed, such as tmpfs, shm segments, shared anonymous mmap()s + zswap + Amount of memory consumed by the zswap compression backend. + + zswapped + Amount of application memory swapped out to zswap. + file_mapped Amount of cached filesystem data mapped with mmap() @@ -1511,6 +1550,21 @@ PAGE_SIZE multiple when read back. higher than the limit for an extended period of time. This reduces the impact on the workload and memory management. + memory.zswap.current + A read-only single value file which exists on non-root + cgroups. + + The total amount of memory consumed by the zswap compression + backend. + + memory.zswap.max + A read-write single value file which exists on non-root + cgroups. The default is "max". + + Zswap usage hard limit. If a cgroup's zswap pool reaches this + limit, it will refuse to take any more stores before existing + entries fault back in or are written out to disk. + memory.pressure A read-only nested-keyed file. @@ -1876,7 +1930,7 @@ IO Latency Interface Files io.latency This takes a similar format as the other controllers. - "MAJOR:MINOR target=<target time in microseconds" + "MAJOR:MINOR target=<target time in microseconds>" io.stat If the controller is enabled you will see extra stats in io.stat in diff --git a/Documentation/admin-guide/devices.txt b/Documentation/admin-guide/devices.txt index c07dc0ee860e..9764d6edb189 100644 --- a/Documentation/admin-guide/devices.txt +++ b/Documentation/admin-guide/devices.txt @@ -1933,7 +1933,7 @@ ... 255= /dev/umem/d15p15 15th partition of 16th board. - 117 char COSA/SRP synchronous serial card + 117 char [REMOVED] COSA/SRP synchronous serial card 0 = /dev/cosa0c0 1st board, 1st channel 1 = /dev/cosa0c1 1st board, 2nd channel ... diff --git a/Documentation/admin-guide/hw-vuln/index.rst b/Documentation/admin-guide/hw-vuln/index.rst index 8cbc711cda93..4df436e7c417 100644 --- a/Documentation/admin-guide/hw-vuln/index.rst +++ b/Documentation/admin-guide/hw-vuln/index.rst @@ -17,3 +17,4 @@ are configurable at compile, boot or run time. special-register-buffer-data-sampling.rst core-scheduling.rst l1d_flush.rst + processor_mmio_stale_data.rst diff --git a/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst b/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst new file mode 100644 index 000000000000..9393c50b5afc --- /dev/null +++ b/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst @@ -0,0 +1,246 @@ +========================================= +Processor MMIO Stale Data Vulnerabilities +========================================= + +Processor MMIO Stale Data Vulnerabilities are a class of memory-mapped I/O +(MMIO) vulnerabilities that can expose data. The sequences of operations for +exposing data range from simple to very complex. Because most of the +vulnerabilities require the attacker to have access to MMIO, many environments +are not affected. System environments using virtualization where MMIO access is +provided to untrusted guests may need mitigation. These vulnerabilities are +not transient execution attacks. However, these vulnerabilities may propagate +stale data into core fill buffers where the data can subsequently be inferred +by an unmitigated transient execution attack. Mitigation for these +vulnerabilities includes a combination of microcode update and software +changes, depending on the platform and usage model. Some of these mitigations +are similar to those used to mitigate Microarchitectural Data Sampling (MDS) or +those used to mitigate Special Register Buffer Data Sampling (SRBDS). + +Data Propagators +================ +Propagators are operations that result in stale data being copied or moved from +one microarchitectural buffer or register to another. Processor MMIO Stale Data +Vulnerabilities are operations that may result in stale data being directly +read into an architectural, software-visible state or sampled from a buffer or +register. + +Fill Buffer Stale Data Propagator (FBSDP) +----------------------------------------- +Stale data may propagate from fill buffers (FB) into the non-coherent portion +of the uncore on some non-coherent writes. Fill buffer propagation by itself +does not make stale data architecturally visible. Stale data must be propagated +to a location where it is subject to reading or sampling. + +Sideband Stale Data Propagator (SSDP) +------------------------------------- +The sideband stale data propagator (SSDP) is limited to the client (including +Intel Xeon server E3) uncore implementation. The sideband response buffer is +shared by all client cores. For non-coherent reads that go to sideband +destinations, the uncore logic returns 64 bytes of data to the core, including +both requested data and unrequested stale data, from a transaction buffer and +the sideband response buffer. As a result, stale data from the sideband +response and transaction buffers may now reside in a core fill buffer. + +Primary Stale Data Propagator (PSDP) +------------------------------------ +The primary stale data propagator (PSDP) is limited to the client (including +Intel Xeon server E3) uncore implementation. Similar to the sideband response +buffer, the primary response buffer is shared by all client cores. For some +processors, MMIO primary reads will return 64 bytes of data to the core fill +buffer including both requested data and unrequested stale data. This is +similar to the sideband stale data propagator. + +Vulnerabilities +=============== +Device Register Partial Write (DRPW) (CVE-2022-21166) +----------------------------------------------------- +Some endpoint MMIO registers incorrectly handle writes that are smaller than +the register size. Instead of aborting the write or only copying the correct +subset of bytes (for example, 2 bytes for a 2-byte write), more bytes than +specified by the write transaction may be written to the register. On +processors affected by FBSDP, this may expose stale data from the fill buffers +of the core that created the write transaction. + +Shared Buffers Data Sampling (SBDS) (CVE-2022-21125) +---------------------------------------------------- +After propagators may have moved data around the uncore and copied stale data +into client core fill buffers, processors affected by MFBDS can leak data from +the fill buffer. It is limited to the client (including Intel Xeon server E3) +uncore implementation. + +Shared Buffers Data Read (SBDR) (CVE-2022-21123) +------------------------------------------------ +It is similar to Shared Buffer Data Sampling (SBDS) except that the data is +directly read into the architectural software-visible state. It is limited to +the client (including Intel Xeon server E3) uncore implementation. + +Affected Processors +=================== +Not all the CPUs are affected by all the variants. For instance, most +processors for the server market (excluding Intel Xeon E3 processors) are +impacted by only Device Register Partial Write (DRPW). + +Below is the list of affected Intel processors [#f1]_: + + =================== ============ ========= + Common name Family_Model Steppings + =================== ============ ========= + HASWELL_X 06_3FH 2,4 + SKYLAKE_L 06_4EH 3 + BROADWELL_X 06_4FH All + SKYLAKE_X 06_55H 3,4,6,7,11 + BROADWELL_D 06_56H 3,4,5 + SKYLAKE 06_5EH 3 + ICELAKE_X 06_6AH 4,5,6 + ICELAKE_D 06_6CH 1 + ICELAKE_L 06_7EH 5 + ATOM_TREMONT_D 06_86H All + LAKEFIELD 06_8AH 1 + KABYLAKE_L 06_8EH 9 to 12 + ATOM_TREMONT 06_96H 1 + ATOM_TREMONT_L 06_9CH 0 + KABYLAKE 06_9EH 9 to 13 + COMETLAKE 06_A5H 2,3,5 + COMETLAKE_L 06_A6H 0,1 + ROCKETLAKE 06_A7H 1 + =================== ============ ========= + +If a CPU is in the affected processor list, but not affected by a variant, it +is indicated by new bits in MSR IA32_ARCH_CAPABILITIES. As described in a later +section, mitigation largely remains the same for all the variants, i.e. to +clear the CPU fill buffers via VERW instruction. + +New bits in MSRs +================ +Newer processors and microcode update on existing affected processors added new +bits to IA32_ARCH_CAPABILITIES MSR. These bits can be used to enumerate +specific variants of Processor MMIO Stale Data vulnerabilities and mitigation +capability. + +MSR IA32_ARCH_CAPABILITIES +-------------------------- +Bit 13 - SBDR_SSDP_NO - When set, processor is not affected by either the + Shared Buffers Data Read (SBDR) vulnerability or the sideband stale + data propagator (SSDP). +Bit 14 - FBSDP_NO - When set, processor is not affected by the Fill Buffer + Stale Data Propagator (FBSDP). +Bit 15 - PSDP_NO - When set, processor is not affected by Primary Stale Data + Propagator (PSDP). +Bit 17 - FB_CLEAR - When set, VERW instruction will overwrite CPU fill buffer + values as part of MD_CLEAR operations. Processors that do not + enumerate MDS_NO (meaning they are affected by MDS) but that do + enumerate support for both L1D_FLUSH and MD_CLEAR implicitly enumerate + FB_CLEAR as part of their MD_CLEAR support. +Bit 18 - FB_CLEAR_CTRL - Processor supports read and write to MSR + IA32_MCU_OPT_CTRL[FB_CLEAR_DIS]. On such processors, the FB_CLEAR_DIS + bit can be set to cause the VERW instruction to not perform the + FB_CLEAR action. Not all processors that support FB_CLEAR will support + FB_CLEAR_CTRL. + +MSR IA32_MCU_OPT_CTRL +--------------------- +Bit 3 - FB_CLEAR_DIS - When set, VERW instruction does not perform the FB_CLEAR +action. This may be useful to reduce the performance impact of FB_CLEAR in +cases where system software deems it warranted (for example, when performance +is more critical, or the untrusted software has no MMIO access). Note that +FB_CLEAR_DIS has no impact on enumeration (for example, it does not change +FB_CLEAR or MD_CLEAR enumeration) and it may not be supported on all processors +that enumerate FB_CLEAR. + +Mitigation +========== +Like MDS, all variants of Processor MMIO Stale Data vulnerabilities have the +same mitigation strategy to force the CPU to clear the affected buffers before +an attacker can extract the secrets. + +This is achieved by using the otherwise unused and obsolete VERW instruction in +combination with a microcode update. The microcode clears the affected CPU +buffers when the VERW instruction is executed. + +Kernel reuses the MDS function to invoke the buffer clearing: + + mds_clear_cpu_buffers() + +On MDS affected CPUs, the kernel already invokes CPU buffer clear on +kernel/userspace, hypervisor/guest and C-state (idle) transitions. No +additional mitigation is needed on such CPUs. + +For CPUs not affected by MDS or TAA, mitigation is needed only for the attacker +with MMIO capability. Therefore, VERW is not required for kernel/userspace. For +virtualization case, VERW is only needed at VMENTER for a guest with MMIO +capability. + +Mitigation points +----------------- +Return to user space +^^^^^^^^^^^^^^^^^^^^ +Same mitigation as MDS when affected by MDS/TAA, otherwise no mitigation +needed. + +C-State transition +^^^^^^^^^^^^^^^^^^ +Control register writes by CPU during C-state transition can propagate data +from fill buffer to uncore buffers. Execute VERW before C-state transition to +clear CPU fill buffers. + +Guest entry point +^^^^^^^^^^^^^^^^^ +Same mitigation as MDS when processor is also affected by MDS/TAA, otherwise +execute VERW at VMENTER only for MMIO capable guests. On CPUs not affected by +MDS/TAA, guest without MMIO access cannot extract secrets using Processor MMIO +Stale Data vulnerabilities, so there is no need to execute VERW for such guests. + +Mitigation control on the kernel command line +--------------------------------------------- +The kernel command line allows to control the Processor MMIO Stale Data +mitigations at boot time with the option "mmio_stale_data=". The valid +arguments for this option are: + + ========== ================================================================= + full If the CPU is vulnerable, enable mitigation; CPU buffer clearing + on exit to userspace and when entering a VM. Idle transitions are + protected as well. It does not automatically disable SMT. + full,nosmt Same as full, with SMT disabled on vulnerable CPUs. This is the + complete mitigation. + off Disables mitigation completely. + ========== ================================================================= + +If the CPU is affected and mmio_stale_data=off is not supplied on the kernel +command line, then the kernel selects the appropriate mitigation. + +Mitigation status information +----------------------------- +The Linux kernel provides a sysfs interface to enumerate the current +vulnerability status of the system: whether the system is vulnerable, and +which mitigations are active. The relevant sysfs file is: + + /sys/devices/system/cpu/vulnerabilities/mmio_stale_data + +The possible values in this file are: + + .. list-table:: + + * - 'Not affected' + - The processor is not vulnerable + * - 'Vulnerable' + - The processor is vulnerable, but no mitigation enabled + * - 'Vulnerable: Clear CPU buffers attempted, no microcode' + - The processor is vulnerable, but microcode is not updated. The + mitigation is enabled on a best effort basis. + * - 'Mitigation: Clear CPU buffers' + - The processor is vulnerable and the CPU buffer clearing mitigation is + enabled. + +If the processor is vulnerable then the following information is appended to +the above information: + + ======================== =========================================== + 'SMT vulnerable' SMT is enabled + 'SMT disabled' SMT is disabled + 'SMT Host state unknown' Kernel runs in a VM, Host SMT state unknown + ======================== =========================================== + +References +---------- +.. [#f1] Affected Processors + https://www.intel.com/content/www/us/en/developer/topic-technology/software-security-guidance/processors-affected-consolidated-product-cpu-model.html diff --git a/Documentation/admin-guide/index.rst b/Documentation/admin-guide/index.rst index 1bedab498104..5bfafcbb9562 100644 --- a/Documentation/admin-guide/index.rst +++ b/Documentation/admin-guide/index.rst @@ -35,6 +35,7 @@ problems and bugs in particular. :maxdepth: 1 reporting-issues + reporting-regressions security-bugs bug-hunting bug-bisect diff --git a/Documentation/admin-guide/iostats.rst b/Documentation/admin-guide/iostats.rst index 9b14b0c2c9c4..609a3201fd4e 100644 --- a/Documentation/admin-guide/iostats.rst +++ b/Documentation/admin-guide/iostats.rst @@ -76,7 +76,7 @@ Field 3 -- # of sectors read (unsigned long) Field 4 -- # of milliseconds spent reading (unsigned int) This is the total number of milliseconds spent by all reads (as - measured from __make_request() to end_that_request_last()). + measured from blk_mq_alloc_request() to __blk_mq_end_request()). Field 5 -- # of writes completed (unsigned long) This is the total number of writes completed successfully. @@ -89,7 +89,7 @@ Field 7 -- # of sectors written (unsigned long) Field 8 -- # of milliseconds spent writing (unsigned int) This is the total number of milliseconds spent by all writes (as - measured from __make_request() to end_that_request_last()). + measured from blk_mq_alloc_request() to __blk_mq_end_request()). Field 9 -- # of I/Os currently in progress (unsigned int) The only field that should go to zero. Incremented as requests are @@ -120,7 +120,7 @@ Field 14 -- # of sectors discarded (unsigned long) Field 15 -- # of milliseconds spent discarding (unsigned int) This is the total number of milliseconds spent by all discards (as - measured from __make_request() to end_that_request_last()). + measured from blk_mq_alloc_request() to __blk_mq_end_request()). Field 16 -- # of flush requests completed This is the total number of flush requests completed successfully. diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst index cb30ca3df27c..a748e7eb4429 100644 --- a/Documentation/admin-guide/kdump/kdump.rst +++ b/Documentation/admin-guide/kdump/kdump.rst @@ -146,9 +146,9 @@ System kernel config options CONFIG_SYSFS=y Note that "sysfs file system support" might not appear in the "Pseudo - filesystems" menu if "Configure standard kernel features (for small - systems)" is not enabled in "General Setup." In this case, check the - .config file itself to ensure that sysfs is turned on, as follows:: + filesystems" menu if "Configure standard kernel features (expert users)" + is not enabled in "General Setup." In this case, check the .config file + itself to ensure that sysfs is turned on, as follows:: grep 'CONFIG_SYSFS' .config @@ -533,6 +533,10 @@ the following command:: cp /proc/vmcore <dump-file> +or use scp to write out the dump file between hosts on a network, e.g:: + + scp /proc/vmcore remote_username@remote_ip:<dump-file> + You can also use makedumpfile utility to write out the dump file with specified options to filter out unwanted contents, e.g:: diff --git a/Documentation/admin-guide/kdump/vmcoreinfo.rst b/Documentation/admin-guide/kdump/vmcoreinfo.rst index 3861a25faae1..8419019b6a88 100644 --- a/Documentation/admin-guide/kdump/vmcoreinfo.rst +++ b/Documentation/admin-guide/kdump/vmcoreinfo.rst @@ -494,6 +494,14 @@ architecture which is used to lookup the page-tables for the Virtual addresses in the higher VA range (refer to ARMv8 ARM document for more details). +MODULES_VADDR|MODULES_END|VMALLOC_START|VMALLOC_END|VMEMMAP_START|VMEMMAP_END +----------------------------------------------------------------------------- + +Used to get the correct ranges: + MODULES_VADDR ~ MODULES_END-1 : Kernel module space. + VMALLOC_START ~ VMALLOC_END-1 : vmalloc() / ioremap() space. + VMEMMAP_START ~ VMEMMAP_END-1 : vmemmap region, used for struct page array. + arm === diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst index 01ba293a2d70..959f73a32712 100644 --- a/Documentation/admin-guide/kernel-parameters.rst +++ b/Documentation/admin-guide/kernel-parameters.rst @@ -99,6 +99,7 @@ parameter is applicable:: ALSA ALSA sound support is enabled. APIC APIC support is enabled. APM Advanced Power Management support is enabled. + APPARMOR AppArmor support is enabled. ARM ARM architecture is enabled. ARM64 ARM64 architecture is enabled. AX25 Appropriate AX.25 support is enabled. @@ -108,15 +109,15 @@ parameter is applicable:: DYNAMIC_DEBUG Build in debug messages and enable them at runtime EDD BIOS Enhanced Disk Drive Services (EDD) is enabled EFI EFI Partitioning (GPT) is enabled - EIDE EIDE/ATAPI support is enabled. EVM Extended Verification Module FB The frame buffer device is enabled. FTRACE Function tracing enabled. GCOV GCOV profiling is enabled. + HIBERNATION HIBERNATION is enabled. HW Appropriate hardware is enabled. + HYPER_V HYPERV support is enabled. IA-64 IA-64 architecture is enabled. IMA Integrity measurement architecture is enabled. - IOSCHED More than one I/O scheduler is enabled. IP_PNP IP DHCP, BOOTP, or RARP is enabled. IPV6 IPv6 support is enabled. ISAPNP ISA PnP code is enabled. @@ -140,7 +141,6 @@ parameter is applicable:: NUMA NUMA support is enabled. NFS Appropriate NFS support is enabled. OF Devicetree is enabled. - OSS OSS sound support is enabled. PV_OPS A paravirtualized kernel is enabled. PARIDE The ParIDE (parallel port IDE) subsystem is enabled. PARISC The PA-RISC architecture is enabled. @@ -160,7 +160,6 @@ parameter is applicable:: the Documentation/scsi/ sub-directory. SECURITY Different security models are enabled. SELINUX SELinux support is enabled. - APPARMOR AppArmor support is enabled. SERIAL Serial support is enabled. SH SuperH architecture is enabled. SMP The kernel is an SMP kernel. @@ -168,7 +167,6 @@ parameter is applicable:: SWSUSP Software suspend (hibernation) is enabled. SUSPEND System suspend states are enabled. TPM TPM drivers are enabled. - TS Appropriate touchscreen support is enabled. UMS USB Mass Storage support is enabled. USB USB support is enabled. USBHID USB Human Interface Device support is enabled. @@ -177,7 +175,6 @@ parameter is applicable:: VGA The VGA console has been enabled. VT Virtual terminal support is enabled. WDT Watchdog support is enabled. - XT IBM PC/XT MFM hard disk support is enabled. X86-32 X86-32, aka i386 architecture is enabled. X86-64 X86-64 architecture is enabled. More X86-64 boot options can be found in @@ -211,7 +208,7 @@ The number of kernel parameters is not limited, but the length of the complete command line (parameters including spaces etc.) is limited to a fixed number of characters. This limit depends on the architecture and is between 256 and 4096 characters. It is defined in the file -./include/asm/setup.h as COMMAND_LINE_SIZE. +./include/uapi/asm-generic/setup.h as COMMAND_LINE_SIZE. Finally, the [KMG] suffix is commonly described after a number of kernel parameter values. These 'K', 'M', and 'G' letters represent the _binary_ diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 7123524a86b8..2522b11e593f 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -461,6 +461,12 @@ Format: <io>,<irq>,<mode> See header of drivers/net/hamradio/baycom_ser_hdx.c. + bert_disable [ACPI] + Disable BERT OS support on buggy BIOSes. + + bgrt_disable [ACPI][X86] + Disable BGRT to avoid flickering OEM logo. + blkdevparts= Manual partition parsing of block device(s) for embedded devices based on command line input. See Documentation/block/cmdline-partition.rst @@ -476,12 +482,6 @@ See Documentation/admin-guide/bootconfig.rst - bert_disable [ACPI] - Disable BERT OS support on buggy BIOSes. - - bgrt_disable [ACPI][X86] - Disable BGRT to avoid flickering OEM logo. - bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) bttv.radio= Most important insmod options are available as kernel args too. @@ -563,6 +563,25 @@ cio_ignore= [S390] See Documentation/s390/common_io.rst for details. + + clearcpuid=X[,X...] [X86] + Disable CPUID feature X for the kernel. See + arch/x86/include/asm/cpufeatures.h for the valid bit + numbers X. Note the Linux-specific bits are not necessarily + stable over kernel options, but the vendor-specific + ones should be. + X can also be a string as appearing in the flags: line + in /proc/cpuinfo which does not have the above + instability issue. However, not all features have names + in /proc/cpuinfo. + Note that using this option will taint your kernel. + Also note that user programs calling CPUID directly + or using the feature without checking anything + will still see it. This just prevents it from + being used by the kernel or shown in /proc/cpuinfo. + Also note the kernel might malfunction if you disable + some critical bits. + clk_ignore_unused [CLK] Prevents the clock framework from automatically gating @@ -631,19 +650,6 @@ Defaults to zero when built as a module and to 10 seconds when built into the kernel. - clearcpuid=BITNUM[,BITNUM...] [X86] - Disable CPUID feature X for the kernel. See - arch/x86/include/asm/cpufeatures.h for the valid bit - numbers. Note the Linux specific bits are not necessarily - stable over kernel options, but the vendor specific - ones should be. - Also note that user programs calling CPUID directly - or using the feature without checking anything - will still see it. This just prevents it from - being used by the kernel or shown in /proc/cpuinfo. - Also note the kernel might malfunction if you disable - some critical bits. - cma=nn[MG]@[start[MG][-end[MG]]] [KNL,CMA] Sets the size of kernel global memory area for @@ -724,6 +730,12 @@ hvc<n> Use the hypervisor console device <n>. This is for both Xen and PowerPC hypervisors. + { null | "" } + Use to disable console output, i.e., to have kernel + console messages discarded. + This must be the only console= parameter used on the + kernel command line. + If the device connected to the port is not a TTY but a braille device, prepend "brl," before the device type, for instance console=brl,ttyS0 @@ -759,6 +771,24 @@ 0: default value, disable debugging 1: enable debugging at boot time + cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver + Format: + <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] + + cpu0_hotplug [X86] Turn on CPU0 hotplug feature when + CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off. + Some features depend on CPU0. Known dependencies are: + 1. Resume from suspend/hibernate depends on CPU0. + Suspend/hibernate will fail if CPU0 is offline and you + need to online CPU0 before suspend/hibernate. + 2. PIC interrupts also depend on CPU0. CPU0 can't be + removed if a PIC interrupt is detected. + It's said poweroff/reboot may depend on CPU0 on some + machines although I haven't seen such issues so far + after CPU0 is offline on a few tested machines. + If the dependencies are under your control, you can + turn on cpu0_hotplug. + cpuidle.off=1 [CPU_IDLE] disable the cpuidle sub-system @@ -779,9 +809,13 @@ on every CPU online, such as boot, and resume from suspend. Default: 10000 - cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver - Format: - <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] + crash_kexec_post_notifiers + Run kdump after running panic-notifiers and dumping + kmsg. This only for the users who doubt kdump always + succeeds in any situation. + Note that this also increases risks of kdump failure, + because some panic notifiers can make the crashed + kernel more unstable. crashkernel=size[KMG][@offset[KMG]] [KNL] Using kexec, Linux can switch to a 'crash kernel' @@ -802,7 +836,7 @@ Documentation/admin-guide/kdump/kdump.rst for an example. crashkernel=size[KMG],high - [KNL, X86-64] range could be above 4G. Allow kernel + [KNL, X86-64, ARM64] range could be above 4G. Allow kernel to allocate physical memory region from top, so could be above 4G if system have more than 4G ram installed. Otherwise memory region will be allocated below 4G, if @@ -815,14 +849,20 @@ that require some amount of low memory, e.g. swiotlb requires at least 64M+32K low memory, also enough extra low memory is needed to make sure DMA buffers for 32-bit - devices won't run out. Kernel would try to allocate at + devices won't run out. Kernel would try to allocate at least 256M below 4G automatically. - This one let user to specify own low range under 4G + This one lets the user specify own low range under 4G for second kernel instead. 0: to disable low allocation. It will be ignored when crashkernel=X,high is not used or memory reserved is below 4G. + [KNL, ARM64] range in low memory. + This one lets the user specify a low range in the + DMA zone for the crash dump kernel. + It will be ignored when crashkernel=X,high is not used + or memory reserved is located in the DMA zones. + cryptomgr.notests [KNL] Disable crypto self-tests @@ -939,11 +979,39 @@ [KNL] Debugging option to set a timeout in seconds for deferred probe to give up waiting on dependencies to probe. Only specific dependencies (subsystems or - drivers) that have opted in will be ignored. A timeout of 0 - will timeout at the end of initcalls. This option will also + drivers) that have opted in will be ignored. A timeout + of 0 will timeout at the end of initcalls. If the time + out hasn't expired, it'll be restarted by each + successful driver registration. This option will also dump out devices still on the deferred probe list after retrying. + delayacct [KNL] Enable per-task delay accounting + + dell_smm_hwmon.ignore_dmi= + [HW] Continue probing hardware even if DMI data + indicates that the driver is running on unsupported + hardware. + + dell_smm_hwmon.force= + [HW] Activate driver even if SMM BIOS signature does + not match list of supported models and enable otherwise + blacklisted features. + + dell_smm_hwmon.power_status= + [HW] Report power status in /proc/i8k + (disabled by default). + + dell_smm_hwmon.restricted= + [HW] Allow controlling fans only if SYS_ADMIN + capability is set. + + dell_smm_hwmon.fan_mult= + [HW] Factor to multiply fan speed with. + + dell_smm_hwmon.fan_max= + [HW] Maximum configurable fan speed. + dfltcc= [HW,S390] Format: { on | off | def_only | inf_only | always } on: s390 zlib hardware support for compression on @@ -973,17 +1041,6 @@ disable= [IPV6] See Documentation/networking/ipv6.rst. - hardened_usercopy= - [KNL] Under CONFIG_HARDENED_USERCOPY, whether - hardening is enabled for this boot. Hardened - usercopy checking is used to protect the kernel - from reading or writing beyond known memory - allocation boundaries as a proactive defense - against bounds-checking flaws in the kernel's - copy_to_user()/copy_from_user() interface. - on Perform hardened usercopy checks (default). - off Disable hardened usercopy checks. - disable_radix [PPC] Disable RADIX MMU mode on POWER9 @@ -1046,7 +1103,10 @@ driver later using sysfs. driver_async_probe= [KNL] - List of driver names to be probed asynchronously. + List of driver names to be probed asynchronously. * + matches with all driver names. If * is specified, the + rest of the listed driver names are those that will NOT + match the *. Format: <driver_name1>,<driver_name2>... drm.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>] @@ -1252,7 +1312,7 @@ Append ",keep" to not disable it when the real console takes over. - Only one of vga, efi, serial, or usb debug port can + Only one of vga, serial, or usb debug port can be used at a time. Currently only ttyS0 and ttyS1 may be specified by @@ -1267,7 +1327,7 @@ Interaction with the standard serial driver is not very good. - The VGA and EFI output is eventually overwritten by + The VGA output is eventually overwritten by the real console. The xen option can only be used in Xen domains. @@ -1286,17 +1346,6 @@ force: enforce the use of EDAC to report H/W event. default: on. - ekgdboc= [X86,KGDB] Allow early kernel console debugging - ekgdboc=kbd - - This is designed to be used in conjunction with - the boot argument: earlyprintk=vga - - This parameter works in place of the kgdboc parameter - but can only be used if the backing tty is available - very early in the boot process. For early debugging - via a serial port see kgdboc_earlycon instead. - edd= [EDD] Format: {"off" | "on" | "skip[mbr]"} @@ -1358,6 +1407,17 @@ eisa_irq_edge= [PARISC,HW] See header of drivers/parisc/eisa.c. + ekgdboc= [X86,KGDB] Allow early kernel console debugging + Format: ekgdboc=kbd + + This is designed to be used in conjunction with + the boot argument: earlyprintk=vga + + This parameter works in place of the kgdboc parameter + but can only be used if the backing tty is available + very early in the boot process. For early debugging + via a serial port see kgdboc_earlycon instead. + elanfreq= [X86-32] See comment before function elanfreq_setup() in arch/x86/kernel/cpu/cpufreq/elanfreq.c. @@ -1435,6 +1495,14 @@ as early as possible in order to facilitate early boot debugging. + ftrace_boot_snapshot + [FTRACE] On boot up, a snapshot will be taken of the + ftrace ring buffer that can be read at: + /sys/kernel/tracing/snapshot. + This is useful if you need tracing information from kernel + boot up that is likely to be overridden by user space + start up functionality. + ftrace_dump_on_oops[=orig_cpu] [FTRACE] will dump the trace buffers on oops. If no parameter is passed, ftrace will dump @@ -1548,6 +1616,17 @@ Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0. Default: 1024 + hardened_usercopy= + [KNL] Under CONFIG_HARDENED_USERCOPY, whether + hardening is enabled for this boot. Hardened + usercopy checking is used to protect the kernel + from reading or writing beyond known memory + allocation boundaries as a proactive defense + against bounds-checking flaws in the kernel's + copy_to_user()/copy_from_user() interface. + on Perform hardened usercopy checks (default). + off Disable hardened usercopy checks. + hardlockup_all_cpu_backtrace= [KNL] Should the hard-lockup detector generate backtraces on all cpus. @@ -1568,6 +1647,15 @@ corresponding firmware-first mode error processing logic will be disabled. + hibernate= [HIBERNATION] + noresume Don't check if there's a hibernation image + present during boot. + nocompress Don't compress/decompress hibernation images. + no Disable hibernation and resume. + protect_image Turn on image protection during restoration + (that will set all pages holding image data + during restoration read-only). + highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact size of <nn>. This works even on boxes that have no highmem otherwise. This also works to reduce highmem @@ -1590,16 +1678,6 @@ hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET registers. Default set by CONFIG_HPET_MMAP_DEFAULT. - hugetlb_cma= [HW,CMA] The size of a CMA area used for allocation - of gigantic hugepages. Or using node format, the size - of a CMA area per node can be specified. - Format: nn[KMGTPE] or (node format) - <node>:nn[KMGTPE][,<node>:nn[KMGTPE]] - - Reserve a CMA area of given size and allocate gigantic - hugepages using the CMA allocator. If enabled, the - boot-time allocation of gigantic hugepages is skipped. - hugepages= [HW] Number of HugeTLB pages to allocate at boot. If this follows hugepagesz (below), it specifies the number of pages of hugepagesz to be allocated. @@ -1621,17 +1699,27 @@ Documentation/admin-guide/mm/hugetlbpage.rst. Format: size[KMG] + hugetlb_cma= [HW,CMA] The size of a CMA area used for allocation + of gigantic hugepages. Or using node format, the size + of a CMA area per node can be specified. + Format: nn[KMGTPE] or (node format) + <node>:nn[KMGTPE][,<node>:nn[KMGTPE]] + + Reserve a CMA area of given size and allocate gigantic + hugepages using the CMA allocator. If enabled, the + boot-time allocation of gigantic hugepages is skipped. + hugetlb_free_vmemmap= - [KNL] Reguires CONFIG_HUGETLB_PAGE_FREE_VMEMMAP + [KNL] Reguires CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP enabled. Allows heavy hugetlb users to free up some more - memory (6 * PAGE_SIZE for each 2MB hugetlb page). - Format: { on | off (default) } + memory (7 * PAGE_SIZE for each 2MB hugetlb page). + Format: { [oO][Nn]/Y/y/1 | [oO][Ff]/N/n/0 (default) } - on: enable the feature - off: disable the feature + [oO][Nn]/Y/y/1: enable the feature + [oO][Ff]/N/n/0: disable the feature - Built with CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON=y, + Built with CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON=y, the default is on. This is not compatible with memory_hotplug.memmap_on_memory. @@ -1703,17 +1791,6 @@ i810= [HW,DRM] - i8k.ignore_dmi [HW] Continue probing hardware even if DMI data - indicates that the driver is running on unsupported - hardware. - i8k.force [HW] Activate i8k driver even if SMM BIOS signature - does not match list of supported models. - i8k.power_status - [HW] Report power status in /proc/i8k - (disabled by default) - i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN - capability is set. - i915.invert_brightness= [DRM] Invert the sense of the variable that is used to set the brightness of the panel backlight. Normally a @@ -1731,26 +1808,6 @@ icn= [HW,ISDN] Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] - ide-core.nodma= [HW] (E)IDE subsystem - Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc - .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr - .cdrom .chs .ignore_cable are additional options - See Documentation/ide/ide.rst. - - ide-generic.probe-mask= [HW] (E)IDE subsystem - Format: <int> - Probe mask for legacy ISA IDE ports. Depending on - platform up to 6 ports are supported, enabled by - setting corresponding bits in the mask to 1. The - default value is 0x0, which has a special meaning. - On systems that have PCI, it triggers scanning the - PCI bus for the first and the second port, which - are then probed. On systems without PCI the value - of 0x0 enables probing the two first ports as if it - was 0x3. - - ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem - Claim all unknown PCI IDE storage controllers. idle= [X86] Format: idle=poll, idle=halt, idle=nomwait @@ -1876,7 +1933,8 @@ ima_template= [IMA] Select one of defined IMA measurements template formats. - Formats: { "ima" | "ima-ng" | "ima-sig" } + Formats: { "ima" | "ima-ng" | "ima-ngv2" | "ima-sig" | + "ima-sigv2" } Default: "ima-ng" ima_template_fmt= @@ -2339,13 +2397,35 @@ kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs. Default is 0 (don't ignore, but inject #GP) + kvm.eager_page_split= + [KVM,X86] Controls whether or not KVM will try to + proactively split all huge pages during dirty logging. + Eager page splitting reduces interruptions to vCPU + execution by eliminating the write-protection faults + and MMU lock contention that would otherwise be + required to split huge pages lazily. + + VM workloads that rarely perform writes or that write + only to a small region of VM memory may benefit from + disabling eager page splitting to allow huge pages to + still be used for reads. + + The behavior of eager page splitting depends on whether + KVM_DIRTY_LOG_INITIALLY_SET is enabled or disabled. If + disabled, all huge pages in a memslot will be eagerly + split when dirty logging is enabled on that memslot. If + enabled, eager page splitting will be performed during + the KVM_CLEAR_DIRTY ioctl, and only for the pages being + cleared. + + Eager page splitting currently only supports splitting + huge pages mapped by the TDP MMU. + + Default is Y (on). + kvm.enable_vmware_backdoor=[KVM] Support VMware backdoor PV interface. Default is false (don't support). - kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit - KVM MMU at runtime. - Default is 0 (off) - kvm.nx_huge_pages= [KVM] Controls the software workaround for the X86_BUG_ITLB_MULTIHIT bug. @@ -2389,7 +2469,6 @@ protected: nVHE-based mode with support for guests whose state is kept private from the host. - Not valid if the kernel is running in EL2. Defaults to VHE/nVHE based on hardware support. Setting mode to "protected" will disable kexec and hibernation @@ -2573,14 +2652,14 @@ when set. Format: <int> - libata.force= [LIBATA] Force configurations. The format is comma- - separated list of "[ID:]VAL" where ID is - PORT[.DEVICE]. PORT and DEVICE are decimal numbers - matching port, link or device. Basically, it matches - the ATA ID string printed on console by libata. If - the whole ID part is omitted, the last PORT and DEVICE - values are used. If ID hasn't been specified yet, the - configuration applies to all ports, links and devices. + libata.force= [LIBATA] Force configurations. The format is a comma- + separated list of "[ID:]VAL" where ID is PORT[.DEVICE]. + PORT and DEVICE are decimal numbers matching port, link + or device. Basically, it matches the ATA ID string + printed on console by libata. If the whole ID part is + omitted, the last PORT and DEVICE values are used. If + ID hasn't been specified yet, the configuration applies + to all ports, links and devices. If only DEVICE is omitted, the parameter applies to the port and all links and devices behind it. DEVICE @@ -2590,7 +2669,7 @@ host link and device attached to it. The VAL specifies the configuration to force. As long - as there's no ambiguity shortcut notation is allowed. + as there is no ambiguity, shortcut notation is allowed. For example, both 1.5 and 1.5G would work for 1.5Gbps. The following configurations can be forced. @@ -2603,27 +2682,64 @@ udma[/][16,25,33,44,66,100,133] notation is also allowed. + * nohrst, nosrst, norst: suppress hard, soft and both + resets. + + * rstonce: only attempt one reset during hot-unplug + link recovery. + + * [no]dbdelay: Enable or disable the extra 200ms delay + before debouncing a link PHY and device presence + detection. + * [no]ncq: Turn on or off NCQ. - * [no]ncqtrim: Turn off queued DSM TRIM. + * [no]ncqtrim: Enable or disable queued DSM TRIM. + + * [no]ncqati: Enable or disable NCQ trim on ATI chipset. + + * [no]trim: Enable or disable (unqueued) TRIM. + + * trim_zero: Indicate that TRIM command zeroes data. + + * max_trim_128m: Set 128M maximum trim size limit. + + * [no]dma: Turn on or off DMA transfers. + + * atapi_dmadir: Enable ATAPI DMADIR bridge support. + + * atapi_mod16_dma: Enable the use of ATAPI DMA for + commands that are not a multiple of 16 bytes. + + * [no]dmalog: Enable or disable the use of the + READ LOG DMA EXT command to access logs. + + * [no]iddevlog: Enable or disable access to the + identify device data log. + + * [no]logdir: Enable or disable access to the general + purpose log directory. + + * max_sec_128: Set transfer size limit to 128 sectors. - * nohrst, nosrst, norst: suppress hard, soft - and both resets. + * max_sec_1024: Set or clear transfer size limit to + 1024 sectors. - * rstonce: only attempt one reset during - hot-unplug link recovery + * max_sec_lba48: Set or clear transfer size limit to + 65535 sectors. - * dump_id: dump IDENTIFY data. + * [no]lpm: Enable or disable link power management. - * atapi_dmadir: Enable ATAPI DMADIR bridge support + * [no]setxfer: Indicate if transfer speed mode setting + should be skipped. + + * dump_id: Dump IDENTIFY data. * disable: Disable this device. If there are multiple matching configurations changing the same attribute, the last one is used. - memblock=debug [KNL] Enable memblock debug messages. - load_ramdisk= [RAM] [Deprecated] lockd.nlm_grace_period=P [NFS] Assign grace period. @@ -2765,7 +2881,7 @@ different yeeloong laptops. Example: machtype=lemote-yeeloong-2f-7inch - max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater + max_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory greater than or equal to this physical address is ignored. maxcpus= [SMP] Maximum number of processors that an SMP kernel @@ -2827,6 +2943,9 @@ For details see: Documentation/admin-guide/hw-vuln/mds.rst + mem=nn[KMG] [HEXAGON] Set the memory size. + Must be specified, otherwise memory size will be 0. + mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory Amount of memory to be used in cases as follows: @@ -2834,6 +2953,13 @@ 2 when the kernel is not able to see the whole system memory; 3 memory that lies after 'mem=' boundary is excluded from the hypervisor, then assigned to KVM guests. + 4 to limit the memory available for kdump kernel. + + [ARC,MICROBLAZE] - the limit applies only to low memory, + high memory is not affected. + + [ARM64] - only limits memory covered by the linear + mapping. The NOMAP regions are not affected. [X86] Work as limiting max address. Use together with memmap= to avoid physical address space collisions. @@ -2844,9 +2970,19 @@ in above case 3, memory may need be hot added after boot if system memory of hypervisor is not sufficient. + mem=nn[KMG]@ss[KMG] + [ARM,MIPS] - override the memory layout reported by + firmware. + Define a memory region of size nn[KMG] starting at + ss[KMG]. + Multiple different regions can be specified with + multiple mem= parameters on the command line. + mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel memory. + memblock=debug [KNL] Enable memblock debug messages. + memchunk=nn[KMG] [KNL,SH] Allow user to override the default size for per-device physically contiguous DMA buffers. @@ -2990,7 +3126,7 @@ mga= [HW,DRM] - min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this + min_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory below this physical address is ignored. mini2440= [ARM,HW,KNL] @@ -3036,8 +3172,10 @@ mds=off [X86] tsx_async_abort=off [X86] kvm.nx_huge_pages=off [X86] + srbds=off [X86,INTEL] no_entry_flush [PPC] no_uaccess_flush [PPC] + mmio_stale_data=off [X86] Exceptions: This does not have any effect on @@ -3059,6 +3197,7 @@ Equivalent to: l1tf=flush,nosmt [X86] mds=full,nosmt [X86] tsx_async_abort=full,nosmt [X86] + mmio_stale_data=full,nosmt [X86] mminit_loglevel= [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this @@ -3068,6 +3207,40 @@ log everything. Information is printed at KERN_DEBUG so loglevel=8 may also need to be specified. + mmio_stale_data= + [X86,INTEL] Control mitigation for the Processor + MMIO Stale Data vulnerabilities. + + Processor MMIO Stale Data is a class of + vulnerabilities that may expose data after an MMIO + operation. Exposed data could originate or end in + the same CPU buffers as affected by MDS and TAA. + Therefore, similar to MDS and TAA, the mitigation + is to clear the affected CPU buffers. + + This parameter controls the mitigation. The + options are: + + full - Enable mitigation on vulnerable CPUs + + full,nosmt - Enable mitigation and disable SMT on + vulnerable CPUs. + + off - Unconditionally disable mitigation + + On MDS or TAA affected machines, + mmio_stale_data=off can be prevented by an active + MDS or TAA mitigation as these vulnerabilities are + mitigated with the same mechanism so in order to + disable this mitigation, you need to specify + mds=off and tsx_async_abort=off too. + + Not specifying this option is equivalent to + mmio_stale_data=full. + + For details see: + Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst + module.sig_enforce [KNL] When CONFIG_MODULE_SIG is set, this means that modules without (valid) signatures will fail to load. @@ -3114,20 +3287,6 @@ mtdparts= [MTD] See drivers/mtd/parsers/cmdlinepart.c - multitce=off [PPC] This parameter disables the use of the pSeries - firmware feature for updating multiple TCE entries - at a time. - - onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration - - Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock] - - boundary - index of last SLC block on Flex-OneNAND. - The remaining blocks are configured as MLC blocks. - lock - Configure if Flex-OneNAND boundary should be locked. - Once locked, the boundary cannot be changed. - 1 indicates lock status, 0 indicates unlock status. - mtdset= [ARM] ARM/S3C2412 JIVE boot control @@ -3154,6 +3313,10 @@ Used for mtrr cleanup. It is spare mtrr entries number. Set to 2 or more if your graphical card needs more. + multitce=off [PPC] This parameter disables the use of the pSeries + firmware feature for updating multiple TCE entries + at a time. + n2= [NET] SDL Inc. RISCom/N2 synchronous serial card netdev= [NET] Network devices parameters @@ -3163,6 +3326,11 @@ This usage is only documented in each driver source file if at all. + netpoll.carrier_timeout= + [NET] Specifies amount of time (in seconds) that + netpoll should wait for a carrier. By default netpoll + waits 4 seconds. + nf_conntrack.acct= [NETFILTER] Enable connection tracking flow accounting 0 to disable accounting @@ -3313,11 +3481,6 @@ These settings can be accessed at runtime via the nmi_watchdog and hardlockup_panic sysctls. - netpoll.carrier_timeout= - [NET] Specifies amount of time (in seconds) that - netpoll should wait for a carrier. By default netpoll - waits 4 seconds. - no387 [BUGS=X86-32] Tells the kernel to use the 387 maths emulation library even if a 387 maths coprocessor is present. @@ -3372,10 +3535,6 @@ nocache [ARM] - noclflush [BUGS=X86] Don't use the CLFLUSH instruction - - delayacct [KNL] Enable per-task delay accounting - nodsp [SH] Disable hardware DSP at boot time. noefi Disable EFI runtime services support. @@ -3384,16 +3543,11 @@ noexec [IA-64] - noexec [X86] - On X86-32 available only on PAE configured kernels. - noexec=on: enable non-executable mappings (default) - noexec=off: disable non-executable mappings - - nosmap [X86,PPC] + nosmap [PPC] Disable SMAP (Supervisor Mode Access Prevention) even if it is supported by processor. - nosmep [X86,PPC64s] + nosmep [PPC64s] Disable SMEP (Supervisor Mode Execution Prevention) even if it is supported by processor. @@ -3485,8 +3639,7 @@ difficult since unequal pointers can no longer be compared. However, if this command-line option is specified, then all normal pointers will have their true - value printed. Pointers printed via %pK may still be - hashed. This option should only be specified when + value printed. This option should only be specified when debugging the kernel. Please do not use on production kernels. @@ -3594,8 +3747,6 @@ nosbagart [IA-64] - nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. - nosgx [X86-64,SGX] Disables Intel SGX kernel support. nosmp [SMP] Tells an SMP kernel to act as a UP kernel, @@ -3612,20 +3763,6 @@ nox2apic [X86-64,APIC] Do not enable x2APIC mode. - cpu0_hotplug [X86] Turn on CPU0 hotplug feature when - CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off. - Some features depend on CPU0. Known dependencies are: - 1. Resume from suspend/hibernate depends on CPU0. - Suspend/hibernate will fail if CPU0 is offline and you - need to online CPU0 before suspend/hibernate. - 2. PIC interrupts also depend on CPU0. CPU0 can't be - removed if a PIC interrupt is detected. - It's said poweroff/reboot may depend on CPU0 on some - machines although I haven't seen such issues so far - after CPU0 is offline on a few tested machines. - If the dependencies are under your control, you can - turn on cpu0_hotplug. - nps_mtm_hs_ctr= [KNL,ARC] This parameter sets the maximum duration, in cycles, each HW thread of the CTOP can run @@ -3678,6 +3815,16 @@ For example, to override I2C bus2: omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100 + onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration + + Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock] + + boundary - index of last SLC block on Flex-OneNAND. + The remaining blocks are configured as MLC blocks. + lock - Configure if Flex-OneNAND boundary should be locked. + Once locked, the boundary cannot be changed. + 1 indicates lock status, 0 indicates unlock status. + oops=panic Always panic on oopses. Default is to just kill the process, but there is a small probability of deadlocking the machine. @@ -3726,6 +3873,11 @@ bit 3: print locks info if CONFIG_LOCKDEP is on bit 4: print ftrace buffer bit 5: print all printk messages in buffer + bit 6: print all CPUs backtrace (if available in the arch) + *Be aware* that this option may print a _lot_ of lines, + so there are risks of losing older messages in the log. + Use this option carefully, maybe worth to setup a + bigger log buffer with "log_buf_len" along with this. panic_on_taint= Bitmask for conditionally calling panic() in add_taint() Format: <hex>[,nousertaint] @@ -3743,14 +3895,6 @@ panic_on_warn panic() instead of WARN(). Useful to cause kdump on a WARN(). - crash_kexec_post_notifiers - Run kdump after running panic-notifiers and dumping - kmsg. This only for the users who doubt kdump always - succeeds in any situation. - Note that this also increases risks of kdump failure, - because some panic notifiers can make the crashed - kernel more unstable. - parkbd.port= [HW] Parallel port number the keyboard adapter is connected to, default is 0. Format: <parport#> @@ -3995,6 +4139,15 @@ please report a bug. nocrs [X86] Ignore PCI host bridge windows from ACPI. If you need to use this, please report a bug. + use_e820 [X86] Use E820 reservations to exclude parts of + PCI host bridge windows. This is a workaround + for BIOS defects in host bridge _CRS methods. + If you need to use this, please report a bug to + <linux-pci@vger.kernel.org>. + no_e820 [X86] Ignore E820 reservations for PCI host + bridge windows. This is the default on modern + hardware. If you need to use this, please report + a bug to <linux-pci@vger.kernel.org>. routeirq Do IRQ routing for all PCI devices. This is normally done in pci_enable_device(), so this option is a temporary workaround @@ -4356,6 +4509,12 @@ fully seed the kernel's CRNG. Default is controlled by CONFIG_RANDOM_TRUST_CPU. + random.trust_bootloader={on,off} + [KNL] Enable or disable trusting the use of a + seed passed by the bootloader (if available) to + fully seed the kernel's CRNG. Default is controlled + by CONFIG_RANDOM_TRUST_BOOTLOADER. + randomize_kstack_offset= [KNL] Enable or disable kernel stack offset randomization, which provides roughly 5 bits of @@ -4504,6 +4663,8 @@ (the least-favored priority). Otherwise, when RCU_BOOST is not set, valid values are 0-99 and the default is zero (non-realtime operation). + When RCU_NOCB_CPU is set, also adjust the + priority of NOCB callback kthreads. rcutree.rcu_nocb_gp_stride= [KNL] Set the number of NOCB callback kthreads in @@ -4814,6 +4975,18 @@ rcupdate.rcu_cpu_stall_timeout= [KNL] Set timeout for RCU CPU stall warning messages. + The value is in seconds and the maximum allowed + value is 300 seconds. + + rcupdate.rcu_exp_cpu_stall_timeout= [KNL] + Set timeout for expedited RCU CPU stall warning + messages. The value is in milliseconds + and the maximum allowed value is 21000 + milliseconds. Please note that this value is + adjusted to an arch timer tick resolution. + Setting this to zero causes the value from + rcupdate.rcu_cpu_stall_timeout to be used (after + conversion from seconds to milliseconds). rcupdate.rcu_expedited= [KNL] Use expedited grace-period primitives, for @@ -4876,10 +5049,34 @@ number avoids disturbing real-time workloads, but lengthens grace periods. + rcupdate.rcu_task_stall_info= [KNL] + Set initial timeout in jiffies for RCU task stall + informational messages, which give some indication + of the problem for those not patient enough to + wait for ten minutes. Informational messages are + only printed prior to the stall-warning message + for a given grace period. Disable with a value + less than or equal to zero. Defaults to ten + seconds. A change in value does not take effect + until the beginning of the next grace period. + + rcupdate.rcu_task_stall_info_mult= [KNL] + Multiplier for time interval between successive + RCU task stall informational messages for a given + RCU tasks grace period. This value is clamped + to one through ten, inclusive. It defaults to + the value three, so that the first informational + message is printed 10 seconds into the grace + period, the second at 40 seconds, the third at + 160 seconds, and then the stall warning at 600 + seconds would prevent a fourth at 640 seconds. + rcupdate.rcu_task_stall_timeout= [KNL] - Set timeout in jiffies for RCU task stall warning - messages. Disable with a value less than or equal - to zero. + Set timeout in jiffies for RCU task stall + warning messages. Disable with a value less + than or equal to zero. Defaults to ten minutes. + A change in value does not take effect until + the beginning of the next grace period. rcupdate.rcu_self_test= [KNL] Run the RCU early boot self tests @@ -4998,15 +5195,6 @@ Useful for devices that are detected asynchronously (e.g. USB and MMC devices). - hibernate= [HIBERNATION] - noresume Don't check if there's a hibernation image - present during boot. - nocompress Don't compress/decompress hibernation images. - no Disable hibernation and resume. - protect_image Turn on image protection during restoration - (that will set all pages holding image data - during restoration read-only). - retain_initrd [RAM] Keep initrd memory after extraction rfkill.default_state= @@ -5229,6 +5417,8 @@ serialnumber [BUGS=X86-32] + sev=option[,option...] [X86-64] See Documentation/x86/x86_64/boot-options.rst + shapers= [NET] Maximal number of shapers. @@ -5298,6 +5488,17 @@ smart2= [HW] Format: <io1>[,<io2>[,...,<io8>]] + smp.csd_lock_timeout= [KNL] + Specify the period of time in milliseconds + that smp_call_function() and friends will wait + for a CPU to release the CSD lock. This is + useful when diagnosing bugs involving CPUs + disabling interrupts for extended periods + of time. Defaults to 5,000 milliseconds, and + setting a value of zero disables this feature. + This feature may be more efficiently disabled + using the csdlock_debug- kernel parameter. + smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port smsc-ircc2.ircc_sir= [HW] SIR base I/O port @@ -5309,7 +5510,7 @@ 1: Fast pin select (default) 2: ATC IRMode - smt [KNL,S390] Set the maximum number of threads (logical + smt= [KNL,S390] Set the maximum number of threads (logical CPUs) to use per physical CPU on systems capable of symmetric multithreading (SMT). Will be capped to the actual hardware limit. @@ -5529,6 +5730,30 @@ off: Disable mitigation and remove performance impact to RDRAND and RDSEED + srcutree.big_cpu_lim [KNL] + Specifies the number of CPUs constituting a + large system, such that srcu_struct structures + should immediately allocate an srcu_node array. + This kernel-boot parameter defaults to 128, + but takes effect only when the low-order four + bits of srcutree.convert_to_big is equal to 3 + (decide at boot). + + srcutree.convert_to_big [KNL] + Specifies under what conditions an SRCU tree + srcu_struct structure will be converted to big + form, that is, with an rcu_node tree: + + 0: Never. + 1: At init_srcu_struct() time. + 2: When rcutorture decides to. + 3: Decide at boot time (default). + 0x1X: Above plus if high contention. + + Either way, the srcu_node tree will be sized based + on the actual runtime number of CPUs (nr_cpu_ids) + instead of the compile-time CONFIG_NR_CPUS. + srcutree.counter_wrap_check [KNL] Specifies how frequently to check for grace-period sequence counter wrap for the @@ -5546,6 +5771,14 @@ expediting. Set to zero to disable automatic expediting. + srcutree.small_contention_lim [KNL] + Specifies the number of update-side contention + events per jiffy will be tolerated before + initiating a conversion of an srcu_struct + structure to big form. Note that the value of + srcutree.convert_to_big must have the 0x10 bit + set for contention-based conversions to occur. + ssbd= [ARM64,HW] Speculative Store Bypass Disable control @@ -5664,8 +5897,9 @@ This parameter controls use of the Protected Execution Facility on pSeries. - swapaccount=[0|1] - [KNL] Enable accounting of swap in memory resource + swapaccount= [KNL] + Format: [0|1] + Enable accounting of swap in memory resource controller if no parameter or 1 is given or disable it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst) @@ -5711,7 +5945,8 @@ tdfx= [HW,DRM] - test_suspend= [SUSPEND][,N] + test_suspend= [SUSPEND] + Format: { "mem" | "standby" | "freeze" }[,N] Specify "mem" (for Suspend-to-RAM) or "standby" (for standby suspend) or "freeze" (for suspend type freeze) as the system sleep state during system startup with @@ -5795,32 +6030,7 @@ This will guarantee that all the other pcrs are saved. - trace_buf_size=nn[KMG] - [FTRACE] will set tracing buffer size on each cpu. - - trace_event=[event-list] - [FTRACE] Set and start specified trace events in order - to facilitate early boot debugging. The event-list is a - comma-separated list of trace events to enable. See - also Documentation/trace/events.rst - - trace_options=[option-list] - [FTRACE] Enable or disable tracer options at boot. - The option-list is a comma delimited list of options - that can be enabled or disabled just as if you were - to echo the option name into - - /sys/kernel/debug/tracing/trace_options - - For example, to enable stacktrace option (to dump the - stack trace of each event), add to the command line: - - trace_options=stacktrace - - See also Documentation/trace/ftrace.rst "trace options" - section. - - tp_printk[FTRACE] + tp_printk [FTRACE] Have the tracepoints sent to printk as well as the tracing ring buffer. This is useful for early boot up where the system hangs or reboots and does not give the @@ -5842,7 +6052,7 @@ frequency tracepoints such as irq or sched, can cause the system to live lock. - tp_printk_stop_on_boot[FTRACE] + tp_printk_stop_on_boot [FTRACE] When tp_printk (above) is set, it can cause a lot of noise on the console. It may be useful to only include the printing of events during boot up, as user space may @@ -5851,6 +6061,53 @@ This command line option will stop the printing of events to console at the late_initcall_sync() time frame. + trace_buf_size=nn[KMG] + [FTRACE] will set tracing buffer size on each cpu. + + trace_clock= [FTRACE] Set the clock used for tracing events + at boot up. + local - Use the per CPU time stamp counter + (converted into nanoseconds). Fast, but + depending on the architecture, may not be + in sync between CPUs. + global - Event time stamps are synchronize across + CPUs. May be slower than the local clock, + but better for some race conditions. + counter - Simple counting of events (1, 2, ..) + note, some counts may be skipped due to the + infrastructure grabbing the clock more than + once per event. + uptime - Use jiffies as the time stamp. + perf - Use the same clock that perf uses. + mono - Use ktime_get_mono_fast_ns() for time stamps. + mono_raw - Use ktime_get_raw_fast_ns() for time + stamps. + boot - Use ktime_get_boot_fast_ns() for time stamps. + Architectures may add more clocks. See + Documentation/trace/ftrace.rst for more details. + + trace_event=[event-list] + [FTRACE] Set and start specified trace events in order + to facilitate early boot debugging. The event-list is a + comma-separated list of trace events to enable. See + also Documentation/trace/events.rst + + trace_options=[option-list] + [FTRACE] Enable or disable tracer options at boot. + The option-list is a comma delimited list of options + that can be enabled or disabled just as if you were + to echo the option name into + + /sys/kernel/debug/tracing/trace_options + + For example, to enable stacktrace option (to dump the + stack trace of each event), add to the command line: + + trace_options=stacktrace + + See also Documentation/trace/ftrace.rst "trace options" + section. + traceoff_on_warning [FTRACE] enable this option to disable tracing when a warning is hit. This turns off "tracing_on". Tracing can @@ -5879,11 +6136,22 @@ sources: - "tpm" - "tee" + - "caam" If not specified then it defaults to iterating through the trust source list starting with TPM and assigns the first trust source as a backend which is initialized successfully during iteration. + trusted.rng= [KEYS] + Format: <string> + The RNG used to generate key material for trusted keys. + Can be one of: + - "kernel" + - the same value as trusted.source: "tpm" or "tee" + - "default" + If not specified, "default" is used. In this case, + the RNG's choice is left to each individual trust source. + tsc= Disable clocksource stability checks for TSC. Format: <string> [x86] reliable: mark tsc clocksource as reliable, this @@ -6191,7 +6459,7 @@ HIGHMEM regardless of setting of CONFIG_HIGHPTE. - vdso= [X86,SH] + vdso= [X86,SH,SPARC] On X86_32, this is an alias for vdso32=. Otherwise: vdso=1: enable VDSO (the default) @@ -6217,11 +6485,12 @@ video= [FB] Frame buffer configuration See Documentation/fb/modedb.rst. - video.brightness_switch_enabled= [0,1] + video.brightness_switch_enabled= [ACPI] + Format: [0|1] If set to 1, on receiving an ACPI notify event generated by hotkey, video driver will adjust brightness level and then send out the event to user space through - the allocated input device; If set to 0, video driver + the allocated input device. If set to 0, video driver will only send out the event without touching backlight brightness level. default: 1 diff --git a/Documentation/admin-guide/laptops/lg-laptop.rst b/Documentation/admin-guide/laptops/lg-laptop.rst index 6fbe165dcd27..67fd6932cef4 100644 --- a/Documentation/admin-guide/laptops/lg-laptop.rst +++ b/Documentation/admin-guide/laptops/lg-laptop.rst @@ -38,7 +38,7 @@ FN lock. Battery care limit ------------------ -Writing 80/100 to /sys/devices/platform/lg-laptop/battery_care_limit +Writing 80/100 to /sys/class/power_supply/CMB0/charge_control_end_threshold sets the maximum capacity to charge the battery. Limiting the charge reduces battery capacity loss over time. diff --git a/Documentation/admin-guide/media/fimc.rst b/Documentation/admin-guide/media/fimc.rst index 56b149d9a527..267ef52fe387 100644 --- a/Documentation/admin-guide/media/fimc.rst +++ b/Documentation/admin-guide/media/fimc.rst @@ -14,7 +14,7 @@ data from LCD controller (FIMD) through the SoC internal writeback data path. There are multiple FIMC instances in the SoCs (up to 4), having slightly different capabilities, like pixel alignment constraints, rotator availability, LCD writeback support, etc. The driver is located at -drivers/media/platform/exynos4-is directory. +drivers/media/platform/samsung/exynos4-is directory. Supported SoCs -------------- diff --git a/Documentation/admin-guide/media/i2c-cardlist.rst b/Documentation/admin-guide/media/i2c-cardlist.rst index db17f39b56cf..ef3b5fff3b01 100644 --- a/Documentation/admin-guide/media/i2c-cardlist.rst +++ b/Documentation/admin-guide/media/i2c-cardlist.rst @@ -284,7 +284,7 @@ tda9887 TDA 9885/6/7 analog IF demodulator tea5761 TEA 5761 radio tuner tea5767 TEA 5767 radio tuner tua9001 Infineon TUA9001 silicon tuner -tuner-xc2028 XCeive xc2028/xc3028 tuners +xc2028 XCeive xc2028/xc3028 tuners xc4000 Xceive XC4000 silicon tuner xc5000 Xceive XC5000 silicon tuner ============ ================================================== diff --git a/Documentation/admin-guide/media/imx7.rst b/Documentation/admin-guide/media/imx7.rst index 4785ae8ac978..2fa27718f52a 100644 --- a/Documentation/admin-guide/media/imx7.rst +++ b/Documentation/admin-guide/media/imx7.rst @@ -33,7 +33,7 @@ reference manual [#f1]_. Entities -------- -imx7-mipi-csi2 +imx-mipi-csi2 -------------- This is the MIPI CSI-2 receiver entity. It has one sink pad to receive the pixel diff --git a/Documentation/admin-guide/media/omap3isp.rst b/Documentation/admin-guide/media/omap3isp.rst index bc447bbec7ce..f32e7375a1a2 100644 --- a/Documentation/admin-guide/media/omap3isp.rst +++ b/Documentation/admin-guide/media/omap3isp.rst @@ -17,7 +17,7 @@ Introduction ------------ This file documents the Texas Instruments OMAP 3 Image Signal Processor (ISP) -driver located under drivers/media/platform/omap3isp. The original driver was +driver located under drivers/media/platform/ti/omap3isp. The original driver was written by Texas Instruments but since that it has been rewritten (twice) at Nokia. diff --git a/Documentation/admin-guide/media/omap4_camera.rst b/Documentation/admin-guide/media/omap4_camera.rst index 24db4222d36d..2ada9b1e6897 100644 --- a/Documentation/admin-guide/media/omap4_camera.rst +++ b/Documentation/admin-guide/media/omap4_camera.rst @@ -25,7 +25,7 @@ As of Revision AB, the ISS is described in detail in section 8. This driver is supporting **only** the CSI2-A/B interfaces for now. It makes use of the Media Controller framework [#f2]_, and inherited most of the -code from OMAP3 ISP driver (found under drivers/media/platform/omap3isp/\*), +code from OMAP3 ISP driver (found under drivers/media/platform/ti/omap3isp/\*), except that it doesn't need an IOMMU now for ISS buffers memory mapping. Supports usage of MMAP buffers only (for now). diff --git a/Documentation/admin-guide/media/vimc.dot b/Documentation/admin-guide/media/vimc.dot index 57863a13fa39..8e829c164626 100644 --- a/Documentation/admin-guide/media/vimc.dot +++ b/Documentation/admin-guide/media/vimc.dot @@ -9,14 +9,14 @@ digraph board { n00000003:port0 -> n00000008:port0 [style=bold] n00000003:port0 -> n0000000f [style=bold] n00000005 [label="{{<port0> 0} | Debayer A\n/dev/v4l-subdev2 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green] - n00000005:port1 -> n00000017:port0 + n00000005:port1 -> n00000015:port0 n00000008 [label="{{<port0> 0} | Debayer B\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green] - n00000008:port1 -> n00000017:port0 [style=dashed] + n00000008:port1 -> n00000015:port0 [style=dashed] n0000000b [label="Raw Capture 0\n/dev/video0", shape=box, style=filled, fillcolor=yellow] n0000000f [label="Raw Capture 1\n/dev/video1", shape=box, style=filled, fillcolor=yellow] - n00000013 [label="RGB/YUV Input\n/dev/video2", shape=box, style=filled, fillcolor=yellow] - n00000013 -> n00000017:port0 [style=dashed] - n00000017 [label="{{<port0> 0} | Scaler\n/dev/v4l-subdev4 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green] - n00000017:port1 -> n0000001a [style=bold] - n0000001a [label="RGB/YUV Capture\n/dev/video3", shape=box, style=filled, fillcolor=yellow] + n00000013 [label="{{} | RGB/YUV Input\n/dev/v4l-subdev4 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green] + n00000013:port0 -> n00000015:port0 [style=dashed] + n00000015 [label="{{<port0> 0} | Scaler\n/dev/v4l-subdev5 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green] + n00000015:port1 -> n00000018 [style=bold] + n00000018 [label="RGB/YUV Capture\n/dev/video2", shape=box, style=filled, fillcolor=yellow] } diff --git a/Documentation/admin-guide/media/vimc.rst b/Documentation/admin-guide/media/vimc.rst index 180507d455f2..0b07f05dde25 100644 --- a/Documentation/admin-guide/media/vimc.rst +++ b/Documentation/admin-guide/media/vimc.rst @@ -76,3 +76,16 @@ vimc-capture: * 1 Pad sink * 1 Pad source + +Module options +-------------- + +Vimc has a module parameter to configure the driver. + +* ``allocator=<unsigned int>`` + + memory allocator selection, default is 0. It specifies the way buffers + will be allocated. + + - 0: vmalloc + - 1: dma-contig diff --git a/Documentation/admin-guide/mm/damon/reclaim.rst b/Documentation/admin-guide/mm/damon/reclaim.rst index 0af51a9705b1..46306f1f34b1 100644 --- a/Documentation/admin-guide/mm/damon/reclaim.rst +++ b/Documentation/admin-guide/mm/damon/reclaim.rst @@ -66,6 +66,17 @@ Setting it as ``N`` disables DAMON_RECLAIM. Note that DAMON_RECLAIM could do no real monitoring and reclamation due to the watermarks-based activation condition. Refer to below descriptions for the watermarks parameter for this. +commit_inputs +------------- + +Make DAMON_RECLAIM reads the input parameters again, except ``enabled``. + +Input parameters that updated while DAMON_RECLAIM is running are not applied +by default. Once this parameter is set as ``Y``, DAMON_RECLAIM reads values +of parametrs except ``enabled`` again. Once the re-reading is done, this +parameter is set as ``N``. If invalid parameters are found while the +re-reading, DAMON_RECLAIM will be disabled. + min_age ------- diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst index 59b84904a854..1bb7b72414b2 100644 --- a/Documentation/admin-guide/mm/damon/usage.rst +++ b/Documentation/admin-guide/mm/damon/usage.rst @@ -4,7 +4,7 @@ Detailed Usages =============== -DAMON provides below three interfaces for different users. +DAMON provides below interfaces for different users. - *DAMON user space tool.* `This <https://github.com/awslabs/damo>`_ is for privileged people such as @@ -14,17 +14,21 @@ DAMON provides below three interfaces for different users. virtual and physical address spaces monitoring. For more detail, please refer to its `usage document <https://github.com/awslabs/damo/blob/next/USAGE.md>`_. -- *debugfs interface.* - :ref:`This <debugfs_interface>` is for privileged user space programmers who +- *sysfs interface.* + :ref:`This <sysfs_interface>` is for privileged user space programmers who want more optimized use of DAMON. Using this, users can use DAMON’s major - features by reading from and writing to special debugfs files. Therefore, - you can write and use your personalized DAMON debugfs wrapper programs that - reads/writes the debugfs files instead of you. The `DAMON user space tool + features by reading from and writing to special sysfs files. Therefore, + you can write and use your personalized DAMON sysfs wrapper programs that + reads/writes the sysfs files instead of you. The `DAMON user space tool <https://github.com/awslabs/damo>`_ is one example of such programs. It supports both virtual and physical address spaces monitoring. Note that this interface provides only simple :ref:`statistics <damos_stats>` for the monitoring results. For detailed monitoring results, DAMON provides a :ref:`tracepoint <tracepoint>`. +- *debugfs interface.* + :ref:`This <debugfs_interface>` is almost identical to :ref:`sysfs interface + <sysfs_interface>`. This will be removed after next LTS kernel is released, + so users should move to the :ref:`sysfs interface <sysfs_interface>`. - *Kernel Space Programming Interface.* :doc:`This </vm/damon/api>` is for kernel space programmers. Using this, users can utilize every feature of DAMON most flexibly and efficiently by @@ -32,6 +36,355 @@ DAMON provides below three interfaces for different users. DAMON for various address spaces. For detail, please refer to the interface :doc:`document </vm/damon/api>`. +.. _sysfs_interface: + +sysfs Interface +=============== + +DAMON sysfs interface is built when ``CONFIG_DAMON_SYSFS`` is defined. It +creates multiple directories and files under its sysfs directory, +``<sysfs>/kernel/mm/damon/``. You can control DAMON by writing to and reading +from the files under the directory. + +For a short example, users can monitor the virtual address space of a given +workload as below. :: + + # cd /sys/kernel/mm/damon/admin/ + # echo 1 > kdamonds/nr && echo 1 > kdamonds/0/contexts/nr + # echo vaddr > kdamonds/0/contexts/0/operations + # echo 1 > kdamonds/0/contexts/0/targets/nr + # echo $(pidof <workload>) > kdamonds/0/contexts/0/targets/0/pid + # echo on > kdamonds/0/state + +Files Hierarchy +--------------- + +The files hierarchy of DAMON sysfs interface is shown below. In the below +figure, parents-children relations are represented with indentations, each +directory is having ``/`` suffix, and files in each directory are separated by +comma (","). :: + + /sys/kernel/mm/damon/admin + │ kdamonds/nr_kdamonds + │ │ 0/state,pid + │ │ │ contexts/nr_contexts + │ │ │ │ 0/avail_operations,operations + │ │ │ │ │ monitoring_attrs/ + │ │ │ │ │ │ intervals/sample_us,aggr_us,update_us + │ │ │ │ │ │ nr_regions/min,max + │ │ │ │ │ targets/nr_targets + │ │ │ │ │ │ 0/pid_target + │ │ │ │ │ │ │ regions/nr_regions + │ │ │ │ │ │ │ │ 0/start,end + │ │ │ │ │ │ │ │ ... + │ │ │ │ │ │ ... + │ │ │ │ │ schemes/nr_schemes + │ │ │ │ │ │ 0/action + │ │ │ │ │ │ │ access_pattern/ + │ │ │ │ │ │ │ │ sz/min,max + │ │ │ │ │ │ │ │ nr_accesses/min,max + │ │ │ │ │ │ │ │ age/min,max + │ │ │ │ │ │ │ quotas/ms,bytes,reset_interval_ms + │ │ │ │ │ │ │ │ weights/sz_permil,nr_accesses_permil,age_permil + │ │ │ │ │ │ │ watermarks/metric,interval_us,high,mid,low + │ │ │ │ │ │ │ stats/nr_tried,sz_tried,nr_applied,sz_applied,qt_exceeds + │ │ │ │ │ │ ... + │ │ │ │ ... + │ │ ... + +Root +---- + +The root of the DAMON sysfs interface is ``<sysfs>/kernel/mm/damon/``, and it +has one directory named ``admin``. The directory contains the files for +privileged user space programs' control of DAMON. User space tools or deamons +having the root permission could use this directory. + +kdamonds/ +--------- + +The monitoring-related information including request specifications and results +are called DAMON context. DAMON executes each context with a kernel thread +called kdamond, and multiple kdamonds could run in parallel. + +Under the ``admin`` directory, one directory, ``kdamonds``, which has files for +controlling the kdamonds exist. In the beginning, this directory has only one +file, ``nr_kdamonds``. Writing a number (``N``) to the file creates the number +of child directories named ``0`` to ``N-1``. Each directory represents each +kdamond. + +kdamonds/<N>/ +------------- + +In each kdamond directory, two files (``state`` and ``pid``) and one directory +(``contexts``) exist. + +Reading ``state`` returns ``on`` if the kdamond is currently running, or +``off`` if it is not running. Writing ``on`` or ``off`` makes the kdamond be +in the state. Writing ``commit`` to the ``state`` file makes kdamond reads the +user inputs in the sysfs files except ``state`` file again. Writing +``update_schemes_stats`` to ``state`` file updates the contents of stats files +for each DAMON-based operation scheme of the kdamond. For details of the +stats, please refer to :ref:`stats section <sysfs_schemes_stats>`. + +If the state is ``on``, reading ``pid`` shows the pid of the kdamond thread. + +``contexts`` directory contains files for controlling the monitoring contexts +that this kdamond will execute. + +kdamonds/<N>/contexts/ +---------------------- + +In the beginning, this directory has only one file, ``nr_contexts``. Writing a +number (``N``) to the file creates the number of child directories named as +``0`` to ``N-1``. Each directory represents each monitoring context. At the +moment, only one context per kdamond is supported, so only ``0`` or ``1`` can +be written to the file. + +contexts/<N>/ +------------- + +In each context directory, two files (``avail_operations`` and ``operations``) +and three directories (``monitoring_attrs``, ``targets``, and ``schemes``) +exist. + +DAMON supports multiple types of monitoring operations, including those for +virtual address space and the physical address space. You can get the list of +available monitoring operations set on the currently running kernel by reading +``avail_operations`` file. Based on the kernel configuration, the file will +list some or all of below keywords. + + - vaddr: Monitor virtual address spaces of specific processes + - fvaddr: Monitor fixed virtual address ranges + - paddr: Monitor the physical address space of the system + +Please refer to :ref:`regions sysfs directory <sysfs_regions>` for detailed +differences between the operations sets in terms of the monitoring target +regions. + +You can set and get what type of monitoring operations DAMON will use for the +context by writing one of the keywords listed in ``avail_operations`` file and +reading from the ``operations`` file. + +contexts/<N>/monitoring_attrs/ +------------------------------ + +Files for specifying attributes of the monitoring including required quality +and efficiency of the monitoring are in ``monitoring_attrs`` directory. +Specifically, two directories, ``intervals`` and ``nr_regions`` exist in this +directory. + +Under ``intervals`` directory, three files for DAMON's sampling interval +(``sample_us``), aggregation interval (``aggr_us``), and update interval +(``update_us``) exist. You can set and get the values in micro-seconds by +writing to and reading from the files. + +Under ``nr_regions`` directory, two files for the lower-bound and upper-bound +of DAMON's monitoring regions (``min`` and ``max``, respectively), which +controls the monitoring overhead, exist. You can set and get the values by +writing to and rading from the files. + +For more details about the intervals and monitoring regions range, please refer +to the Design document (:doc:`/vm/damon/design`). + +contexts/<N>/targets/ +--------------------- + +In the beginning, this directory has only one file, ``nr_targets``. Writing a +number (``N``) to the file creates the number of child directories named ``0`` +to ``N-1``. Each directory represents each monitoring target. + +targets/<N>/ +------------ + +In each target directory, one file (``pid_target``) and one directory +(``regions``) exist. + +If you wrote ``vaddr`` to the ``contexts/<N>/operations``, each target should +be a process. You can specify the process to DAMON by writing the pid of the +process to the ``pid_target`` file. + +.. _sysfs_regions: + +targets/<N>/regions +------------------- + +When ``vaddr`` monitoring operations set is being used (``vaddr`` is written to +the ``contexts/<N>/operations`` file), DAMON automatically sets and updates the +monitoring target regions so that entire memory mappings of target processes +can be covered. However, users could want to set the initial monitoring region +to specific address ranges. + +In contrast, DAMON do not automatically sets and updates the monitoring target +regions when ``fvaddr`` or ``paddr`` monitoring operations sets are being used +(``fvaddr`` or ``paddr`` have written to the ``contexts/<N>/operations``). +Therefore, users should set the monitoring target regions by themselves in the +cases. + +For such cases, users can explicitly set the initial monitoring target regions +as they want, by writing proper values to the files under this directory. + +In the beginning, this directory has only one file, ``nr_regions``. Writing a +number (``N``) to the file creates the number of child directories named ``0`` +to ``N-1``. Each directory represents each initial monitoring target region. + +regions/<N>/ +------------ + +In each region directory, you will find two files (``start`` and ``end``). You +can set and get the start and end addresses of the initial monitoring target +region by writing to and reading from the files, respectively. + +contexts/<N>/schemes/ +--------------------- + +For usual DAMON-based data access aware memory management optimizations, users +would normally want the system to apply a memory management action to a memory +region of a specific access pattern. DAMON receives such formalized operation +schemes from the user and applies those to the target memory regions. Users +can get and set the schemes by reading from and writing to files under this +directory. + +In the beginning, this directory has only one file, ``nr_schemes``. Writing a +number (``N``) to the file creates the number of child directories named ``0`` +to ``N-1``. Each directory represents each DAMON-based operation scheme. + +schemes/<N>/ +------------ + +In each scheme directory, four directories (``access_pattern``, ``quotas``, +``watermarks``, and ``stats``) and one file (``action``) exist. + +The ``action`` file is for setting and getting what action you want to apply to +memory regions having specific access pattern of the interest. The keywords +that can be written to and read from the file and their meaning are as below. + + - ``willneed``: Call ``madvise()`` for the region with ``MADV_WILLNEED`` + - ``cold``: Call ``madvise()`` for the region with ``MADV_COLD`` + - ``pageout``: Call ``madvise()`` for the region with ``MADV_PAGEOUT`` + - ``hugepage``: Call ``madvise()`` for the region with ``MADV_HUGEPAGE`` + - ``nohugepage``: Call ``madvise()`` for the region with ``MADV_NOHUGEPAGE`` + - ``stat``: Do nothing but count the statistics + +schemes/<N>/access_pattern/ +--------------------------- + +The target access pattern of each DAMON-based operation scheme is constructed +with three ranges including the size of the region in bytes, number of +monitored accesses per aggregate interval, and number of aggregated intervals +for the age of the region. + +Under the ``access_pattern`` directory, three directories (``sz``, +``nr_accesses``, and ``age``) each having two files (``min`` and ``max``) +exist. You can set and get the access pattern for the given scheme by writing +to and reading from the ``min`` and ``max`` files under ``sz``, +``nr_accesses``, and ``age`` directories, respectively. + +schemes/<N>/quotas/ +------------------- + +Optimal ``target access pattern`` for each ``action`` is workload dependent, so +not easy to find. Worse yet, setting a scheme of some action too aggressive +can cause severe overhead. To avoid such overhead, users can limit time and +size quota for each scheme. In detail, users can ask DAMON to try to use only +up to specific time (``time quota``) for applying the action, and to apply the +action to only up to specific amount (``size quota``) of memory regions having +the target access pattern within a given time interval (``reset interval``). + +When the quota limit is expected to be exceeded, DAMON prioritizes found memory +regions of the ``target access pattern`` based on their size, access frequency, +and age. For personalized prioritization, users can set the weights for the +three properties. + +Under ``quotas`` directory, three files (``ms``, ``bytes``, +``reset_interval_ms``) and one directory (``weights``) having three files +(``sz_permil``, ``nr_accesses_permil``, and ``age_permil``) in it exist. + +You can set the ``time quota`` in milliseconds, ``size quota`` in bytes, and +``reset interval`` in milliseconds by writing the values to the three files, +respectively. You can also set the prioritization weights for size, access +frequency, and age in per-thousand unit by writing the values to the three +files under the ``weights`` directory. + +schemes/<N>/watermarks/ +----------------------- + +To allow easy activation and deactivation of each scheme based on system +status, DAMON provides a feature called watermarks. The feature receives five +values called ``metric``, ``interval``, ``high``, ``mid``, and ``low``. The +``metric`` is the system metric such as free memory ratio that can be measured. +If the metric value of the system is higher than the value in ``high`` or lower +than ``low`` at the memoent, the scheme is deactivated. If the value is lower +than ``mid``, the scheme is activated. + +Under the watermarks directory, five files (``metric``, ``interval_us``, +``high``, ``mid``, and ``low``) for setting each value exist. You can set and +get the five values by writing to the files, respectively. + +Keywords and meanings of those that can be written to the ``metric`` file are +as below. + + - none: Ignore the watermarks + - free_mem_rate: System's free memory rate (per thousand) + +The ``interval`` should written in microseconds unit. + +.. _sysfs_schemes_stats: + +schemes/<N>/stats/ +------------------ + +DAMON counts the total number and bytes of regions that each scheme is tried to +be applied, the two numbers for the regions that each scheme is successfully +applied, and the total number of the quota limit exceeds. This statistics can +be used for online analysis or tuning of the schemes. + +The statistics can be retrieved by reading the files under ``stats`` directory +(``nr_tried``, ``sz_tried``, ``nr_applied``, ``sz_applied``, and +``qt_exceeds``), respectively. The files are not updated in real time, so you +should ask DAMON sysfs interface to updte the content of the files for the +stats by writing a special keyword, ``update_schemes_stats`` to the relevant +``kdamonds/<N>/state`` file. + +Example +~~~~~~~ + +Below commands applies a scheme saying "If a memory region of size in [4KiB, +8KiB] is showing accesses per aggregate interval in [0, 5] for aggregate +interval in [10, 20], page out the region. For the paging out, use only up to +10ms per second, and also don't page out more than 1GiB per second. Under the +limitation, page out memory regions having longer age first. Also, check the +free memory rate of the system every 5 seconds, start the monitoring and paging +out when the free memory rate becomes lower than 50%, but stop it if the free +memory rate becomes larger than 60%, or lower than 30%". :: + + # cd <sysfs>/kernel/mm/damon/admin + # # populate directories + # echo 1 > kdamonds/nr_kdamonds; echo 1 > kdamonds/0/contexts/nr_contexts; + # echo 1 > kdamonds/0/contexts/0/schemes/nr_schemes + # cd kdamonds/0/contexts/0/schemes/0 + # # set the basic access pattern and the action + # echo 4096 > access_patterns/sz/min + # echo 8192 > access_patterns/sz/max + # echo 0 > access_patterns/nr_accesses/min + # echo 5 > access_patterns/nr_accesses/max + # echo 10 > access_patterns/age/min + # echo 20 > access_patterns/age/max + # echo pageout > action + # # set quotas + # echo 10 > quotas/ms + # echo $((1024*1024*1024)) > quotas/bytes + # echo 1000 > quotas/reset_interval_ms + # # set watermark + # echo free_mem_rate > watermarks/metric + # echo 5000000 > watermarks/interval_us + # echo 600 > watermarks/high + # echo 500 > watermarks/mid + # echo 300 > watermarks/low + +Please note that it's highly recommended to use user space tools like `damo +<https://github.com/awslabs/damo>`_ rather than manually reading and writing +the files as above. Above is only for an example. .. _debugfs_interface: @@ -47,7 +400,7 @@ Attributes ---------- Users can get and set the ``sampling interval``, ``aggregation interval``, -``regions update interval``, and min/max number of monitoring target regions by +``update interval``, and min/max number of monitoring target regions by reading from and writing to the ``attrs`` file. To know about the monitoring attributes in detail, please refer to the :doc:`/vm/damon/design`. For example, below commands set those values to 5 ms, 100 ms, 1,000 ms, 10 and @@ -108,24 +461,28 @@ In such cases, users can explicitly set the initial monitoring target regions as they want, by writing proper values to the ``init_regions`` file. Each line of the input should represent one region in below form.:: - <target id> <start address> <end address> + <target idx> <start address> <end address> -The ``target id`` should already in ``target_ids`` file, and the regions should -be passed in address order. For example, below commands will set a couple of -address ranges, ``1-100`` and ``100-200`` as the initial monitoring target -region of process 42, and another couple of address ranges, ``20-40`` and -``50-100`` as that of process 4242.:: +The ``target idx`` should be the index of the target in ``target_ids`` file, +starting from ``0``, and the regions should be passed in address order. For +example, below commands will set a couple of address ranges, ``1-100`` and +``100-200`` as the initial monitoring target region of pid 42, which is the +first one (index ``0``) in ``target_ids``, and another couple of address +ranges, ``20-40`` and ``50-100`` as that of pid 4242, which is the second one +(index ``1``) in ``target_ids``.:: # cd <debugfs>/damon - # echo "42 1 100 - 42 100 200 - 4242 20 40 - 4242 50 100" > init_regions + # cat target_ids + 42 4242 + # echo "0 1 100 + 0 100 200 + 1 20 40 + 1 50 100" > init_regions Note that this sets the initial monitoring target regions only. In case of virtual memory monitoring, DAMON will automatically updates the boundary of the -regions after one ``regions update interval``. Therefore, users should set the -``regions update interval`` large enough in this case, if they don't want the +regions after one ``update interval``. Therefore, users should set the +``update interval`` large enough in this case, if they don't want the update. diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst index 0166f9de3428..a90330d0a837 100644 --- a/Documentation/admin-guide/mm/hugetlbpage.rst +++ b/Documentation/admin-guide/mm/hugetlbpage.rst @@ -164,7 +164,7 @@ default_hugepagesz will all result in 256 2M huge pages being allocated. Valid default huge page size is architecture dependent. hugetlb_free_vmemmap - When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this enables freeing + When CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP is set, this enables optimizing unused vmemmap pages associated with each HugeTLB page. When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages`` diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-guide/mm/ksm.rst index 97d816791aca..b244f0202a03 100644 --- a/Documentation/admin-guide/mm/ksm.rst +++ b/Documentation/admin-guide/mm/ksm.rst @@ -184,6 +184,24 @@ The maximum possible ``pages_sharing/pages_shared`` ratio is limited by the ``max_page_sharing`` tunable. To increase the ratio ``max_page_sharing`` must be increased accordingly. +Monitoring KSM events +===================== + +There are some counters in /proc/vmstat that may be used to monitor KSM events. +KSM might help save memory, it's a tradeoff by may suffering delay on KSM COW +or on swapping in copy. Those events could help users evaluate whether or how +to use KSM. For example, if cow_ksm increases too fast, user may decrease the +range of madvise(, , MADV_MERGEABLE). + +cow_ksm + is incremented every time a KSM page triggers copy on write (COW) + when users try to write to a KSM page, we have to make a copy. + +ksm_swpin_copy + is incremented every time a KSM page is copied when swapping in + note that KSM page might be copied when swapping in because do_swap_page() + cannot do all the locking needed to reconstitute a cross-anon_vma KSM page. + -- Izik Eidus, Hugh Dickins, 17 Nov 2009 diff --git a/Documentation/admin-guide/mm/zswap.rst b/Documentation/admin-guide/mm/zswap.rst index 8edb8d578caf..6e6f7b0d6562 100644 --- a/Documentation/admin-guide/mm/zswap.rst +++ b/Documentation/admin-guide/mm/zswap.rst @@ -130,9 +130,25 @@ attribute, e.g.:: echo 1 > /sys/module/zswap/parameters/same_filled_pages_enabled When zswap same-filled page identification is disabled at runtime, it will stop -checking for the same-value filled pages during store operation. However, the -existing pages which are marked as same-value filled pages remain stored -unchanged in zswap until they are either loaded or invalidated. +checking for the same-value filled pages during store operation. +In other words, every page will be then considered non-same-value filled. +However, the existing pages which are marked as same-value filled pages remain +stored unchanged in zswap until they are either loaded or invalidated. + +In some circumstances it might be advantageous to make use of just the zswap +ability to efficiently store same-filled pages without enabling the whole +compressed page storage. +In this case the handling of non-same-value pages by zswap (enabled by default) +can be disabled by setting the ``non_same_filled_pages_enabled`` attribute +to 0, e.g. ``zswap.non_same_filled_pages_enabled=0``. +It can also be enabled and disabled at runtime using the sysfs +``non_same_filled_pages_enabled`` attribute, e.g.:: + + echo 1 > /sys/module/zswap/parameters/non_same_filled_pages_enabled + +Disabling both ``zswap.same_filled_pages_enabled`` and +``zswap.non_same_filled_pages_enabled`` effectively disables accepting any new +pages by zswap. To prevent zswap from shrinking pool when zswap is full and there's a high pressure on swap (this will result in flipping pages in and out zswap pool diff --git a/Documentation/admin-guide/nfs/nfs-client.rst b/Documentation/admin-guide/nfs/nfs-client.rst index 6adb6457bc69..36760685dd34 100644 --- a/Documentation/admin-guide/nfs/nfs-client.rst +++ b/Documentation/admin-guide/nfs/nfs-client.rst @@ -36,10 +36,9 @@ administrative requirements that require particular behavior that does not work well as part of an nfs_client_id4 string. The nfs.nfs4_unique_id boot parameter specifies a unique string that can be -used instead of a system's node name when an NFS client identifies itself to -a server. Thus, if the system's node name is not unique, or it changes, its -nfs.nfs4_unique_id stays the same, preventing collision with other clients -or loss of state during NFS reboot recovery or transparent state migration. +used together with a system's node name when an NFS client identifies itself to +a server. Thus, if the system's node name is not unique, its +nfs.nfs4_unique_id can help prevent collisions with other clients. The nfs.nfs4_unique_id string is typically a UUID, though it can contain anything that is believed to be unique across all NFS clients. An @@ -53,8 +52,12 @@ outstanding NFSv4 state has expired, to prevent loss of NFSv4 state. This string can be stored in an NFS client's grub.conf, or it can be provided via a net boot facility such as PXE. It may also be specified as an nfs.ko -module parameter. Specifying a uniquifier string is not support for NFS -clients running in containers. +module parameter. + +This uniquifier string will be the same for all NFS clients running in +containers unless it is overridden by a value written to +/sys/fs/nfs/net/nfs_client/identifier which will be local to the network +namespace of the process which writes. The DNS resolver diff --git a/Documentation/admin-guide/perf/index.rst b/Documentation/admin-guide/perf/index.rst index 5a8f2529a033..69b23f087c05 100644 --- a/Documentation/admin-guide/perf/index.rst +++ b/Documentation/admin-guide/perf/index.rst @@ -8,6 +8,7 @@ Performance monitor support :maxdepth: 1 hisi-pmu + hisi-pcie-pmu imx-ddr qcom_l2_pmu qcom_l3_pmu diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst index 2f066df4ee9c..83b58eb4ab4d 100644 --- a/Documentation/admin-guide/pm/amd-pstate.rst +++ b/Documentation/admin-guide/pm/amd-pstate.rst @@ -19,7 +19,7 @@ Linux kernel. The new mechanism is based on Collaborative Processor Performance Control (CPPC) which provides finer grain frequency management than legacy ACPI hardware P-States. Current AMD CPU/APU platforms are using the ACPI P-states driver to manage CPU frequency and clocks with switching -only in 3 P-states. CPPC replaces the ACPI P-states controls, allows a +only in 3 P-states. CPPC replaces the ACPI P-states controls and allows a flexible, low-latency interface for the Linux kernel to directly communicate the performance hints to hardware. @@ -27,7 +27,7 @@ communicate the performance hints to hardware. ``ondemand``, etc. to manage the performance hints which are provided by CPPC hardware functionality that internally follows the hardware specification (for details refer to AMD64 Architecture Programmer's Manual -Volume 2: System Programming [1]_). Currently ``amd-pstate`` supports basic +Volume 2: System Programming [1]_). Currently, ``amd-pstate`` supports basic frequency control function according to kernel governors on some of the Zen2 and Zen3 processors, and we will implement more AMD specific functions in future after we verify them on the hardware and SBIOS. @@ -41,9 +41,9 @@ continuous, abstract, and unit-less performance value in a scale that is not tied to a specific performance state / frequency. This is an ACPI standard [2]_ which software can specify application performance goals and hints as a relative target to the infrastructure limits. AMD processors -provides the low latency register model (MSR) instead of AML code +provide the low latency register model (MSR) instead of an AML code interpreter for performance adjustments. ``amd-pstate`` will initialize a -``struct cpufreq_driver`` instance ``amd_pstate_driver`` with the callbacks +``struct cpufreq_driver`` instance, ``amd_pstate_driver``, with the callbacks to manage each performance update behavior. :: Highest Perf ------>+-----------------------+ +-----------------------+ @@ -91,26 +91,26 @@ AMD CPPC Performance Capability Highest Performance (RO) ......................... -It is the absolute maximum performance an individual processor may reach, +This is the absolute maximum performance an individual processor may reach, assuming ideal conditions. This performance level may not be sustainable for long durations and may only be achievable if other platform components -are in a specific state; for example, it may require other processors be in +are in a specific state; for example, it may require other processors to be in an idle state. This would be equivalent to the highest frequencies supported by the processor. Nominal (Guaranteed) Performance (RO) ...................................... -It is the maximum sustained performance level of the processor, assuming -ideal operating conditions. In absence of an external constraint (power, -thermal, etc.) this is the performance level the processor is expected to +This is the maximum sustained performance level of the processor, assuming +ideal operating conditions. In the absence of an external constraint (power, +thermal, etc.), this is the performance level the processor is expected to be able to maintain continuously. All cores/processors are expected to be able to sustain their nominal performance state simultaneously. Lowest non-linear Performance (RO) ................................... -It is the lowest performance level at which nonlinear power savings are +This is the lowest performance level at which nonlinear power savings are achieved, for example, due to the combined effects of voltage and frequency scaling. Above this threshold, lower performance levels should be generally more energy efficient than higher performance levels. This register @@ -119,7 +119,7 @@ effectively conveys the most efficient performance level to ``amd-pstate``. Lowest Performance (RO) ........................ -It is the absolute lowest performance level of the processor. Selecting a +This is the absolute lowest performance level of the processor. Selecting a performance level lower than the lowest nonlinear performance level may cause an efficiency penalty but should reduce the instantaneous power consumption of the processor. @@ -149,14 +149,14 @@ a relative number. This can be expressed as percentage of nominal performance (infrastructure max). Below the nominal sustained performance level, desired performance expresses the average performance level of the processor subject to hardware. Above the nominal performance level, -processor must provide at least nominal performance requested and go higher +the processor must provide at least nominal performance requested and go higher if current operating conditions allow. Energy Performance Preference (EPP) (RW) ......................................... -Provides a hint to the hardware if software wants to bias toward performance -(0x0) or energy efficiency (0xff). +This attribute provides a hint to the hardware if software wants to bias +toward performance (0x0) or energy efficiency (0xff). Key Governors Support @@ -173,35 +173,34 @@ operating frequencies supported by the hardware. Users can check the ``amd-pstate`` mainly supports ``schedutil`` and ``ondemand`` for dynamic frequency control. It is to fine tune the processor configuration on ``amd-pstate`` to the ``schedutil`` with CPU CFS scheduler. ``amd-pstate`` -registers adjust_perf callback to implement the CPPC similar performance -update behavior. It is initialized by ``sugov_start`` and then populate the -CPU's update_util_data pointer to assign ``sugov_update_single_perf`` as -the utilization update callback function in CPU scheduler. CPU scheduler -will call ``cpufreq_update_util`` and assign the target performance -according to the ``struct sugov_cpu`` that utilization update belongs to. -Then ``amd-pstate`` updates the desired performance according to the CPU +registers the adjust_perf callback to implement performance update behavior +similar to CPPC. It is initialized by ``sugov_start`` and then populates the +CPU's update_util_data pointer to assign ``sugov_update_single_perf`` as the +utilization update callback function in the CPU scheduler. The CPU scheduler +will call ``cpufreq_update_util`` and assigns the target performance according +to the ``struct sugov_cpu`` that the utilization update belongs to. +Then, ``amd-pstate`` updates the desired performance according to the CPU scheduler assigned. Processor Support ======================= -The ``amd-pstate`` initialization will fail if the _CPC in ACPI SBIOS is -not existed at the detected processor, and it uses ``acpi_cpc_valid`` to -check the _CPC existence. All Zen based processors support legacy ACPI -hardware P-States function, so while the ``amd-pstate`` fails to be -initialized, the kernel will fall back to initialize ``acpi-cpufreq`` -driver. +The ``amd-pstate`` initialization will fail if the ``_CPC`` entry in the ACPI +SBIOS does not exist in the detected processor. It uses ``acpi_cpc_valid`` +to check the existence of ``_CPC``. All Zen based processors support the legacy +ACPI hardware P-States function, so when ``amd-pstate`` fails initialization, +the kernel will fall back to initialize the ``acpi-cpufreq`` driver. There are two types of hardware implementations for ``amd-pstate``: one is `Full MSR Support <perf_cap_>`_ and another is `Shared Memory Support -<perf_cap_>`_. It can use :c:macro:`X86_FEATURE_CPPC` feature flag (for -details refer to Processor Programming Reference (PPR) for AMD Family -19h Model 51h, Revision A1 Processors [3]_) to indicate the different -types. ``amd-pstate`` is to register different ``static_call`` instances -for different hardware implementations. +<perf_cap_>`_. It can use the :c:macro:`X86_FEATURE_CPPC` feature flag to +indicate the different types. (For details, refer to the Processor Programming +Reference (PPR) for AMD Family 19h Model 51h, Revision A1 Processors [3]_.) +``amd-pstate`` is to register different ``static_call`` instances for different +hardware implementations. -Currently, some of Zen2 and Zen3 processors support ``amd-pstate``. In the +Currently, some of the Zen2 and Zen3 processors support ``amd-pstate``. In the future, it will be supported on more and more AMD processors. Full MSR Support @@ -210,18 +209,18 @@ Full MSR Support Some new Zen3 processors such as Cezanne provide the MSR registers directly while the :c:macro:`X86_FEATURE_CPPC` CPU feature flag is set. ``amd-pstate`` can handle the MSR register to implement the fast switch -function in ``CPUFreq`` that can shrink latency of frequency control on the -interrupt context. The functions with ``pstate_xxx`` prefix represent the -operations of MSR registers. +function in ``CPUFreq`` that can reduce the latency of frequency control in +interrupt context. The functions with a ``pstate_xxx`` prefix represent the +operations on MSR registers. Shared Memory Support ---------------------- -If :c:macro:`X86_FEATURE_CPPC` CPU feature flag is not set, that means the -processor supports shared memory solution. In this case, ``amd-pstate`` +If the :c:macro:`X86_FEATURE_CPPC` CPU feature flag is not set, the +processor supports the shared memory solution. In this case, ``amd-pstate`` uses the ``cppc_acpi`` helper methods to implement the callback functions -that defined on ``static_call``. The functions with ``cppc_xxx`` prefix -represent the operations of acpi cppc helpers for shared memory solution. +that are defined on ``static_call``. The functions with the ``cppc_xxx`` prefix +represent the operations of ACPI CPPC helpers for the shared memory solution. AMD P-States and ACPI hardware P-States always can be supported in one @@ -234,7 +233,7 @@ User Space Interface in ``sysfs`` ================================== ``amd-pstate`` exposes several global attributes (files) in ``sysfs`` to -control its functionality at the system level. They located in the +control its functionality at the system level. They are located in the ``/sys/devices/system/cpu/cpufreq/policyX/`` directory and affect all CPUs. :: root@hr-test1:/home/ray# ls /sys/devices/system/cpu/cpufreq/policy0/*amd* @@ -246,38 +245,38 @@ control its functionality at the system level. They located in the ``amd_pstate_highest_perf / amd_pstate_max_freq`` Maximum CPPC performance and CPU frequency that the driver is allowed to -set in percent of the maximum supported CPPC performance level (the highest +set, in percent of the maximum supported CPPC performance level (the highest performance supported in `AMD CPPC Performance Capability <perf_cap_>`_). -In some of ASICs, the highest CPPC performance is not the one in the _CPC -table, so we need to expose it to sysfs. If boost is not active but -supported, this maximum frequency will be larger than the one in +In some ASICs, the highest CPPC performance is not the one in the ``_CPC`` +table, so we need to expose it to sysfs. If boost is not active, but +still supported, this maximum frequency will be larger than the one in ``cpuinfo``. This attribute is read-only. ``amd_pstate_lowest_nonlinear_freq`` -The lowest non-linear CPPC CPU frequency that the driver is allowed to set -in percent of the maximum supported CPPC performance level (Please see the +The lowest non-linear CPPC CPU frequency that the driver is allowed to set, +in percent of the maximum supported CPPC performance level. (Please see the lowest non-linear performance in `AMD CPPC Performance Capability -<perf_cap_>`_). +<perf_cap_>`_.) This attribute is read-only. -For other performance and frequency values, we can read them back from +Other performance and frequency values can be read back from ``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`. ``amd-pstate`` vs ``acpi-cpufreq`` ====================================== -On majority of AMD platforms supported by ``acpi-cpufreq``, the ACPI tables -provided by the platform firmware used for CPU performance scaling, but -only provides 3 P-states on AMD processors. -However, on modern AMD APU and CPU series, it provides the collaborative -processor performance control according to ACPI protocol and customize this -for AMD platforms. That is fine-grain and continuous frequency range +On the majority of AMD platforms supported by ``acpi-cpufreq``, the ACPI tables +provided by the platform firmware are used for CPU performance scaling, but +only provide 3 P-states on AMD processors. +However, on modern AMD APU and CPU series, hardware provides the Collaborative +Processor Performance Control according to the ACPI protocol and customizes this +for AMD platforms. That is, fine-grained and continuous frequency ranges instead of the legacy hardware P-states. ``amd-pstate`` is the kernel -module which supports the new AMD P-States mechanism on most of future AMD -platforms. The AMD P-States mechanism will be the more performance and energy +module which supports the new AMD P-States mechanism on most of the future AMD +platforms. The AMD P-States mechanism is the more performance and energy efficiency frequency management method on AMD processors. Kernel Module Options for ``amd-pstate`` @@ -287,25 +286,25 @@ Kernel Module Options for ``amd-pstate`` Use a module param (shared_mem) to enable related processors manually with **amd_pstate.shared_mem=1**. Due to the performance issue on the processors with `Shared Memory Support -<perf_cap_>`_, so we disable it for the moment and will enable this by default -once we address performance issue on this solution. +<perf_cap_>`_, we disable it presently and will re-enable this by default +once we address performance issue with this solution. -The way to check whether current processor is `Full MSR Support <perf_cap_>`_ +To check whether the current processor is using `Full MSR Support <perf_cap_>`_ or `Shared Memory Support <perf_cap_>`_ : :: ray@hr-test1:~$ lscpu | grep cppc Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid aperfmperf rapl pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb cat_l3 cdp_l3 hw_pstate ssbd mba ibrs ibpb stibp vmmcall fsgsbase bmi1 avx2 smep bmi2 erms invpcid cqm rdt_a rdseed adx smap clflushopt clwb sha_ni xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local clzero irperf xsaveerptr rdpru wbnoinvd cppc arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold avic v_vmsave_vmload vgif v_spec_ctrl umip pku ospke vaes vpclmulqdq rdpid overflow_recov succor smca fsrm -If CPU Flags have cppc, then this processor supports `Full MSR Support -<perf_cap_>`_. Otherwise it supports `Shared Memory Support <perf_cap_>`_. +If the CPU flags have ``cppc``, then this processor supports `Full MSR Support +<perf_cap_>`_. Otherwise, it supports `Shared Memory Support <perf_cap_>`_. ``cpupower`` tool support for ``amd-pstate`` =============================================== -``amd-pstate`` is supported on ``cpupower`` tool that can be used to dump the frequency -information. And it is in progress to support more and more operations for new -``amd-pstate`` module with this tool. :: +``amd-pstate`` is supported by the ``cpupower`` tool, which can be used to dump +frequency information. Development is in progress to support more and more +operations for the new ``amd-pstate`` module with this tool. :: root@hr-test1:/home/ray# cpupower frequency-info analyzing CPU 0: @@ -336,10 +335,10 @@ Trace Events -------------- There are two static trace events that can be used for ``amd-pstate`` -diagnostics. One of them is the cpu_frequency trace event generally used +diagnostics. One of them is the ``cpu_frequency`` trace event generally used by ``CPUFreq``, and the other one is the ``amd_pstate_perf`` trace event specific to ``amd-pstate``. The following sequence of shell commands can -be used to enable them and see their output (if the kernel is generally +be used to enable them and see their output (if the kernel is configured to support event tracing). :: root@hr-test1:/home/ray# cd /sys/kernel/tracing/ @@ -364,11 +363,37 @@ configured to support event tracing). :: <idle>-0 [003] d.s.. 4995.980971: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=3 changed=false fast_switch=true <idle>-0 [011] d.s.. 4995.980996: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=11 changed=false fast_switch=true -The cpu_frequency trace event will be triggered either by the ``schedutil`` scaling +The ``cpu_frequency`` trace event will be triggered either by the ``schedutil`` scaling governor (for the policies it is attached to), or by the ``CPUFreq`` core (for the policies with other scaling governors). +Tracer Tool +------------- + +``amd_pstate_tracer.py`` can record and parse ``amd-pstate`` trace log, then +generate performance plots. This utility can be used to debug and tune the +performance of ``amd-pstate`` driver. The tracer tool needs to import intel +pstate tracer. + +Tracer tool located in ``linux/tools/power/x86/amd_pstate_tracer``. It can be +used in two ways. If trace file is available, then directly parse the file +with command :: + + ./amd_pstate_trace.py [-c cpus] -t <trace_file> -n <test_name> + +Or generate trace file with root privilege, then parse and plot with command :: + + sudo ./amd_pstate_trace.py [-c cpus] -n <test_name> -i <interval> [-m kbytes] + +The test result can be found in ``results/test_name``. Following is the example +about part of the output. :: + + common_cpu common_secs common_usecs min_perf des_perf max_perf freq mperf apef tsc load duration_ms sample_num elapsed_time common_comm + CPU_005 712 116384 39 49 166 0.7565 9645075 2214891 38431470 25.1 11.646 469 2.496 kworker/5:0-40 + CPU_006 712 116408 39 49 166 0.6769 8950227 1839034 37192089 24.06 11.272 470 2.496 kworker/6:0-1264 + + Reference =========== diff --git a/Documentation/admin-guide/pm/intel-speed-select.rst b/Documentation/admin-guide/pm/intel-speed-select.rst index 0a1fbdb54bfe..a2bfb971654f 100644 --- a/Documentation/admin-guide/pm/intel-speed-select.rst +++ b/Documentation/admin-guide/pm/intel-speed-select.rst @@ -262,6 +262,28 @@ Which shows that the base frequency now increased from 2600 MHz at performance level 0 to 2800 MHz at performance level 4. As a result, any workload, which can use fewer CPUs, can see a boost of 200 MHz compared to performance level 0. +Changing performance level via BMC Interface +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +It is possible to change SST-PP level using out of band (OOB) agent (Via some +remote management console, through BMC "Baseboard Management Controller" +interface). This mode is supported from the Sapphire Rapids processor +generation. The kernel and tool change to support this mode is added to Linux +kernel version 5.18. To enable this feature, kernel config +"CONFIG_INTEL_HFI_THERMAL" is required. The minimum version of the tool +is "v1.12" to support this feature, which is part of Linux kernel version 5.18. + +To support such configuration, this tool can be used as a daemon. Add +a command line option --oob:: + + # intel-speed-select --oob + Intel(R) Speed Select Technology + Executing on CPU model:143[0x8f] + OOB mode is enabled and will run as daemon + +In this mode the tool will online/offline CPUs based on the new performance +level. + Check presence of other Intel(R) SST features --------------------------------------------- diff --git a/Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst b/Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst new file mode 100644 index 000000000000..09169d935835 --- /dev/null +++ b/Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst @@ -0,0 +1,60 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. include:: <isonum.txt> + +============================== +Intel Uncore Frequency Scaling +============================== + +:Copyright: |copy| 2022 Intel Corporation + +:Author: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> + +Introduction +------------ + +The uncore can consume significant amount of power in Intel's Xeon servers based +on the workload characteristics. To optimize the total power and improve overall +performance, SoCs have internal algorithms for scaling uncore frequency. These +algorithms monitor workload usage of uncore and set a desirable frequency. + +It is possible that users have different expectations of uncore performance and +want to have control over it. The objective is similar to allowing users to set +the scaling min/max frequencies via cpufreq sysfs to improve CPU performance. +Users may have some latency sensitive workloads where they do not want any +change to uncore frequency. Also, users may have workloads which require +different core and uncore performance at distinct phases and they may want to +use both cpufreq and the uncore scaling interface to distribute power and +improve overall performance. + +Sysfs Interface +--------------- + +To control uncore frequency, a sysfs interface is provided in the directory: +`/sys/devices/system/cpu/intel_uncore_frequency/`. + +There is one directory for each package and die combination as the scope of +uncore scaling control is per die in multiple die/package SoCs or per +package for single die per package SoCs. The name represents the +scope of control. For example: 'package_00_die_00' is for package id 0 and +die 0. + +Each package_*_die_* contains the following attributes: + +``initial_max_freq_khz`` + Out of reset, this attribute represent the maximum possible frequency. + This is a read-only attribute. If users adjust max_freq_khz, + they can always go back to maximum using the value from this attribute. + +``initial_min_freq_khz`` + Out of reset, this attribute represent the minimum possible frequency. + This is a read-only attribute. If users adjust min_freq_khz, + they can always go back to minimum using the value from this attribute. + +``max_freq_khz`` + This attribute is used to set the maximum uncore frequency. + +``min_freq_khz`` + This attribute is used to set the minimum uncore frequency. + +``current_freq_khz`` + This attribute is used to get the current uncore frequency. diff --git a/Documentation/admin-guide/pm/working-state.rst b/Documentation/admin-guide/pm/working-state.rst index 5d2757e2de65..ee45887811ff 100644 --- a/Documentation/admin-guide/pm/working-state.rst +++ b/Documentation/admin-guide/pm/working-state.rst @@ -15,3 +15,4 @@ Working-State Power Management cpufreq_drivers intel_epb intel-speed-select + intel_uncore_frequency_scaling diff --git a/Documentation/admin-guide/reporting-issues.rst b/Documentation/admin-guide/reporting-issues.rst index d7ac13f789cc..ec62151fe672 100644 --- a/Documentation/admin-guide/reporting-issues.rst +++ b/Documentation/admin-guide/reporting-issues.rst @@ -1,14 +1,5 @@ .. SPDX-License-Identifier: (GPL-2.0+ OR CC-BY-4.0) -.. - If you want to distribute this text under CC-BY-4.0 only, please use 'The - Linux kernel developers' for author attribution and link this as source: - https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/Documentation/admin-guide/reporting-issues.rst -.. - Note: Only the content of this RST file as found in the Linux kernel sources - is available under CC-BY-4.0, as versions of this text that were processed - (for example by the kernel's build system) might contain content taken from - files which use a more restrictive license. - +.. See the bottom of this file for additional redistribution information. Reporting issues ++++++++++++++++ @@ -395,22 +386,16 @@ fixed as soon as possible, hence there are 'issues of high priority' that get handled slightly differently in the reporting process. Three type of cases qualify: regressions, security issues, and really severe problems. -You deal with a 'regression' if something that worked with an older version of -the Linux kernel does not work with a newer one or somehow works worse with it. -It thus is a regression when a WiFi driver that did a fine job with Linux 5.7 -somehow misbehaves with 5.8 or doesn't work at all. It's also a regression if -an application shows erratic behavior with a newer kernel, which might happen -due to incompatible changes in the interface between the kernel and the -userland (like procfs and sysfs). Significantly reduced performance or -increased power consumption also qualify as regression. But keep in mind: the -new kernel needs to be built with a configuration that is similar to the one -from the old kernel (see below how to achieve that). That's because the kernel -developers sometimes can not avoid incompatibilities when implementing new -features; but to avoid regressions such features have to be enabled explicitly -during build time configuration. +You deal with a regression if some application or practical use case running +fine with one Linux kernel works worse or not at all with a newer version +compiled using a similar configuration. The document +Documentation/admin-guide/reporting-regressions.rst explains this in more +detail. It also provides a good deal of other information about regressions you +might want to be aware of; it for example explains how to add your issue to the +list of tracked regressions, to ensure it won't fall through the cracks. What qualifies as security issue is left to your judgment. Consider reading -'Documentation/admin-guide/security-bugs.rst' before proceeding, as it +Documentation/admin-guide/security-bugs.rst before proceeding, as it provides additional details how to best handle security issues. An issue is a 'really severe problem' when something totally unacceptably bad @@ -517,7 +502,7 @@ line starting with 'CPU:'. It should end with 'Not tainted' if the kernel was not tainted when it noticed the problem; it was tainted if you see 'Tainted:' followed by a few spaces and some letters. -If your kernel is tainted, study 'Documentation/admin-guide/tainted-kernels.rst' +If your kernel is tainted, study Documentation/admin-guide/tainted-kernels.rst to find out why. Try to eliminate the reason. Often it's caused by one these three things: @@ -1043,7 +1028,7 @@ down the culprit, as maintainers often won't have the time or setup at hand to reproduce it themselves. To find the change there is a process called 'bisection' which the document -'Documentation/admin-guide/bug-bisect.rst' describes in detail. That process +Documentation/admin-guide/bug-bisect.rst describes in detail. That process will often require you to build about ten to twenty kernel images, trying to reproduce the issue with each of them before building the next. Yes, that takes some time, but don't worry, it works a lot quicker than most people assume. @@ -1073,10 +1058,11 @@ When dealing with regressions make sure the issue you face is really caused by the kernel and not by something else, as outlined above already. In the whole process keep in mind: an issue only qualifies as regression if the -older and the newer kernel got built with a similar configuration. The best way -to archive this: copy the configuration file (``.config``) from the old working -kernel freshly to each newer kernel version you try. Afterwards run ``make -olddefconfig`` to adjust it for the needs of the new version. +older and the newer kernel got built with a similar configuration. This can be +achieved by using ``make olddefconfig``, as explained in more detail by +Documentation/admin-guide/reporting-regressions.rst; that document also +provides a good deal of other information about regressions you might want to be +aware of. Write and send the report @@ -1283,7 +1269,7 @@ them when sending the report by mail. If you filed it in a bug tracker, forward the report's text to these addresses; but on top of it put a small note where you mention that you filed it with a link to the ticket. -See 'Documentation/admin-guide/security-bugs.rst' for more information. +See Documentation/admin-guide/security-bugs.rst for more information. Duties after the report went out @@ -1571,7 +1557,7 @@ Once your report is out your might get asked to do a proper one, as it allows to pinpoint the exact change that causes the issue (which then can easily get reverted to fix the issue quickly). Hence consider to do a proper bisection right away if time permits. See the section 'Special care for regressions' and -the document 'Documentation/admin-guide/bug-bisect.rst' for details how to +the document Documentation/admin-guide/bug-bisect.rst for details how to perform one. In case of a successful bisection add the author of the culprit to the recipients; also CC everyone in the signed-off-by chain, which you find at the end of its commit message. @@ -1594,7 +1580,7 @@ Some fixes are too complex Even small and seemingly obvious code-changes sometimes introduce new and totally unexpected problems. The maintainers of the stable and longterm kernels are very aware of that and thus only apply changes to these kernels that are -within rules outlined in 'Documentation/process/stable-kernel-rules.rst'. +within rules outlined in Documentation/process/stable-kernel-rules.rst. Complex or risky changes for example do not qualify and thus only get applied to mainline. Other fixes are easy to get backported to the newest stable and @@ -1756,10 +1742,23 @@ art will lay some groundwork to improve the situation over time. .. - This text is maintained by Thorsten Leemhuis <linux@leemhuis.info>. If you - spot a typo or small mistake, feel free to let him know directly and he'll - fix it. You are free to do the same in a mostly informal way if you want - to contribute changes to the text, but for copyright reasons please CC + end-of-content +.. + This document is maintained by Thorsten Leemhuis <linux@leemhuis.info>. If + you spot a typo or small mistake, feel free to let him know directly and + he'll fix it. You are free to do the same in a mostly informal way if you + want to contribute changes to the text, but for copyright reasons please CC linux-doc@vger.kernel.org and "sign-off" your contribution as Documentation/process/submitting-patches.rst outlines in the section "Sign your work - the Developer's Certificate of Origin". +.. + This text is available under GPL-2.0+ or CC-BY-4.0, as stated at the top + of the file. If you want to distribute this text under CC-BY-4.0 only, + please use "The Linux kernel developers" for author attribution and link + this as source: + https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/Documentation/admin-guide/reporting-issues.rst +.. + Note: Only the content of this RST file as found in the Linux kernel sources + is available under CC-BY-4.0, as versions of this text that were processed + (for example by the kernel's build system) might contain content taken from + files which use a more restrictive license. diff --git a/Documentation/admin-guide/reporting-regressions.rst b/Documentation/admin-guide/reporting-regressions.rst new file mode 100644 index 000000000000..d8adccdae23f --- /dev/null +++ b/Documentation/admin-guide/reporting-regressions.rst @@ -0,0 +1,451 @@ +.. SPDX-License-Identifier: (GPL-2.0+ OR CC-BY-4.0) +.. [see the bottom of this file for redistribution information] + +Reporting regressions ++++++++++++++++++++++ + +"*We don't cause regressions*" is the first rule of Linux kernel development; +Linux founder and lead developer Linus Torvalds established it himself and +ensures it's obeyed. + +This document describes what the rule means for users and how the Linux kernel's +development model ensures to address all reported regressions; aspects relevant +for kernel developers are left to Documentation/process/handling-regressions.rst. + + +The important bits (aka "TL;DR") +================================ + +#. It's a regression if something running fine with one Linux kernel works worse + or not at all with a newer version. Note, the newer kernel has to be compiled + using a similar configuration; the detailed explanations below describes this + and other fine print in more detail. + +#. Report your issue as outlined in Documentation/admin-guide/reporting-issues.rst, + it already covers all aspects important for regressions and repeated + below for convenience. Two of them are important: start your report's subject + with "[REGRESSION]" and CC or forward it to `the regression mailing list + <https://lore.kernel.org/regressions/>`_ (regressions@lists.linux.dev). + +#. Optional, but recommended: when sending or forwarding your report, make the + Linux kernel regression tracking bot "regzbot" track the issue by specifying + when the regression started like this:: + + #regzbot introduced v5.13..v5.14-rc1 + + +All the details on Linux kernel regressions relevant for users +============================================================== + + +The important basics +-------------------- + + +What is a "regression" and what is the "no regressions rule"? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +It's a regression if some application or practical use case running fine with +one Linux kernel works worse or not at all with a newer version compiled using a +similar configuration. The "no regressions rule" forbids this to take place; if +it happens by accident, developers that caused it are expected to quickly fix +the issue. + +It thus is a regression when a WiFi driver from Linux 5.13 works fine, but with +5.14 doesn't work at all, works significantly slower, or misbehaves somehow. +It's also a regression if a perfectly working application suddenly shows erratic +behavior with a newer kernel version; such issues can be caused by changes in +procfs, sysfs, or one of the many other interfaces Linux provides to userland +software. But keep in mind, as mentioned earlier: 5.14 in this example needs to +be built from a configuration similar to the one from 5.13. This can be achieved +using ``make olddefconfig``, as explained in more detail below. + +Note the "practical use case" in the first sentence of this section: developers +despite the "no regressions" rule are free to change any aspect of the kernel +and even APIs or ABIs to userland, as long as no existing application or use +case breaks. + +Also be aware the "no regressions" rule covers only interfaces the kernel +provides to the userland. It thus does not apply to kernel-internal interfaces +like the module API, which some externally developed drivers use to hook into +the kernel. + +How do I report a regression? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Just report the issue as outlined in +Documentation/admin-guide/reporting-issues.rst, it already describes the +important points. The following aspects outlined there are especially relevant +for regressions: + + * When checking for existing reports to join, also search the `archives of the + Linux regressions mailing list <https://lore.kernel.org/regressions/>`_ and + `regzbot's web-interface <https://linux-regtracking.leemhuis.info/regzbot/>`_. + + * Start your report's subject with "[REGRESSION]". + + * In your report, clearly mention the last kernel version that worked fine and + the first broken one. Ideally try to find the exact change causing the + regression using a bisection, as explained below in more detail. + + * Remember to let the Linux regressions mailing list + (regressions@lists.linux.dev) know about your report: + + * If you report the regression by mail, CC the regressions list. + + * If you report your regression to some bug tracker, forward the submitted + report by mail to the regressions list while CCing the maintainer and the + mailing list for the subsystem in question. + + If it's a regression within a stable or longterm series (e.g. + v5.15.3..v5.15.5), remember to CC the `Linux stable mailing list + <https://lore.kernel.org/stable/>`_ (stable@vger.kernel.org). + + In case you performed a successful bisection, add everyone to the CC the + culprit's commit message mentions in lines starting with "Signed-off-by:". + +When CCing for forwarding your report to the list, consider directly telling the +aforementioned Linux kernel regression tracking bot about your report. To do +that, include a paragraph like this in your mail:: + + #regzbot introduced: v5.13..v5.14-rc1 + +Regzbot will then consider your mail a report for a regression introduced in the +specified version range. In above case Linux v5.13 still worked fine and Linux +v5.14-rc1 was the first version where you encountered the issue. If you +performed a bisection to find the commit that caused the regression, specify the +culprit's commit-id instead:: + + #regzbot introduced: 1f2e3d4c5d + +Placing such a "regzbot command" is in your interest, as it will ensure the +report won't fall through the cracks unnoticed. If you omit this, the Linux +kernel's regressions tracker will take care of telling regzbot about your +regression, as long as you send a copy to the regressions mailing lists. But the +regression tracker is just one human which sometimes has to rest or occasionally +might even enjoy some time away from computers (as crazy as that might sound). +Relying on this person thus will result in an unnecessary delay before the +regressions becomes mentioned `on the list of tracked and unresolved Linux +kernel regressions <https://linux-regtracking.leemhuis.info/regzbot/>`_ and the +weekly regression reports sent by regzbot. Such delays can result in Linus +Torvalds being unaware of important regressions when deciding between "continue +development or call this finished and release the final?". + +Are really all regressions fixed? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Nearly all of them are, as long as the change causing the regression (the +"culprit commit") is reliably identified. Some regressions can be fixed without +this, but often it's required. + +Who needs to find the root cause of a regression? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Developers of the affected code area should try to locate the culprit on their +own. But for them that's often impossible to do with reasonable effort, as quite +a lot of issues only occur in a particular environment outside the developer's +reach -- for example, a specific hardware platform, firmware, Linux distro, +system's configuration, or application. That's why in the end it's often up to +the reporter to locate the culprit commit; sometimes users might even need to +run additional tests afterwards to pinpoint the exact root cause. Developers +should offer advice and reasonably help where they can, to make this process +relatively easy and achievable for typical users. + +How can I find the culprit? +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Perform a bisection, as roughly outlined in +Documentation/admin-guide/reporting-issues.rst and described in more detail by +Documentation/admin-guide/bug-bisect.rst. It might sound like a lot of work, but +in many cases finds the culprit relatively quickly. If it's hard or +time-consuming to reliably reproduce the issue, consider teaming up with other +affected users to narrow down the search range together. + +Who can I ask for advice when it comes to regressions? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Send a mail to the regressions mailing list (regressions@lists.linux.dev) while +CCing the Linux kernel's regression tracker (regressions@leemhuis.info); if the +issue might better be dealt with in private, feel free to omit the list. + + +Additional details about regressions +------------------------------------ + + +What is the goal of the "no regressions rule"? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Users should feel safe when updating kernel versions and not have to worry +something might break. This is in the interest of the kernel developers to make +updating attractive: they don't want users to stay on stable or longterm Linux +series that are either abandoned or more than one and a half years old. That's +in everybody's interest, as `those series might have known bugs, security +issues, or other problematic aspects already fixed in later versions +<http://www.kroah.com/log/blog/2018/08/24/what-stable-kernel-should-i-use/>`_. +Additionally, the kernel developers want to make it simple and appealing for +users to test the latest pre-release or regular release. That's also in +everybody's interest, as it's a lot easier to track down and fix problems, if +they are reported shortly after being introduced. + +Is the "no regressions" rule really adhered in practice? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +It's taken really seriously, as can be seen by many mailing list posts from +Linux creator and lead developer Linus Torvalds, some of which are quoted in +Documentation/process/handling-regressions.rst. + +Exceptions to this rule are extremely rare; in the past developers almost always +turned out to be wrong when they assumed a particular situation was warranting +an exception. + +Who ensures the "no regressions" is actually followed? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The subsystem maintainers should take care of that, which are watched and +supported by the tree maintainers -- e.g. Linus Torvalds for mainline and +Greg Kroah-Hartman et al. for various stable/longterm series. + +All of them are helped by people trying to ensure no regression report falls +through the cracks. One of them is Thorsten Leemhuis, who's currently acting as +the Linux kernel's "regressions tracker"; to facilitate this work he relies on +regzbot, the Linux kernel regression tracking bot. That's why you want to bring +your report on the radar of these people by CCing or forwarding each report to +the regressions mailing list, ideally with a "regzbot command" in your mail to +get it tracked immediately. + +How quickly are regressions normally fixed? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Developers should fix any reported regression as quickly as possible, to provide +affected users with a solution in a timely manner and prevent more users from +running into the issue; nevertheless developers need to take enough time and +care to ensure regression fixes do not cause additional damage. + +The answer thus depends on various factors like the impact of a regression, its +age, or the Linux series in which it occurs. In the end though, most regressions +should be fixed within two weeks. + +Is it a regression, if the issue can be avoided by updating some software? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Almost always: yes. If a developer tells you otherwise, ask the regression +tracker for advice as outlined above. + +Is it a regression, if a newer kernel works slower or consumes more energy? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Yes, but the difference has to be significant. A five percent slow-down in a +micro-benchmark thus is unlikely to qualify as regression, unless it also +influences the results of a broad benchmark by more than one percent. If in +doubt, ask for advice. + +Is it a regression, if an external kernel module breaks when updating Linux? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +No, as the "no regression" rule is about interfaces and services the Linux +kernel provides to the userland. It thus does not cover building or running +externally developed kernel modules, as they run in kernel-space and hook into +the kernel using internal interfaces occasionally changed. + +How are regressions handled that are caused by security fixes? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +In extremely rare situations security issues can't be fixed without causing +regressions; those fixes are given way, as they are the lesser evil in the end. +Luckily this middling almost always can be avoided, as key developers for the +affected area and often Linus Torvalds himself try very hard to fix security +issues without causing regressions. + +If you nevertheless face such a case, check the mailing list archives if people +tried their best to avoid the regression. If not, report it; if in doubt, ask +for advice as outlined above. + +What happens if fixing a regression is impossible without causing another? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Sadly these things happen, but luckily not very often; if they occur, expert +developers of the affected code area should look into the issue to find a fix +that avoids regressions or at least their impact. If you run into such a +situation, do what was outlined already for regressions caused by security +fixes: check earlier discussions if people already tried their best and ask for +advice if in doubt. + +A quick note while at it: these situations could be avoided, if people would +regularly give mainline pre-releases (say v5.15-rc1 or -rc3) from each +development cycle a test run. This is best explained by imagining a change +integrated between Linux v5.14 and v5.15-rc1 which causes a regression, but at +the same time is a hard requirement for some other improvement applied for +5.15-rc1. All these changes often can simply be reverted and the regression thus +solved, if someone finds and reports it before 5.15 is released. A few days or +weeks later this solution can become impossible, as some software might have +started to rely on aspects introduced by one of the follow-up changes: reverting +all changes would then cause a regression for users of said software and thus is +out of the question. + +Is it a regression, if some feature I relied on was removed months ago? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +It is, but often it's hard to fix such regressions due to the aspects outlined +in the previous section. It hence needs to be dealt with on a case-by-case +basis. This is another reason why it's in everybody's interest to regularly test +mainline pre-releases. + +Does the "no regression" rule apply if I seem to be the only affected person? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +It does, but only for practical usage: the Linux developers want to be free to +remove support for hardware only to be found in attics and museums anymore. + +Note, sometimes regressions can't be avoided to make progress -- and the latter +is needed to prevent Linux from stagnation. Hence, if only very few users seem +to be affected by a regression, it for the greater good might be in their and +everyone else's interest to lettings things pass. Especially if there is an +easy way to circumvent the regression somehow, for example by updating some +software or using a kernel parameter created just for this purpose. + +Does the regression rule apply for code in the staging tree as well? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Not according to the `help text for the configuration option covering all +staging code <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/staging/Kconfig>`_, +which since its early days states:: + + Please note that these drivers are under heavy development, may or + may not work, and may contain userspace interfaces that most likely + will be changed in the near future. + +The staging developers nevertheless often adhere to the "no regressions" rule, +but sometimes bend it to make progress. That's for example why some users had to +deal with (often negligible) regressions when a WiFi driver from the staging +tree was replaced by a totally different one written from scratch. + +Why do later versions have to be "compiled with a similar configuration"? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Because the Linux kernel developers sometimes integrate changes known to cause +regressions, but make them optional and disable them in the kernel's default +configuration. This trick allows progress, as the "no regressions" rule +otherwise would lead to stagnation. + +Consider for example a new security feature blocking access to some kernel +interfaces often abused by malware, which at the same time are required to run a +few rarely used applications. The outlined approach makes both camps happy: +people using these applications can leave the new security feature off, while +everyone else can enable it without running into trouble. + +How to create a configuration similar to the one of an older kernel? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Start your machine with a known-good kernel and configure the newer Linux +version with ``make olddefconfig``. This makes the kernel's build scripts pick +up the configuration file (the ".config" file) from the running kernel as base +for the new one you are about to compile; afterwards they set all new +configuration options to their default value, which should disable new features +that might cause regressions. + +Can I report a regression I found with pre-compiled vanilla kernels? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +You need to ensure the newer kernel was compiled with a similar configuration +file as the older one (see above), as those that built them might have enabled +some known-to-be incompatible feature for the newer kernel. If in doubt, report +the matter to the kernel's provider and ask for advice. + + +More about regression tracking with "regzbot" +--------------------------------------------- + +What is regression tracking and why should I care about it? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Rules like "no regressions" need someone to ensure they are followed, otherwise +they are broken either accidentally or on purpose. History has shown this to be +true for Linux kernel development as well. That's why Thorsten Leemhuis, the +Linux Kernel's regression tracker, and some people try to ensure all regression +are fixed by keeping an eye on them until they are resolved. Neither of them are +paid for this, that's why the work is done on a best effort basis. + +Why and how are Linux kernel regressions tracked using a bot? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Tracking regressions completely manually has proven to be quite hard due to the +distributed and loosely structured nature of Linux kernel development process. +That's why the Linux kernel's regression tracker developed regzbot to facilitate +the work, with the long term goal to automate regression tracking as much as +possible for everyone involved. + +Regzbot works by watching for replies to reports of tracked regressions. +Additionally, it's looking out for posted or committed patches referencing such +reports with "Link:" tags; replies to such patch postings are tracked as well. +Combined this data provides good insights into the current state of the fixing +process. + +How to see which regressions regzbot tracks currently? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Check out `regzbot's web-interface <https://linux-regtracking.leemhuis.info/regzbot/>`_. + +What kind of issues are supposed to be tracked by regzbot? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The bot is meant to track regressions, hence please don't involve regzbot for +regular issues. But it's okay for the Linux kernel's regression tracker if you +involve regzbot to track severe issues, like reports about hangs, corrupted +data, or internal errors (Panic, Oops, BUG(), warning, ...). + +How to change aspects of a tracked regression? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +By using a 'regzbot command' in a direct or indirect reply to the mail with the +report. The easiest way to do that: find the report in your "Sent" folder or the +mailing list archive and reply to it using your mailer's "Reply-all" function. +In that mail, use one of the following commands in a stand-alone paragraph (IOW: +use blank lines to separate one or multiple of these commands from the rest of +the mail's text). + + * Update when the regression started to happen, for example after performing a + bisection:: + + #regzbot introduced: 1f2e3d4c5d + + * Set or update the title:: + + #regzbot title: foo + + * Monitor a discussion or bugzilla.kernel.org ticket where additions aspects of + the issue or a fix are discussed::: + + #regzbot monitor: https://lore.kernel.org/r/30th.anniversary.repost@klaava.Helsinki.FI/ + #regzbot monitor: https://bugzilla.kernel.org/show_bug.cgi?id=123456789 + + * Point to a place with further details of interest, like a mailing list post + or a ticket in a bug tracker that are slightly related, but about a different + topic:: + + #regzbot link: https://bugzilla.kernel.org/show_bug.cgi?id=123456789 + + * Mark a regression as invalid:: + + #regzbot invalid: wasn't a regression, problem has always existed + +Regzbot supports a few other commands primarily used by developers or people +tracking regressions. They and more details about the aforementioned regzbot +commands can be found in the `getting started guide +<https://gitlab.com/knurd42/regzbot/-/blob/main/docs/getting_started.md>`_ and +the `reference documentation <https://gitlab.com/knurd42/regzbot/-/blob/main/docs/reference.md>`_ +for regzbot. + +.. + end-of-content +.. + This text is available under GPL-2.0+ or CC-BY-4.0, as stated at the top + of the file. If you want to distribute this text under CC-BY-4.0 only, + please use "The Linux kernel developers" for author attribution and link + this as source: + https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/Documentation/admin-guide/reporting-regressions.rst +.. + Note: Only the content of this RST file as found in the Linux kernel sources + is available under CC-BY-4.0, as versions of this text that were processed + (for example by the kernel's build system) might contain content taken from + files which use a more restrictive license. diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index d359bcfadd39..ddccd1077462 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -595,65 +595,33 @@ Documentation/admin-guide/kernel-parameters.rst). numa_balancing ============== -Enables/disables automatic page fault based NUMA memory -balancing. Memory is moved automatically to nodes -that access it often. +Enables/disables and configures automatic page fault based NUMA memory +balancing. Memory is moved automatically to nodes that access it often. +The value to set can be the result of ORing the following: -Enables/disables automatic NUMA memory balancing. On NUMA machines, there -is a performance penalty if remote memory is accessed by a CPU. When this -feature is enabled the kernel samples what task thread is accessing memory -by periodically unmapping pages and later trapping a page fault. At the -time of the page fault, it is determined if the data being accessed should -be migrated to a local memory node. += ================================= +0 NUMA_BALANCING_DISABLED +1 NUMA_BALANCING_NORMAL +2 NUMA_BALANCING_MEMORY_TIERING += ================================= + +Or NUMA_BALANCING_NORMAL to optimize page placement among different +NUMA nodes to reduce remote accessing. On NUMA machines, there is a +performance penalty if remote memory is accessed by a CPU. When this +feature is enabled the kernel samples what task thread is accessing +memory by periodically unmapping pages and later trapping a page +fault. At the time of the page fault, it is determined if the data +being accessed should be migrated to a local memory node. The unmapping of pages and trapping faults incur additional overhead that ideally is offset by improved memory locality but there is no universal guarantee. If the target workload is already bound to NUMA nodes then this -feature should be disabled. Otherwise, if the system overhead from the -feature is too high then the rate the kernel samples for NUMA hinting -faults may be controlled by the `numa_balancing_scan_period_min_ms, -numa_balancing_scan_delay_ms, numa_balancing_scan_period_max_ms, -numa_balancing_scan_size_mb`_, and numa_balancing_settle_count sysctls. - - -numa_balancing_scan_period_min_ms, numa_balancing_scan_delay_ms, numa_balancing_scan_period_max_ms, numa_balancing_scan_size_mb -=============================================================================================================================== - - -Automatic NUMA balancing scans tasks address space and unmaps pages to -detect if pages are properly placed or if the data should be migrated to a -memory node local to where the task is running. Every "scan delay" the task -scans the next "scan size" number of pages in its address space. When the -end of the address space is reached the scanner restarts from the beginning. - -In combination, the "scan delay" and "scan size" determine the scan rate. -When "scan delay" decreases, the scan rate increases. The scan delay and -hence the scan rate of every task is adaptive and depends on historical -behaviour. If pages are properly placed then the scan delay increases, -otherwise the scan delay decreases. The "scan size" is not adaptive but -the higher the "scan size", the higher the scan rate. - -Higher scan rates incur higher system overhead as page faults must be -trapped and potentially data must be migrated. However, the higher the scan -rate, the more quickly a tasks memory is migrated to a local node if the -workload pattern changes and minimises performance impact due to remote -memory accesses. These sysctls control the thresholds for scan delays and -the number of pages scanned. - -``numa_balancing_scan_period_min_ms`` is the minimum time in milliseconds to -scan a tasks virtual memory. It effectively controls the maximum scanning -rate for each task. - -``numa_balancing_scan_delay_ms`` is the starting "scan delay" used for a task -when it initially forks. - -``numa_balancing_scan_period_max_ms`` is the maximum time in milliseconds to -scan a tasks virtual memory. It effectively controls the minimum scanning -rate for each task. - -``numa_balancing_scan_size_mb`` is how many megabytes worth of pages are -scanned for a given scan. +feature should be disabled. +Or NUMA_BALANCING_MEMORY_TIERING to optimize page placement among +different types of memory (represented as different NUMA nodes) to +place the hot pages in the fast memory. This is implemented based on +unmapping and page fault too. oops_all_cpu_backtrace ====================== @@ -795,6 +763,8 @@ bit 1 print system memory info bit 2 print timer info bit 3 print locks info if ``CONFIG_LOCKDEP`` is on bit 4 print ftrace buffer +bit 5 print all printk messages in buffer +bit 6 print all CPUs backtrace (if available in the arch) ===== ============================================ So for example to print tasks and memory info on panic, user can:: @@ -813,6 +783,13 @@ is useful to define the root cause of RCU stalls using a vmcore. 1 panic() after printing RCU stall messages. = ============================================================ +max_rcu_stall_to_panic +====================== + +When ``panic_on_rcu_stall`` is set to 1, this value determines the +number of times that RCU can stall before panic() is called. + +When ``panic_on_rcu_stall`` is set to 0, this value is has no effect. perf_cpu_time_max_percent ========================= @@ -1024,28 +1001,22 @@ This is a directory, with the following entries: * ``boot_id``: a UUID generated the first time this is retrieved, and unvarying after that; +* ``uuid``: a UUID generated every time this is retrieved (this can + thus be used to generate UUIDs at will); + * ``entropy_avail``: the pool's entropy count, in bits; * ``poolsize``: the entropy pool size, in bits; * ``urandom_min_reseed_secs``: obsolete (used to determine the minimum - number of seconds between urandom pool reseeding). - -* ``uuid``: a UUID generated every time this is retrieved (this can - thus be used to generate UUIDs at will); + number of seconds between urandom pool reseeding). This file is + writable for compatibility purposes, but writing to it has no effect + on any RNG behavior; * ``write_wakeup_threshold``: when the entropy count drops below this (as a number of bits), processes waiting to write to ``/dev/random`` - are woken up. - -If ``drivers/char/random.c`` is built with ``ADD_INTERRUPT_BENCH`` -defined, these additional entries are present: - -* ``add_interrupt_avg_cycles``: the average number of cycles between - interrupts used to feed the pool; - -* ``add_interrupt_avg_deviation``: the standard deviation seen on the - number of cycles between interrupts used to feed the pool. + are woken up. This file is writable for compatibility purposes, but + writing to it has no effect on any RNG behavior. randomize_va_space diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst index 4150f74c521a..fcd650bdbc7e 100644 --- a/Documentation/admin-guide/sysctl/net.rst +++ b/Documentation/admin-guide/sysctl/net.rst @@ -322,6 +322,14 @@ a leaked reference faster. A larger value may be useful to prevent false warnings on slow/loaded systems. Default value is 10, minimum 1, maximum 3600. +skb_defer_max +------------- + +Max size (in skbs) of the per-cpu list of skbs being freed +by the cpu which allocated them. Used by TCP stack so far. + +Default: 64 + optmem_max ---------- @@ -365,6 +373,24 @@ new netns has been created. Default : 0 (for compatibility reasons) +txrehash +-------- + +Controls default hash rethink behaviour on listening socket when SO_TXREHASH +option is set to SOCK_TXREHASH_DEFAULT (i. e. not overridden by setsockopt). + +If set to 1 (default), hash rethink is performed on listening socket. +If set to 0, hash rethink is not performed. + +gro_normal_batch +---------------- + +Maximum number of the segments to batch up on output of GRO. When a packet +exits GRO, either as a coalesced superframe or as an original packet which +GRO has decided not to coalesce, it is placed on a per-NAPI list. This +list is then passed to the stack when the number of segments reaches the +gro_normal_batch limit. + 2. /proc/sys/net/unix - Parameters for Unix domain sockets ---------------------------------------------------------- diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst index f4804ce37c58..5c9aa171a0d3 100644 --- a/Documentation/admin-guide/sysctl/vm.rst +++ b/Documentation/admin-guide/sysctl/vm.rst @@ -62,6 +62,7 @@ Currently, these files are in /proc/sys/vm: - overcommit_memory - overcommit_ratio - page-cluster +- page_lock_unfairness - panic_on_oom - percpu_pagelist_high_fraction - stat_interval @@ -561,6 +562,45 @@ Change the minimum size of the hugepage pool. See Documentation/admin-guide/mm/hugetlbpage.rst +hugetlb_optimize_vmemmap +======================== + +This knob is not available when memory_hotplug.memmap_on_memory (kernel parameter) +is configured or the size of 'struct page' (a structure defined in +include/linux/mm_types.h) is not power of two (an unusual system config could +result in this). + +Enable (set to 1) or disable (set to 0) the feature of optimizing vmemmap pages +associated with each HugeTLB page. + +Once enabled, the vmemmap pages of subsequent allocation of HugeTLB pages from +buddy allocator will be optimized (7 pages per 2MB HugeTLB page and 4095 pages +per 1GB HugeTLB page), whereas already allocated HugeTLB pages will not be +optimized. When those optimized HugeTLB pages are freed from the HugeTLB pool +to the buddy allocator, the vmemmap pages representing that range needs to be +remapped again and the vmemmap pages discarded earlier need to be rellocated +again. If your use case is that HugeTLB pages are allocated 'on the fly' (e.g. +never explicitly allocating HugeTLB pages with 'nr_hugepages' but only set +'nr_overcommit_hugepages', those overcommitted HugeTLB pages are allocated 'on +the fly') instead of being pulled from the HugeTLB pool, you should weigh the +benefits of memory savings against the more overhead (~2x slower than before) +of allocation or freeing HugeTLB pages between the HugeTLB pool and the buddy +allocator. Another behavior to note is that if the system is under heavy memory +pressure, it could prevent the user from freeing HugeTLB pages from the HugeTLB +pool to the buddy allocator since the allocation of vmemmap pages could be +failed, you have to retry later if your system encounter this situation. + +Once disabled, the vmemmap pages of subsequent allocation of HugeTLB pages from +buddy allocator will not be optimized meaning the extra overhead at allocation +time from buddy allocator disappears, whereas already optimized HugeTLB pages +will not be affected. If you want to make sure there are no optimized HugeTLB +pages, you can set "nr_hugepages" to 0 first and then disable this. Note that +writing 0 to nr_hugepages will make any "in use" HugeTLB pages become surplus +pages. So, those surplus pages are still optimized until they are no longer +in use. You would need to wait for those surplus pages to be released before +there are no optimized pages in the system. + + nr_hugepages_mempolicy ====================== @@ -754,6 +794,14 @@ extra faults and I/O delays for following faults if they would have been part of that consecutive pages readahead would have brought in. +page_lock_unfairness +==================== + +This value determines the number of times that the page lock can be +stolen from under a waiter. After the lock is stolen the number of times +specified in this file (default is 5), the "fair lock handoff" semantics +will apply, and the waiter will only be awakened if the lock can be taken. + panic_on_oom ============ |