diff options
Diffstat (limited to 'Documentation/admin-guide/mm/damon')
| -rw-r--r-- | Documentation/admin-guide/mm/damon/index.rst | 12 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/damon/lru_sort.rst | 72 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/damon/reclaim.rst | 35 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/damon/start.rst | 2 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/damon/stat.rst | 91 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/damon/usage.rst | 204 |
6 files changed, 358 insertions, 58 deletions
diff --git a/Documentation/admin-guide/mm/damon/index.rst b/Documentation/admin-guide/mm/damon/index.rst index 33d37bb2fb4e..3ce3164480c7 100644 --- a/Documentation/admin-guide/mm/damon/index.rst +++ b/Documentation/admin-guide/mm/damon/index.rst @@ -1,12 +1,11 @@ .. SPDX-License-Identifier: GPL-2.0 -========================== -DAMON: Data Access MONitor -========================== +================================================================ +DAMON: Data Access MONitoring and Access-aware System Operations +================================================================ -:doc:`DAMON </mm/damon/index>` allows light-weight data access monitoring. -Using DAMON, users can analyze the memory access patterns of their systems and -optimize those. +:doc:`DAMON </mm/damon/index>` is a Linux kernel subsystem for efficient data +access monitoring and access-aware system operations. .. toctree:: :maxdepth: 2 @@ -15,3 +14,4 @@ optimize those. usage reclaim lru_sort + stat diff --git a/Documentation/admin-guide/mm/damon/lru_sort.rst b/Documentation/admin-guide/mm/damon/lru_sort.rst index 7b0775d281b4..14cc6b2db897 100644 --- a/Documentation/admin-guide/mm/damon/lru_sort.rst +++ b/Documentation/admin-guide/mm/damon/lru_sort.rst @@ -79,6 +79,47 @@ 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_LRU_SORT will be disabled. +Once ``Y`` is written to this parameter, the user must not write to any +parameters until reading ``commit_inputs`` again returns ``N``. If users +violate this rule, the kernel may exhibit undefined behavior. + +active_mem_bp +------------- + +Desired active to [in]active memory ratio in bp (1/10,000). + +While keeping the caps that set by other quotas, DAMON_LRU_SORT automatically +increases and decreases the effective level of the quota aiming the LRU +[de]prioritizations of the hot and cold memory resulting in this active to +[in]active memory ratio. Value zero means disabling this auto-tuning feature. + +Disabled by default. + +autotune_monitoring_intervals +----------------------------- + +If this parameter is set as ``Y``, DAMON_LRU_SORT automatically tunes DAMON's +sampling and aggregation intervals. The auto-tuning aims to capture meaningful +amount of access events in each DAMON-snapshot, while keeping the sampling +interval 5 milliseconds in minimum, and 10 seconds in maximum. Setting this as +``N`` disables the auto-tuning. + +Disabled by default. + +filter_young_pages +------------------ + +Filter [non-]young pages accordingly for LRU [de]prioritizations. + +If this is set, check page level access (youngness) once again before each +LRU [de]prioritization operation. LRU prioritization operation is skipped +if the page has not accessed since the last check (not young). LRU +deprioritization operation is skipped if the page has accessed since the +last check (young). The feature is enabled or disabled if this parameter is +set as ``Y`` or ``N``, respectively. + +Disabled by default. + hot_thres_access_freq --------------------- @@ -184,6 +225,10 @@ But, setting this too high could result in increased monitoring overhead. Please refer to the DAMON documentation (:doc:`usage`) for more detail. 10 by default. +Note that this must be 3 or higher. Please refer to the :ref:`Monitoring +<damon_design_monitoring>` section of the design document for the rationale +behind this lower bound. + max_nr_regions -------------- @@ -211,6 +256,28 @@ End of target memory region in physical address. The end physical address of memory region that DAMON_LRU_SORT will do work against. By default, biggest System RAM is used as the region. +addr_unit +--------- + +A scale factor for memory addresses and bytes. + +This parameter is for setting and getting the :ref:`address unit +<damon_design_addr_unit>` parameter of the DAMON instance for DAMON_RECLAIM. + +``monitor_region_start`` and ``monitor_region_end`` should be provided in this +unit. For example, let's suppose ``addr_unit``, ``monitor_region_start`` and +``monitor_region_end`` are set as ``1024``, ``0`` and ``10``, respectively. +Then DAMON_LRU_SORT will work for 10 KiB length of physical address range that +starts from address zero (``[0 * 1024, 10 * 1024)`` in bytes). + +Stat parameters having ``bytes_`` prefix are also in this unit. For example, +let's suppose values of ``addr_unit``, ``bytes_lru_sort_tried_hot_regions`` and +``bytes_lru_sorted_hot_regions`` are ``1024``, ``42``, and ``32``, +respectively. Then it means DAMON_LRU_SORT tried to LRU-sort 42 KiB of hot +memory and successfully LRU-sorted 32 KiB of the memory in total. + +If unsure, use only the default value (``1``) and forget about this. + kdamond_pid ----------- @@ -292,3 +359,8 @@ the LRU-list based page granularity reclamation. :: # echo 400 > wmarks_mid # echo 200 > wmarks_low # echo Y > enabled + +Note that this module (damon_lru_sort) cannot run simultaneously with other +DAMON-based special-purpose modules. Refer to :ref:`DAMON design special +purpose modules exclusivity <damon_design_special_purpose_modules_exclusivity>` +for more details. diff --git a/Documentation/admin-guide/mm/damon/reclaim.rst b/Documentation/admin-guide/mm/damon/reclaim.rst index af05ae617018..d7a0225b4950 100644 --- a/Documentation/admin-guide/mm/damon/reclaim.rst +++ b/Documentation/admin-guide/mm/damon/reclaim.rst @@ -71,6 +71,10 @@ 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. +Once ``Y`` is written to this parameter, the user must not write to any +parameters until reading ``commit_inputs`` again returns ``N``. If users +violate this rule, the kernel may exhibit undefined behavior. + min_age ------- @@ -204,6 +208,10 @@ monitoring. This can be used to set lower-bound of the monitoring quality. But, setting this too high could result in increased monitoring overhead. Please refer to the DAMON documentation (:doc:`usage`) for more detail. +Note that this must be 3 or higher. Please refer to the :ref:`Monitoring +<damon_design_monitoring>` section of the design document for the rationale +behind this lower bound. + max_nr_regions -------------- @@ -232,6 +240,28 @@ The end physical address of memory region that DAMON_RECLAIM will do work against. That is, DAMON_RECLAIM will find cold memory regions in this region and reclaims. By default, biggest System RAM is used as the region. +addr_unit +--------- + +A scale factor for memory addresses and bytes. + +This parameter is for setting and getting the :ref:`address unit +<damon_design_addr_unit>` parameter of the DAMON instance for DAMON_RECLAIM. + +``monitor_region_start`` and ``monitor_region_end`` should be provided in this +unit. For example, let's suppose ``addr_unit``, ``monitor_region_start`` and +``monitor_region_end`` are set as ``1024``, ``0`` and ``10``, respectively. +Then DAMON_RECLAIM will work for 10 KiB length of physical address range that +starts from address zero (``[0 * 1024, 10 * 1024)`` in bytes). + +``bytes_reclaim_tried_regions`` and ``bytes_reclaimed_regions`` are also in +this unit. For example, let's suppose values of ``addr_unit``, +``bytes_reclaim_tried_regions`` and ``bytes_reclaimed_regions`` are ``1024``, +``42``, and ``32``, respectively. Then it means DAMON_RECLAIM tried to reclaim +42 KiB memory and successfully reclaimed 32 KiB memory in total. + +If unsure, use only the default value (``1``) and forget about this. + skip_anon --------- @@ -296,6 +326,11 @@ granularity reclamation. :: # echo 200 > wmarks_low # echo Y > enabled +Note that this module (damon_reclaim) cannot run simultaneously with other +DAMON-based special-purpose modules. Refer to :ref:`DAMON design special +purpose modules exclusivity <damon_design_special_purpose_modules_exclusivity>` +for more details. + .. [1] https://research.google/pubs/pub48551/ .. [2] https://lwn.net/Articles/787611/ .. [3] https://www.kernel.org/doc/html/latest/mm/free_page_reporting.html diff --git a/Documentation/admin-guide/mm/damon/start.rst b/Documentation/admin-guide/mm/damon/start.rst index ede14b679d02..ec8c34b2d32f 100644 --- a/Documentation/admin-guide/mm/damon/start.rst +++ b/Documentation/admin-guide/mm/damon/start.rst @@ -175,4 +175,4 @@ Below command makes every memory region of size >=4K that has not accessed for $ sudo damo start --damos_access_rate 0 0 --damos_sz_region 4K max \ --damos_age 60s max --damos_action pageout \ - <pid of your workload> + --target_pid <pid of your workload> diff --git a/Documentation/admin-guide/mm/damon/stat.rst b/Documentation/admin-guide/mm/damon/stat.rst new file mode 100644 index 000000000000..c4b14daeb2dd --- /dev/null +++ b/Documentation/admin-guide/mm/damon/stat.rst @@ -0,0 +1,91 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=================================== +Data Access Monitoring Results Stat +=================================== + +Data Access Monitoring Results Stat (DAMON_STAT) is a static kernel module that +is aimed to be used for simple access pattern monitoring. It monitors accesses +on the system's entire physical memory using DAMON, and provides simplified +access monitoring results statistics, namely idle time percentiles and +estimated memory bandwidth. + +.. _damon_stat_monitoring_accuracy_overhead: + +Monitoring Accuracy and Overhead +================================ + +DAMON_STAT uses monitoring intervals :ref:`auto-tuning +<damon_design_monitoring_intervals_autotuning>` to make its accuracy high and +overhead minimum. It auto-tunes the intervals aiming 4 % of observable access +events to be captured in each snapshot, while limiting the resulting sampling +interval to be 5 milliseconds in minimum and 10 seconds in maximum. On a few +production server systems, it resulted in consuming only 0.x % single CPU time, +while capturing reasonable quality of access patterns. The tuning-resulting +intervals can be retrieved via ``aggr_interval_us`` :ref:`parameter +<damon_stat_aggr_interval_us>`. + +Interface: Module Parameters +============================ + +To use this feature, you should first ensure your system is running on a kernel +that is built with ``CONFIG_DAMON_STAT=y``. The feature can be enabled by +default at build time, by setting ``CONFIG_DAMON_STAT_ENABLED_DEFAULT`` true. + +To let sysadmins enable or disable it at boot and/or runtime, and read the +monitoring results, DAMON_STAT provides module parameters. Following +sections are descriptions of the parameters. + +enabled +------- + +Enable or disable DAMON_STAT. + +You can enable DAMON_STAT by setting the value of this parameter as ``Y``. +Setting it as ``N`` disables DAMON_STAT. The default value is set by +``CONFIG_DAMON_STAT_ENABLED_DEFAULT`` build config option. + +Note that this module (damon_stat) cannot run simultaneously with other +DAMON-based special-purpose modules. Refer to :ref:`DAMON design special +purpose modules exclusivity <damon_design_special_purpose_modules_exclusivity>` +for more details. + +.. _damon_stat_aggr_interval_us: + +aggr_interval_us +---------------- + +Auto-tuned aggregation time interval in microseconds. + +Users can read the aggregation interval of DAMON that is being used by the +DAMON instance for DAMON_STAT. It is :ref:`auto-tuned +<damon_stat_monitoring_accuracy_overhead>` and therefore the value is +dynamically changed. + +estimated_memory_bandwidth +-------------------------- + +Estimated memory bandwidth consumption (bytes per second) of the system. + +DAMON_STAT reads observed access events on the current DAMON results snapshot +and converts it to memory bandwidth consumption estimation in bytes per second. +The resulting metric is exposed to user via this read-only parameter. Because +DAMON uses sampling, this is only an estimation of the access intensity rather +than accurate memory bandwidth. + +memory_idle_ms_percentiles +-------------------------- + +Per-byte idle time (milliseconds) percentiles of the system. + +DAMON_STAT calculates how long each byte of the memory was not accessed until +now (idle time), based on the current DAMON results snapshot. For regions +having access frequency (nr_accesses) larger than zero, how long the current +access frequency level was kept multiplied by ``-1`` becomes the idlee time of +every byte of the region. If a region has zero access frequency (nr_accesses), +how long the region was keeping the zero access frequency (age) becomes the +idle time of every byte of the region. Then, DAMON_STAT exposes the +percentiles of the idle time values via this read-only parameter. Reading the +parameter returns 101 idle time values in milliseconds, separated by comma. +Each value represents 0-th, 1st, 2nd, 3rd, ..., 99th and 100th percentile idle +times. diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst index 47a44bd348ab..534e1199cf09 100644 --- a/Documentation/admin-guide/mm/damon/usage.rst +++ b/Documentation/admin-guide/mm/damon/usage.rst @@ -6,6 +6,11 @@ Detailed Usages DAMON provides below interfaces for different users. +- *Special-purpose DAMON modules.* + :ref:`This <damon_modules_special_purpose>` is for people who are building, + distributing, and/or administrating the kernel with special-purpose DAMON + usages. Using this, users can use DAMON's major features for the given + purposes in build, boot, or runtime in simple ways. - *DAMON user space tool.* `This <https://github.com/damonitor/damo>`_ is for privileged people such as system administrators who want a just-working human-friendly interface. @@ -59,14 +64,15 @@ comma (","). :ref:`/sys/kernel/mm/damon <sysfs_root>`/admin │ :ref:`kdamonds <sysfs_kdamonds>`/nr_kdamonds - │ │ :ref:`0 <sysfs_kdamond>`/state,pid + │ │ :ref:`0 <sysfs_kdamond>`/state,pid,refresh_ms │ │ │ :ref:`contexts <sysfs_contexts>`/nr_contexts - │ │ │ │ :ref:`0 <sysfs_context>`/avail_operations,operations + │ │ │ │ :ref:`0 <sysfs_context>`/avail_operations,operations,addr_unit │ │ │ │ │ :ref:`monitoring_attrs <sysfs_monitoring_attrs>`/ │ │ │ │ │ │ intervals/sample_us,aggr_us,update_us + │ │ │ │ │ │ │ intervals_goal/access_bp,aggrs,min_sample_us,max_sample_us │ │ │ │ │ │ nr_regions/min,max │ │ │ │ │ :ref:`targets <sysfs_targets>`/nr_targets - │ │ │ │ │ │ :ref:`0 <sysfs_target>`/pid_target + │ │ │ │ │ │ :ref:`0 <sysfs_target>`/pid_target,obsolete_target │ │ │ │ │ │ │ :ref:`regions <sysfs_regions>`/nr_regions │ │ │ │ │ │ │ │ :ref:`0 <sysfs_region>`/start,end │ │ │ │ │ │ │ │ ... @@ -77,14 +83,16 @@ comma (","). │ │ │ │ │ │ │ │ sz/min,max │ │ │ │ │ │ │ │ nr_accesses/min,max │ │ │ │ │ │ │ │ age/min,max - │ │ │ │ │ │ │ :ref:`quotas <sysfs_quotas>`/ms,bytes,reset_interval_ms,effective_bytes + │ │ │ │ │ │ │ :ref:`quotas <sysfs_quotas>`/ms,bytes,reset_interval_ms,effective_bytes,goal_tuner │ │ │ │ │ │ │ │ weights/sz_permil,nr_accesses_permil,age_permil │ │ │ │ │ │ │ │ :ref:`goals <sysfs_schemes_quota_goals>`/nr_goals - │ │ │ │ │ │ │ │ │ 0/target_metric,target_value,current_value + │ │ │ │ │ │ │ │ │ 0/target_metric,target_value,current_value,nid,path │ │ │ │ │ │ │ :ref:`watermarks <sysfs_watermarks>`/metric,interval_us,high,mid,low - │ │ │ │ │ │ │ :ref:`filters <sysfs_filters>`/nr_filters - │ │ │ │ │ │ │ │ 0/type,matching,allow,memcg_path,addr_start,addr_end,target_idx - │ │ │ │ │ │ │ :ref:`stats <sysfs_schemes_stats>`/nr_tried,sz_tried,nr_applied,sz_applied,sz_ops_filter_passed,qt_exceeds + │ │ │ │ │ │ │ :ref:`{core_,ops_,}filters <sysfs_filters>`/nr_filters + │ │ │ │ │ │ │ │ 0/type,matching,allow,memcg_path,addr_start,addr_end,target_idx,min,max + │ │ │ │ │ │ │ :ref:`dests <damon_sysfs_dests>`/nr_dests + │ │ │ │ │ │ │ │ 0/id,weight + │ │ │ │ │ │ │ :ref:`stats <sysfs_schemes_stats>`/nr_tried,sz_tried,nr_applied,sz_applied,sz_ops_filter_passed,qt_exceeds,nr_snapshots,max_nr_snapshots │ │ │ │ │ │ │ :ref:`tried_regions <sysfs_schemes_tried_regions>`/total_bytes │ │ │ │ │ │ │ │ 0/start,end,nr_accesses,age,sz_filter_passed │ │ │ │ │ │ │ │ ... @@ -120,8 +128,8 @@ kdamond. kdamonds/<N>/ ------------- -In each kdamond directory, two files (``state`` and ``pid``) and one directory -(``contexts``) exist. +In each kdamond directory, three files (``state``, ``pid`` and ``refresh_ms``) +and one directory (``contexts``) exist. Reading ``state`` returns ``on`` if the kdamond is currently running, or ``off`` if it is not running. @@ -131,7 +139,13 @@ Users can write below commands for the kdamond to the ``state`` file. - ``on``: Start running. - ``off``: Stop running. - ``commit``: Read the user inputs in the sysfs files except ``state`` file - again. + again. Monitoring :ref:`target region <sysfs_regions>` inputs are also be + ignored if no target region is specified. +- ``update_tuned_intervals``: Update the contents of ``sample_us`` and + ``aggr_us`` files of the kdamond with the auto-tuning applied ``sampling + interval`` and ``aggregation interval`` for the files. Please refer to + :ref:`intervals_goal section <damon_usage_sysfs_monitoring_intervals_goal>` + for more details. - ``commit_schemes_quota_goals``: Read the DAMON-based operation schemes' :ref:`quota goals <sysfs_schemes_quota_goals>`. - ``update_schemes_stats``: Update the contents of stats files for each @@ -153,6 +167,13 @@ Users can write below commands for the kdamond to the ``state`` file. If the state is ``on``, reading ``pid`` shows the pid of the kdamond thread. +Users can ask the kernel to periodically update files showing auto-tuned +parameters and DAMOS stats instead of manually writing +``update_tuned_intervals`` like keywords to ``state`` file. For this, users +should write the desired update time interval in milliseconds to ``refresh_ms`` +file. If the interval is zero, the periodic update is disabled. Reading the +file shows currently set time interval. + ``contexts`` directory contains files for controlling the monitoring contexts that this kdamond will execute. @@ -173,9 +194,9 @@ details). At the moment, only one context per kdamond is supported, so only contexts/<N>/ ------------- -In each context directory, two files (``avail_operations`` and ``operations``) -and three directories (``monitoring_attrs``, ``targets``, and ``schemes``) -exist. +In each context directory, three files (``avail_operations``, ``operations`` +and ``addr_unit``) and three directories (``monitoring_attrs``, ``targets``, +and ``schemes``) exist. DAMON supports multiple types of :ref:`monitoring operations <damon_design_configurable_operations_set>`, including those for virtual address @@ -190,6 +211,9 @@ 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. +``addr_unit`` file is for setting and getting the :ref:`address unit +<damon_design_addr_unit>` parameter of the operations set. + .. _sysfs_monitoring_attrs: contexts/<N>/monitoring_attrs/ @@ -213,6 +237,25 @@ writing to and rading from the files. For more details about the intervals and monitoring regions range, please refer to the Design document (:doc:`/mm/damon/design`). +.. _damon_usage_sysfs_monitoring_intervals_goal: + +contexts/<N>/monitoring_attrs/intervals/intervals_goal/ +------------------------------------------------------- + +Under the ``intervals`` directory, one directory for automated tuning of +``sample_us`` and ``aggr_us``, namely ``intervals_goal`` directory also exists. +Under the directory, four files for the auto-tuning control, namely +``access_bp``, ``aggrs``, ``min_sample_us`` and ``max_sample_us`` exist. +Please refer to the :ref:`design document of the feature +<damon_design_monitoring_intervals_autotuning>` for the internal of the tuning +mechanism. Reading and writing the four files under ``intervals_goal`` +directory shows and updates the tuning parameters that described in the +:ref:design doc <damon_design_monitoring_intervals_autotuning>` with the same +names. The tuning starts with the user-set ``sample_us`` and ``aggr_us``. The +tuning-applied current values of the two intervals can be read from the +``sample_us`` and ``aggr_us`` files after writing ``update_tuned_intervals`` to +the ``state`` file. + .. _sysfs_targets: contexts/<N>/targets/ @@ -227,13 +270,20 @@ to ``N-1``. Each directory represents each monitoring target. targets/<N>/ ------------ -In each target directory, one file (``pid_target``) and one directory -(``regions``) exist. +In each target directory, two files (``pid_target`` and ``obsolete_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. +Users can selectively remove targets in the middle of the targets array by +writing non-zero value to ``obsolete_target`` file and committing it (writing +``commit`` to ``state`` file). DAMON will remove the matching targets from its +internal targets array. Users are responsible to construct target directories +again, so that those correctly represent the changed internal targets array. + + .. _sysfs_regions: targets/<N>/regions @@ -252,6 +302,11 @@ 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. +If ``nr_regions`` is zero when committing new DAMON parameters online (writing +``commit`` to ``state`` file of :ref:`kdamond <sysfs_kdamond>`), the commit +logic ignores the target regions. In other words, the current monitoring +results for the target are preserved. + .. _sysfs_region: regions/<N>/ @@ -282,9 +337,10 @@ to ``N-1``. Each directory represents each DAMON-based operation scheme. schemes/<N>/ ------------ -In each scheme directory, five directories (``access_pattern``, ``quotas``, -``watermarks``, ``filters``, ``stats``, and ``tried_regions``) and three files -(``action``, ``target_nid`` and ``apply_interval``) exist. +In each scheme directory, eight directories (``access_pattern``, ``quotas``, +``watermarks``, ``core_filters``, ``ops_filters``, ``filters``, ``dests``, +``stats``, and ``tried_regions``) and three files (``action``, ``target_nid`` +and ``apply_interval``) exist. The ``action`` file is for setting and getting the scheme's :ref:`action <damon_design_damos_action>`. The keywords that can be written to and read @@ -321,9 +377,9 @@ schemes/<N>/quotas/ The directory for the :ref:`quotas <damon_design_damos_quotas>` of the given DAMON-based operation scheme. -Under ``quotas`` directory, four files (``ms``, ``bytes``, -``reset_interval_ms``, ``effective_bytes``) and two directores (``weights`` and -``goals``) exist. +Under ``quotas`` directory, five files (``ms``, ``bytes``, +``reset_interval_ms``, ``effective_bytes`` and ``goal_tuner``) and two +directories (``weights`` and ``goals``) 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, @@ -334,6 +390,14 @@ apply the action to only up to ``bytes`` bytes of memory regions within the quota limits unless at least one :ref:`goal <sysfs_schemes_quota_goals>` is set. +You can set the goal-based effective quota auto-tuning algorithm to use, by +writing the algorithm name to ``goal_tuner`` file. Reading the file returns +the currently selected tuner algorithm. Refer to the design documentation of +:ref:`automatic quota tuning goals <damon_design_damos_quotas_auto_tuning>` for +the background design of the feature and the name of the selectable algorithms. +Refer to :ref:`goals directory <sysfs_schemes_quota_goals>` for the goals +setup. + The time quota is internally transformed to a size quota. Between the transformed size quota and user-specified size quota, smaller one is applied. Based on the user-specified :ref:`goal <sysfs_schemes_quota_goals>`, the @@ -364,11 +428,11 @@ number (``N``) to the file creates the number of child directories named ``0`` to ``N-1``. Each directory represents each goal and current achievement. Among the multiple feedback, the best one is used. -Each goal directory contains three files, namely ``target_metric``, -``target_value`` and ``current_value``. Users can set and get the three -parameters for the quota auto-tuning goals that specified on the :ref:`design -doc <damon_design_damos_quotas_auto_tuning>` by writing to and reading from each -of the files. Note that users should further write +Each goal directory contains five files, namely ``target_metric``, +``target_value``, ``current_value`` ``nid`` and ``path``. Users can set and +get the five parameters for the quota auto-tuning goals that specified on the +:ref:`design doc <damon_design_damos_quotas_auto_tuning>` by writing to and +reading from each of the files. Note that users should further write ``commit_schemes_quota_goals`` to the ``state`` file of the :ref:`kdamond directory <sysfs_kdamond>` to pass the feedback to DAMON. @@ -395,33 +459,43 @@ The ``interval`` should written in microseconds unit. .. _sysfs_filters: -schemes/<N>/filters/ --------------------- +schemes/<N>/{core\_,ops\_,}filters/ +----------------------------------- -The directory for the :ref:`filters <damon_design_damos_filters>` of the given +Directories for :ref:`filters <damon_design_damos_filters>` of the given DAMON-based operation scheme. -In the beginning, this directory has only one file, ``nr_filters``. Writing a +``core_filters`` and ``ops_filters`` directories are for the filters handled by +the DAMON core layer and operations set layer, respectively. ``filters`` +directory can be used for installing filters regardless of their handled +layers. Filters that requested by ``core_filters`` and ``ops_filters`` will be +installed before those of ``filters``. All three directories have same files. + +Use of ``filters`` directory can make expecting evaluation orders of given +filters with the files under directory bit confusing. Users are hence +recommended to use ``core_filters`` and ``ops_filters`` directories. The +``filters`` directory could be deprecated in future. + +In the beginning, the directory has only one file, ``nr_filters``. Writing a number (``N``) to the file creates the number of child directories named ``0`` to ``N-1``. Each directory represents each filter. The filters are evaluated in the numeric order. -Each filter directory contains seven files, namely ``type``, ``matching``, -``allow``, ``memcg_path``, ``addr_start``, ``addr_end``, and ``target_idx``. -To ``type`` file, you can write one of five special keywords: ``anon`` for -anonymous pages, ``memcg`` for specific memory cgroup, ``young`` for young -pages, ``addr`` for specific address range (an open-ended interval), or -``target`` for specific DAMON monitoring target filtering. Meaning of the -types are same to the description on the :ref:`design doc -<damon_design_damos_filters>`. - -In case of the memory cgroup filtering, you can specify the memory cgroup of -the interest by writing the path of the memory cgroup from the cgroups mount -point to ``memcg_path`` file. In case of the address range filtering, you can -specify the start and end address of the range to ``addr_start`` and -``addr_end`` files, respectively. For the DAMON monitoring target filtering, -you can specify the index of the target between the list of the DAMON context's -monitoring targets list to ``target_idx`` file. +Each filter directory contains nine files, namely ``type``, ``matching``, +``allow``, ``memcg_path``, ``addr_start``, ``addr_end``, ``min``, ``max`` +and ``target_idx``. To ``type`` file, you can write the type of the filter. +Refer to :ref:`the design doc <damon_design_damos_filters>` for available type +names, their meaning and on what layer those are handled. + +For ``memcg`` type, you can specify the memory cgroup of the interest by +writing the path of the memory cgroup from the cgroups mount point to +``memcg_path`` file. For ``addr`` type, you can specify the start and end +address of the range (open-ended interval) to ``addr_start`` and ``addr_end`` +files, respectively. For ``hugepage_size`` type, you can specify the minimum +and maximum size of the range (closed interval) to ``min`` and ``max`` files, +respectively. For ``target`` type, you can specify the index of the target +between the list of the DAMON context's monitoring targets list to +``target_idx`` file. You can write ``Y`` or ``N`` to ``matching`` file to specify whether the filter is for memory that matches the ``type``. You can write ``Y`` or ``N`` to @@ -431,6 +505,7 @@ the ``type`` and ``matching`` should be allowed or not. For example, below restricts a DAMOS action to be applied to only non-anonymous pages of all memory cgroups except ``/having_care_already``.:: + # cd ops_filters/0/ # echo 2 > nr_filters # # disallow anonymous pages echo anon > 0/type @@ -447,6 +522,29 @@ Refer to the :ref:`DAMOS filters design documentation of different ``allow`` works, when each of the filters are supported, and differences on stats. +.. _damon_sysfs_dests: + +schemes/<N>/dests/ +------------------ + +Directory for specifying the destinations of given DAMON-based operation +scheme's action. This directory is ignored if the action of the given scheme +is not supporting multiple destinations. Only ``DAMOS_MIGRATE_{HOT,COLD}`` +actions are supporting multiple destinations. + +In the beginning, the directory has only one file, ``nr_dests``. Writing a +number (``N``) to the file creates the number of child directories named ``0`` +to ``N-1``. Each directory represents each action destination. + +Each destination directory contains two files, namely ``id`` and ``weight``. +Users can write and read the identifier of the destination to ``id`` file. +For ``DAMOS_MIGRATE_{HOT,COLD}`` actions, the migrate destination node's node +id should be written to ``id`` file. Users can write and read the weight of +the destination among the given destinations to the ``weight`` file. The +weight can be an arbitrary integer. When DAMOS apply the action to each entity +of the memory region, it will select the destination of the action based on the +relative weights of the destinations. + .. _sysfs_schemes_stats: schemes/<N>/stats/ @@ -458,10 +556,14 @@ online analysis or tuning of the schemes. Refer to :ref:`design doc The statistics can be retrieved by reading the files under ``stats`` directory (``nr_tried``, ``sz_tried``, ``nr_applied``, ``sz_applied``, -``sz_ops_filter_passed``, and ``qt_exceeds``), respectively. The files are not -updated in real time, so you should ask DAMON sysfs interface to update the -content of the files for the stats by writing a special keyword, -``update_schemes_stats`` to the relevant ``kdamonds/<N>/state`` file. +``sz_ops_filter_passed``, ``qt_exceeds``, ``nr_snapshots`` and +``max_nr_snapshots``), respectively. + +The files are not updated in real time by default. Users should ask DAMON +sysfs interface to periodically update those using ``refresh_ms``, or do a one +time update by writing a special keyword, ``update_schemes_stats`` to the +relevant ``kdamonds/<N>/state`` file. Refer to :ref:`kdamond directory +<sysfs_kdamond>` for more details. .. _sysfs_schemes_tried_regions: |