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2010-05-25cpuset,mm: fix no node to alloc memory when changing cpuset's memsMiao Xie
Before applying this patch, cpuset updates task->mems_allowed and mempolicy by setting all new bits in the nodemask first, and clearing all old unallowed bits later. But in the way, the allocator may find that there is no node to alloc memory. The reason is that cpuset rebinds the task's mempolicy, it cleans the nodes which the allocater can alloc pages on, for example: (mpol: mempolicy) task1 task1's mpol task2 alloc page 1 alloc on node0? NO 1 1 change mems from 1 to 0 1 rebind task1's mpol 0-1 set new bits 0 clear disallowed bits alloc on node1? NO 0 ... can't alloc page goto oom This patch fixes this problem by expanding the nodes range first(set newly allowed bits) and shrink it lazily(clear newly disallowed bits). So we use a variable to tell the write-side task that read-side task is reading nodemask, and the write-side task clears newly disallowed nodes after read-side task ends the current memory allocation. [akpm@linux-foundation.org: fix spello] Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Paul Menage <menage@google.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Ravikiran Thirumalai <kiran@scalex86.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-05-18Merge branch 'sched-core-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (49 commits) stop_machine: Move local variable closer to the usage site in cpu_stop_cpu_callback() sched, wait: Use wrapper functions sched: Remove a stale comment ondemand: Make the iowait-is-busy time a sysfs tunable ondemand: Solve a big performance issue by counting IOWAIT time as busy sched: Intoduce get_cpu_iowait_time_us() sched: Eliminate the ts->idle_lastupdate field sched: Fold updating of the last_update_time_info into update_ts_time_stats() sched: Update the idle statistics in get_cpu_idle_time_us() sched: Introduce a function to update the idle statistics sched: Add a comment to get_cpu_idle_time_us() cpu_stop: add dummy implementation for UP sched: Remove rq argument to the tracepoints rcu: need barrier() in UP synchronize_sched_expedited() sched: correctly place paranioa memory barriers in synchronize_sched_expedited() sched: kill paranoia check in synchronize_sched_expedited() sched: replace migration_thread with cpu_stop stop_machine: reimplement using cpu_stop cpu_stop: implement stop_cpu[s]() sched: Fix select_idle_sibling() logic in select_task_rq_fair() ...
2010-05-18Merge branch 'perf-core-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (311 commits) perf tools: Add mode to build without newt support perf symbols: symbol inconsistency message should be done only at verbose=1 perf tui: Add explicit -lslang option perf options: Type check all the remaining OPT_ variants perf options: Type check OPT_BOOLEAN and fix the offenders perf options: Check v type in OPT_U?INTEGER perf options: Introduce OPT_UINTEGER perf tui: Add workaround for slang < 2.1.4 perf record: Fix bug mismatch with -c option definition perf options: Introduce OPT_U64 perf tui: Add help window to show key associations perf tui: Make <- exit menus too perf newt: Add single key shortcuts for zoom into DSO and threads perf newt: Exit browser unconditionally when CTRL+C, q or Q is pressed perf newt: Fix the 'A'/'a' shortcut for annotate perf newt: Make <- exit the ui_browser x86, perf: P4 PMU - fix counters management logic perf newt: Make <- zoom out filters perf report: Report number of events, not samples perf hist: Clarify events_stats fields usage ... Fix up trivial conflicts in kernel/fork.c and tools/perf/builtin-record.c
2010-05-11revert "procfs: provide stack information for threads" and its fixup commitsRobin Holt
Originally, commit d899bf7b ("procfs: provide stack information for threads") attempted to introduce a new feature for showing where the threadstack was located and how many pages are being utilized by the stack. Commit c44972f1 ("procfs: disable per-task stack usage on NOMMU") was applied to fix the NO_MMU case. Commit 89240ba0 ("x86, fs: Fix x86 procfs stack information for threads on 64-bit") was applied to fix a bug in ia32 executables being loaded. Commit 9ebd4eba7 ("procfs: fix /proc/<pid>/stat stack pointer for kernel threads") was applied to fix a bug which had kernel threads printing a userland stack address. Commit 1306d603f ('proc: partially revert "procfs: provide stack information for threads"') was then applied to revert the stack pages being used to solve a significant performance regression. This patch nearly undoes the effect of all these patches. The reason for reverting these is it provides an unusable value in field 28. For x86_64, a fork will result in the task->stack_start value being updated to the current user top of stack and not the stack start address. This unpredictability of the stack_start value makes it worthless. That includes the intended use of showing how much stack space a thread has. Other architectures will get different values. As an example, ia64 gets 0. The do_fork() and copy_process() functions appear to treat the stack_start and stack_size parameters as architecture specific. I only partially reverted c44972f1 ("procfs: disable per-task stack usage on NOMMU") . If I had completely reverted it, I would have had to change mm/Makefile only build pagewalk.o when CONFIG_PROC_PAGE_MONITOR is configured. Since I could not test the builds without significant effort, I decided to not change mm/Makefile. I only partially reverted 89240ba0 ("x86, fs: Fix x86 procfs stack information for threads on 64-bit") . I left the KSTK_ESP() change in place as that seemed worthwhile. Signed-off-by: Robin Holt <holt@sgi.com> Cc: Stefani Seibold <stefani@seibold.net> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Simek <monstr@monstr.eu> Cc: Ingo Molnar <mingo@elte.hu> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-04-23sched: Pre-compute cpumask_weight(sched_domain_span(sd))Peter Zijlstra
Dave reported that his large SPARC machines spend lots of time in hweight64(), try and optimize some of those needless cpumask_weight() invocations (esp. with the large offstack cpumasks these are very expensive indeed). Reported-by: David Miller <davem@davemloft.net> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-04-02sched: Add enqueue/dequeue flagsPeter Zijlstra
In order to reduce the dependency on TASK_WAKING rework the enqueue interface to support a proper flags field. Replace the int wakeup, bool head arguments with an int flags argument and create the following flags: ENQUEUE_WAKEUP - the enqueue is a wakeup of a sleeping task, ENQUEUE_WAKING - the enqueue has relative vruntime due to having sched_class::task_waking() called, ENQUEUE_HEAD - the waking task should be places on the head of the priority queue (where appropriate). For symmetry also convert sched_class::dequeue() to a flags scheme. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-04-02sched: Fix TASK_WAKING vs fork deadlockPeter Zijlstra
Oleg noticed a few races with the TASK_WAKING usage on fork. - since TASK_WAKING is basically a spinlock, it should be IRQ safe - since we set TASK_WAKING (*) without holding rq->lock it could be there still is a rq->lock holder, thereby not actually providing full serialization. (*) in fact we clear PF_STARTING, which in effect enables TASK_WAKING. Cure the second issue by not setting TASK_WAKING in sched_fork(), but only temporarily in wake_up_new_task() while calling select_task_rq(). Cure the first by holding rq->lock around the select_task_rq() call, this will disable IRQs, this however requires that we push down the rq->lock release into select_task_rq_fair()'s cgroup stuff. Because select_task_rq_fair() still needs to drop the rq->lock we cannot fully get rid of TASK_WAKING. Reported-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-04-02sched: _cpu_down(): Don't play with current->cpus_allowedOleg Nesterov
_cpu_down() changes the current task's affinity and then recovers it at the end. The problems are well known: we can't restore old_allowed if it was bound to the now-dead-cpu, and we can race with the userspace which can change cpu-affinity during unplug. _cpu_down() should not play with current->cpus_allowed at all. Instead, take_cpu_down() can migrate the caller of _cpu_down() after __cpu_disable() removes the dying cpu from cpu_online_mask. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20100315091023.GA9148@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-04-02Merge branch 'linus' into sched/coreIngo Molnar
Merge reason: update to latest upstream Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-03-26x86, perf, bts, mm: Delete the never used BTS-ptrace codePeter Zijlstra
Support for the PMU's BTS features has been upstreamed in v2.6.32, but we still have the old and disabled ptrace-BTS, as Linus noticed it not so long ago. It's buggy: TIF_DEBUGCTLMSR is trampling all over that MSR without regard for other uses (perf) and doesn't provide the flexibility needed for perf either. Its users are ptrace-block-step and ptrace-bts, since ptrace-bts was never used and ptrace-block-step can be implemented using a much simpler approach. So axe all 3000 lines of it. That includes the *locked_memory*() APIs in mm/mlock.c as well. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Roland McGrath <roland@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Markus Metzger <markus.t.metzger@intel.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Andrew Morton <akpm@linux-foundation.org> LKML-Reference: <20100325135413.938004390@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-03-13Merge branch 'core-fixes-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: locking: Make sparse work with inline spinlocks and rwlocks x86/mce: Fix RCU lockdep splats rcu: Increase RCU CPU stall timeouts if PROVE_RCU ftrace: Replace read_barrier_depends() with rcu_dereference_raw() rcu: Suppress RCU lockdep warnings during early boot rcu, ftrace: Fix RCU lockdep splat in ftrace_perf_buf_prepare() rcu: Suppress __mpol_dup() false positive from RCU lockdep rcu: Make rcu_read_lock_sched_held() handle !PREEMPT rcu: Add control variables to lockdep_rcu_dereference() diagnostics rcu, cgroup: Relax the check in task_subsys_state() as early boot is now handled by lockdep-RCU rcu: Use wrapper function instead of exporting tasklist_lock sched, rcu: Fix rcu_dereference() for RCU-lockdep rcu: Make task_subsys_state() RCU-lockdep checks handle boot-time use rcu: Fix holdoff for accelerated GPs for last non-dynticked CPU x86/gart: Unexport gart_iommu_aperture Fix trivial conflicts in kernel/trace/ftrace.c
2010-03-12Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (56 commits) doc: fix typo in comment explaining rb_tree usage Remove fs/ntfs/ChangeLog doc: fix console doc typo doc: cpuset: Update the cpuset flag file Fix of spelling in arch/sparc/kernel/leon_kernel.c no longer needed Remove drivers/parport/ChangeLog Remove drivers/char/ChangeLog doc: typo - Table 1-2 should refer to "status", not "statm" tree-wide: fix typos "ass?o[sc]iac?te" -> "associate" in comments No need to patch AMD-provided drivers/gpu/drm/radeon/atombios.h devres/irq: Fix devm_irq_match comment Remove reference to kthread_create_on_cpu tree-wide: Assorted spelling fixes tree-wide: fix 'lenght' typo in comments and code drm/kms: fix spelling in error message doc: capitalization and other minor fixes in pnp doc devres: typo fix s/dev/devm/ Remove redundant trailing semicolons from macros fix typo "definetly" -> "definitely" in comment tree-wide: s/widht/width/g typo in comments ... Fix trivial conflict in Documentation/laptops/00-INDEX
2010-03-12copy_signal() cleanup: clean thread_group_cputime_init()Veaceslav Falico
Remove unneeded initializations in thread_group_cputime_init() and in posix_cpu_timers_init_group(). They are useless after kmem_cache_zalloc() was used in copy_signal(). Signed-off-by: Veaceslav Falico <vfalico@redhat.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-11sched: Remove avg_overlapMike Galbraith
Both avg_overlap and avg_wakeup had an inherent problem in that their accuracy was detrimentally affected by cross-cpu wakeups, this because we are missing the necessary call to update_curr(). This can't be fixed without increasing overhead in our already too fat fastpath. Additionally, with recent load balancing changes making us prefer to place tasks in an idle cache domain (which is good for compute bound loads), communicating tasks suffer when a sync wakeup, which would enable affine placement, is turned into a non-sync wakeup by SYNC_LESS. With one task on the runqueue, wake_affine() rejects the affine wakeup request, leaving the unfortunate where placed, taking frequent cache misses. Remove it, and recover some fastpath cycles. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1268301121.6785.30.camel@marge.simson.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-03-11sched: Remove avg_wakeupMike Galbraith
Testing the load which led to this heuristic (nfs4 kbuild) shows that it has outlived it's usefullness. With intervening load balancing changes, I cannot see any difference with/without, so recover there fastpath cycles. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1268301062.6785.29.camel@marge.simson.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-03-11sched: Rate-limit nohzMike Galbraith
Entering nohz code on every micro-idle is costing ~10% throughput for netperf TCP_RR when scheduling cross-cpu. Rate limiting entry fixes this, but raises ticks a bit. On my Q6600, an idle box goes from ~85 interrupts/sec to 128. The higher the context switch rate, the more nohz entry costs. With this patch and some cycle recovery patches in my tree, max cross cpu context switch rate is improved by ~16%, a large portion of which of which is this ratelimiting. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1268301003.6785.28.camel@marge.simson.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-03-11sched: Implement group scheduler statistics in one structLucas De Marchi
Put all statistic fields of sched_entity in one struct, sched_statistics, and embed it into sched_entity. This change allows to memset the sched_statistics to 0 when needed (for instance when forking), avoiding bugs of non initialized fields. Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1268275065-18542-1-git-send-email-lucas.de.marchi@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-03-08Merge branch 'for-next' into for-linusJiri Kosina
Conflicts: Documentation/filesystems/proc.txt arch/arm/mach-u300/include/mach/debug-macro.S drivers/net/qlge/qlge_ethtool.c drivers/net/qlge/qlge_main.c drivers/net/typhoon.c
2010-03-06mm: avoid false sharing of mm_counterKAMEZAWA Hiroyuki
Considering the nature of per mm stats, it's the shared object among threads and can be a cache-miss point in the page fault path. This patch adds per-thread cache for mm_counter. RSS value will be counted into a struct in task_struct and synchronized with mm's one at events. Now, in this patch, the event is the number of calls to handle_mm_fault. Per-thread value is added to mm at each 64 calls. rough estimation with small benchmark on parallel thread (2threads) shows [before] 4.5 cache-miss/faults [after] 4.0 cache-miss/faults Anyway, the most contended object is mmap_sem if the number of threads grows. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-06mm: clean up mm_counterKAMEZAWA Hiroyuki
Presently, per-mm statistics counter is defined by macro in sched.h This patch modifies it to - defined in mm.h as inlinf functions - use array instead of macro's name creation. This patch is for reducing patch size in future patch to modify implementation of per-mm counter. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-04rcu: Use wrapper function instead of exporting tasklist_lockPaul E. McKenney
Lockdep-RCU commit d11c563d exported tasklist_lock, which is not a good thing. This patch instead exports a function that uses lockdep to check whether tasklist_lock is held. Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com Cc: Christoph Hellwig <hch@lst.de> LKML-Reference: <1267631219-8713-1-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-03-01Merge branch 'for-2.6.34' of git://git.kernel.dk/linux-2.6-blockLinus Torvalds
* 'for-2.6.34' of git://git.kernel.dk/linux-2.6-block: (38 commits) block: don't access jiffies when initialising io_context cfq: remove 8 bytes of padding from cfq_rb_root on 64 bit builds block: fix for "Consolidate phys_segment and hw_segment limits" cfq-iosched: quantum check tweak blktrace: perform cleanup after setup error blkdev: fix merge_bvec_fn return value checks cfq-iosched: requests "in flight" vs "in driver" clarification cciss: Fix problem with scatter gather elements in the scsi half of the driver cciss: eliminate unnecessary pointer use in cciss scsi code cciss: do not use void pointer for scsi hba data cciss: factor out scatter gather chain block mapping code cciss: fix scatter gather chain block dma direction kludge cciss: simplify scatter gather code cciss: factor out scatter gather chain block allocation and freeing cciss: detect bad alignment of scsi commands at build time cciss: clarify command list padding calculation cfq-iosched: rethink seeky detection for SSDs cfq-iosched: rework seeky detection block: remove padding from io_context on 64bit builds block: Consolidate phys_segment and hw_segment limits ...
2010-02-23blk-core: use BIO list management functionsAkinobu Mita
Now that the bio list management stuff is generic, convert generic_make_request to use bio lists instead of its own private bio list implementation. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2010-02-16Merge branch 'sched/urgent' into sched/coreThomas Gleixner
Conflicts: kernel/sched.c Necessary due to the urgent fixes which conflict with the code move from sched.c to sched_fair.c Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-02-16sched: Fix sched_mv_power_savings for !SMTVaidyanathan Srinivasan
Fix for sched_mc_powersavigs for pre-Nehalem platforms. Child sched domain should clear SD_PREFER_SIBLING if parent will have SD_POWERSAVINGS_BALANCE because they are contradicting. Sets the flags correctly based on sched_mc_power_savings. Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20100208100555.GD2931@dirshya.in.ibm.com> Cc: stable@kernel.org [2.6.32.x] Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-02-09tree-wide: Assorted spelling fixesDaniel Mack
In particular, several occurances of funny versions of 'success', 'unknown', 'therefore', 'acknowledge', 'argument', 'achieve', 'address', 'beginning', 'desirable', 'separate' and 'necessary' are fixed. Signed-off-by: Daniel Mack <daniel@caiaq.de> Cc: Joe Perches <joe@perches.com> Cc: Junio C Hamano <gitster@pobox.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2010-02-08Merge branch 'sched/urgent' into sched/coreIngo Molnar
Merge reason: Merge dependent fix, update to latest -rc. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-02-04Merge branch 'core-fixes-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: futex: Handle futex value corruption gracefully futex: Handle user space corruption gracefully futex_lock_pi() key refcnt fix softlockup: Add sched_clock_tick() to avoid kernel warning on kgdb resume
2010-02-01softlockup: Add sched_clock_tick() to avoid kernel warning on kgdb resumeJason Wessel
When CONFIG_HAVE_UNSTABLE_SCHED_CLOCK is set, sched_clock() gets the time from hardware such as the TSC on x86. In this configuration kgdb will report a softlock warning message on resuming or detaching from a debug session. Sequence of events in the problem case: 1) "cpu sched clock" and "hardware time" are at 100 sec prior to a call to kgdb_handle_exception() 2) Debugger waits in kgdb_handle_exception() for 80 sec and on exit the following is called ... touch_softlockup_watchdog() --> __raw_get_cpu_var(touch_timestamp) = 0; 3) "cpu sched clock" = 100s (it was not updated, because the interrupt was disabled in kgdb) but the "hardware time" = 180 sec 4) The first timer interrupt after resuming from kgdb_handle_exception updates the watchdog from the "cpu sched clock" update_process_times() { ... run_local_timers() --> softlockup_tick() --> check (touch_timestamp == 0) (it is "YES" here, we have set "touch_timestamp = 0" at kgdb) --> __touch_softlockup_watchdog() ***(A)--> reset "touch_timestamp" to "get_timestamp()" (Here, the "touch_timestamp" will still be set to 100s.) ... scheduler_tick() ***(B)--> sched_clock_tick() (update "cpu sched clock" to "hardware time" = 180s) ... } 5) The Second timer interrupt handler appears to have a large jump and trips the softlockup warning. update_process_times() { ... run_local_timers() --> softlockup_tick() --> "cpu sched clock" - "touch_timestamp" = 180s-100s > 60s --> printk "soft lockup error messages" ... } note: ***(A) reset "touch_timestamp" to "get_timestamp(this_cpu)" Why is "touch_timestamp" 100 sec, instead of 180 sec? When CONFIG_HAVE_UNSTABLE_SCHED_CLOCK is set, the call trace of get_timestamp() is: get_timestamp(this_cpu) -->cpu_clock(this_cpu) -->sched_clock_cpu(this_cpu) -->__update_sched_clock(sched_clock_data, now) The __update_sched_clock() function uses the GTOD tick value to create a window to normalize the "now" values. So if "now" value is too big for sched_clock_data, it will be ignored. The fix is to invoke sched_clock_tick() to update "cpu sched clock" in order to recover from this state. This is done by introducing the function touch_softlockup_watchdog_sync(). This allows kgdb to request that the sched clock is updated when the watchdog thread runs the first time after a resume from kgdb. [yong.zhang0@gmail.com: Use per cpu instead of an array] Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Dongdong Deng <Dongdong.Deng@windriver.com> Cc: kgdb-bugreport@lists.sourceforge.net Cc: peterz@infradead.org LKML-Reference: <1264631124-4837-2-git-send-email-jason.wessel@windriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-01-29Split 'flush_old_exec' into two functionsLinus Torvalds
'flush_old_exec()' is the point of no return when doing an execve(), and it is pretty badly misnamed. It doesn't just flush the old executable environment, it also starts up the new one. Which is very inconvenient for things like setting up the new personality, because we want the new personality to affect the starting of the new environment, but at the same time we do _not_ want the new personality to take effect if flushing the old one fails. As a result, the x86-64 '32-bit' personality is actually done using this insane "I'm going to change the ABI, but I haven't done it yet" bit (TIF_ABI_PENDING), with SET_PERSONALITY() not actually setting the personality, but just the "pending" bit, so that "flush_thread()" can do the actual personality magic. This patch in no way changes any of that insanity, but it does split the 'flush_old_exec()' function up into a preparatory part that can fail (still called flush_old_exec()), and a new part that will actually set up the new exec environment (setup_new_exec()). All callers are changed to trivially comply with the new world order. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-01-22sched: Extend enqueue_task to allow head queueingThomas Gleixner
The ability of enqueueing a task to the head of a SCHED_FIFO priority list is required to fix some violations of POSIX scheduling policy. Extend the related functions with a "head" argument. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Tested-by: Carsten Emde <cbe@osadl.org> Tested-by: Mathias Weber <mathias.weber.mw1@roche.com> LKML-Reference: <20100120171629.734886007@linutronix.de>
2010-01-21sched: Remove USER_SCHEDDhaval Giani
Remove the USER_SCHED feature. It has been scheduled to be removed in 2.6.34 as per http://marc.info/?l=linux-kernel&m=125728479022976&w=2 Signed-off-by: Dhaval Giani <dhaval.giani@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1263990378.24844.3.camel@localhost> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-01-21sched: Remove the sched_class load_balance methodsPeter Zijlstra
Take out the sched_class methods for load-balancing. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-01-16nommu: don't need get_unmapped_area() for NOMMUDavid Howells
get_unmapped_area() is unnecessary for NOMMU as no-one calls it. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Greg Ungerer <gerg@snapgear.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-01-04resource: add helpers for fetching rlimitsJiri Slaby
We want to be sure that compiler fetches the limit variable only once, so add helpers for fetching current and maximal resource limits which do that. Add them to sched.h (instead of resource.h) due to circular dependency sched.h->resource.h->task_struct Alternative would be to create a separate res_access.h or similar. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: James Morris <jmorris@namei.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>
2009-12-19Merge branch 'sched-fixes-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (25 commits) sched: Fix broken assertion sched: Assert task state bits at build time sched: Update task_state_arraypwith new states sched: Add missing state chars to TASK_STATE_TO_CHAR_STR sched: Move TASK_STATE_TO_CHAR_STR near the TASK_state bits sched: Teach might_sleep() about preemptible RCU sched: Make warning less noisy sched: Simplify set_task_cpu() sched: Remove the cfs_rq dependency from set_task_cpu() sched: Add pre and post wakeup hooks sched: Move kthread_bind() back to kthread.c sched: Fix select_task_rq() vs hotplug issues sched: Fix sched_exec() balancing sched: Ensure set_task_cpu() is never called on blocked tasks sched: Use TASK_WAKING for fork wakups sched: Select_task_rq_fair() must honour SD_LOAD_BALANCE sched: Fix task_hot() test order sched: Fix set_cpu_active() in cpu_down() sched: Mark boot-cpu active before smp_init() sched: Fix cpu_clock() in NMIs, on !CONFIG_HAVE_UNSTABLE_SCHED_CLOCK ...
2009-12-17Merge branch 'cpumask-cleanups' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus * 'cpumask-cleanups' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus: cpumask: rename tsk_cpumask to tsk_cpus_allowed cpumask: don't recommend set_cpus_allowed hack in Documentation/cpu-hotplug.txt cpumask: avoid dereferencing struct cpumask cpumask: convert drivers/idle/i7300_idle.c to cpumask_var_t cpumask: use modern cpumask style in drivers/scsi/fcoe/fcoe.c cpumask: avoid deprecated function in mm/slab.c cpumask: use cpu_online in kernel/perf_event.c
2009-12-17Revert "task_struct: make journal_info conditional"Linus Torvalds
This reverts commit e4c570c4cb7a95dbfafa3d016d2739bf3fdfe319, as requested by Alexey: "I think I gave a good enough arguments to not merge it. To iterate: * patch makes impossible to start using ext3 on EXT3_FS=n kernels without reboot. * this is done only for one pointer on task_struct" None of config options which define task_struct are tristate directly or effectively." Requested-by: Alexey Dobriyan <adobriyan@gmail.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-17sched: Assert task state bits at build timePeter Zijlstra
Since everybody is lazy and prone to forgetting things, make the compiler help us a bit. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20091217121830.060186433@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-12-17sched: Add missing state chars to TASK_STATE_TO_CHAR_STRPeter Zijlstra
We grew 3 new task states since the last time someone touched it. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20091217121829.892737686@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-12-17sched: Move TASK_STATE_TO_CHAR_STR near the TASK_state bitsPeter Zijlstra
So that we don't keep forgetting about it. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20091217121829.815779372@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-12-17cpumask: rename tsk_cpumask to tsk_cpus_allowedRusty Russell
Noone uses this wrapper yet, and Ingo asked that it be kept consistent with current task_struct usage. (One user crept in via linux-next: fixed) Signed-off-by: Rusty Russell <rusty@rustcorp.com.au. Cc: Ingo Molnar <mingo@elte.hu> Cc: Tejun Heo <tj@kernel.org>
2009-12-16sched: Remove the cfs_rq dependency from set_task_cpu()Peter Zijlstra
In order to remove the cfs_rq dependency from set_task_cpu() we need to ensure the task is cfs_rq invariant for all callsites. The simple approach is to substract cfs_rq->min_vruntime from se->vruntime on dequeue, and add cfs_rq->min_vruntime on enqueue. However, this has the downside of breaking FAIR_SLEEPERS since we loose the old vruntime as we only maintain the relative position. To solve this, we observe that we only migrate runnable tasks, we do this using deactivate_task(.sleep=0) and activate_task(.wakeup=0), therefore we can restrain the min_vruntime invariance to that state. The only other case is wakeup balancing, since we want to maintain the old vruntime we cannot make it relative on dequeue, but since we don't migrate inactive tasks, we can do so right before we activate it again. This is where we need the new pre-wakeup hook, we need to call this while still holding the old rq->lock. We could fold it into ->select_task_rq(), but since that has multiple callsites and would obfuscate the locking requirements, that seems like a fudge. This leaves the fork() case, simply make sure that ->task_fork() leaves the ->vruntime in a relative state. This covers all cases where set_task_cpu() gets called, and ensures it sees a relative vruntime. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> LKML-Reference: <20091216170518.191697025@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-12-16sched: Add pre and post wakeup hooksPeter Zijlstra
As will be apparent in the next patch, we need a pre wakeup hook for sched_fair task migration, hence rename the post wakeup hook and one pre wakeup. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> LKML-Reference: <20091216170518.114746117@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-12-16signals: kill force_sig_specific()Oleg Nesterov
Kill force_sig_specific(), this trivial wrapper has no callers. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Roland McGrath <roland@redhat.com> Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-16signals: SEND_SIG_NOINFO should be considered as SI_FROMUSER()Oleg Nesterov
No changes in compiled code. The patch adds the new helper, si_fromuser() and changes check_kill_permission() to use this helper. The real effect of this patch is that from now we "officially" consider SEND_SIG_NOINFO signal as "from user-space" signals. This is already true if we look at the code which uses SEND_SIG_NOINFO, except __send_signal() has another opinion - see the next patch. The naming of these special SEND_SIG_XXX siginfo's is really bad imho. From __send_signal()'s pov they mean SEND_SIG_NOINFO from user SEND_SIG_PRIV from kernel SEND_SIG_FORCED no info Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Roland McGrath <roland@redhat.com> Reviewed-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-16memcg: coalesce uncharge during unmap/truncateKAMEZAWA Hiroyuki
In massive parallel enviroment, res_counter can be a performance bottleneck. One strong techinque to reduce lock contention is reducing calls by coalescing some amount of calls into one. Considering charge/uncharge chatacteristic, - charge is done one by one via demand-paging. - uncharge is done by - in chunk at munmap, truncate, exit, execve... - one by one via vmscan/paging. It seems we have a chance to coalesce uncharges for improving scalability at unmap/truncation. This patch is a for coalescing uncharge. For avoiding scattering memcg's structure to functions under /mm, this patch adds memcg batch uncharge information to the task. A reason for per-task batching is for making use of caller's context information. We do batched uncharge (deleyed uncharge) when truncation/unmap occurs but do direct uncharge when uncharge is called by memory reclaim (vmscan.c). The degree of coalescing depends on callers - at invalidate/trucate... pagevec size - at unmap ....ZAP_BLOCK_SIZE (memory itself will be freed in this degree.) Then, we'll not coalescing too much. On x86-64 8cpu server, I tested overheads of memcg at page fault by running a program which does map/fault/unmap in a loop. Running a task per a cpu by taskset and see sum of the number of page faults in 60secs. [without memcg config] 40156968 page-faults # 0.085 M/sec ( +- 0.046% ) 27.67 cache-miss/faults [root cgroup] 36659599 page-faults # 0.077 M/sec ( +- 0.247% ) 31.58 miss/faults [in a child cgroup] 18444157 page-faults # 0.039 M/sec ( +- 0.133% ) 69.96 miss/faults [child with this patch] 27133719 page-faults # 0.057 M/sec ( +- 0.155% ) 47.16 miss/faults We can see some amounts of improvement. (root cgroup doesn't affected by this patch) Another patch for "charge" will follow this and above will be improved more. Changelog(since 2009/10/02): - renamed filed of memcg_batch (as pages to bytes, memsw to memsw_bytes) - some clean up and commentary/description updates. - added initialize code to copy_process(). (possible bug fix) Changelog(old): - fixed !CONFIG_MEM_CGROUP case. - rebased onto the latest mmotm + softlimit fix patches. - unified patch for callers - added commetns. - make ->do_batch as bool. - removed css_get() at el. We don't need it. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15Merge branch 'core-locking-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (26 commits) clockevents: Convert to raw_spinlock clockevents: Make tick_device_lock static debugobjects: Convert to raw_spinlocks perf_event: Convert to raw_spinlock hrtimers: Convert to raw_spinlocks genirq: Convert irq_desc.lock to raw_spinlock smp: Convert smplocks to raw_spinlocks rtmutes: Convert rtmutex.lock to raw_spinlock sched: Convert pi_lock to raw_spinlock sched: Convert cpupri lock to raw_spinlock sched: Convert rt_runtime_lock to raw_spinlock sched: Convert rq->lock to raw_spinlock plist: Make plist debugging raw_spinlock aware bkl: Fixup core_lock fallout locking: Cleanup the name space completely locking: Further name space cleanups alpha: Fix fallout from locking changes locking: Implement new raw_spinlock locking: Convert raw_rwlock functions to arch_rwlock locking: Convert raw_rwlock to arch_rwlock ...
2009-12-15task_struct: make journal_info conditionalHiroshi Shimamoto
journal_info in task_struct is used in journaling file system only. So introduce CONFIG_FS_JOURNAL_INFO and make it conditional. Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-14sched: Convert pi_lock to raw_spinlockThomas Gleixner
Convert locks which cannot be sleeping locks in preempt-rt to raw_spinlocks. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Ingo Molnar <mingo@elte.hu>