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* Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds2012-10-121-0/+69
|\ | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar: "A CPU hotplug related crash fix and a nohz accounting fixlet." * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Update sched_domains_numa_masks[][] when new cpus are onlined sched: Ensure 'sched_domains_numa_levels' is safe to use in other functions nohz: Fix one jiffy count too far in idle cputime
| * sched: Update sched_domains_numa_masks[][] when new cpus are onlinedTang Chen2012-10-051-0/+56
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Once array sched_domains_numa_masks[] []is defined, it is never updated. When a new cpu on a new node is onlined, the coincident member in sched_domains_numa_masks[][] is not initialized, and all the masks are 0. As a result, the build_overlap_sched_groups() will initialize a NULL sched_group for the new cpu on the new node, which will lead to kernel panic: [ 3189.403280] Call Trace: [ 3189.403286] [<ffffffff8106c36f>] warn_slowpath_common+0x7f/0xc0 [ 3189.403289] [<ffffffff8106c3ca>] warn_slowpath_null+0x1a/0x20 [ 3189.403292] [<ffffffff810b1d57>] build_sched_domains+0x467/0x470 [ 3189.403296] [<ffffffff810b2067>] partition_sched_domains+0x307/0x510 [ 3189.403299] [<ffffffff810b1ea2>] ? partition_sched_domains+0x142/0x510 [ 3189.403305] [<ffffffff810fcc93>] cpuset_update_active_cpus+0x83/0x90 [ 3189.403308] [<ffffffff810b22a8>] cpuset_cpu_active+0x38/0x70 [ 3189.403316] [<ffffffff81674b87>] notifier_call_chain+0x67/0x150 [ 3189.403320] [<ffffffff81664647>] ? native_cpu_up+0x18a/0x1b5 [ 3189.403328] [<ffffffff810a044e>] __raw_notifier_call_chain+0xe/0x10 [ 3189.403333] [<ffffffff81070470>] __cpu_notify+0x20/0x40 [ 3189.403337] [<ffffffff8166663e>] _cpu_up+0xe9/0x131 [ 3189.403340] [<ffffffff81666761>] cpu_up+0xdb/0xee [ 3189.403348] [<ffffffff8165667c>] store_online+0x9c/0xd0 [ 3189.403355] [<ffffffff81437640>] dev_attr_store+0x20/0x30 [ 3189.403361] [<ffffffff8124aa63>] sysfs_write_file+0xa3/0x100 [ 3189.403368] [<ffffffff811ccbe0>] vfs_write+0xd0/0x1a0 [ 3189.403371] [<ffffffff811ccdb4>] sys_write+0x54/0xa0 [ 3189.403375] [<ffffffff81679c69>] system_call_fastpath+0x16/0x1b [ 3189.403377] ---[ end trace 1e6cf85d0859c941 ]--- [ 3189.403398] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 This patch registers a new notifier for cpu hotplug notify chain, and updates sched_domains_numa_masks every time a new cpu is onlined or offlined. Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> [ fixed compile warning ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1348578751-16904-3-git-send-email-tangchen@cn.fujitsu.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * sched: Ensure 'sched_domains_numa_levels' is safe to use in other functionsTang Chen2012-10-051-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We should temporarily reset 'sched_domains_numa_levels' to 0 after it is reset to 'level' in sched_init_numa(). If it fails to allocate memory for array sched_domains_numa_masks[][], the array will contain less then 'level' members. This could be dangerous when we use it to iterate array sched_domains_numa_masks[][] in other functions. This patch set sched_domains_numa_levels to 0 before initializing array sched_domains_numa_masks[][], and reset it to 'level' when sched_domains_numa_masks[][] is fully initialized. Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1348578751-16904-2-git-send-email-tangchen@cn.fujitsu.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | Merge branch 'for-linus' of ↵Linus Torvalds2012-10-121-1/+1
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal Pull pile 2 of execve and kernel_thread unification work from Al Viro: "Stuff in there: kernel_thread/kernel_execve/sys_execve conversions for several more architectures plus assorted signal fixes and cleanups. There'll be more (in particular, real fixes for the alpha do_notify_resume() irq mess)..." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal: (43 commits) alpha: don't open-code trace_report_syscall_{enter,exit} Uninclude linux/freezer.h m32r: trim masks avr32: trim masks tile: don't bother with SIGTRAP in setup_frame microblaze: don't bother with SIGTRAP in setup_rt_frame() mn10300: don't bother with SIGTRAP in setup_frame() frv: no need to raise SIGTRAP in setup_frame() x86: get rid of duplicate code in case of CONFIG_VM86 unicore32: remove pointless test h8300: trim _TIF_WORK_MASK parisc: decide whether to go to slow path (tracesys) based on thread flags parisc: don't bother looping in do_signal() parisc: fix double restarts bury the rest of TIF_IRET sanitize tsk_is_polling() bury _TIF_RESTORE_SIGMASK unicore32: unobfuscate _TIF_WORK_MASK mips: NOTIFY_RESUME is not needed in TIF masks mips: merge the identical "return from syscall" per-ABI code ... Conflicts: arch/arm/include/asm/thread_info.h
| * sanitize tsk_is_polling()Al Viro2012-10-011-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | Make default just return 0. The current default (checking TIF_POLLING_NRFLAG) is taken to architectures that need it; ones that don't do polling in their idle threads don't need to defined TIF_POLLING_NRFLAG at all. ia64 defined both TS_POLLING (used by its tsk_is_polling()) and TIF_POLLING_NRFLAG (not used at all). Killed the latter... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | Merge branch 'sched-core-for-linus' of ↵Linus Torvalds2012-10-017-693/+679
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler changes from Ingo Molnar: "Continued quest to clean up and enhance the cputime code by Frederic Weisbecker, in preparation for future tickless kernel features. Other than that, smallish changes." Fix up trivial conflicts due to additions next to each other in arch/{x86/}Kconfig * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) cputime: Make finegrained irqtime accounting generally available cputime: Gather time/stats accounting config options into a single menu ia64: Reuse system and user vtime accounting functions on task switch ia64: Consolidate user vtime accounting vtime: Consolidate system/idle context detection cputime: Use a proper subsystem naming for vtime related APIs sched: cpu_power: enable ARCH_POWER sched/nohz: Clean up select_nohz_load_balancer() sched: Fix load avg vs. cpu-hotplug sched: Remove __ARCH_WANT_INTERRUPTS_ON_CTXSW sched: Fix nohz_idle_balance() sched: Remove useless code in yield_to() sched: Add time unit suffix to sched sysctl knobs sched/debug: Limit sd->*_idx range on sysctl sched: Remove AFFINE_WAKEUPS feature flag s390: Remove leftover account_tick_vtime() header cputime: Consolidate vtime handling on context switch sched: Move cputime code to its own file cputime: Generalize CONFIG_VIRT_CPU_ACCOUNTING tile: Remove SD_PREFER_LOCAL leftover ...
| * | vtime: Consolidate system/idle context detectionFrederic Weisbecker2012-09-251-0/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Move the code that finds out to which context we account the cputime into generic layer. Archs that consider the whole time spent in the idle task as idle time (ia64, powerpc) can rely on the generic vtime_account() and implement vtime_account_system() and vtime_account_idle(), letting the generic code to decide when to call which API. Archs that have their own meaning of idle time, such as s390 that only considers the time spent in CPU low power mode as idle time, can just override vtime_account(). Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org>
| * | cputime: Use a proper subsystem naming for vtime related APIsFrederic Weisbecker2012-09-252-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Use a naming based on vtime as a prefix for virtual based cputime accounting APIs: - account_system_vtime() -> vtime_account() - account_switch_vtime() -> vtime_task_switch() It makes it easier to allow for further declension such as vtime_account_system(), vtime_account_idle(), ... if we want to find out the context we account to from generic code. This also make it better to know on which subsystem these APIs refer to. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org>
| * | sched: cpu_power: enable ARCH_POWERVincent Guittot2012-09-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Heteregeneous ARM platform uses arch_scale_freq_power function to reflect the relative capacity of each core Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1341826026-6504-6-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/nohz: Clean up select_nohz_load_balancer()Alex Shi2012-09-131-15/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is no load_balancer to be selected now. It just sets the state of the nohz tick to stop. So rename the function, pass the 'cpu' as a parameter and then remove the useless call from tick_nohz_restart_sched_tick(). [ s/set_nohz_tick_stopped/nohz_balance_enter_idle/g s/clear_nohz_tick_stopped/nohz_balance_exit_idle/g ] Signed-off-by: Alex Shi <alex.shi@intel.com> Acked-by: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Venkatesh Pallipadi <venki@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1347261059-24747-1-git-send-email-alex.shi@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Fix load avg vs. cpu-hotplugPeter Zijlstra2012-09-131-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit f319da0c68 ("sched: Fix load avg vs cpu-hotplug") was an incomplete fix: In particular, the problem is that at the point it calls calc_load_migrate() nr_running := 1 (the stopper thread), so move the call to CPU_DEAD where we're sure that nr_running := 0. Also note that we can call calc_load_migrate() without serialization, we know the state of rq is stable since its cpu is dead, and we modify the global state using appropriate atomic ops. Suggested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1346882630.2600.59.camel@twins Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Remove __ARCH_WANT_INTERRUPTS_ON_CTXSWPeter Zijlstra2012-09-133-50/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now that the last architecture to use this has stopped doing so (ARM, thanks Catalin!) we can remove this complexity from the scheduler core. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Link: http://lkml.kernel.org/n/tip-g9p2a1w81xxbrze25v9zpzbf@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Fix nohz_idle_balance()Vincent Guittot2012-09-131-5/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On tickless systems, one CPU runs load balance for all idle CPUs. The cpu_load of this CPU is updated before starting the load balance of each other idle CPUs. We should instead update the cpu_load of the balance_cpu. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Venkatesh Pallipadi <venki@google.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Link: http://lkml.kernel.org/r/1347509486-8688-1-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Remove useless code in yield_to()Michael Wang2012-09-041-7/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It's impossible to enter the else branch if we have set skip_clock_update in task_yield_fair(), as yield_to_task_fair() will directly return true after invoke task_yield_fair(). Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com> Acked-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/4FF2925A.9060005@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/debug: Limit sd->*_idx range on sysctlNamhyung Kim2012-09-041-13/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Various sd->*_idx's are used for refering the rq's load average table when selecting a cpu to run. However they can be set to any number with sysctl knobs so that it can crash the kernel if something bad is given. Fix it by limiting them into the actual range. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1345104204-8317-1-git-send-email-namhyung@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Remove AFFINE_WAKEUPS feature flagNamhyung Kim2012-09-041-8/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit beac4c7e4a1c ("sched: Remove AFFINE_WAKEUPS feature") removed use of the flag but left the definition. Get rid of it. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> Link: http://lkml.kernel.org/r/1345090865-20851-1-git-send-email-namhyung@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | Merge branch 'sched/urgent' into sched/coreIngo Molnar2012-09-044-29/+16
| |\ \ | | | | | | | | | | | | | | | | | | | | Merge in the current fixes branch, we are going to apply dependent patches. Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | cputime: Consolidate vtime handling on context switchFrederic Weisbecker2012-08-201-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The archs that implement virtual cputime accounting all flush the cputime of a task when it gets descheduled and sometimes set up some ground initialization for the next task to account its cputime. These archs all put their own hooks in their context switch callbacks and handle the off-case themselves. Consolidate this by creating a new account_switch_vtime() callback called in generic code right after a context switch and that these archs must implement to flush the prev task cputime and initialize the next task cputime related state. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org>
| * | | sched: Move cputime code to its own fileFrederic Weisbecker2012-08-204-556/+570
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Extract cputime code from the giant sched/core.c and put it in its own file. This make it easier to deal with this particular area and de-bloat a bit more core.c Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org>
| * | | sched: recover SD_WAKE_AFFINE in select_task_rq_fair and code clean upAlex Shi2012-08-132-32/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since power saving code was removed from sched now, the implement code is out of service in this function, and even pollute other logical. like, 'want_sd' never has chance to be set '0', that remove the effect of SD_WAKE_AFFINE here. So, clean up the obsolete code, includes SD_PREFER_LOCAL. Signed-off-by: Alex Shi <alex.shi@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/5028F431.6000306@intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | | sched: using dst_rq instead of this_rq during load balanceMichael Wang2012-08-131-5/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As we already have dst_rq in lb_env, using or changing "this_rq" do not make sense. This patch will replace "this_rq" with dst_rq in load_balance, and we don't need to change "this_rq" while process LBF_SOME_PINNED any more. Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/501F8357.3070102@linux.vnet.ibm.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | | sched: Document schedule() entry pointsPekka Enberg2012-08-131-0/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds a comment on top of the schedule() function to explain to scheduler newbies how the main scheduler function is entered. Acked-by: Randy Dunlap <rdunlap@xenotime.net> Explained-by: Ingo Molnar <mingo@kernel.org> Explained-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Pekka Enberg <penberg@kernel.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1344070187-2420-1-git-send-email-penberg@kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | | sched: Fix __sched_period commentBorislav Petkov2012-08-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It should be sched_nr_latency so fix it before it annoys me more. Signed-off-by: Borislav Petkov <borislav.petkov@amd.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1344435364-18632-1-git-send-email-bp@amd64.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | | Merge branch 'sched/urgent' into sched/coreThomas Gleixner2012-08-135-19/+70
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* | | | | rcu: Exit RCU extended QS on user preemptionFrederic Weisbecker2012-09-261-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When exceptions or irq are about to resume userspace, if the task needs to be rescheduled, the arch low level code calls schedule() directly. If we call it, it is because we have the TIF_RESCHED flag: - It can be set after random local calls to set_need_resched() (RCU, drm, ...) - A wake up happened and the CPU needs preemption. This can happen in several ways: * Remotely: the remote waking CPU has set TIF_RESCHED and send the wakee an IPI to schedule the new task. * Remotely enqueued: the remote waking CPU sends an IPI to the target and the wake up is made by the target. * Locally: waking CPU == wakee CPU and the wakeup is done locally. set_need_resched() is called without IPI. In the case of local and remotely enqueued wake ups, the tick can be restarted when we enqueue the new task and RCU can exit the extended quiescent state at the same time. Then by the time we reach irq exit path and we call schedule, we are not in RCU user mode. But if we call schedule() only because something called set_need_resched(), RCU may still be in user mode when we reach schedule. Also if a wake up is done remotely, the CPU might see the TIF_RESCHED flag and call schedule while the IPI has not yet happen to restart the tick and exit RCU user mode. We need to manually protect against these corner cases. Create a new API schedule_user() that calls schedule() inside rcu_user_exit()-rcu_user_enter() in order to protect it. Archs will need to rely on it now to implement user preemption safely. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Alessio Igor Bogani <abogani@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Avi Kivity <avi@redhat.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Kevin Hilman <khilman@ti.com> Cc: Max Krasnyansky <maxk@qualcomm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Hemminger <shemminger@vyatta.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* | | | | rcu: Exit RCU extended QS on kernel preemption after irq/exceptionFrederic Weisbecker2012-09-261-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When an exception or an irq exits, and we are going to resume into interrupted kernel code, the low level architecture code calls preempt_schedule_irq() if there is a need to reschedule. If the interrupt/exception occured between a call to rcu_user_enter() (from syscall exit, exception exit, do_notify_resume exit, ...) and a real resume to userspace (iret,...), preempt_schedule_irq() can be called whereas RCU thinks we are in userspace. But preempt_schedule_irq() is going to run kernel code and may be some RCU read side critical section. We must exit the userspace extended quiescent state before we call it. To solve this, just call rcu_user_exit() in the beginning of preempt_schedule_irq(). Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Alessio Igor Bogani <abogani@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Avi Kivity <avi@redhat.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Kevin Hilman <khilman@ti.com> Cc: Max Krasnyansky <maxk@qualcomm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Hemminger <shemminger@vyatta.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* | | | | rcu: Switch task's syscall hooks on context switchFrederic Weisbecker2012-09-261-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Clear the syscalls hook of a task when it's scheduled out so that if the task migrates, it doesn't run the syscall slow path on a CPU that might not need it. Also set the syscalls hook on the next task if needed. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Alessio Igor Bogani <abogani@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Avi Kivity <avi@redhat.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Kevin Hilman <khilman@ti.com> Cc: Max Krasnyansky <maxk@qualcomm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Hemminger <shemminger@vyatta.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* | | | | Merge remote-tracking branch 'tip/core/rcu' into next.2012.09.25bPaul E. McKenney2012-09-254-62/+29
|\ \ \ \ \ | | |_|_|/ | |/| | | | | | | | | | | | | Resolved conflict in kernel/sched/core.c using Peter Zijlstra's approach from https://lkml.org/lkml/2012/9/5/585.
| * | | | Revert "sched: Improve scalability via 'CPU buddies', which withstand random ↵Linus Torvalds2012-09-162-45/+22
| | |_|/ | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | perturbations" This reverts commit 970e178985cadbca660feb02f4d2ee3a09f7fdda. Nikolay Ulyanitsky reported thatthe 3.6-rc5 kernel has a 15-20% performance drop on PostgreSQL 9.2 on his machine (running "pgbench"). Borislav Petkov was able to reproduce this, and bisected it to this commit 970e178985ca ("sched: Improve scalability via 'CPU buddies' ...") apparently because the new single-idle-buddy model simply doesn't find idle CPU's to reschedule on aggressively enough. Mike Galbraith suspects that it is likely due to the user-mode spinlocks in PostgreSQL not reacting well to preemption, but we don't really know the details - I'll just revert the commit for now. There are hopefully other approaches to improve scheduler scalability without it causing these kinds of downsides. Reported-by: Nikolay Ulyanitsky <lystor@gmail.com> Bisected-by: Borislav Petkov <bp@alien8.de> Acked-by: Mike Galbraith <efault@gmx.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * | | sched: Fix kernel-doc warnings in kernel/sched/fair.cRandy Dunlap2012-09-041-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix two kernel-doc warnings in kernel/sched/fair.c: Warning(kernel/sched/fair.c:3660): Excess function parameter 'cpus' description in 'update_sg_lb_stats' Warning(kernel/sched/fair.c:3806): Excess function parameter 'cpus' description in 'update_sd_lb_stats' Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/50303714.3090204@xenotime.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | sched: Unthrottle rt runqueues in __disable_runtime()Peter Boonstoppel2012-09-044-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | migrate_tasks() uses _pick_next_task_rt() to get tasks from the real-time runqueues to be migrated. When rt_rq is throttled _pick_next_task_rt() won't return anything, in which case migrate_tasks() can't move all threads over and gets stuck in an infinite loop. Instead unthrottle rt runqueues before migrating tasks. Additionally: move unthrottle_offline_cfs_rqs() to rq_offline_fair() Signed-off-by: Peter Boonstoppel <pboonstoppel@nvidia.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Turner <pjt@google.com> Link: http://lkml.kernel.org/r/5FBF8E85CA34454794F0F7ECBA79798F379D3648B7@HQMAIL04.nvidia.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | sched: Fix load avg vs cpu-hotplugPeter Zijlstra2012-09-041-21/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rabik and Paul reported two different issues related to the same few lines of code. Rabik's issue is that the nr_uninterruptible migration code is wrong in that he sees artifacts due to this (Rabik please do expand in more detail). Paul's issue is that this code as it stands relies on us using stop_machine() for unplug, we all would like to remove this assumption so that eventually we can remove this stop_machine() usage altogether. The only reason we'd have to migrate nr_uninterruptible is so that we could use for_each_online_cpu() loops in favour of for_each_possible_cpu() loops, however since nr_uninterruptible() is the only such loop and its using possible lets not bother at all. The problem Rabik sees is (probably) caused by the fact that by migrating nr_uninterruptible we screw rq->calc_load_active for both rqs involved. So don't bother with fancy migration schemes (meaning we now have to keep using for_each_possible_cpu()) and instead fold any nr_active delta after we migrate all tasks away to make sure we don't have any skewed nr_active accounting. Reported-by: Rakib Mullick <rakib.mullick@gmail.com> Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1345454817.23018.27.camel@twins Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | | sched: Fix load avg vs cpu-hotplugPeter Zijlstra2012-09-231-21/+20
|/ / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rabik and Paul reported two different issues related to the same few lines of code. Rabik's issue is that the nr_uninterruptible migration code is wrong in that he sees artifacts due to this (Rabik please do expand in more detail). Paul's issue is that this code as it stands relies on us using stop_machine() for unplug, we all would like to remove this assumption so that eventually we can remove this stop_machine() usage altogether. The only reason we'd have to migrate nr_uninterruptible is so that we could use for_each_online_cpu() loops in favour of for_each_possible_cpu() loops, however since nr_uninterruptible() is the only such loop and its using possible lets not bother at all. The problem Rabik sees is (probably) caused by the fact that by migrating nr_uninterruptible we screw rq->calc_load_active for both rqs involved. So don't bother with fancy migration schemes (meaning we now have to keep using for_each_possible_cpu()) and instead fold any nr_active delta after we migrate all tasks away to make sure we don't have any skewed nr_active accounting. [ paulmck: Move call to calc_load_migration to CPU_DEAD to avoid miscounting noted by Rakib. ] Reported-by: Rakib Mullick <rakib.mullick@gmail.com> Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
* | | Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds2012-08-205-19/+70
|\ \ \ | |/ / |/| / | |/ | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar. * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Fix migration thread runtime bogosity sched,rt: fix isolated CPUs leaving root_task_group indefinitely throttled sched,cgroup: Fix up task_groups list sched: fix divide by zero at {thread_group,task}_times sched, cgroup: Reduce rq->lock hold times for large cgroup hierarchies
| * sched: Fix migration thread runtime bogosityMike Galbraith2012-08-131-1/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make stop scheduler class do the same accounting as other classes, Migration threads can be caught in the act while doing exec balancing, leading to the below due to use of unmaintained ->se.exec_start. The load that triggered this particular instance was an apparently out of control heavily threaded application that does system monitoring in what equated to an exec bomb, with one of the VERY frequently migrated tasks being ps. %CPU PID USER CMD 99.3 45 root [migration/10] 97.7 53 root [migration/12] 97.0 57 root [migration/13] 90.1 49 root [migration/11] 89.6 65 root [migration/15] 88.7 17 root [migration/3] 80.4 37 root [migration/8] 78.1 41 root [migration/9] 44.2 13 root [migration/2] Signed-off-by: Mike Galbraith <mgalbraith@suse.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1344051854.6739.19.camel@marge.simpson.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * sched,rt: fix isolated CPUs leaving root_task_group indefinitely throttledMike Galbraith2012-08-131-0/+13
| | | | | | | | | | | | | | | | | | | | | | Root task group bandwidth replenishment must service all CPUs, regardless of where the timer was last started, and regardless of the isolation mechanism, lest 'Quoth the Raven, "Nevermore"' become rt scheduling policy. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1344326558.6968.25.camel@marge.simpson.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * sched,cgroup: Fix up task_groups listMike Galbraith2012-08-132-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | With multiple instances of task_groups, for_each_rt_rq() is a noop, no task groups having been added to the rt.c list instance. This renders __enable/disable_runtime() and print_rt_stats() noop, the user (non) visible effect being that rt task groups are missing in /proc/sched_debug. Signed-off-by: Mike Galbraith <efault@gmx.de> Cc: stable@kernel.org # v3.3+ Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1344308413.6846.7.camel@marge.simpson.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * sched: fix divide by zero at {thread_group,task}_timesStanislaw Gruszka2012-08-131-14/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On architectures where cputime_t is 64 bit type, is possible to trigger divide by zero on do_div(temp, (__force u32) total) line, if total is a non zero number but has lower 32 bit's zeroed. Removing casting is not a good solution since some do_div() implementations do cast to u32 internally. This problem can be triggered in practice on very long lived processes: PID: 2331 TASK: ffff880472814b00 CPU: 2 COMMAND: "oraagent.bin" #0 [ffff880472a51b70] machine_kexec at ffffffff8103214b #1 [ffff880472a51bd0] crash_kexec at ffffffff810b91c2 #2 [ffff880472a51ca0] oops_end at ffffffff814f0b00 #3 [ffff880472a51cd0] die at ffffffff8100f26b #4 [ffff880472a51d00] do_trap at ffffffff814f03f4 #5 [ffff880472a51d60] do_divide_error at ffffffff8100cfff #6 [ffff880472a51e00] divide_error at ffffffff8100be7b [exception RIP: thread_group_times+0x56] RIP: ffffffff81056a16 RSP: ffff880472a51eb8 RFLAGS: 00010046 RAX: bc3572c9fe12d194 RBX: ffff880874150800 RCX: 0000000110266fad RDX: 0000000000000000 RSI: ffff880472a51eb8 RDI: 001038ae7d9633dc RBP: ffff880472a51ef8 R8: 00000000b10a3a64 R9: ffff880874150800 R10: 00007fcba27ab680 R11: 0000000000000202 R12: ffff880472a51f08 R13: ffff880472a51f10 R14: 0000000000000000 R15: 0000000000000007 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 #7 [ffff880472a51f00] do_sys_times at ffffffff8108845d #8 [ffff880472a51f40] sys_times at ffffffff81088524 #9 [ffff880472a51f80] system_call_fastpath at ffffffff8100b0f2 RIP: 0000003808caac3a RSP: 00007fcba27ab6d8 RFLAGS: 00000202 RAX: 0000000000000064 RBX: ffffffff8100b0f2 RCX: 0000000000000000 RDX: 00007fcba27ab6e0 RSI: 000000000076d58e RDI: 00007fcba27ab6e0 RBP: 00007fcba27ab700 R8: 0000000000000020 R9: 000000000000091b R10: 00007fcba27ab680 R11: 0000000000000202 R12: 00007fff9ca41940 R13: 0000000000000000 R14: 00007fcba27ac9c0 R15: 00007fff9ca41940 ORIG_RAX: 0000000000000064 CS: 0033 SS: 002b Cc: stable@vger.kernel.org Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20120808092714.GA3580@redhat.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * sched, cgroup: Reduce rq->lock hold times for large cgroup hierarchiesPeter Zijlstra2012-08-132-3/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Peter Portante reported that for large cgroup hierarchies (and or on large CPU counts) we get immense lock contention on rq->lock and stuff stops working properly. His workload was a ton of processes, each in their own cgroup, everybody idling except for a sporadic wakeup once every so often. It was found that: schedule() idle_balance() load_balance() local_irq_save() double_rq_lock() update_h_load() walk_tg_tree(tg_load_down) tg_load_down() Results in an entire cgroup hierarchy walk under rq->lock for every new-idle balance and since new-idle balance isn't throttled this results in a lot of work while holding the rq->lock. This patch does two things, it removes the work from under rq->lock based on the good principle of race and pray which is widely employed in the load-balancer as a whole. And secondly it throttles the update_h_load() calculation to max once per jiffy. I considered excluding update_h_load() for new-idle balance all-together, but purely relying on regular balance passes to update this data might not work out under some rare circumstances where the new-idle busiest isn't the regular busiest for a while (unlikely, but a nightmare to debug if someone hits it and suffers). Cc: pjt@google.com Cc: Larry Woodman <lwoodman@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Reported-by: Peter Portante <pportant@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-aaarrzfpnaam7pqrekofu8a6@git.kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds2012-08-033-23/+20
|\| | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar: "Fixes and two late cleanups" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/cleanups: Add load balance cpumask pointer to 'struct lb_env' sched: Fix comment about PREEMPT_ACTIVE bit location sched: Fix minor code style issues sched: Use task_rq_unlock() in __sched_setscheduler() sched/numa: Add SD_PERFER_SIBLING to CPU domain
| * sched/cleanups: Add load balance cpumask pointer to 'struct lb_env'Michael Wang2012-07-311-15/+14
| | | | | | | | | | | | | | | | | | | | With this patch struct ld_env will have a pointer of the load balancing cpumask and we don't need to pass a cpumask around anymore. Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/4FFE8665.3080705@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * sched: Fix minor code style issuesYing Xue2012-07-261-5/+5
| | | | | | | | | | | | | | | | | | Delete redudant spaces between type name and data name or operators. Signed-off-by: Ying Xue <ying.xue0@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1342076622-6606-1-git-send-email-ying.xue0@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * sched: Use task_rq_unlock() in __sched_setscheduler()Namhyung Kim2012-07-261-3/+1
| | | | | | | | | | | | | | | | | | | | | | It seems there's no specific reason to open-code it. I guess commit 0122ec5b02f76 ("sched: Add p->pi_lock to task_rq_lock()") simply missed it. Let's be consistent with others. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1341647342-6742-1-git-send-email-namhyung@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | Merge branch 'perf-core-for-linus' of ↵Linus Torvalds2012-08-011-1/+1
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf updates from Ingo Molnar: "The biggest changes are Intel Nehalem-EX PMU uncore support, uprobes updates/cleanups/fixes from Oleg and diverse tooling updates (mostly fixes) now that Arnaldo is back from vacation." * 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (40 commits) uprobes: __replace_page() needs munlock_vma_page() uprobes: Rename vma_address() and make it return "unsigned long" uprobes: Fix register_for_each_vma()->vma_address() check uprobes: Introduce vaddr_to_offset(vma, vaddr) uprobes: Teach build_probe_list() to consider the range uprobes: Remove insert_vm_struct()->uprobe_mmap() uprobes: Remove copy_vma()->uprobe_mmap() uprobes: Fix overflow in vma_address()/find_active_uprobe() uprobes: Suppress uprobe_munmap() from mmput() uprobes: Uprobe_mmap/munmap needs list_for_each_entry_safe() uprobes: Clean up and document write_opcode()->lock_page(old_page) uprobes: Kill write_opcode()->lock_page(new_page) uprobes: __replace_page() should not use page_address_in_vma() uprobes: Don't recheck vma/f_mapping in write_opcode() perf/x86: Fix missing struct before structure name perf/x86: Fix format definition of SNB-EP uncore QPI box perf/x86: Make bitfield unsigned perf/x86: Fix LLC-* and node-* events on Intel SandyBridge perf/x86: Add Intel Nehalem-EX uncore support perf/x86: Fix typo in format definition of uncore PCU filter ...
| * sched: Deliver sched_switch events to the current taskAndrew Vagin2012-07-261-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Otherwise they can't be filtered for a defined task: perf record -e sched:sched_switch ./foo This command doesn't report any events without this patch. I think it isn't a security concern if someone knows who will be executed next - this can already be observed by polling /proc state. By default perf is disabled for non-root users in any case. I need these events for profiling sleep times. sched_switch is used for getting callchains and sched_stat_* is used for getting time periods. These events are combined in user space, then it can be analyzed by perf tools. Signed-off-by: Andrew Vagin <avagin@openvz.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Arun Sharma <asharma@fb.com> Link: http://lkml.kernel.org/r/1342088069-1005148-1-git-send-email-avagin@openvz.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | sched: Fix race in task_group()Peter Zijlstra2012-07-242-14/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Stefan reported a crash on a kernel before a3e5d1091c1 ("sched: Don't call task_group() too many times in set_task_rq()"), he found the reason to be that the multiple task_group() invocations in set_task_rq() returned different values. Looking at all that I found a lack of serialization and plain wrong comments. The below tries to fix it using an extra pointer which is updated under the appropriate scheduler locks. Its not pretty, but I can't really see another way given how all the cgroup stuff works. Reported-and-tested-by: Stefan Bader <stefan.bader@canonical.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1340364965.18025.71.camel@twins Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | sched: Improve balance_cpu() to consider other cpus in its group as target ↵Srivatsa Vaddagiri2012-07-241-4/+74
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | of (pinned) task Current load balance scheme requires only one cpu in a sched_group (balance_cpu) to look at other peer sched_groups for imbalance and pull tasks towards itself from a busy cpu. Tasks thus pulled by balance_cpu could later get picked up by cpus that are in the same sched_group as that of balance_cpu. This scheme however fails to pull tasks that are not allowed to run on balance_cpu (but are allowed to run on other cpus in its sched_group). That can affect fairness and in some worst case scenarios cause starvation. Consider a two core (2 threads/core) system running tasks as below: Core0 Core1 / \ / \ C0 C1 C2 C3 | | | | v v v v F0 T1 F1 [idle] T2 F0 = SCHED_FIFO task (pinned to C0) F1 = SCHED_FIFO task (pinned to C2) T1 = SCHED_OTHER task (pinned to C1) T2 = SCHED_OTHER task (pinned to C1 and C2) F1 could become a cpu hog, which will starve T2 unless C1 pulls it. Between C0 and C1 however, C0 is required to look for imbalance between cores, which will fail to pull T2 towards Core0. T2 will starve eternally in this case. The same scenario can arise in presence of non-rt tasks as well (say we replace F1 with high irq load). We tackle this problem by having balance_cpu move pinned tasks to one of its sibling cpus (where they can run). We first check if load balance goal can be met by ignoring pinned tasks, failing which we retry move_tasks() with a new env->dst_cpu. This patch modifies load balance semantics on who can move load towards a given cpu in a given sched_domain. Before this patch, a given_cpu or a ilb_cpu acting on behalf of an idle given_cpu is responsible for moving load to given_cpu. With this patch applied, balance_cpu can in addition decide on moving some load to a given_cpu. There is a remote possibility that excess load could get moved as a result of this (balance_cpu and given_cpu/ilb_cpu deciding *independently* and at *same* time to move some load to a given_cpu). However we should see less of such conflicting decisions in practice and moreover subsequent load balance cycles should correct the excess load moved to given_cpu. Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Prashanth Nageshappa <prashanth@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/4FE06CDB.2060605@linux.vnet.ibm.com [ minor edits ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | sched: Reset loop counters if all tasks are pinned and we need to redo load ↵Prashanth Nageshappa2012-07-241-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | balance While load balancing, if all tasks on the source runqueue are pinned, we retry after excluding the corresponding source cpu. However, loop counters env.loop and env.loop_break are not reset before retrying, which can lead to failure in moving the tasks. In this patch we reset env.loop and env.loop_break to their inital values before we retry. Signed-off-by: Prashanth Nageshappa <prashanth@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/4FE06EEF.2090709@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | sched: Reorder 'struct lb_env' members to reduce its sizePrashanth Nageshappa2012-07-241-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Members of 'struct lb_env' are not in appropriate order to reuse compiler added padding on 64bit architectures. In this patch we reorder those struct members and help reduce the size of the structure from 96 bytes to 80 bytes on 64 bit architectures. Suggested-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Prashanth Nageshappa <prashanth@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/4FE06DDE.7000403@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | sched: Improve scalability via 'CPU buddies', which withstand random ↵Mike Galbraith2012-07-242-22/+45
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | perturbations Traversing an entire package is not only expensive, it also leads to tasks bouncing all over a partially idle and possible quite large package. Fix that up by assigning a 'buddy' CPU to try to motivate. Each buddy may try to motivate that one other CPU, if it's busy, tough, it may then try its SMT sibling, but that's all this optimization is allowed to cost. Sibling cache buddies are cross-wired to prevent bouncing. 4 socket 40 core + SMT Westmere box, single 30 sec tbench runs, higher is better: clients 1 2 4 8 16 32 64 128 .......................................................................... pre 30 41 118 645 3769 6214 12233 14312 post 299 603 1211 2418 4697 6847 11606 14557 A nice increase in performance. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1339471112.7352.32.camel@marge.simpson.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
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