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* sched, nohz: Fix missing RCU read lockPeter Zijlstra2011-12-081-2/+7
| | | | | | | | | | | | | | | | | | | | | Yong Zhang reported: > [ INFO: suspicious RCU usage. ] > kernel/sched/fair.c:5091 suspicious rcu_dereference_check() usage! This is due to the sched_domain stuff being RCU protected and commit 0b005cf5 ("sched, nohz: Implement sched group, domain aware nohz idle load balancing") overlooking this fact. The sd variable only lives inside the for_each_domain() block, so we only need to wrap that. Reported-by: Yong Zhang <yong.zhang0@gmail.com> Tested-by: Yong Zhang <yong.zhang0@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Link: http://lkml.kernel.org/r/1323264728.32012.107.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched, nohz: Set the NOHZ_BALANCE_KICK flag for idle load balancerSuresh Siddha2011-12-061-1/+1
| | | | | | | | | | | Intention is to set the NOHZ_BALANCE_KICK flag for the 'ilb_cpu'. Not for the 'cpu' which is the local cpu. Fix the typo. Reported-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1323199594.1984.18.camel@sbsiddha-desk.sc.intel.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched, nohz: Fix the idle cpu check in nohz_idle_balanceSuresh Siddha2011-12-061-1/+1
| | | | | | | | | | | | | | | cpu bit in the nohz.idle_cpu_mask are reset in the first busy tick after exiting idle. So during nohz_idle_balance(), intention is to double check if the cpu that is part of the idle_cpu_mask is indeed idle before going ahead in performing idle balance for that cpu. Fix the cpu typo in the idle_cpu() check during nohz_idle_balance(). Reported-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1323199177.1984.12.camel@sbsiddha-desk.sc.intel.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Use jump_labels for sched_featPeter Zijlstra2011-12-063-22/+81
| | | | | | | | | | Now that we initialize jump_labels before sched_init() we can use them for the debug features without having to worry about a window where they have the wrong setting. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-vpreo4hal9e0kzqmg5y0io2k@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched/accounting: Fix parameter passing in task_group_account_fieldGlauber Costa2011-12-061-2/+2
| | | | | | | | | | The order of parameters is inverted. The index parameter should come first. Signed-off-by: Glauber Costa <glommer@parallels.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1322863119-14225-3-git-send-email-glommer@parallels.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched/accounting: Fix user/system tick double accountingGlauber Costa2011-12-061-10/+2
| | | | | | | | | | | | Now that we're pointing cpuacct's root cgroup to cpustat and accounting through task_group_account_field(), we should not access cpustat directly. Since it is done anyway inside the acessor function, we end up accounting it twice, which is wrong. Signed-off-by: Glauber Costa <glommer@parallels.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1322863119-14225-2-git-send-email-glommer@parallels.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched/accounting: Re-use scheduler statistics for the root cgroupGlauber Costa2011-12-062-93/+106
| | | | | | | | | | | | | | | | | | | Right now, after we collect tick statistics for user and system and store them in a well known location, we keep the same statistics again for cpuacct. Since cpuacct is hierarchical, the numbers for the root cgroup should be absolutely equal to the system-wide numbers. So it would be better to just use it: this patch changes cpuacct accounting in a way that the cpustat statistics are kept in a struct kernel_cpustat percpu array. In the root cgroup case, we just point it to the main array. The rest of the hierarchy walk can be totally disabled later with a static branch - but I am not doing it here. Signed-off-by: Glauber Costa <glommer@parallels.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Tuner <pjt@google.com> Link: http://lkml.kernel.org/r/1322498719-2255-4-git-send-email-glommer@parallels.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Save some hrtick_start_fair cyclesMike Galbraith2011-12-062-3/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | hrtick_start_fair() shows up in profiles even when disabled. v3.0.6 taskset -c 3 pipe-test PerfTop: 997 irqs/sec kernel:89.5% exact: 0.0% [1000Hz cycles], (all, CPU: 3) ------------------------------------------------------------------------------------------------ Virgin Patched samples pcnt function samples pcnt function _______ _____ ___________________________ _______ _____ ___________________________ 2880.00 10.2% __schedule 3136.00 11.3% __schedule 1634.00 5.8% pipe_read 1615.00 5.8% pipe_read 1458.00 5.2% system_call 1534.00 5.5% system_call 1382.00 4.9% _raw_spin_lock_irqsave 1412.00 5.1% _raw_spin_lock_irqsave 1202.00 4.3% pipe_write 1255.00 4.5% copy_user_generic_string 1164.00 4.1% copy_user_generic_string 1241.00 4.5% __switch_to 1097.00 3.9% __switch_to 929.00 3.3% mutex_lock 872.00 3.1% mutex_lock 846.00 3.0% mutex_unlock 687.00 2.4% mutex_unlock 804.00 2.9% pipe_write 682.00 2.4% native_sched_clock 713.00 2.6% native_sched_clock 643.00 2.3% system_call_after_swapgs 653.00 2.3% _raw_spin_unlock_irqrestore 617.00 2.2% sched_clock_local 633.00 2.3% fsnotify 612.00 2.2% fsnotify 605.00 2.2% sched_clock_local 596.00 2.1% _raw_spin_unlock_irqrestore 593.00 2.1% system_call_after_swapgs 542.00 1.9% sysret_check 559.00 2.0% sysret_check 467.00 1.7% fget_light 472.00 1.7% fget_light 462.00 1.6% finish_task_switch 461.00 1.7% finish_task_switch 437.00 1.5% vfs_write 442.00 1.6% vfs_write 431.00 1.5% do_sync_write 428.00 1.5% do_sync_write 413.00 1.5% select_task_rq_fair 404.00 1.5% _raw_spin_lock_irq 386.00 1.4% update_curr 402.00 1.4% update_curr 385.00 1.4% rw_verify_area 389.00 1.4% do_sync_read 377.00 1.3% _raw_spin_lock_irq 378.00 1.4% vfs_read 369.00 1.3% do_sync_read 340.00 1.2% pipe_iov_copy_from_user 360.00 1.3% vfs_read 316.00 1.1% __wake_up_sync_key * 342.00 1.2% hrtick_start_fair 313.00 1.1% __wake_up_common Signed-off-by: Mike Galbraith <efault@gmx.de> [ fixed !CONFIG_SCHED_HRTICK borkage ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1321971607.6855.17.camel@marge.simson.net Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched/accounting, cgroups: Reuse cgroup's parent pointerGlauber Costa2011-12-061-6/+9
| | | | | | | | | | | | | | | | We already have a pointer to the cgroup parent (whose data is more likely to be in the cache than this, anyway), so there is no need to have this one in cpuacct. This patch makes the underlying cgroup be used instead. Signed-off-by: Glauber Costa <glommer@parallels.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Paul Tuner <pjt@google.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1322498719-2255-3-git-send-email-glommer@parallels.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched/accounting: Change cpustat fields to an arrayGlauber Costa2011-12-061-38/+40
| | | | | | | | | | | | | | This patch changes fields in cpustat from a structure, to an u64 array. Math gets easier, and the code is more flexible. Signed-off-by: Glauber Costa <glommer@parallels.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Paul Tuner <pjt@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1322498719-2255-2-git-send-email-glommer@parallels.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched, nohz: Clean up the find_new_ilb() using sched groups nr_busy_cpusSuresh Siddha2011-12-061-36/+12
| | | | | | | | | | | | | nr_busy_cpus in the sched_group_power indicates whether the group is semi idle or not. This helps remove the is_semi_idle_group() and simplify the find_new_ilb() in the context of finding an optimal cpu that can do idle load balancing. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20111202010832.656983582@sbsiddha-desk.sc.intel.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched, nohz: Implement sched group, domain aware nohz idle load balancingSuresh Siddha2011-12-061-113/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When there are many logical cpu's that enter and exit idle often, members of the global nohz data structure are getting modified very frequently causing lot of cache-line contention. Make the nohz idle load balancing more scalabale by using the sched domain topology and 'nr_busy_cpu's in the struct sched_group_power. Idle load balance is kicked on one of the idle cpu's when there is atleast one idle cpu and: - a busy rq having more than one task or - a busy rq's scheduler group that share package resources (like HT/MC siblings) and has more than one member in that group busy or - for the SD_ASYM_PACKING domain, if the lower numbered cpu's in that domain are idle compared to the busy ones. This will help in kicking the idle load balancing request only when there is a potential imbalance. And once it is mostly balanced, these kicks will be minimized. These changes helped improve the workload that is context switch intensive between number of task pairs by 2x on a 8 socket NHM-EX based system. Reported-by: Tim Chen <tim.c.chen@intel.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20111202010832.602203411@sbsiddha-desk.sc.intel.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched, nohz: Track nr_busy_cpus in the sched_group_powerSuresh Siddha2011-12-063-0/+33
| | | | | | | | | | | | | | | | | | | Introduce nr_busy_cpus in the struct sched_group_power [Not in sched_group because sched groups are duplicated for the SD_OVERLAP scheduler domain] and for each cpu that enters and exits idle, this parameter will be updated in each scheduler group of the scheduler domain that this cpu belongs to. To avoid the frequent update of this state as the cpu enters and exits idle, the update of the stat during idle exit is delayed to the first timer tick that happens after the cpu becomes busy. This is done using NOHZ_IDLE flag in the struct rq's nohz_flags. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20111202010832.555984323@sbsiddha-desk.sc.intel.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched, nohz: Introduce nohz_flags in 'struct rq'Suresh Siddha2011-12-063-24/+40
| | | | | | | | | | | | | | | | | | | | | | | Introduce nohz_flags in the struct rq, which will track these two flags for now. NOHZ_TICK_STOPPED keeps track of the tick stopped status that gets set when the tick is stopped. It will be used to update the nohz idle load balancer data structures during the first busy tick after the tick is restarted. At this first busy tick after tickless idle, NOHZ_TICK_STOPPED flag will be reset. This will minimize the nohz idle load balancer status updates that currently happen for every tickless exit, making it more scalable when there are many logical cpu's that enter and exit idle often. NOHZ_BALANCE_KICK will track the need for nohz idle load balance on this rq. This will replace the nohz_balance_kick in the rq, which was not being updated atomically. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20111202010832.499438999@sbsiddha-desk.sc.intel.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched/rt: Code cleanup, remove a redundant function callShan Hai2011-12-061-1/+1
| | | | | | | | | | | The second call to sched_rt_period() is redundant, because the value of the rt_runtime was already read and it was protected by the ->rt_runtime_lock. Signed-off-by: Shan Hai <haishan.bai@gmail.com> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1322535836-13590-2-git-send-email-haishan.bai@gmail.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Fix the sched group node allocation for SD_OVERLAP domainsSuresh Siddha2011-12-061-1/+1
| | | | | | | | | | | | For the SD_OVERLAP domain, sched_groups for each CPU's sched_domain are privately allocated and not shared with any other cpu. So the sched group allocation should come from the cpu's node for which SD_OVERLAP sched domain is being setup. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20111118230554.164910950@sbsiddha-desk.sc.intel.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Set skip_clock_update in yield_task_fair()Mike Galbraith2011-12-062-0/+13
| | | | | | | | | | | This is another case where we are on our way to schedule(), so can save a useless clock update and resulting microscopic vruntime update. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1321971686.6855.18.camel@marge.simson.net Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Use rt.nr_cpus_allowed to recover select_task_rq() cyclesMike Galbraith2011-12-062-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | rt.nr_cpus_allowed is always available, use it to bail from select_task_rq() when only one cpu can be used, and saves some cycles for pinned tasks. See the line marked with '*' below: # taskset -c 3 pipe-test PerfTop: 997 irqs/sec kernel:89.5% exact: 0.0% [1000Hz cycles], (all, CPU: 3) ------------------------------------------------------------------------------------------------ Virgin Patched samples pcnt function samples pcnt function _______ _____ ___________________________ _______ _____ ___________________________ 2880.00 10.2% __schedule 3136.00 11.3% __schedule 1634.00 5.8% pipe_read 1615.00 5.8% pipe_read 1458.00 5.2% system_call 1534.00 5.5% system_call 1382.00 4.9% _raw_spin_lock_irqsave 1412.00 5.1% _raw_spin_lock_irqsave 1202.00 4.3% pipe_write 1255.00 4.5% copy_user_generic_string 1164.00 4.1% copy_user_generic_string 1241.00 4.5% __switch_to 1097.00 3.9% __switch_to 929.00 3.3% mutex_lock 872.00 3.1% mutex_lock 846.00 3.0% mutex_unlock 687.00 2.4% mutex_unlock 804.00 2.9% pipe_write 682.00 2.4% native_sched_clock 713.00 2.6% native_sched_clock 643.00 2.3% system_call_after_swapgs 653.00 2.3% _raw_spin_unlock_irqrestore 617.00 2.2% sched_clock_local 633.00 2.3% fsnotify 612.00 2.2% fsnotify 605.00 2.2% sched_clock_local 596.00 2.1% _raw_spin_unlock_irqrestore 593.00 2.1% system_call_after_swapgs 542.00 1.9% sysret_check 559.00 2.0% sysret_check 467.00 1.7% fget_light 472.00 1.7% fget_light 462.00 1.6% finish_task_switch 461.00 1.7% finish_task_switch 437.00 1.5% vfs_write 442.00 1.6% vfs_write 431.00 1.5% do_sync_write 428.00 1.5% do_sync_write * 413.00 1.5% select_task_rq_fair 404.00 1.5% _raw_spin_lock_irq 386.00 1.4% update_curr 402.00 1.4% update_curr 385.00 1.4% rw_verify_area 389.00 1.4% do_sync_read 377.00 1.3% _raw_spin_lock_irq 378.00 1.4% vfs_read 369.00 1.3% do_sync_read 340.00 1.2% pipe_iov_copy_from_user 360.00 1.3% vfs_read 316.00 1.1% __wake_up_sync_key 342.00 1.2% hrtick_start_fair 313.00 1.1% __wake_up_common Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1321971504.6855.15.camel@marge.simson.net Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Clean up domain traversal in select_idle_sibling()Suresh Siddha2011-12-062-13/+27
| | | | | | | | | | | | | | | | | Instead of going through the scheduler domain hierarchy multiple times (for giving priority to an idle core over an idle SMT sibling in a busy core), start with the highest scheduler domain with the SD_SHARE_PKG_RESOURCES flag and traverse the domain hierarchy down till we find an idle group. This cleanup also addresses an issue reported by Mike where the recent changes returned the busy thread even in the presence of an idle SMT sibling in single socket platforms. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Tested-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1321556904.15339.25.camel@sbsiddha-desk.sc.intel.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* events, sched: Add tracepoint for accounting blocked timeAndrew Vagin2011-12-061-0/+2
| | | | | | | | | | | This tracepoint shows how long a task is sleeping in uninterruptible state. E.g. it may show how long and where a mutex is waited for. Signed-off-by: Andrew Vagin <avagin@openvz.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1322471015-107825-8-git-send-email-avagin@openvz.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Move all scheduler bits into kernel/sched/Peter Zijlstra2011-11-1716-0/+18909
There's too many sched*.[ch] files in kernel/, give them their own directory. (No code changed, other than Makefile glue added.) Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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