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2016-01-13Merge branch 'for-4.5' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup updates from Tejun Heo: - cgroup v2 interface is now official. It's no longer hidden behind a devel flag and can be mounted using the new cgroup2 fs type. Unfortunately, cpu v2 interface hasn't made it yet due to the discussion around in-process hierarchical resource distribution and only memory and io controllers can be used on the v2 interface at the moment. - The existing documentation which has always been a bit of mess is relocated under Documentation/cgroup-v1/. Documentation/cgroup-v2.txt is added as the authoritative documentation for the v2 interface. - Some features are added through for-4.5-ancestor-test branch to enable netfilter xt_cgroup match to use cgroup v2 paths. The actual netfilter changes will be merged through the net tree which pulled in the said branch. - Various cleanups * 'for-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: rename cgroup documentations cgroup: fix a typo. cgroup: Remove resource_counter.txt in Documentation/cgroup-legacy/00-INDEX. cgroup: demote subsystem init messages to KERN_DEBUG cgroup: Fix uninitialized variable warning cgroup: put controller Kconfig options in meaningful order cgroup: clean up the kernel configuration menu nomenclature cgroup_pids: fix a typo. Subject: cgroup: Fix incomplete dd command in blkio documentation cgroup: kill cgrp_ss_priv[CGROUP_CANFORK_COUNT] and friends cpuset: Replace all instances of time_t with time64_t cgroup: replace unified-hierarchy.txt with a proper cgroup v2 documentation cgroup: rename Documentation/cgroups/ to Documentation/cgroup-legacy/ cgroup: replace __DEVEL__sane_behavior with cgroup2 fs type
2016-01-13Merge tag 'for-linus-4.5-rc0-tag' of ↵Linus Torvalds1-0/+3
git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip Pull xen updates from David Vrabel: "Xen features and fixes for 4.5-rc0: - Stolen ticks and PV wallclock support for arm/arm64 - Add grant copy ioctl to gntdev device" * tag 'for-linus-4.5-rc0-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: xen/gntdev: add ioctl for grant copy x86/xen: don't reset vcpu_info on a cancelled suspend xen/gntdev: constify mmu_notifier_ops structures xen/grant-table: constify gnttab_ops structure xen/time: use READ_ONCE xen/x86: convert remaining timespec to timespec64 in xen_pvclock_gtod_notify xen/x86: support XENPF_settime64 xen/arm: set the system time in Xen via the XENPF_settime64 hypercall xen/arm: introduce xen_read_wallclock arm: extend pvclock_wall_clock with sec_hi xen: introduce XENPF_settime64 xen/arm: introduce HYPERVISOR_platform_op on arm and arm64 xen: rename dom0_op to platform_op xen/arm: account for stolen ticks arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops arm: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops missing include asm/paravirt.h in cputime.c xen: move xen_setup_runstate_info and get_runstate_snapshot to drivers/xen/time.c
2016-01-12Merge branch 'for-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wqLinus Torvalds1-1/+1
Pull workqueue update from Tejun Heo: "Workqueue changes for v4.5. One cleanup patch and three to improve the debuggability. Workqueue now has a stall detector which dumps workqueue state if any worker pool hasn't made forward progress over a certain amount of time (30s by default) and also triggers a warning if a workqueue which can be used in memory reclaim path tries to wait on something which can't be. These should make workqueue hangs a lot easier to debug." * 'for-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: simplify the apply_workqueue_attrs_locked() workqueue: implement lockup detector watchdog: introduce touch_softlockup_watchdog_sched() workqueue: warn if memory reclaim tries to flush !WQ_MEM_RECLAIM workqueue
2016-01-12Merge branch 'sched-core-for-linus' of ↵Linus Torvalds7-236/+356
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: "The main changes in this cycle were: - tickless load average calculation enhancements (Byungchul Park) - vtime handling enhancements (Frederic Weisbecker) - scalability improvement via properly aligning a key structure field (Jiri Olsa) - various stop_machine() fixes (Oleg Nesterov) - sched/numa enhancement (Rik van Riel) - various fixes and improvements (Andi Kleen, Dietmar Eggemann, Geliang Tang, Hiroshi Shimamoto, Joonwoo Park, Peter Zijlstra, Waiman Long, Wanpeng Li, Yuyang Du)" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits) sched/fair: Fix new task's load avg removed from source CPU in wake_up_new_task() sched/core: Move sched_entity::avg into separate cache line x86/fpu: Properly align size in CHECK_MEMBER_AT_END_OF() macro sched/deadline: Fix the earliest_dl.next logic sched/fair: Disable the task group load_avg update for the root_task_group sched/fair: Move the cache-hot 'load_avg' variable into its own cacheline sched/fair: Avoid redundant idle_cpu() call in update_sg_lb_stats() sched/core: Move the sched_to_prio[] arrays out of line sched/cputime: Convert vtime_seqlock to seqcount sched/cputime: Introduce vtime accounting check for readers sched/cputime: Rename vtime_accounting_enabled() to vtime_accounting_cpu_enabled() sched/cputime: Correctly handle task guest time on housekeepers sched/cputime: Clarify vtime symbols and document them sched/cputime: Remove extra cost in task_cputime() sched/fair: Make it possible to account fair load avg consistently sched/fair: Modify the comment about lock assumptions in migrate_task_rq_fair() stop_machine: Clean up the usage of the preemption counter in cpu_stopper_thread() stop_machine: Shift the 'done != NULL' check from cpu_stop_signal_done() to callers stop_machine: Kill cpu_stop_done->executed stop_machine: Change __stop_cpus() to rely on cpu_stop_queue_work() ...
2016-01-12Merge branch 'locking-core-for-linus' of ↵Linus Torvalds2-8/+93
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: "So we have a laundry list of locking subsystem changes: - continuing barrier API and code improvements - futex enhancements - atomics API improvements - pvqspinlock enhancements: in particular lock stealing and adaptive spinning - qspinlock micro-enhancements" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op futex: Cleanup the goto confusion in requeue_pi() futex: Remove pointless put_pi_state calls in requeue() futex: Document pi_state refcounting in requeue code futex: Rename free_pi_state() to put_pi_state() futex: Drop refcount if requeue_pi() acquired the rtmutex locking/barriers, arch: Remove ambiguous statement in the smp_store_mb() documentation lcoking/barriers, arch: Use smp barriers in smp_store_release() locking/cmpxchg, arch: Remove tas() definitions locking/pvqspinlock: Queue node adaptive spinning locking/pvqspinlock: Allow limited lock stealing locking/pvqspinlock: Collect slowpath lock statistics sched/core, locking: Document Program-Order guarantees locking, sched: Introduce smp_cond_acquire() and use it locking/pvqspinlock, x86: Optimize the PV unlock code path locking/qspinlock: Avoid redundant read of next pointer locking/qspinlock: Prefetch the next node cacheline locking/qspinlock: Use _acquire/_release() versions of cmpxchg() & xchg() atomics: Add test for atomic operations with _relaxed variants
2016-01-12Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds1-2/+4
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU updates from Ingo Molnar: "The changes in this cycle were: - Adding transitivity uniformly to rcu_node structure ->lock acquisitions. (This is implemented by the first two commits on top of v4.4-rc2 due to the pervasive nature of this change.) - Documentation updates, including RCU requirements. - Expedited grace-period changes. - Miscellaneous fixes. - Linked-list fixes, courtesy of KTSAN. - Torture-test updates. - Late-breaking fix to sysrq-generated crash. One thing I should note is that these pieces of documentation are fairly large files: .../RCU/Design/Requirements/Requirements.html | 2897 ++++++++++++++++++++ .../RCU/Design/Requirements/Requirements.htmlx | 2741 ++++++++++++++++++ and are written in HTML, not the usual .txt style. I hope they are fine" Paul McKenney explains the html docs: "For whatever it is worth, the reason for this unconventional choice was that attempts to do the diagrams in ASCII art failed miserably. And attempts to do ASCII art for the upcoming documentation of the data structures failed even more miserably" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (49 commits) sysrq: Fix warning in sysrq generated crash. list: Add lockless list traversal primitives rcu: Make rcu_gp_init() be bool rather than int rcu: Move wakeup out from under rnp->lock rcu: Fix comment for rcu_dereference_raw_notrace rcu: Don't redundantly disable irqs in rcu_irq_{enter,exit}() rcu: Make cpu_needs_another_gp() be bool rcu: Eliminate unused rcu_init_one() argument rcu: Remove TINY_RCU bloat from pointless boot parameters torture: Place console.log files correctly from the get-go torture: Abbreviate console error dump rcutorture: Print symbolic name for ->gp_state rcutorture: Print symbolic name for rcu_torture_writer_state rcutorture: Remove CONFIG_RCU_USER_QS from rcutorture selftest doc rcutorture: Default grace period to three minutes, allow override rcutorture: Dump stack when GP kthread stalls rcutorture: Flag nonexistent RCU GP kthread rcutorture: Add batch number to script printout Documentation/memory-barriers.txt: Fix ACCESS_ONCE thinko documentation: Update RCU requirements based on expedited changes ...
2016-01-06Merge branch 'for-mingo' of ↵Ingo Molnar1-2/+4
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu Pull RCU changes from Paul E. McKenney: - Adding transitivity uniformly to rcu_node structure ->lock acquisitions. (This is implemented by the first two commits on top of v4.4-rc2 due to the pervasive nature of this change.) - Documentation updates, including RCU requirements. - Expedited grace-period changes. - Miscellaneous fixes. - Linked-list fixes, courtesy of KTSAN. - Torture-test updates. - Late-breaking fix to sysrq-generated crash. Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-06sched/fair: Fix new task's load avg removed from source CPU in ↵Yuyang Du1-10/+28
wake_up_new_task() If a newly created task is selected to go to a different CPU in fork balance when it wakes up the first time, its load averages should not be removed from the source CPU since they are never added to it before. The same is also applicable to a never used group entity. Fix it in remove_entity_load_avg(): when entity's last_update_time is 0, simply return. This should precisely identify the case in question, because in other migrations, the last_update_time is set to 0 after remove_entity_load_avg(). Reported-by: Steve Muckle <steve.muckle@linaro.org> Signed-off-by: Yuyang Du <yuyang.du@intel.com> [peterz: cfs_rq_last_update_time] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Juri Lelli <Juri.Lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Patrick Bellasi <patrick.bellasi@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vincent Guittot <vincent.guittot@linaro.org> Link: http://lkml.kernel.org/r/20151216233427.GJ28098@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-06sched/deadline: Fix the earliest_dl.next logicWanpeng Li1-52/+7
earliest_dl.next should cache deadline of the earliest ready task that is also enqueued in the pushable rbtree, as pull algorithm uses this information to find candidates for migration: if the earliest_dl.next deadline of source rq is earlier than the earliest_dl.curr deadline of destination rq, the task from the source rq can be pulled. However, current implementation only guarantees that earliest_dl.next is the deadline of the next ready task instead of the next pushable task; which will result in potentially holding both rqs' lock and find nothing to migrate because of affinity constraints. In addition, current logic doesn't update the next candidate for pushing in pick_next_task_dl(), even if the running task is never eligible. This patch fixes both problems by updating earliest_dl.next when pushable dl task is enqueued/dequeued, similar to what we already do for RT. Tested-by: Luca Abeni <luca.abeni@unitn.it> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1449135730-27202-1-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-06Merge branch 'sched/urgent' into sched/core, to pick up fixes before merging ↵Ingo Molnar4-19/+19
new patches Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-06sched/fair: Fix multiplication overflow on 32-bit systemsAndrey Ryabinin1-1/+1
Make 'r' 64-bit type to avoid overflow in 'r * LOAD_AVG_MAX' on 32-bit systems: UBSAN: Undefined behaviour in kernel/sched/fair.c:2785:18 signed integer overflow: 87950 * 47742 cannot be represented in type 'int' The most likely effect of this bug are bad load average numbers resulting in weird scheduling. It's also likely that this can persist for a longer time - until the system goes idle for a long time so that all load avg numbers get reset. [ This is the CFS load average metric, not the procfs output, which is separate. ] Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 9d89c257dfb9 ("sched/fair: Rewrite runnable load and utilization average tracking") Link: http://lkml.kernel.org/r/1450097243-30137-1-git-send-email-aryabinin@virtuozzo.com [ Improved the changelog. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-21missing include asm/paravirt.h in cputime.cStefano Stabellini1-0/+3
Add include asm/paravirt.h to cputime.c, as steal_account_process_tick calls paravirt_steal_clock, which is defined in asm/paravirt.h. The ifdef CONFIG_PARAVIRT is necessary because not all archs have an asm/paravirt.h to include. The reason why currently cputime.c compiles, even though include <asm/paravirt.h> is missing, is that on x86 asm/paravirt.h is included by one of the other headers included in kernel/sched/cputime.c: On arm and arm64, where I am about to introduce asm/paravirt.h and stolen time support, without #include <asm/paravirt.h> in cputime.c, I would get an error. Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2015-12-14sched/wait: Fix the signal handling fixPeter Zijlstra1-10/+10
Jan Stancek reported that I wrecked things for him by fixing things for Vladimir :/ His report was due to an UNINTERRUPTIBLE wait getting -EINTR, which should not be possible, however my previous patch made this possible by unconditionally checking signal_pending(). We cannot use current->state as was done previously, because the instruction after the store to that variable it can be changed. We must instead pass the initial state along and use that. Fixes: 68985633bccb ("sched/wait: Fix signal handling in bit wait helpers") Reported-by: Jan Stancek <jstancek@redhat.com> Reported-by: Chris Mason <clm@fb.com> Tested-by: Jan Stancek <jstancek@redhat.com> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> Tested-by: Chris Mason <clm@fb.com> Reviewed-by: Paul Turner <pjt@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: tglx@linutronix.de Cc: Oleg Nesterov <oleg@redhat.com> Cc: hpa@zytor.com Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-09Merge branch 'for-4.4-fixes' of ↵Linus Torvalds1-6/+6
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup fixes from Tejun Heo: "More change than I'd have liked at this stage. The pids controller and the changes made to cgroup core to support it introduced and revealed several important issues. - Assigning membership to a newly created task and migrating it can race leading to incorrect accounting. Oleg fixed it by widening threadgroup synchronization. It looks like we'll be able to merge it with a different percpu rwsem which is used in fork path making things simpler and cheaper. - The recent change to extend cgroup membership to zombies (so that pid accounting can extend till the pid is actually released) missed pinning the underlying data structures leading to use-after-free. Fixed. - v2 hierarchy was calling subsystem callbacks with the wrong target cgroup_subsys_state based on the incorrect assumption that they share the same target. pids is the first controller affected by this. Subsys callbacks updated so that they can deal with multi-target migrations" * 'for-4.4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup_pids: don't account for the root cgroup cgroup: fix handling of multi-destination migration from subtree_control enabling cgroup_freezer: simplify propagation of CGROUP_FROZEN clearing in freezer_attach() cgroup: pids: kill pids_fork(), simplify pids_can_fork() and pids_cancel_fork() cgroup: pids: fix race between cgroup_post_fork() and cgroup_migrate() cgroup: make css_set pin its css's to avoid use-afer-free cgroup: fix cftype->file_offset handling
2015-12-09Merge branch 'perf-urgent-for-linus' of ↵Linus Torvalds2-2/+2
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf fixes from Ingo Molnar: "This tree includes four core perf fixes for misc bugs, three fixes to x86 PMU drivers, and two updates to old email addresses" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf: Do not send exit event twice perf/x86/intel: Fix INTEL_FLAGS_UEVENT_CONSTRAINT_DATALA_NA macro perf/x86/intel: Make L1D_PEND_MISS.FB_FULL not constrained on Haswell perf: Fix PERF_EVENT_IOC_PERIOD deadlock treewide: Remove old email address perf/x86: Fix LBR call stack save/restore perf: Update email address in MAINTAINERS perf/core: Robustify the perf_cgroup_from_task() RCU checks perf/core: Fix RCU problem with cgroup context switching code
2015-12-08watchdog: introduce touch_softlockup_watchdog_sched()Tejun Heo1-1/+1
touch_softlockup_watchdog() is used to tell watchdog that scheduler stall is expected. One group of usage is from paths where the task may not be able to yield for a long time such as performing slow PIO to finicky device and coming out of suspend. The other is to account for scheduler and timer going idle. For scheduler softlockup detection, there's no reason to distinguish the two cases; however, workqueue lockup detector is planned and it can use the same signals from the former group while the latter would spuriously prevent detection. This patch introduces a new function touch_softlockup_watchdog_sched() and convert the latter group to call it instead. For now, it just calls touch_softlockup_watchdog() and there's no functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org>
2015-12-07Merge branch 'master' into for-4.4-fixesTejun Heo5-15/+45
The following commit which went into mainline through networking tree 3b13758f51de ("cgroups: Allow dynamically changing net_classid") conflicts in net/core/netclassid_cgroup.c with the following pending fix in cgroup/for-4.4-fixes. 1f7dd3e5a6e4 ("cgroup: fix handling of multi-destination migration from subtree_control enabling") The former separates out update_classid() from cgrp_attach() and updates it to walk all fds of all tasks in the target css so that it can be used from both migration and config change paths. The latter drops @css from cgrp_attach(). Resolve the conflict by making cgrp_attach() call update_classid() with the css from the first task. We can revive @tset walking in cgrp_attach() but given that net_cls is v1 only where there always is only one target css during migration, this is fine. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Nina Schiff <ninasc@fb.com>
2015-12-04rcu: Stop disabling interrupts in scheduler fastpathsPaul E. McKenney1-2/+4
We need the scheduler's fastpaths to be, well, fast, and unnecessarily disabling and re-enabling interrupts is not necessarily consistent with this goal. Especially given that there are regions of the scheduler that already have interrupts disabled. This commit therefore moves the call to rcu_note_context_switch() to one of the interrupts-disabled regions of the scheduler, and removes the now-redundant disabling and re-enabling of interrupts from rcu_note_context_switch() and the functions it calls. Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [ paulmck: Shift rcu_note_context_switch() to avoid deadlock, as suggested by Peter Zijlstra. ]
2015-12-04sched/fair: Disable the task group load_avg update for the root_task_groupWaiman Long1-0/+6
Currently, the update_tg_load_avg() function attempts to update the tg's load_avg value whenever the load changes even for root_task_group where the load_avg value will never be used. This patch will disable the load_avg update when the given task group is the root_task_group. Running a Java benchmark with noautogroup and a 4.3 kernel on a 16-socket IvyBridge-EX system, the amount of CPU time (as reported by perf) consumed by task_tick_fair() which includes update_tg_load_avg() decreased from 0.71% to 0.22%, a more than 3X reduction. The Max-jOPs results also increased slightly from 983015 to 986449. Signed-off-by: Waiman Long <Waiman.Long@hpe.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ben Segall <bsegall@google.com> Cc: Douglas Hatch <doug.hatch@hpe.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Scott J Norton <scott.norton@hpe.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yuyang Du <yuyang.du@intel.com> Link: http://lkml.kernel.org/r/1449081710-20185-4-git-send-email-Waiman.Long@hpe.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/fair: Move the cache-hot 'load_avg' variable into its own cachelineWaiman Long2-4/+13
If a system with large number of sockets was driven to full utilization, it was found that the clock tick handling occupied a rather significant proportion of CPU time when fair group scheduling and autogroup were enabled. Running a java benchmark on a 16-socket IvyBridge-EX system, the perf profile looked like: 10.52% 0.00% java [kernel.vmlinux] [k] smp_apic_timer_interrupt 9.66% 0.05% java [kernel.vmlinux] [k] hrtimer_interrupt 8.65% 0.03% java [kernel.vmlinux] [k] tick_sched_timer 8.56% 0.00% java [kernel.vmlinux] [k] update_process_times 8.07% 0.03% java [kernel.vmlinux] [k] scheduler_tick 6.91% 1.78% java [kernel.vmlinux] [k] task_tick_fair 5.24% 5.04% java [kernel.vmlinux] [k] update_cfs_shares In particular, the high CPU time consumed by update_cfs_shares() was mostly due to contention on the cacheline that contained the task_group's load_avg statistical counter. This cacheline may also contains variables like shares, cfs_rq & se which are accessed rather frequently during clock tick processing. This patch moves the load_avg variable into another cacheline separated from the other frequently accessed variables. It also creates a cacheline aligned kmemcache for task_group to make sure that all the allocated task_group's are cacheline aligned. By doing so, the perf profile became: 9.44% 0.00% java [kernel.vmlinux] [k] smp_apic_timer_interrupt 8.74% 0.01% java [kernel.vmlinux] [k] hrtimer_interrupt 7.83% 0.03% java [kernel.vmlinux] [k] tick_sched_timer 7.74% 0.00% java [kernel.vmlinux] [k] update_process_times 7.27% 0.03% java [kernel.vmlinux] [k] scheduler_tick 5.94% 1.74% java [kernel.vmlinux] [k] task_tick_fair 4.15% 3.92% java [kernel.vmlinux] [k] update_cfs_shares The %cpu time is still pretty high, but it is better than before. The benchmark results before and after the patch was as follows: Before patch - Max-jOPs: 907533 Critical-jOps: 134877 After patch - Max-jOPs: 916011 Critical-jOps: 142366 Signed-off-by: Waiman Long <Waiman.Long@hpe.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Ben Segall <bsegall@google.com> Cc: Douglas Hatch <doug.hatch@hpe.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Scott J Norton <scott.norton@hpe.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yuyang Du <yuyang.du@intel.com> Link: http://lkml.kernel.org/r/1449081710-20185-3-git-send-email-Waiman.Long@hpe.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/fair: Avoid redundant idle_cpu() call in update_sg_lb_stats()Waiman Long1-3/+7
Part of the responsibility of the update_sg_lb_stats() function is to update the idle_cpus statistical counter in struct sg_lb_stats. This check is done by calling idle_cpu(). The idle_cpu() function, in turn, checks a number of fields within the run queue structure such as rq->curr and rq->nr_running. With the current layout of the run queue structure, rq->curr and rq->nr_running are in separate cachelines. The rq->curr variable is checked first followed by nr_running. As nr_running is also accessed by update_sg_lb_stats() earlier, it makes no sense to load another cacheline when nr_running is not 0 as idle_cpu() will always return false in this case. This patch eliminates this redundant cacheline load by checking the cached nr_running before calling idle_cpu(). Signed-off-by: Waiman Long <Waiman.Long@hpe.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Douglas Hatch <doug.hatch@hpe.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Scott J Norton <scott.norton@hpe.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1448478580-26467-2-git-send-email-Waiman.Long@hpe.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/core: Move the sched_to_prio[] arrays out of lineAndi Kleen3-43/+46
When building a kernel with a gcc 6 snapshot the compiler complains about unused const static variables for prio_to_weight and prio_to_mult for multiple scheduler files (all but core.c and autogroup.c) The way the array is currently declared it will be duplicated in every scheduler file that includes sched.h, which seems rather wasteful. Move the array out of line into core.c. I also added a sched_ prefix to avoid any potential name space collisions. Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1448859583-3252-1-git-send-email-andi@firstfloor.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/cputime: Convert vtime_seqlock to seqcountFrederic Weisbecker1-22/+24
The cputime can only be updated by the current task itself, even in vtime case. So we can safely use seqcount instead of seqlock as there is no writer concurrency involved. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1447948054-28668-8-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/cputime: Introduce vtime accounting check for readersFrederic Weisbecker1-3/+3
Readers need to know if vtime runs at all on some CPU somewhere, this is a fast-path check to determine if we need to check further the need to add up any tickless cputime delta. This fast path check uses context tracking state because vtime is tied to context tracking as of now. This check appears to be confusing though so lets use a vtime function that deals with context tracking details in vtime implementation instead. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1447948054-28668-7-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/cputime: Rename vtime_accounting_enabled() to ↵Frederic Weisbecker1-1/+1
vtime_accounting_cpu_enabled() vtime_accounting_enabled() checks if vtime is running on the current CPU and is as such a misnomer. Lets rename it to a function that reflect its locality. We are going to need the current name for a function that tells if vtime runs at all on some CPU. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1447948054-28668-6-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/cputime: Correctly handle task guest time on housekeepersFrederic Weisbecker1-1/+1
When a task runs on a housekeeper (a CPU running with the periodic tick with neighbours running tickless), it doesn't account cputime using vtime but relies on the tick. Such a task has its vtime_snap_whence value set to VTIME_INACTIVE. Readers won't handle that correctly though. As long as vtime is running on some CPU, readers incorretly assume that vtime runs on all CPUs and always compute the tickless cputime delta, which is only junk on housekeepers. So lets fix this with checking that the target runs on a vtime CPU through the appropriate state check before computing the tickless delta. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1447948054-28668-5-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/cputime: Clarify vtime symbols and document themFrederic Weisbecker1-3/+3
VTIME_SLEEPING state happens either when: 1) The task is sleeping and no tickless delta is to be added on the task cputime stats. 2) The CPU isn't running vtime at all, so the same properties of 1) applies. Lets rename the vtime symbol to reflect both states. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1447948054-28668-4-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/cputime: Remove extra cost in task_cputime()Hiroshi Shimamoto1-0/+16
There is an extra cost in task_cputime() and task_cputime_scaled() when nohz_full is not activated. When vtime accounting is not enabled, we don't need to get deltas of utime and stime under vtime seqlock. This patch removes that cost with adding a shortcut route if vtime accounting is not enabled. Use context_tracking_is_enabled() to check if vtime is accounting on some cpu, in which case only we need to check the tickless cputime delta. Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1447948054-28668-3-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/fair: Make it possible to account fair load avg consistentlyByungchul Park3-1/+60
The current code accounts for the time a task was absent from the fair class (per ATTACH_AGE_LOAD). However it does not work correctly when a task got migrated or moved to another cgroup while outside of the fair class. This patch tries to address that by aging on migration. We locklessly read the 'last_update_time' stamp from both the old and new cfs_rq, ages the load upto the old time, and sets it to the new time. These timestamps should in general not be more than 1 tick apart from one another, so there is a definite bound on things. Signed-off-by: Byungchul Park <byungchul.park@lge.com> [ Changelog, a few edits and !SMP build fix ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1445616981-29904-2-git-send-email-byungchul.park@lge.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/core, locking: Document Program-Order guaranteesPeter Zijlstra1-0/+91
These are some notes on the scheduler locking and how it provides program order guarantees on SMP systems. ( This commit is in the locking tree, because the new documentation refers to a newly introduced locking primitive. ) Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: David Howells <dhowells@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04locking, sched: Introduce smp_cond_acquire() and use itPeter Zijlstra2-8/+2
Introduce smp_cond_acquire() which combines a control dependency and a read barrier to form acquire semantics. This primitive has two benefits: - it documents control dependencies, - its typically cheaper than using smp_load_acquire() in a loop. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04Merge branch 'sched/urgent' into sched/core, to pick up fixes before ↵Ingo Molnar4-14/+44
applying new changes Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/core: Fix an SMP ordering race in try_to_wake_up() vs. schedule()Peter Zijlstra1-0/+19
Oleg noticed that its possible to falsely observe p->on_cpu == 0 such that we'll prematurely continue with the wakeup and effectively run p on two CPUs at the same time. Even though the overlap is very limited; the task is in the middle of being scheduled out; it could still result in corruption of the scheduler data structures. CPU0 CPU1 set_current_state(...) <preempt_schedule> context_switch(X, Y) prepare_lock_switch(Y) Y->on_cpu = 1; finish_lock_switch(X) store_release(X->on_cpu, 0); try_to_wake_up(X) LOCK(p->pi_lock); t = X->on_cpu; // 0 context_switch(Y, X) prepare_lock_switch(X) X->on_cpu = 1; finish_lock_switch(Y) store_release(Y->on_cpu, 0); </preempt_schedule> schedule(); deactivate_task(X); X->on_rq = 0; if (X->on_rq) // false if (t) while (X->on_cpu) cpu_relax(); context_switch(X, ..) finish_lock_switch(X) store_release(X->on_cpu, 0); Avoid the load of X->on_cpu being hoisted over the X->on_rq load. Reported-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/core: Better document the try_to_wake_up() barriersPeter Zijlstra2-1/+10
Explain how the control dependency and smp_rmb() end up providing ACQUIRE semantics and pair with smp_store_release() in finish_lock_switch(). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/cputime: Fix invalid gtime in procHiroshi Shimamoto1-0/+3
/proc/stats shows invalid gtime when the thread is running in guest. When vtime accounting is not enabled, we cannot get a valid delta. The delta is calculated with now - tsk->vtime_snap, but tsk->vtime_snap is only updated when vtime accounting is runtime enabled. This patch makes task_gtime() just return gtime without computing the buggy non-existing tickless delta when vtime accounting is not enabled. Use context_tracking_is_enabled() to check if vtime is accounting on some cpu, in which case only we need to check the tickless delta. This way we fix the gtime value regression on machines not running nohz full. The kernel config contains CONFIG_VIRT_CPU_ACCOUNTING_GEN=y and CONFIG_NO_HZ_FULL_ALL=n and boot without nohz_full. I ran and stop a busy loop in VM and see the gtime in host. Dump the 43rd field which shows the gtime in every second: # while :; do awk '{print $3" "$43}' /proc/3955/task/4014/stat; sleep 1; done S 4348 R 7064566 R 7064766 R 7064967 R 7065168 S 4759 S 4759 During running busy loop, it returns large value. After applying this patch, we can see right gtime. # while :; do awk '{print $3" "$43}' /proc/10913/task/10956/stat; sleep 1; done S 5338 R 5365 R 5465 R 5566 R 5666 S 5726 S 5726 Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1447948054-28668-2-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/core: Clear the root_domain cpumasks in init_rootdomain()Xunlei Pang1-4/+4
root_domain::rto_mask allocated through alloc_cpumask_var() contains garbage data, this may cause problems. For instance, When doing pull_rt_task(), it may do useless iterations if rto_mask retains some extra garbage bits. Worse still, this violates the isolated domain rule for clustered scheduling using cpuset, because the tasks(with all the cpus allowed) belongs to one root domain can be pulled away into another root domain. The patch cleans the garbage by using zalloc_cpumask_var() instead of alloc_cpumask_var() for root_domain::rto_mask allocation, thereby addressing the issues. Do the same thing for root_domain's other cpumask memembers: dlo_mask, span, and online. Signed-off-by: Xunlei Pang <xlpang@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <stable@vger.kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1449057179-29321-1-git-send-email-xlpang@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/core: Remove false-positive warning from wake_up_process()Sasha Levin1-1/+0
Because wakeups can (fundamentally) be late, a task might not be in the expected state. Therefore testing against a task's state is racy, and can yield false positives. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: oleg@redhat.com Fixes: 9067ac85d533 ("wake_up_process() should be never used to wakeup a TASK_STOPPED/TRACED task") Link: http://lkml.kernel.org/r/1448933660-23082-1-git-send-email-sasha.levin@oracle.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04sched/wait: Fix signal handling in bit wait helpersPeter Zijlstra1-8/+8
Vladimir reported getting RCU stall warnings and bisected it back to commit: 743162013d40 ("sched: Remove proliferation of wait_on_bit() action functions") That commit inadvertently reversed the calls to schedule() and signal_pending(), thereby not handling the case where the signal receives while we sleep. Reported-by: Vladimir Murzin <vladimir.murzin@arm.com> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: mark.rutland@arm.com Cc: neilb@suse.de Cc: oleg@redhat.com Fixes: 743162013d40 ("sched: Remove proliferation of wait_on_bit() action functions") Fixes: cbbce8220949 ("SCHED: add some "wait..on_bit...timeout()" interfaces.") Link: http://lkml.kernel.org/r/20151201130404.GL3816@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-03cgroup: kill cgrp_ss_priv[CGROUP_CANFORK_COUNT] and friendsOleg Nesterov1-1/+1
Now that nobody use the "priv" arg passed to can_fork/cancel_fork/fork we can kill CGROUP_CANFORK_COUNT/SUBSYS_TAG/etc and cgrp_ss_priv[] in copy_process(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2015-12-03cgroup: fix handling of multi-destination migration from subtree_control ↵Tejun Heo1-6/+6
enabling Consider the following v2 hierarchy. P0 (+memory) --- P1 (-memory) --- A \- B P0 has memory enabled in its subtree_control while P1 doesn't. If both A and B contain processes, they would belong to the memory css of P1. Now if memory is enabled on P1's subtree_control, memory csses should be created on both A and B and A's processes should be moved to the former and B's processes the latter. IOW, enabling controllers can cause atomic migrations into different csses. The core cgroup migration logic has been updated accordingly but the controller migration methods haven't and still assume that all tasks migrate to a single target css; furthermore, the methods were fed the css in which subtree_control was updated which is the parent of the target csses. pids controller depends on the migration methods to move charges and this made the controller attribute charges to the wrong csses often triggering the following warning by driving a counter negative. WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40() Modules linked in: CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29 ... ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000 ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00 ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8 Call Trace: [<ffffffff81551ffc>] dump_stack+0x4e/0x82 [<ffffffff810de202>] warn_slowpath_common+0x82/0xc0 [<ffffffff810de2fa>] warn_slowpath_null+0x1a/0x20 [<ffffffff8118e031>] pids_cancel.constprop.6+0x31/0x40 [<ffffffff8118e0fd>] pids_can_attach+0x6d/0xf0 [<ffffffff81188a4c>] cgroup_taskset_migrate+0x6c/0x330 [<ffffffff81188e05>] cgroup_migrate+0xf5/0x190 [<ffffffff81189016>] cgroup_attach_task+0x176/0x200 [<ffffffff8118949d>] __cgroup_procs_write+0x2ad/0x460 [<ffffffff81189684>] cgroup_procs_write+0x14/0x20 [<ffffffff811854e5>] cgroup_file_write+0x35/0x1c0 [<ffffffff812e26f1>] kernfs_fop_write+0x141/0x190 [<ffffffff81265f88>] __vfs_write+0x28/0xe0 [<ffffffff812666fc>] vfs_write+0xac/0x1a0 [<ffffffff81267019>] SyS_write+0x49/0xb0 [<ffffffff81bcef32>] entry_SYSCALL_64_fastpath+0x12/0x76 This patch fixes the bug by removing @css parameter from the three migration methods, ->can_attach, ->cancel_attach() and ->attach() and updating cgroup_taskset iteration helpers also return the destination css in addition to the task being migrated. All controllers are updated accordingly. * Controllers which don't care whether there are one or multiple target csses can be converted trivially. cpu, io, freezer, perf, netclassid and netprio fall in this category. * cpuset's current implementation assumes that there's single source and destination and thus doesn't support v2 hierarchy already. The only change made by this patchset is how that single destination css is obtained. * memory migration path already doesn't do anything on v2. How the single destination css is obtained is updated and the prep stage of mem_cgroup_can_attach() is reordered to accomodate the change. * pids is the only controller which was affected by this bug. It now correctly handles multi-destination migrations and no longer causes counter underflow from incorrect accounting. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Aleksa Sarai <cyphar@cyphar.com>
2015-11-23sched/fair: Modify the comment about lock assumptions in migrate_task_rq_fair()Byungchul Park1-2/+1
The comment describing migrate_task_rq_fair() says that the caller should hold p->pi_lock. But in some cases the caller can hold task_rq(p)->lock instead of p->pi_lock. So the comment is broken and this patch fixes it. Signed-off-by: Byungchul Park <byungchul.park@lge.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1447806899-20303-1-git-send-email-byungchul.park@lge.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23sched/core: Use list_is_singular() in sched_can_stop_tick()Geliang Tang1-1/+1
Use list_is_singular() to check if run_list has only one entry. Signed-off-by: Geliang Tang <geliangtang@163.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/a5453fafd735affcf28e53a1d0a3d6965cb5dbb5.1447582547.git.geliangtang@163.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23sched/core: Fix incorrect wait time and wait count statisticsJoonwoo Park2-22/+60
At present scheduler resets task's wait start timestamp when the task migrates to another rq. This misleads scheduler itself into reporting less wait time than actual by omitting time spent for waiting prior to migration and also more wait count than actual by counting migration as wait end event which can be seen by trace or /proc/<pid>/sched with CONFIG_SCHEDSTATS=y. Carry forward migrating task's wait time prior to migration and don't count migration as a wait end event to fix such statistics error. In order to determine whether task is migrating mark task->on_rq with TASK_ON_RQ_MIGRATING while dequeuing and enqueuing due to migration. Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: ohaugan@codeaurora.org Link: http://lkml.kernel.org/r/20151113033854.GA4247@codeaurora.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23treewide: Remove old email addressPeter Zijlstra2-2/+2
There were still a number of references to my old Red Hat email address in the kernel source. Remove these while keeping the Red Hat copyright notices intact. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23sched/numa: Cap PTE scanning overhead to 3% of run timeRik van Riel1-0/+12
There is a fundamental mismatch between the runtime based NUMA scanning at the task level, and the wall clock time NUMA scanning at the mm level. On a severely overloaded system, with very large processes, this mismatch can cause the system to spend all of its time in change_prot_numa(). This can happen if the task spends at least two ticks in change_prot_numa(), and only gets two ticks of CPU time in the real time between two scan intervals of the mm. This patch ensures that a task never spends more than 3% of run time scanning PTEs. It does that by ensuring that in-between task_numa_work() runs, the task spends at least 32x as much time on other things than it did on task_numa_work(). This is done stochastically: if a timer tick happens, or the task gets rescheduled during task_numa_work(), we delay a future run of task_numa_work() until the task has spent at least 32x the amount of CPU time doing something else, as it spent inside task_numa_work(). The longer task_numa_work() takes, the more likely it is this happens. If task_numa_work() takes very little time, chances are low that that code will do anything, but we will not care. Reported-and-tested-by: Jan Stancek <jstancek@redhat.com> Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: mgorman@suse.de Link: http://lkml.kernel.org/r/1446756983-28173-3-git-send-email-riel@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23sched/fair: Consider missed ticks in NOHZ_FULL in update_cpu_load_nohz()Byungchul Park1-4/+6
Usually the tick can be stopped for an idle CPU in NOHZ. However in NOHZ_FULL mode, a non-idle CPU's tick can also be stopped. However, update_cpu_load_nohz() does not consider the case a non-idle CPU's tick has been stopped at all. This patch makes the update_cpu_load_nohz() know if the calling path comes from NOHZ_FULL or idle NOHZ. Signed-off-by: Byungchul Park <byungchul.park@lge.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1447115762-19734-3-git-send-email-byungchul.park@lge.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23sched/fair: Prepare __update_cpu_load() to handle active ticklessByungchul Park1-8/+41
There are some cases where distance between ticks is more than one tick while the CPU is not idle, e.g. full NOHZ. However __update_cpu_load() assumes it is the idle tickless case if the distance between ticks is more than 1, even though it can be the active tickless case as well. Thus in the active tickless case, updating the CPU load will not be performed correctly. Where the current code assumes the load for each tick is zero, this is (obviously) not true in non-idle tickless case. We can approximately consider the load ~= this_rq->cpu_load[0] during tickless in non-idle tickless case. Signed-off-by: Byungchul Park <byungchul.park@lge.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1444816056-11886-2-git-send-email-byungchul.park@lge.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23sched/fair: Clean up the explanation around decaying load update missesPeter Zijlstra1-29/+24
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23sched/fair: Remove empty idle enter and exit functionsDietmar Eggemann3-32/+1
Commit cd126afe838d ("sched/fair: Remove rq's runnable avg") got rid of rq->avg and so there is no need to update it any more when entering or exiting idle. Remove the now empty functions idle_{enter|exit}_fair(). Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yuyang Du <yuyang.du@intel.com> Link: http://lkml.kernel.org/r/1445342681-17171-1-git-send-email-dietmar.eggemann@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23sched/rt: Hide the push_irq_work_func() declarationArnd Bergmann1-1/+1
The push_irq_work_func() function is conditionally defined only when both CONFIG_SMP and HAVE_RT_PUSH_IPI are defined, but the forward declaration remains visibile without HAVE_RT_PUSH_IPI, causing a gcc warning in ARM64 allnoconfig: kernel/sched/rt.c:68:13: warning: 'push_irq_work_func' declared 'static' but never defined [-Wunused-function] This changes the code to use the same condition for both the declaration and the function definition, which gets rid of the warning. As Peter Zijlstra, we can possibly get rid of the whole HAVE_RT_PUSH_IPI thing after: 8053871d0f7f ("smp: Fix smp_call_function_single_async() locking") Until that is done, this patch can be used to avoid the warning. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: b6366f048e0c ("sched/rt: Use IPI to trigger RT task push migration instead of pulling") Link: http://lkml.kernel.org/r/3828565.oKfGk7yNIT@wuerfel Signed-off-by: Ingo Molnar <mingo@kernel.org>