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* sched/rt: Fix task stack corruption under __ARCH_WANT_INTERRUPTS_ON_CTXSWChanho Min2012-01-271-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This issue happens under the following conditions: 1. preemption is off 2. __ARCH_WANT_INTERRUPTS_ON_CTXSW is defined 3. RT scheduling class 4. SMP system Sequence is as follows: 1.suppose current task is A. start schedule() 2.task A is enqueued pushable task at the entry of schedule() __schedule prev = rq->curr; ... put_prev_task put_prev_task_rt enqueue_pushable_task 4.pick the task B as next task. next = pick_next_task(rq); 3.rq->curr set to task B and context_switch is started. rq->curr = next; 4.At the entry of context_swtich, release this cpu's rq->lock. context_switch prepare_task_switch prepare_lock_switch raw_spin_unlock_irq(&rq->lock); 5.Shortly after rq->lock is released, interrupt is occurred and start IRQ context 6.try_to_wake_up() which called by ISR acquires rq->lock try_to_wake_up ttwu_remote rq = __task_rq_lock(p) ttwu_do_wakeup(rq, p, wake_flags); task_woken_rt 7.push_rt_task picks the task A which is enqueued before. task_woken_rt push_rt_tasks(rq) next_task = pick_next_pushable_task(rq) 8.At find_lock_lowest_rq(), If double_lock_balance() returns 0, lowest_rq can be the remote rq. (But,If preemption is on, double_lock_balance always return 1 and it does't happen.) push_rt_task find_lock_lowest_rq if (double_lock_balance(rq, lowest_rq)).. 9.find_lock_lowest_rq return the available rq. task A is migrated to the remote cpu/rq. push_rt_task ... deactivate_task(rq, next_task, 0); set_task_cpu(next_task, lowest_rq->cpu); activate_task(lowest_rq, next_task, 0); 10. But, task A is on irq context at this cpu. So, task A is scheduled by two cpus at the same time until restore from IRQ. Task A's stack is corrupted. To fix it, don't migrate an RT task if it's still running. Signed-off-by: Chanho Min <chanho.min@lge.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: <stable@kernel.org> Link: http://lkml.kernel.org/r/CAOAMb1BHA=5fm7KTewYyke6u-8DP0iUuJMpgQw54vNeXFsGpoQ@mail.gmail.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched/nohz: Fix nohz cpu idle load balancing state with cpu hotplugSuresh Siddha2012-01-261-5/+29
| | | | | | | | | | | | | | | | | | | | | | | | | With the recent nohz scheduler changes, rq's nohz flag 'NOHZ_TICK_STOPPED' and its associated state doesn't get cleared immediately after the cpu exits idle. This gets cleared as part of the next tick seen on that cpu. For the cpu offline support, we need to clear this state manually. Fix it by registering a cpu notifier, which clears the nohz idle load balance state for this rq explicitly during the CPU_DYING notification. There won't be any nohz updates for that cpu, after the CPU_DYING notification. But lets be extra paranoid and skip updating the nohz state in the select_nohz_load_balancer() if the cpu is not in active state anymore. Reported-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Reviewed-and-tested-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.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/1327026538.16150.40.camel@sbsiddha-desk.sc.intel.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched/s390: Fix compile error in sched/core.cChristian Borntraeger2012-01-261-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | Commit 029632fbb7b7c9d85063cc9eb470de6c54873df3 ("sched: Make separate sched*.c translation units") removed the include of asm/mutex.h from sched.c. This breaks the combination of: CONFIG_MUTEX_SPIN_ON_OWNER=yes CONFIG_HAVE_ARCH_MUTEX_CPU_RELAX=yes like s390 without mutex debugging: CC kernel/sched/core.o kernel/sched/core.c: In function ‘mutex_spin_on_owner’: kernel/sched/core.c:3287: error: implicit declaration of function ‘arch_mutex_cpu_relax’ Lets re-add the include to kernel/sched/core.c Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1326268696-30904-1-git-send-email-borntraeger@de.ibm.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Fix rq->nr_uninterruptible update racePeter Zijlstra2012-01-261-12/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | KOSAKI Motohiro noticed the following race: > CPU0 CPU1 > -------------------------------------------------------- > deactivate_task() > task->state = TASK_UNINTERRUPTIBLE; > activate_task() > rq->nr_uninterruptible--; > > schedule() > deactivate_task() > rq->nr_uninterruptible++; > Kosaki-San's scenario is possible when CPU0 runs __sched_setscheduler() against CPU1's current @task. __sched_setscheduler() does a dequeue/enqueue in order to move the task to its new queue (position) to reflect the newly provided scheduling parameters. However it should be completely invariant to nr_uninterruptible accounting, sched_setscheduler() doesn't affect readyness to run, merely policy on when to run. So convert the inappropriate activate/deactivate_task usage to enqueue/dequeue_task, which avoids the nr_uninterruptible accounting. Also convert the two other sites: __migrate_task() and normalize_task() that still use activate/deactivate_task. These sites aren't really a problem since __migrate_task() will only be called on non-running task (and therefore are immume to the described problem) and normalize_task() isn't ever used on regular systems. Also remove the comments from activate/deactivate_task since they're misleading at best. Reported-by: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1327486224.2614.45.camel@laptop Signed-off-by: Ingo Molnar <mingo@elte.hu>
* kernel-doc: fix kernel-doc warnings in schedRandy Dunlap2012-01-231-2/+1
| | | | | | | | | | | | | | | Fix new kernel-doc notation warnings: Warning(include/linux/sched.h:2094): No description found for parameter 'p' Warning(include/linux/sched.h:2094): Excess function parameter 'tsk' description in 'is_idle_task' Warning(kernel/sched/cpupri.c:139): No description found for parameter 'newpri' Warning(kernel/sched/cpupri.c:139): Excess function parameter 'pri' description in 'cpupri_set' Warning(kernel/sched/cpupri.c:208): Excess function parameter 'bootmem' description in 'cpupri_init' Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'for-linus' of git://selinuxproject.org/~jmorris/linux-securityLinus Torvalds2012-01-141-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * 'for-linus' of git://selinuxproject.org/~jmorris/linux-security: capabilities: remove __cap_full_set definition security: remove the security_netlink_recv hook as it is equivalent to capable() ptrace: do not audit capability check when outputing /proc/pid/stat capabilities: remove task_ns_* functions capabitlies: ns_capable can use the cap helpers rather than lsm call capabilities: style only - move capable below ns_capable capabilites: introduce new has_ns_capabilities_noaudit capabilities: call has_ns_capability from has_capability capabilities: remove all _real_ interfaces capabilities: introduce security_capable_noaudit capabilities: reverse arguments to security_capable capabilities: remove the task from capable LSM hook entirely selinux: sparse fix: fix several warnings in the security server cod selinux: sparse fix: fix warnings in netlink code selinux: sparse fix: eliminate warnings for selinuxfs selinux: sparse fix: declare selinux_disable() in security.h selinux: sparse fix: move selinux_complete_init selinux: sparse fix: make selinux_secmark_refcount static SELinux: Fix RCU deref check warning in sel_netport_insert() Manually fix up a semantic mis-merge wrt security_netlink_recv(): - the interface was removed in commit fd7784615248 ("security: remove the security_netlink_recv hook as it is equivalent to capable()") - a new user of it appeared in commit a38f7907b926 ("crypto: Add userspace configuration API") causing no automatic merge conflict, but Eric Paris pointed out the issue.
* Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds2012-01-112-10/+7
|\ | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Fix lockup by limiting load-balance retries on lock-break sched: Fix CONFIG_CGROUP_SCHED dependency sched: Remove empty #ifdefs
| * sched: Fix lockup by limiting load-balance retries on lock-breakPeter Zijlstra2012-01-111-3/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Eric and David reported dead machines and traced it to commit a195f004 ("sched: Fix load-balance lock-breaking"), it turns out there's still a scenario where we can end up re-trying forever. Since there is no strict forward progress guarantee in the load-balance iteration we can get stuck re-retrying the same task-set over and over. Creating a forward progress guarantee with the existing structure is somewhat non-trivial, for now simply terminate the retry loop after a few tries. Reported-by: Eric Dumazet <eric.dumazet@gmail.com> Tested-by: Eric Dumazet <eric.dumazet@gmail.com> Reported-by: David Ahern <dsahern@gmail.com> [ logic cleanup as suggested by Eric ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Link: http://lkml.kernel.org/r/1326297936.2442.157.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: Remove empty #ifdefsHiroshi Shimamoto2012-01-101-7/+0
| | | | | | | | | | | | | | Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/4F0B8525.8070901@ct.jp.nec.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | Merge branch 'for-3.3' of ↵Linus Torvalds2012-01-091-12/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup * 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (21 commits) cgroup: fix to allow mounting a hierarchy by name cgroup: move assignement out of condition in cgroup_attach_proc() cgroup: Remove task_lock() from cgroup_post_fork() cgroup: add sparse annotation to cgroup_iter_start() and cgroup_iter_end() cgroup: mark cgroup_rmdir_waitq and cgroup_attach_proc() as static cgroup: only need to check oldcgrp==newgrp once cgroup: remove redundant get/put of task struct cgroup: remove redundant get/put of old css_set from migrate cgroup: Remove unnecessary task_lock before fetching css_set on migration cgroup: Drop task_lock(parent) on cgroup_fork() cgroups: remove redundant get/put of css_set from css_set_check_fetched() resource cgroups: remove bogus cast cgroup: kill subsys->can_attach_task(), pre_attach() and attach_task() cgroup, cpuset: don't use ss->pre_attach() cgroup: don't use subsys->can_attach_task() or ->attach_task() cgroup: introduce cgroup_taskset and use it in subsys->can_attach(), cancel_attach() and attach() cgroup: improve old cgroup handling in cgroup_attach_proc() cgroup: always lock threadgroup during migration threadgroup: extend threadgroup_lock() to cover exit and exec threadgroup: rename signal->threadgroup_fork_lock to ->group_rwsem ... Fix up conflict in kernel/cgroup.c due to commit e0197aae59e5: "cgroups: fix a css_set not found bug in cgroup_attach_proc" that already mentioned that the bug is fixed (differently) in Tejun's cgroup patchset. This one, in other words.
* | Merge branch 'for-linus2' of ↵Linus Torvalds2012-01-081-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs * 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (165 commits) reiserfs: Properly display mount options in /proc/mounts vfs: prevent remount read-only if pending removes vfs: count unlinked inodes vfs: protect remounting superblock read-only vfs: keep list of mounts for each superblock vfs: switch ->show_options() to struct dentry * vfs: switch ->show_path() to struct dentry * vfs: switch ->show_devname() to struct dentry * vfs: switch ->show_stats to struct dentry * switch security_path_chmod() to struct path * vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb vfs: trim includes a bit switch mnt_namespace ->root to struct mount vfs: take /proc/*/mounts and friends to fs/proc_namespace.c vfs: opencode mntget() mnt_set_mountpoint() vfs: spread struct mount - remaining argument of next_mnt() vfs: move fsnotify junk to struct mount vfs: move mnt_devname vfs: move mnt_list to struct mount vfs: switch pnode.h macros to struct mount * ...
* | Merge branch 'driver-core-next' of ↵Linus Torvalds2012-01-071-21/+19
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core * 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (73 commits) arm: fix up some samsung merge sysdev conversion problems firmware: Fix an oops on reading fw_priv->fw in sysfs loading file Drivers:hv: Fix a bug in vmbus_driver_unregister() driver core: remove __must_check from device_create_file debugfs: add missing #ifdef HAS_IOMEM arm: time.h: remove device.h #include driver-core: remove sysdev.h usage. clockevents: remove sysdev.h arm: convert sysdev_class to a regular subsystem arm: leds: convert sysdev_class to a regular subsystem kobject: remove kset_find_obj_hinted() m86k: gpio - convert sysdev_class to a regular subsystem mips: txx9_sram - convert sysdev_class to a regular subsystem mips: 7segled - convert sysdev_class to a regular subsystem sh: dma - convert sysdev_class to a regular subsystem sh: intc - convert sysdev_class to a regular subsystem power: suspend - convert sysdev_class to a regular subsystem power: qe_ic - convert sysdev_class to a regular subsystem power: cmm - convert sysdev_class to a regular subsystem s390: time - convert sysdev_class to a regular subsystem ... Fix up conflicts with 'struct sysdev' removal from various platform drivers that got changed: - arch/arm/mach-exynos/cpu.c - arch/arm/mach-exynos/irq-eint.c - arch/arm/mach-s3c64xx/common.c - arch/arm/mach-s3c64xx/cpu.c - arch/arm/mach-s5p64x0/cpu.c - arch/arm/mach-s5pv210/common.c - arch/arm/plat-samsung/include/plat/cpu.h - arch/powerpc/kernel/sysfs.c and fix up cpu_is_hotpluggable() as per Greg in include/linux/cpu.h
* sched/tracing: Add a new tracepoint for sleeptimeArun Sharma2011-12-232-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | If CONFIG_SCHEDSTATS is defined, the kernel maintains information about how long the task was sleeping or in the case of iowait, blocking in the kernel before getting woken up. This will be useful for sleep time profiling. Note: this information is only provided for sched_fair. Other scheduling classes may choose to provide this in the future. Note: the delay includes the time spent on the runqueue as well. Signed-off-by: Arun Sharma <asharma@fb.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Andrew Vagin <avagin@openvz.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/1324512940-32060-2-git-send-email-asharma@fb.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Disable scheduler warnings during oopsesDave Jones2011-12-231-0/+3
| | | | | | | | | | | | | | The panic-on-framebuffer code seems to cause a schedule to occur during an oops. This causes a bunch of extra spew as can be seen in: https://bugzilla.redhat.com/attachment.cgi?id=549230 Don't do scheduler debug checks when we are oopsing already. Signed-off-by: Dave Jones <davej@redhat.com> Link: http://lkml.kernel.org/r/20111222213929.GA4722@redhat.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Fix cgroup movement of waking processDaisuke Nishimura2011-12-211-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is a small race between try_to_wake_up() and sched_move_task(), which is trying to move the process being woken up. try_to_wake_up() on CPU0 sched_move_task() on CPU1 --------------------------------+--------------------------------- raw_spin_lock_irqsave(p->pi_lock) task_waking_fair() ->p.se.vruntime -= cfs_rq->min_vruntime ttwu_queue() ->send reschedule IPI to CPU1 raw_spin_unlock_irqsave(p->pi_lock) task_rq_lock() -> tring to aquire both p->pi_lock and rq->lock with IRQ disabled task_move_group_fair() -> p.se.vruntime -= (old)cfs_rq->min_vruntime += (new)cfs_rq->min_vruntime task_rq_unlock() (via IPI) sched_ttwu_pending() raw_spin_lock(rq->lock) ttwu_do_activate() ... enqueue_entity() child.se->vruntime += cfs_rq->min_vruntime raw_spin_unlock(rq->lock) As a result, vruntime of the process becomes far bigger than min_vruntime, if (new)cfs_rq->min_vruntime >> (old)cfs_rq->min_vruntime. This patch fixes this problem by just ignoring such process in task_move_group_fair(), because the vruntime has already been normalized in task_waking_fair(). Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20111215143741.df82dd50.nishimura@mxp.nes.nec.co.jp Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Fix cgroup movement of newly created processDaisuke Nishimura2011-12-211-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is a small race between do_fork() and sched_move_task(), which is trying to move the child. do_fork() sched_move_task() --------------------------------+--------------------------------- copy_process() sched_fork() task_fork_fair() -> vruntime of the child is initialized based on that of the parent. -> we can see the child in "tasks" file now. task_rq_lock() task_move_group_fair() -> child.se.vruntime -= (old)cfs_rq->min_vruntime += (new)cfs_rq->min_vruntime task_rq_unlock() wake_up_new_task() ... enqueue_entity() child.se.vruntime += cfs_rq->min_vruntime As a result, vruntime of the child becomes far bigger than min_vruntime, if (new)cfs_rq->min_vruntime >> (old)cfs_rq->min_vruntime. This patch fixes this problem by just ignoring such process in task_move_group_fair(), because the vruntime has already been normalized in task_fork_fair(). Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20111215143607.2ee12c5d.nishimura@mxp.nes.nec.co.jp Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Fix cgroup movement of forking processDaisuke Nishimura2011-12-211-2/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is a small race between task_fork_fair() and sched_move_task(), which is trying to move the parent. task_fork_fair() sched_move_task() --------------------------------+--------------------------------- cfs_rq = task_cfs_rq(current) -> cfs_rq is the "old" one. curr = cfs_rq->curr -> curr is set to the parent. task_rq_lock() dequeue_task() ->parent.se.vruntime -= (old)cfs_rq->min_vruntime enqueue_task() ->parent.se.vruntime += (new)cfs_rq->min_vruntime task_rq_unlock() raw_spin_lock_irqsave(rq->lock) se->vruntime = curr->vruntime -> vruntime of the child is set to that of the parent which has already been updated by sched_move_task(). se->vruntime -= (old)cfs_rq->min_vruntime. raw_spin_unlock_irqrestore(rq->lock) As a result, vruntime of the child becomes far bigger than expected, if (new)cfs_rq->min_vruntime >> (old)cfs_rq->min_vruntime. This patch fixes this problem by setting "cfs_rq" and "curr" after holding the rq->lock. Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Acked-by: Paul Turner <pjt@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20111215143655.662676b0.nishimura@mxp.nes.nec.co.jp Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Remove cfs bandwidth period check in tg_set_cfs_period()Kamalesh Babulal2011-12-211-3/+0
| | | | | | | | | | | | | | | | | | | | | Remove cfs bandwidth period check from tg_set_cfs_period. Invalid bandwidth period's lower/upper limits are denoted by min_cfs_quota_period/max_cfs_quota_period repsectively, and are checked against valid period in tg_set_cfs_bandwidth(). As pjt pointed out, negative input will result in very large unsigned numbers and will be caught by the max allowed period test. Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Acked-by: Paul Turner <pjt@google.com> [ammended changelog to mention negative values] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20111210135925.GA14593@linux.vnet.ibm.com -- kernel/sched/core.c | 3 --- 1 file changed, 3 deletions(-) Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Fix load-balance lock-breakingPeter Zijlstra2011-12-211-7/+25
| | | | | | | | | | | | | | | | | | | The current lock break relies on contention on the rq locks, something which might never come because we've got IRQs disabled. Or will be very likely because on anything with more than 2 cpus a synchronized load-balance pass will very likely cause contention on the rq locks. Also the sched_nr_migrate thing fails when it gets trapped the loops of either the cgroup muck in load_balance_fair() or the move_tasks() load condition. Instead, use the new lb_flags field to propagate break/abort conditions for all these loops and create a new loop outside the irq disabled on the break being required. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-tsceb6w61q0gakmsccix6xxi@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Replace all_pinned with a generic flags fieldPeter Zijlstra2011-12-211-16/+19
| | | | | | | | | Replace the all_pinned argument with a flags field so that we can add some extra controls throughout that entire call chain. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-33kevm71m924ok1gpxd720v3@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Only queue remote wakeups when crossing cache boundariesPeter Zijlstra2011-12-213-30/+70
| | | | | | | | | | | | | | | | | | | Mike reported a 13% drop in netperf TCP_RR performance due to the new remote wakeup code. Suresh too noticed some performance issues with it. Reducing the IPIs to only cross cache domains solves the observed performance issues. Reported-by: Suresh Siddha <suresh.b.siddha@intel.com> Reported-by: Mike Galbraith <efault@gmx.de> Acked-by: Suresh Siddha <suresh.b.siddha@intel.com> Acked-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Kleikamp <dave.kleikamp@oracle.com> Link: http://lkml.kernel.org/r/1323338531.17673.7.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Merge branch 'sched/core' of ↵Martin Schwidefsky2011-12-192-43/+34
| | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into cputime-tip Conflicts: drivers/cpufreq/cpufreq_conservative.c drivers/cpufreq/cpufreq_ondemand.c drivers/macintosh/rack-meter.c fs/proc/stat.c fs/proc/uptime.c kernel/sched/core.c
* sched: Add missing rcu_dereference() around ->real_parent usageKees Cook2011-12-161-1/+1
| | | | | | | | | | | | | Wrap another ->real_parent dereference while under rcu_read_lock. Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Glauber Costa <glommer@parallels.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Link: http://lkml.kernel.org/r/20111215164918.GA13003@www.outflux.net [ tidied up the changelog ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 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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