Messages in this thread Patch in this message | | | Subject | Re: [RFC][PATCH 0/7] perf trace: general-purpose scripting support, v2 | From | Peter Zijlstra <> | Date | Wed, 25 Nov 2009 10:38:11 +0100 |
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On Wed, 2009-11-25 at 09:28 +0100, Peter Zijlstra wrote: > On Wed, 2009-11-25 at 01:15 -0600, Tom Zanussi wrote: > > sched::sched_wakeup 0 01238.657997033 6183 firefox comm=firefox, pid=6199, prio=120, success=1, target_cpu=1 > > sched::sched_switch 1 01238.657991740 7140 firefox prev_comm=firefox, prev_pid=7140, prev_prio=120, prev_state=S, next_comm=firefox, next_pid=6199, next_prio=120 > > > > min_wakeup_latency: -5293 > > Looks like we missed a clock update on the cross cpu wakeup, Mike was > busy plugging those holes -- I've been starting at a patch that might > cure this (amongst other things).
Hmm, current -tip should have that cured as per:
--- commit 055a00865dcfc8e61f3cbefbb879c9577bd36ae5 Author: Mike Galbraith <efault@gmx.de> Date: Thu Nov 12 11:07:44 2009 +0100
sched: Fix/add missing update_rq_clock() calls kthread_bind(), migrate_task() and sched_fork were missing updates, and try_to_wake_up() was updating after having already used the stale clock. Aside from preventing potential latency hits, there' a side benefit in that early boot printk time stamps become monotonic. Signed-off-by: Mike Galbraith <efault@gmx.de> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1258020464.6491.2.camel@marge.simson.net> Signed-off-by: Ingo Molnar <mingo@elte.hu> LKML-Reference: <new-submission>
diff --git a/kernel/sched.c b/kernel/sched.c index 3c11ae0..701eca4 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2017,6 +2017,7 @@ void kthread_bind(struct task_struct *p, unsigned int cpu) } spin_lock_irqsave(&rq->lock, flags); + update_rq_clock(rq); set_task_cpu(p, cpu); p->cpus_allowed = cpumask_of_cpu(cpu); p->rt.nr_cpus_allowed = 1; @@ -2115,6 +2116,7 @@ migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req) * it is sufficient to simply update the task's cpu field. */ if (!p->se.on_rq && !task_running(rq, p)) { + update_rq_clock(rq); set_task_cpu(p, dest_cpu); return 0; } @@ -2376,14 +2378,15 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, task_rq_unlock(rq, &flags); cpu = p->sched_class->select_task_rq(p, SD_BALANCE_WAKE, wake_flags); - if (cpu != orig_cpu) + if (cpu != orig_cpu) { + local_irq_save(flags); + rq = cpu_rq(cpu); + update_rq_clock(rq); set_task_cpu(p, cpu); - + local_irq_restore(flags); + } rq = task_rq_lock(p, &flags); - if (rq != orig_rq) - update_rq_clock(rq); - WARN_ON(p->state != TASK_WAKING); cpu = task_cpu(p); @@ -2545,6 +2548,7 @@ static void __sched_fork(struct task_struct *p) void sched_fork(struct task_struct *p, int clone_flags) { int cpu = get_cpu(); + unsigned long flags; __sched_fork(p); @@ -2581,7 +2585,10 @@ void sched_fork(struct task_struct *p, int clone_flags) #ifdef CONFIG_SMP cpu = p->sched_class->select_task_rq(p, SD_BALANCE_FORK, 0); #endif + local_irq_save(flags); + update_rq_clock(cpu_rq(cpu)); set_task_cpu(p, cpu); + local_irq_restore(flags); #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) if (likely(sched_info_on()))
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