From 46ac22bab42cc868b9c1d0e915ddbc8e8065a44d Mon Sep 17 00:00:00 2001 From: Ankita Garg Date: Tue, 1 Jul 2008 14:30:06 +0530 Subject: sched: fix accounting in task delay accounting & migration On Thu, Jun 19, 2008 at 12:27:14PM +0200, Peter Zijlstra wrote: > On Thu, 2008-06-05 at 10:50 +0530, Ankita Garg wrote: > > > Thanks Peter for the explanation... > > > > I agree with the above and that is the reason why I did not see weird > > values with cpu_time. But, run_delay still would suffer skews as the end > > points for delta could be taken on different cpus due to migration (more > > so on RT kernel due to the push-pull operations). With the below patch, > > I could not reproduce the issue I had seen earlier. After every dequeue, > > we take the delta and start wait measurements from zero when moved to a > > different rq. > > OK, so task delay delay accounting is broken because it doesn't take > migration into account. > > What you've done is make it symmetric wrt enqueue, and account it like > > cpu0 cpu1 > > enqueue > > dequeue > enqueue > > run > > Where you add both d1 and d2 to the run_delay,.. right? > Thanks for reviewing the patch. The above is exactly what I have done. > This seems like a good fix, however it looks like the patch will break > compilation in !CONFIG_SCHEDSTATS && !CONFIG_TASK_DELAY_ACCT, of it > failing to provide a stub for sched_info_dequeue() in that case. Fixed. Pl. find the new patch below. Signed-off-by: Ankita Garg Acked-by: Peter Zijlstra Cc: Gregory Haskins Cc: rostedt@goodmis.org Cc: suresh.b.siddha@intel.com Cc: aneesh.kumar@linux.vnet.ibm.com Cc: dhaval@linux.vnet.ibm.com Cc: vatsa@linux.vnet.ibm.com Cc: David Bahi Signed-off-by: Ingo Molnar --- kernel/sched.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/sched.c') diff --git a/kernel/sched.c b/kernel/sched.c index bbc40c3a065..996bc15196a 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1714,6 +1714,7 @@ static void dequeue_task(struct rq *rq, struct task_struct *p, int sleep) p->se.last_wakeup = 0; } + sched_info_dequeued(p); p->sched_class->dequeue_task(rq, p, sleep); p->se.on_rq = 0; } -- cgit v1.2.3