Messages in this thread | | | Date | Wed, 29 Apr 2009 11:20:03 +0200 | From | Eric Dumazet <> | Subject | Re: [PATCH] sched: account system time properly |
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Martin Schwidefsky a écrit : > On Wed, 29 Apr 2009 09:46:17 +0200 > Eric Dumazet <dada1@cosmosbay.com> wrote: > >> Eric Dumazet a écrit : >>> Andrew Morton a écrit : >>> >>> So, if IRQs are interrupting idle task, I guess if (p != rq->idle) will be false. >>> > > If an IRQ interrupts the idle task the tick is supposed to be accounted > as an idle tick. Only if the IRQ interrupted the system while it has > been in hardirq or softirq processing then it should be accounted as > system tick. > >> Maybe following patch is needed ? >> >> [PATCH] sched: account system time properly >> >> When idle task is interrupted by an IRQ, time accounting considers CPU is idle, >> even while it should account for hard or softirq. >> >> Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> >> >> diff --git a/kernel/sched.c b/kernel/sched.c >> index b902e58..26efa47 100644 >> --- a/kernel/sched.c >> +++ b/kernel/sched.c >> @@ -4732,7 +4732,7 @@ void account_process_tick(struct task_struct *p, int user_tick) >> >> if (user_tick) >> account_user_time(p, one_jiffy, one_jiffy_scaled); >> - else if (p != rq->idle) >> + else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET)) >> account_system_time(p, HARDIRQ_OFFSET, one_jiffy, >> one_jiffy_scaled); >> else > > That patch makes a lot of sense to me. Does it fix the problem? >
Yes it does, on my machine at least :
11:18:48 AM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle 11:18:58 AM all 0.00 0.00 0.00 0.00 0.21 0.69 0.00 0.00 99.10 11:18:58 AM 0 0.00 0.00 0.00 0.00 1.70 5.50 0.00 0.00 92.80 << HERE >> 11:18:58 AM 1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 11:18:58 AM 2 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 11:18:58 AM 3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 11:18:58 AM 4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 11:18:58 AM 5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 11:18:58 AM 6 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 11:18:58 AM 7 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00
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