lkml.org 
[lkml]   [2009]   [Apr]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] sched: account system time properly
    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?

    --
    blue skies,
    Martin.

    "Reality continues to ruin my life." - Calvin.

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2009-04-29 10:15    [W:0.023 / U:31.164 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site