[lkml]   [2012]   [Jan]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [Question] sched: Should nr_uninterruptible be decremented in ttwu_do_activate()?
On Wed, Jan 11, 2012 at 11:29 PM, Peter Zijlstra <> wrote:
> On Wed, 2012-01-11 at 23:22 +0600, Rakib Mullick wrote:
>> Hello all,
>> In ttwu_do_activate(), we're decrementing nr_uninterruptible if
>> p->sched_contributes_to_load (for SMP=y). But, we're also decrementing
>> nr_uninterruptible from activate_task at the same path. Why we're
>> doing it twice for a single task activation path?
> activate_task() does:
>  if (task_contributes_to_load(p))
>   rq->nr_uninterruptible--;
> Now task_contributes_to_load() reads like:
> #define task_contributes_to_load(task)  \
>                                ((task->state & TASK_UNINTERRUPTIBLE) != 0 && \
>                                 (task->flags & PF_FREEZING) == 0)
> which will be false, since we've set TASK_WAKING.

Enough confusing. TASK_WAKING will be set when called from
try_to_wake_up(). ttwu_do_activate() gets called from other places:
scheduler_ipi() and sched_ttwu_pending() (at the time of cpu goes
down). TASK_WAKING will be not set at that time, moreover it is
possible that, task has p->sched_contributes_to_load is set and latter
on gets wake up by sched_ttwu_pending/scheduler_ipi() call.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2012-01-12 07:11    [W:0.051 / U:0.152 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site