Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1189684 > unrolled thread

Re: [RFCv5 PATCH 11/46] sched: Remove blocked load and utilization contributions of dying tasks

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: [RFCv5 PATCH 11/46] sched: Remove blocked load and utilization  contributions of dying tasks Leo Yan <leo.yan@linaro.org> - 2015-07-22 09:00 +0200
    Re: [RFCv5 PATCH 11/46] sched: Remove blocked load and utilization  contributions of dying tasks Morten Rasmussen <morten.rasmussen@arm.com> - 2015-07-22 15:50 +0200

#1189684 — Re: [RFCv5 PATCH 11/46] sched: Remove blocked load and utilization contributions of dying tasks

On Tue, Jul 07, 2015 at 07:23:54PM +0100, Morten Rasmussen wrote:
> Tasks being dequeued for the last time (state == TASK_DEAD) are dequeued
> with the DEQUEUE_SLEEP flag which causes their load and utilization
> contributions to be added to the runqueue blocked load and utilization.
> Hence they will contain load or utilization that is gone away. The issue
> only exists for the root cfs_rq as cgroup_exit() doesn't set
> DEQUEUE_SLEEP for task group exits.
> 
> If runnable+blocked load is to be used as a better estimate for cpu
> load the dead task contributions need to be removed to prevent
> load_balance() (idle_balance() in particular) from over-estimating the
> cpu load.
> 
> cc: Ingo Molnar <mingo@redhat.com>
> cc: Peter Zijlstra <peterz@infradead.org>
> 
> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
> ---
>  kernel/sched/fair.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 775b0c7..fa12ce5 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -3217,6 +3217,8 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
>  	 * Update run-time statistics of the 'current'.
>  	 */
>  	update_curr(cfs_rq);
> +	if (entity_is_task(se) && task_of(se)->state == TASK_DEAD)
> +		flags &= !DEQUEUE_SLEEP;

So flags will be set to zero? Could be replaced by "flags &= ~DEQUEUE_SLEEP"?

>  	dequeue_entity_load_avg(cfs_rq, se, flags & DEQUEUE_SLEEP);
>  
>  	update_stats_dequeue(cfs_rq, se);
> -- 
> 1.9.1
> 
> --
> 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/
--
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/

[toc] | [next] | [standalone]

#1189954

On Wed, Jul 22, 2015 at 02:51:01PM +0800, Leo Yan wrote:
> On Tue, Jul 07, 2015 at 07:23:54PM +0100, Morten Rasmussen wrote:
> > Tasks being dequeued for the last time (state == TASK_DEAD) are dequeued
> > with the DEQUEUE_SLEEP flag which causes their load and utilization
> > contributions to be added to the runqueue blocked load and utilization.
> > Hence they will contain load or utilization that is gone away. The issue
> > only exists for the root cfs_rq as cgroup_exit() doesn't set
> > DEQUEUE_SLEEP for task group exits.
> > 
> > If runnable+blocked load is to be used as a better estimate for cpu
> > load the dead task contributions need to be removed to prevent
> > load_balance() (idle_balance() in particular) from over-estimating the
> > cpu load.
> > 
> > cc: Ingo Molnar <mingo@redhat.com>
> > cc: Peter Zijlstra <peterz@infradead.org>
> > 
> > Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
> > ---
> >  kernel/sched/fair.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index 775b0c7..fa12ce5 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -3217,6 +3217,8 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> >  	 * Update run-time statistics of the 'current'.
> >  	 */
> >  	update_curr(cfs_rq);
> > +	if (entity_is_task(se) && task_of(se)->state == TASK_DEAD)
> > +		flags &= !DEQUEUE_SLEEP;
> 
> So flags will be set to zero? Could be replaced by "flags &= ~DEQUEUE_SLEEP"?

Not could, should :)

I meant to clear the flag, but used the wrong operator. We only have
DEQUEUE_SLEEP and 0 at the moment so it doesn't matter, but it might
later.

Thanks,
Morten
--
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/

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web