Messages in this thread | | | Date | Tue, 12 May 2015 17:33:22 -0700 | From | Sai Gurrappadi <> | Subject | Re: [RFCv4 PATCH 11/34] sched: Remove blocked load and utilization contributions of dying tasks |
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On 05/12/2015 12:38 PM, Morten Rasmussen wrote: > Task 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 e40cd88..d045404 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -3202,6 +3202,8 @@ 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; > dequeue_entity_load_avg(cfs_rq, se, flags & DEQUEUE_SLEEP); > > update_stats_dequeue(cfs_rq, se); >
Maybe you could use the sched_class->task_dead() callback instead? I remember seeing a patch from Yuyang that did that.
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