On Wed, May 13, 2015 at 01:33:22AM +0100, Sai Gurrappadi wrote: > 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 <mi...@redhat.com> > > cc: Peter Zijlstra <pet...@infradead.org> > > > > Signed-off-by: Morten Rasmussen <morten.rasmus...@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.
Now that you mention it, I remember that thread I think. I will have a look again and see if there are any good reasons not to use task_dead(). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
