Messages in this thread | | | Date | Fri, 6 Jul 2018 14:20:57 +0100 | From | Quentin Perret <> | Subject | Re: [RFC PATCH v4 08/12] sched: Add over-utilization/tipping point indicator |
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On Friday 06 Jul 2018 at 13:32:08 (+0200), Peter Zijlstra wrote: > On Thu, Jun 28, 2018 at 12:40:39PM +0100, Quentin Perret wrote: > > @@ -5384,6 +5402,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) > > { > > struct cfs_rq *cfs_rq; > > struct sched_entity *se = &p->se; > > + int task_new = !(flags & ENQUEUE_WAKEUP); > > > > /* > > * The code below (indirectly) updates schedutil which looks at > > @@ -5431,8 +5450,12 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) > > update_cfs_group(se); > > } > > > > - if (!se) > > + if (!se) { > > add_nr_running(rq, 1); > > + if (!task_new) > > + update_overutilized_status(rq); > > I'm confused... why only for !ENQUEUE_WAKEUP
So, what we try to do here is to _not_ set the overutilized flag based on the utilization of a new task, because its utilization is 'wrong'. That should help avoiding spurious transitions above the overutilized threshold.
Was there also something else Morten ?
> and why use a local > variable for something that's used only once?
No good reasons. An older version of this patch used 'task_new' in two different locations. This is no longer true, I'll clean that up for v5.
Thanks, Quentin
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