Messages in this thread | | | Date | Thu, 2 Aug 2018 14:03:38 +0100 | From | Quentin Perret <> | Subject | Re: [PATCH v5 09/14] sched: Add over-utilization/tipping point indicator |
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On Thursday 02 Aug 2018 at 14:26:29 (+0200), Peter Zijlstra wrote: > On Tue, Jul 24, 2018 at 01:25:16PM +0100, Quentin Perret wrote: > > @@ -5100,8 +5118,17 @@ 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); > > + /* > > + * The utilization of a new task is 'wrong' so wait for it > > + * to build some utilization history before trying to detect > > + * the overutilized flag. > > + */ > > + if (flags & ENQUEUE_WAKEUP) > > + update_overutilized_status(rq); > > + > > + } > > > > hrtick_update(rq); > > } > > That is a somewhat dodgy hack. There is no guarantee what so ever that > when the task wakes next its history is any better. The comment doesn't > reflect this I feel.
AFAICT the main use-case here is to avoid re-enabling the load balance and ruining all the task placement because of a tiny task. I don't really see how we can do that differently ...
Or am I missing something Morten ?
In the meantime, I can try to improve the comment at least :-)
Thanks, Quentin
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