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Groups > linux.kernel > #1426524

Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks

From Dietmar Eggemann <dietmar.eggemann@arm.com>
Newsgroups linux.kernel
Subject Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks
Date 2016-06-20 14:00 +0200
Message-ID <rM620-7K7-117@gated-at.bofh.it> (permalink)
References (1 earlier) <rL0L0-6mx-23@gated-at.bofh.it> <rL2D8-7yf-9@gated-at.bofh.it> <rL2Wt-7ET-29@gated-at.bofh.it> <rL4vf-jd-3@gated-at.bofh.it> <rL4EV-my-11@gated-at.bofh.it>
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On 17/06/16 17:18, Peter Zijlstra wrote:
> On Fri, Jun 17, 2016 at 06:02:39PM +0200, Peter Zijlstra wrote:
>> So yes, ho-humm, how to go about doing that bestest. Lemme have a play.
> 
> This is what I came up with, not entirely pretty, but I suppose it'll
> have to do.
> 
> ---
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -724,6 +724,7 @@ void post_init_entity_util_avg(struct sc
>  	struct cfs_rq *cfs_rq = cfs_rq_of(se);
>  	struct sched_avg *sa = &se->avg;
>  	long cap = (long)(SCHED_CAPACITY_SCALE - cfs_rq->avg.util_avg) / 2;
> +	u64 now = cfs_rq_clock_task(cfs_rq);
>  
>  	if (cap > 0) {
>  		if (cfs_rq->avg.util_avg != 0) {
> @@ -738,7 +739,20 @@ void post_init_entity_util_avg(struct sc
>  		sa->util_sum = sa->util_avg * LOAD_AVG_MAX;
>  	}
>  
> -	update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq, false);
> +	if (entity_is_task(se)) {
> +		struct task_struct *p = task_of(se);
> +		if (p->sched_class != &fair_sched_class) {
> +			/*
> +			 * For !fair tasks do attach_entity_load_avg()
> +			 * followed by detach_entity_load_avg() as per
> +			 * switched_from_fair().
> +			 */
> +			se->avg.last_update_time = now;
> +			return;
> +		}
> +	}
> +
> +	update_cfs_rq_load_avg(now, cfs_rq, false);
>  	attach_entity_load_avg(cfs_rq, se);
>  }
>  
> 

Doesn't a sleeping !fair_sched_class task which switches to fair uses
try_to_wake_up() rather than wake_up_new_task() so it won't go through
post_init_entity_util_avg()?

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Thread

[PATCH 0/4] sched/fair: Fix PELT wobblies Peter Zijlstra <peterz@infradead.org> - 2016-06-17 14:10 +0200
  [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Peter Zijlstra <peterz@infradead.org> - 2016-06-17 14:10 +0200
    Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Vincent Guittot <vincent.guittot@linaro.org> - 2016-06-17 16:10 +0200
      Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Peter Zijlstra <peterz@infradead.org> - 2016-06-17 16:30 +0200
        Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Peter Zijlstra <peterz@infradead.org> - 2016-06-17 18:10 +0200
          Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Vincent Guittot <vincent.guittot@linaro.org> - 2016-06-17 18:20 +0200
          Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Peter Zijlstra <peterz@infradead.org> - 2016-06-17 18:20 +0200
            Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Yuyang Du <yuyang.du@intel.com> - 2016-06-20 09:00 +0200
            Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Vincent Guittot <vincent.guittot@linaro.org> - 2016-06-20 11:30 +0200
              Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Peter Zijlstra <peterz@infradead.org> - 2016-06-20 12:00 +0200
                Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Vincent Guittot <vincent.guittot@linaro.org> - 2016-06-20 12:10 +0200
              Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Peter Zijlstra <peterz@infradead.org> - 2016-06-21 13:50 +0200
                Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Vincent Guittot <vincent.guittot@linaro.org> - 2016-06-21 14:40 +0200
                Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Peter Zijlstra <peterz@infradead.org> - 2016-06-21 14:50 +0200
                Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Vincent Guittot <vincent.guittot@linaro.org> - 2016-06-21 15:10 +0200
            Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Dietmar Eggemann <dietmar.eggemann@arm.com> - 2016-06-20 14:00 +0200
              Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Vincent Guittot <vincent.guittot@linaro.org> - 2016-06-20 14:40 +0200
                Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Dietmar Eggemann <dietmar.eggemann@arm.com> - 2016-06-20 17:00 +0200
                Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Peter Zijlstra <peterz@infradead.org> - 2016-06-21 10:50 +0200
                Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Yuyang Du <yuyang.du@intel.com> - 2016-06-21 14:50 +0200
                Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Vincent Guittot <vincent.guittot@linaro.org> - 2016-06-21 15:40 +0200
                Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Peter Zijlstra <peterz@infradead.org> - 2016-06-22 13:50 +0200
                Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Peter Zijlstra <peterz@infradead.org> - 2016-06-21 16:20 +0200
                Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Dietmar Eggemann <dietmar.eggemann@arm.com> - 2016-06-23 17:40 +0200
              Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Peter Zijlstra <peterz@infradead.org> - 2016-06-20 16:50 +0200
    Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Peter Zijlstra <peterz@infradead.org> - 2016-06-23 13:20 +0200
  [PATCH 2/4] sched/fair: Fix PELT integrity for new groups Peter Zijlstra <peterz@infradead.org> - 2016-06-17 14:10 +0200
    Re: [PATCH 2/4] sched/fair: Fix PELT integrity for new groups Vincent Guittot <vincent.guittot@linaro.org> - 2016-06-17 16:00 +0200
  [PATCH 3/4] sched,cgroup: Fix cpu_cgroup_fork() Peter Zijlstra <peterz@infradead.org> - 2016-06-17 14:10 +0200
    Re: [PATCH 3/4] sched,cgroup: Fix cpu_cgroup_fork() Vincent Guittot <vincent.guittot@linaro.org> - 2016-06-17 16:00 +0200
      Re: [PATCH 3/4] sched,cgroup: Fix cpu_cgroup_fork() Peter Zijlstra <peterz@infradead.org> - 2016-06-17 16:10 +0200

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