Re: [PATCH v5 2/2] sched/fair: update scale invariance of PELT

[Dietmar Eggemann]

On 10/31/18 10:18 AM, Vincent Guittot wrote:
> Hi Dietmar,
>
> On Wed, 31 Oct 2018 at 08:20, Dietmar Eggemann <dietmar.eggemann@xxxxxxx> wrote:
> > On 10/26/18 6:11 PM, Vincent Guittot wrote:
> >
> > [...]
> >
> > >    static int select_idle_sibling(struct task_struct *p, int prev_cpu, int cpu);
> > >    static unsigned long task_h_load(struct task_struct *p);
> > > @@ -764,7 +763,7 @@ void post_init_entity_util_avg(struct sched_entity *se)
> > >                         * such that the next switched_to_fair() has the
> > >                         * expected state.
> > >                         */
> > > -                     se->avg.last_update_time = cfs_rq_clock_task(cfs_rq);
> > > +                     se->avg.last_update_time = cfs_rq_clock_pelt(cfs_rq);
> > >                        return;
> > >                }
> > >        }
> >
> > There is this 1/cpu scaling of se->avg.util_sum (running_sum) in
> > update_tg_cfs_runnable() so it can be used to calculate
> > se->avg.runnable_load_sum (runnable_sum). I guess with your approach
> > this should be removed.
>
> Yes good catch

Another thing, since you do not need the cpu parameter in 
accumulate_sum() anymore, you could also get rid of it in 
___update_load_sum() and further in __update_load_avg_blocked_se(),
__update_load_avg_cfs_rq() and __update_load_avg_se().

Nitpick: The function header of update_cfs_rq_load_avg() mentions '@now: 
current time, as per cfs_rq_clock_task()' ... should mention 
cfs_rq_clock_pelt() instead.

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