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Date: Sat, 15 Aug 2015 13:24:12 +0900
From: Byungchul Park <byungchul.park@....com>
To: "T. Zhou" <t.s.zhou@...mail.com>
Cc: mingo@...nel.org, peterz@...radead.org,
linux-kernel@...r.kernel.org, yuyang.du@...el.com
Subject: Re: [PATCH] sched: sync with the cfs_rq when changing sched class
On Fri, Aug 14, 2015 at 08:59:02PM +0800, T. Zhou wrote:
> Hi,
>
> On Thu, Aug 13, 2015 at 02:55:55PM +0900, byungchul.park@....com wrote:
> > +static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
> > +{
> > + se->avg.last_update_time = cfs_rq->avg.last_update_time;
> > + cfs_rq->avg.load_avg += se->avg.load_avg;
> > + cfs_rq->avg.load_sum += se->avg.load_sum;
> > + cfs_rq->avg.util_avg += se->avg.util_avg;
> > + cfs_rq->avg.util_sum += se->avg.util_sum;
> > +}
>
> I see this function is used in enqueue_entity_load_avg() also.
> In tip tree code, enqueue_entity_load_avg() uses cfs_rq_clock_task()
> as se->last_update_time in migration condition.
> Here, you use cfs_rq->avg.last_update_time as se->last_update_time.
> If se->last_update_time is different, next decay may be different too.
> Just from inspecting code, maybe some reasonable there?
hello zhou,
update_cfs_rq_load_avg() would update cfs_rq->avg.last_update_time to now,
which is returned from cfs_rq_clock_task(). :)
thanks,
byungchul
>
> Thanks
> > +static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
> > +{
> > + __update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq_of(cfs_rq)),
> > + &se->avg, se->on_rq * scale_load_down(se->load.weight),
> > + cfs_rq->curr == se, NULL);
> > +
> > + cfs_rq->avg.load_avg =
> > + max_t(long, cfs_rq->avg.load_avg - se->avg.load_avg, 0);
> > + cfs_rq->avg.load_sum =
> > + max_t(s64, cfs_rq->avg.load_sum - se->avg.load_sum, 0);
> > + cfs_rq->avg.util_avg =
> > + max_t(long, cfs_rq->avg.util_avg - se->avg.util_avg, 0);
> > + cfs_rq->avg.util_sum =
> > + max_t(s32, cfs_rq->avg.util_sum - se->avg.util_sum, 0);
> > +}
> > +
> > /* Add the load generated by se into cfs_rq's load average */
> > static inline void
> > enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
> > @@ -2717,27 +2742,20 @@ enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
> > u64 now = cfs_rq_clock_task(cfs_rq);
> > int migrated = 0, decayed;
> >
> > - if (sa->last_update_time == 0) {
> > - sa->last_update_time = now;
> > + if (sa->last_update_time == 0)
> > migrated = 1;
> > - }
> > - else {
> > + else
> > __update_load_avg(now, cpu_of(rq_of(cfs_rq)), sa,
> > - se->on_rq * scale_load_down(se->load.weight),
> > - cfs_rq->curr == se, NULL);
> > - }
> > + se->on_rq * scale_load_down(se->load.weight),
> > + cfs_rq->curr == se, NULL);
> >
> > decayed = update_cfs_rq_load_avg(now, cfs_rq);
> >
> > cfs_rq->runnable_load_avg += sa->load_avg;
> > cfs_rq->runnable_load_sum += sa->load_sum;
> >
> > - if (migrated) {
> > - cfs_rq->avg.load_avg += sa->load_avg;
> > - cfs_rq->avg.load_sum += sa->load_sum;
> > - cfs_rq->avg.util_avg += sa->util_avg;
> > - cfs_rq->avg.util_sum += sa->util_sum;
> > - }
> > + if (migrated)
> > + attach_entity_load_avg(cfs_rq, se);
> >
> > if (decayed || migrated)
> > update_tg_load_avg(cfs_rq, 0);
> > @@ -7911,17 +7929,7 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p)
> >
> > #ifdef CONFIG_SMP
> > /* Catch up with the cfs_rq and remove our load when we leave */
> > - __update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq), &se->avg,
> > - se->on_rq * scale_load_down(se->load.weight), cfs_rq->curr == se, NULL);
> > -
> > - cfs_rq->avg.load_avg =
> > - max_t(long, cfs_rq->avg.load_avg - se->avg.load_avg, 0);
> > - cfs_rq->avg.load_sum =
> > - max_t(s64, cfs_rq->avg.load_sum - se->avg.load_sum, 0);
> > - cfs_rq->avg.util_avg =
> > - max_t(long, cfs_rq->avg.util_avg - se->avg.util_avg, 0);
> > - cfs_rq->avg.util_sum =
> > - max_t(s32, cfs_rq->avg.util_sum - se->avg.util_sum, 0);
> > + detach_entity_load_avg(cfs_rq, se);
> > #endif
> > }
> >
> > @@ -7938,6 +7946,11 @@ static void switched_to_fair(struct rq *rq, struct task_struct *p)
> > */
> > se->depth = se->parent ? se->parent->depth + 1 : 0;
> > #endif
> > +
> > +#ifdef CONFIG_SMP
> > + /* synchronize task with its cfs_rq */
> > + attach_entity_load_avg(cfs_rq_of(&p->se), &p->se);
> > +#endif
> > if (!task_on_rq_queued(p))
> > return;
> >
> > @@ -8023,16 +8036,7 @@ static void task_move_group_fair(struct task_struct *p, int queued)
> >
> > #ifdef CONFIG_SMP
> > /* synchronize task with its prev cfs_rq */
> > - if (!queued)
> > - __update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq_of(cfs_rq)),
> > - &se->avg, se->on_rq * scale_load_down(se->load.weight),
> > - cfs_rq->curr == se, NULL);
> > -
> > - /* remove our load when we leave */
> > - cfs_rq->avg.load_avg = max_t(long, cfs_rq->avg.load_avg - se->avg.load_avg, 0);
> > - cfs_rq->avg.load_sum = max_t(s64, cfs_rq->avg.load_sum - se->avg.load_sum, 0);
> > - cfs_rq->avg.util_avg = max_t(long, cfs_rq->avg.util_avg - se->avg.util_avg, 0);
> > - cfs_rq->avg.util_sum = max_t(s32, cfs_rq->avg.util_sum - se->avg.util_sum, 0);
> > + detach_entity_load_avg(cfs_rq, se);
> > #endif
> > set_task_rq(p, task_cpu(p));
> > se->depth = se->parent ? se->parent->depth + 1 : 0;
> > @@ -8042,11 +8046,7 @@ static void task_move_group_fair(struct task_struct *p, int queued)
> >
> > #ifdef CONFIG_SMP
> > /* Virtually synchronize task with its new cfs_rq */
> > - p->se.avg.last_update_time = cfs_rq->avg.last_update_time;
> > - cfs_rq->avg.load_avg += p->se.avg.load_avg;
> > - cfs_rq->avg.load_sum += p->se.avg.load_sum;
> > - cfs_rq->avg.util_avg += p->se.avg.util_avg;
> > - cfs_rq->avg.util_sum += p->se.avg.util_sum;
> > + attach_entity_load_avg(cfs_rq, se);
> > #endif
> > }
>
> --
> Tao
> --
> --
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