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Message-ID: <BLU436-SMTP9799BE9F3CEDC9A77A29D2C07C0@phx.gbl>
Date: Fri, 14 Aug 2015 20:59:02 +0800
From: "T. Zhou" <t.s.zhou@...mail.com>
To: byungchul.park@....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
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?
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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