Hi,Vincent,
At first, I think "sa->util_avg = cfs_rq->avg.util_avg * se_weight(se)" should
apply to all classes, but I am not sure how this modification would affect
other classes.
so I added this cfs condition.
As you said, this is meaningless for this else keeps using se->load.weight.
Thanks!
________________________________________
发件人: Vincent Guittot <vincent.guit...@linaro.org>
发送时间: 2020年11月5日 20:30
收件人: 闫学文 (Xuewen Yan)
抄送: Ingo Molnar; Peter Zijlstra; Juri Lelli; Dietmar Eggemann; Steven Rostedt;
Ben Segall; Mel Gorman; Daniel Bristot de Oliveira; linux-kernel;
xuewen.ya...@gmail.com
主题: Re: [PATCH v2] sched: revise the initial value of the util_avg.
On Thu, 5 Nov 2020 at 12:22, Xuewen Yan <xuewen....@unisoc.com> wrote:
>
> According to the original code logic:
> cfs_rq->avg.util_avg
> sa->util_avg = -------------------- * se->load.weight
> cfs_rq->avg.load_avg
this should have been scale_load_down(se->load.weight) from the beginning
> but for fair_sched_class:
> se->load.weight = 1024 * sched_prio_to_weight[prio];
This is only true for 64bits platform otherwise scale_load and
scale_load_down are nop
> cfs_rq->avg.util_avg
> so the -------------------- must be extremely small, the
> cfs_rq->avg.load_avg
> judgment condition "sa->util_avg < cap" could be established.
> It's not fair for those tasks who has smaller nice value.
>
> Signed-off-by: Xuewen Yan <xuewen....@unisoc.com>
> ---
> kernel/sched/fair.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 290f9e3..079760b 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -794,7 +794,11 @@ void post_init_entity_util_avg(struct task_struct *p)
>
> if (cap > 0) {
> if (cfs_rq->avg.util_avg != 0) {
We should now use cpu_util() instead of cfs_rq->avg.util_avg which
takes into account other classes
> - sa->util_avg = cfs_rq->avg.util_avg *
> se->load.weight;
> + if (p->sched_class == &fair_sched_class)
> + sa->util_avg = cfs_rq->avg.util_avg *
> se_weight(se);
> + else
> + sa->util_avg = cfs_rq->avg.util_avg *
> se->load.weight;
Why this else keeps using se->load.weight ?
Either we uses sa->util_avg = cfs_rq->avg.util_avg * se_weight(se);
for all classes
Or we want a different init value for other classes. But in this case
se->load.weight is meaningless and we should simply set them to 0
although we could probably compute a value based on bandwidth for
deadline class
> +
> sa->util_avg /= (cfs_rq->avg.load_avg + 1);
>
> if (sa->util_avg > cap)
> --
> 1.9.1
>
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confidential or otherwise protected from disclosure. Unauthorized use,
dissemination, distribution or copying of this email or the information herein
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copy, use or disclose any part of this e-mail to others. Please notify the
sender immediately and permanently delete this e-mail and any attachments if
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