Messages in this thread | | | Date | Thu, 16 Nov 2023 13:07:18 +0800 | Subject | Re: [PATCH 1/4] sched/eevdf: Fix vruntime adjustment on reweight | From | Abel Wu <> |
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On 11/16/23 12:48 PM, Abel Wu Wrote: > On 11/15/23 11:36 PM, Yiwei Lin Wrote: >> >>> @@ -3712,8 +3811,17 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, >>> enqueue_load_avg(cfs_rq, se); >>> if (se->on_rq) { >>> update_load_add(&cfs_rq->load, se->load.weight); >>> - if (cfs_rq->curr != se) >>> - avg_vruntime_add(cfs_rq, se); >>> + if (!curr) { >>> + /* >>> + * The entity's vruntime has been adjusted, so let's check >>> + * whether the rq-wide min_vruntime needs updated too. Since >>> + * the calculations above require stable min_vruntime rather >>> + * than up-to-date one, we do the update at the end of the >>> + * reweight process. >>> + */ >>> + __enqueue_entity(cfs_rq, se); >>> + update_min_vruntime(cfs_rq); >>> + } >>> } >>> } >> Sorry if I am asking stupid question...... It looks like reweight_entity() may have chance to change the weight of cfs_rq->curr entity, but we'll never update_min_vruntime() when reweighting it. Is there any reason that we can skip the update_min_vruntime() for this case? > > No, you are right!
I was intended to update_min_vruntime() if se->on_rq and no matter it is curr or not, just as you suggested. But after a second thought I wonder if it is necessary to update *NOW*, since we will always update_curr() before making any change to cfs_rq. Thoughts?
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