Messages in this thread | | | From | Josh Don <> | Date | Mon, 23 Aug 2021 10:40:18 -0700 | Subject | Re: [PATCH v3 3/4] sched: reduce sched slice for SCHED_IDLE entities |
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On Mon, Aug 23, 2021 at 3:08 AM Vincent Guittot <vincent.guittot@linaro.org> wrote: > > On Fri, 20 Aug 2021 at 03:04, Josh Don <joshdon@google.com> wrote: > > > > @@ -684,12 +696,13 @@ static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) > > for_each_sched_entity(se) { > > struct load_weight *load; > > struct load_weight lw; > > + struct cfs_rq *qcfs_rq; > > > > - cfs_rq = cfs_rq_of(se); > > - load = &cfs_rq->load; > > + qcfs_rq = cfs_rq_of(se); > > + load = &qcfs_rq->load; > > > > if (unlikely(!se->on_rq)) { > > - lw = cfs_rq->load; > > + lw = qcfs_rq->load; > > > > update_load_add(&lw, se->load.weight); > > load = &lw; > > @@ -697,8 +710,14 @@ static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) > > slice = __calc_delta(slice, se->load.weight, load); > > } > > > > - if (sched_feat(BASE_SLICE)) > > - slice = max(slice, (u64)sysctl_sched_min_granularity); > > + if (sched_feat(BASE_SLICE)) { > > + if (se_is_idle(init_se) && !sched_idle_cfs_rq(cfs_rq)) > > Like for place_entity, we should probably not dynamically switch > between the 2 values below depending on the presence or not of non > sched idle tasks and always use sysctl_sched_idle_min_granularity
My reasoning here is that sched_slice is something we reasonably expect to change as tasks enqueue/dequeue, and unlike place_entity() it does not create fairness issues by messing with vruntime. Additionally, it would be preferable to use the larger min granularity on a cpu running only idle tasks.
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