From: Vincent Guittot <vincent.guittot@linaro.org>
To: Josh Don <joshdon@google.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Paul Turner <pjt@google.com>, Oleg Rombakh <olegrom@google.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Steve Sistare <steven.sistare@oracle.com>,
Tejun Heo <tj@kernel.org>, Rik van Riel <riel@surriel.com>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 3/4] sched: reduce sched slice for SCHED_IDLE entities
Date: Tue, 24 Aug 2021 09:56:09 +0200 [thread overview]
Message-ID: <CAKfTPtDDNgbneGrQ+p8FOKLZ=SqvY59GO+itYwje6MU7xEN9LQ@mail.gmail.com> (raw)
In-Reply-To: <CABk29NvEW+aa3ysMOK2J24OHpWpjiAVqjfQ6+T_49V9Dp8T4Hg@mail.gmail.com>
On Mon, 23 Aug 2021 at 19:40, Josh Don <joshdon@google.com> wrote:
>
> 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.
Fair enough
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
next prev parent reply other threads:[~2021-08-24 7:56 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-20 1:03 [PATCH v3 0/4] SCHED_IDLE extensions Josh Don
2021-08-20 1:04 ` [PATCH v3 2/4] sched: account number of SCHED_IDLE entities on each cfs_rq Josh Don
2021-08-24 7:57 ` Vincent Guittot
2021-09-09 11:18 ` [tip: sched/core] sched: Account " tip-bot2 for Josh Don
2021-10-05 14:12 ` tip-bot2 for Josh Don
2021-08-20 1:04 ` [PATCH v3 3/4] sched: reduce sched slice for SCHED_IDLE entities Josh Don
2021-08-23 10:08 ` Vincent Guittot
2021-08-23 17:40 ` Josh Don
2021-08-24 7:56 ` Vincent Guittot [this message]
2021-08-24 10:24 ` Jiang Biao
2021-08-24 17:04 ` Josh Don
2021-08-25 2:43 ` Jiang Biao
2021-09-09 11:18 ` [tip: sched/core] " tip-bot2 for Josh Don
2021-10-05 14:12 ` tip-bot2 for Josh Don
2021-08-20 1:04 ` [PATCH v3 4/4] sched: adjust sleeper credit " Josh Don
2021-08-23 10:09 ` Vincent Guittot
2021-08-24 8:16 ` Jiang Biao
2021-08-24 17:12 ` Josh Don
2021-09-09 11:18 ` [tip: sched/core] " tip-bot2 for Josh Don
2021-10-05 14:12 ` tip-bot2 for Josh Don
[not found] ` <20210906124702.Q6G0oOWwFOmQSl_jmRms3XQgfz4ROzfE71r3SNgWSf0@z>
2021-09-06 12:47 ` [PATCH v3 1/4] sched: cgroup SCHED_IDLE support alexs
2021-08-20 8:39 ` Tao Zhou
2021-08-23 17:29 ` Josh Don
2021-08-23 22:45 ` Tao Zhou
2021-09-02 1:22 ` Daniel Jordan
2021-09-03 1:21 ` Josh Don
2021-09-08 20:38 ` Daniel Jordan
2021-09-08 18:36 ` Josh Don
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