From: Jiang Biao <benbjiang@gmail.com>
To: Josh Don <joshdon@google.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
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: Wed, 25 Aug 2021 10:43:56 +0800 [thread overview]
Message-ID: <CAPJCdBk-8vjg6GtGx3ft3KoyeeXvovxF53kwE7vJGY2eTYOwyg@mail.gmail.com> (raw)
In-Reply-To: <CABk29NtVaUehs2gChfFPJmjxzbTn0eM49ivHr=a9F2+X20vAtg@mail.gmail.com>
On Wed, 25 Aug 2021 at 01:04, Josh Don <joshdon@google.com> wrote:
>
> Hi Jiang,
>
> On Tue, Aug 24, 2021 at 3:25 AM Jiang Biao <benbjiang@gmail.com> wrote:
> >
> > Why not just ignore min granularity when normal entities compete with
> > a SCHED_IDLE entity? something like this,
> >
> > @@ -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)
> > + && (!se_is_idle(init_se) || sched_idle_cfs_rq(cfs_rq)))
> > + slice = max(slice, (u64)sysctl_sched_min_granularity);
> >
> > return slice;
> > }
> > If so, there seems no need to introduce sysctl_sched_idle_min_granularity? :)
>
> Ignoring min_gran entirely could lead to some really tiny slices; see
> discussion at https://lkml.org/lkml/2021/8/12/651.
Got it, tiny slices could be a problem in SCHED_HRTICK case.
But the sysctl_sched_idle_min_granularity used in sched_slice() and
sysctl_sched_min_granularity used in check_preempt_tick would have
different semantics for SCHED_IDLE task, which could be functional ok
but a little confusing.
Regards,
Jiang
next prev parent reply other threads:[~2021-08-25 2:45 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
2021-08-24 10:24 ` Jiang Biao
2021-08-24 17:04 ` Josh Don
2021-08-25 2:43 ` Jiang Biao [this message]
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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