From: Josh Don <joshdon@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@kernel.org, vincent.guittot@linaro.org,
linux-kernel@vger.kernel.org, juri.lelli@redhat.com,
dietmar.eggemann@arm.com, rostedt@goodmis.org,
bsegall@google.com, mgorman@suse.de, bristot@redhat.com,
corbet@lwn.net, qyousef@layalina.io, chris.hyser@oracle.com,
patrick.bellasi@matbug.net, pjt@google.com, pavel@ucw.cz,
qperret@google.com, tim.c.chen@linux.intel.com, timj@gnu.org,
kprateek.nayak@amd.com, yu.c.chen@intel.com,
youssefesmat@chromium.org, joel@joelfernandes.org, efault@gmx.de
Subject: Re: [PATCH 08/17] sched/fair: Implement an EEVDF like policy
Date: Wed, 29 Mar 2023 11:54:58 -0700 [thread overview]
Message-ID: <CABk29Nud5dBo9ZdYhPLAPiVtQ9qh8aPOytydp7EXa-rYyYaMHA@mail.gmail.com> (raw)
In-Reply-To: <20230329081239.GM4253@hirez.programming.kicks-ass.net>
On Wed, Mar 29, 2023 at 1:12 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Tue, Mar 28, 2023 at 06:26:51PM -0700, Josh Don wrote:
>
> > > @@ -5088,19 +5307,20 @@ dequeue_entity(struct cfs_rq *cfs_rq, st
> > > static void
> > > check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
> > > {
> > > - unsigned long ideal_runtime, delta_exec;
> > > + unsigned long delta_exec;
> > > struct sched_entity *se;
> > > s64 delta;
> > >
> > > - /*
> > > - * When many tasks blow up the sched_period; it is possible that
> > > - * sched_slice() reports unusually large results (when many tasks are
> > > - * very light for example). Therefore impose a maximum.
> > > - */
> > > - ideal_runtime = min_t(u64, sched_slice(cfs_rq, curr), sysctl_sched_latency);
> > > + if (sched_feat(EEVDF)) {
> > > + if (pick_eevdf(cfs_rq) != curr)
> > > + goto preempt;
> >
> > This could shortcircuit the loop in pick_eevdf once we find a best
> > that has less vruntime and sooner deadline than curr, since we know
> > we'll never pick curr in that case. Might help performance when we
> > have a large tree for this cfs_rq.
>
> Yeah, one of the things I did consider was having this set cfs_rq->next
> such that the reschedule pick doesn't have to do the pick again. But I
> figured keep things simple for now.
Yea that makes sense. I was thinking something similar along the lines
of cfs_rq->next as another way to avoid duplicate computation. But
agreed this can be a future optimization.
next prev parent reply other threads:[~2023-03-29 18:55 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-28 9:26 [PATCH 00/17] sched: EEVDF using latency-nice Peter Zijlstra
2023-03-28 9:26 ` [PATCH 01/17] sched: Introduce latency-nice as a per-task attribute Peter Zijlstra
2023-03-28 9:26 ` [PATCH 02/17] sched/fair: Add latency_offset Peter Zijlstra
2023-03-28 9:26 ` [PATCH 03/17] sched/fair: Add sched group latency support Peter Zijlstra
2023-03-28 9:26 ` [PATCH 04/17] sched/fair: Add avg_vruntime Peter Zijlstra
2023-03-28 23:57 ` Josh Don
2023-03-29 7:50 ` Peter Zijlstra
2023-04-05 19:13 ` Peter Zijlstra
2023-03-28 9:26 ` [PATCH 05/17] sched/fair: Remove START_DEBIT Peter Zijlstra
2023-03-28 9:26 ` [PATCH 06/17] sched/fair: Add lag based placement Peter Zijlstra
2023-04-03 9:18 ` Chen Yu
2023-04-05 9:47 ` Peter Zijlstra
2023-04-06 3:03 ` Chen Yu
2023-04-13 15:42 ` Chen Yu
2023-04-13 15:55 ` Chen Yu
2023-03-28 9:26 ` [PATCH 07/17] rbtree: Add rb_add_augmented_cached() helper Peter Zijlstra
2023-03-28 9:26 ` [PATCH 08/17] sched/fair: Implement an EEVDF like policy Peter Zijlstra
2023-03-29 1:26 ` Josh Don
2023-03-29 8:02 ` Peter Zijlstra
2023-03-29 8:06 ` Peter Zijlstra
2023-03-29 8:22 ` Peter Zijlstra
2023-03-29 18:48 ` Josh Don
2023-03-29 8:12 ` Peter Zijlstra
2023-03-29 18:54 ` Josh Don [this message]
2023-03-29 8:18 ` Peter Zijlstra
2023-03-29 14:35 ` Vincent Guittot
2023-03-30 8:01 ` Peter Zijlstra
2023-03-30 17:05 ` Vincent Guittot
2023-04-04 12:00 ` Peter Zijlstra
2023-03-28 9:26 ` [PATCH 09/17] sched: Commit to lag based placement Peter Zijlstra
2023-03-28 9:26 ` [PATCH 10/17] sched/smp: Use lag to simplify cross-runqueue placement Peter Zijlstra
2023-03-28 9:26 ` [PATCH 11/17] sched: Commit to EEVDF Peter Zijlstra
2023-03-28 9:26 ` [PATCH 12/17] sched/debug: Rename min_granularity to base_slice Peter Zijlstra
2023-03-28 9:26 ` [PATCH 13/17] sched: Merge latency_offset into slice Peter Zijlstra
2023-03-28 9:26 ` [PATCH 14/17] sched/eevdf: Better handle mixed slice length Peter Zijlstra
2023-03-31 15:26 ` Vincent Guittot
2023-04-04 9:29 ` Peter Zijlstra
2023-04-04 13:50 ` Joel Fernandes
2023-04-05 5:41 ` Mike Galbraith
2023-04-05 8:35 ` Peter Zijlstra
2023-04-05 20:05 ` Joel Fernandes
2023-04-14 11:18 ` Phil Auld
2023-04-16 5:10 ` Joel Fernandes
[not found] ` <20230401232355.336-1-hdanton@sina.com>
2023-04-02 2:40 ` Mike Galbraith
2023-03-28 9:26 ` [PATCH 15/17] [RFC] sched/eevdf: Sleeper bonus Peter Zijlstra
2023-03-29 9:10 ` Mike Galbraith
2023-03-28 9:26 ` [PATCH 16/17] [RFC] sched/eevdf: Minimal vavg option Peter Zijlstra
2023-03-28 9:26 ` [PATCH 17/17] [DEBUG] sched/eevdf: Debug / validation crud Peter Zijlstra
2023-04-03 7:42 ` [PATCH 00/17] sched: EEVDF using latency-nice Shrikanth Hegde
2023-04-10 3:13 ` David Vernet
2023-04-11 2:09 ` David Vernet
[not found] ` <20230410082307.1327-1-hdanton@sina.com>
2023-04-11 10:15 ` Mike Galbraith
[not found] ` <20230411133333.1790-1-hdanton@sina.com>
2023-04-11 14:56 ` Mike Galbraith
[not found] ` <20230412025042.1413-1-hdanton@sina.com>
2023-04-12 4:05 ` Mike Galbraith
2023-04-25 12:32 ` Phil Auld
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