From: Mel Gorman <mgorman@techsingularity•net>
To: LKML <linux-kernel@vger•kernel.org>
Cc: Barry Song <song.bao.hua@hisilicon•com>,
Juri Lelli <juri.lelli@redhat•com>,
Vincent Guittot <vincent.guittot@linaro•org>,
Peter Ziljstra <peterz@infradead•org>,
Aubrey Li <aubrey.li@linux•intel.com>,
Ingo Molnar <mingo@redhat•com>,
Mel Gorman <mgorman@techsingularity•net>,
Valentin Schneider <valentin.schneider@arm•com>,
Linux-ARM <linux-arm-kernel@lists•infradead.org>
Subject: [RFC PATCH 0/4] Reduce worst-case scanning of runqueues in select_idle_sibling
Date: Mon, 7 Dec 2020 09:15:12 +0000 [thread overview]
Message-ID: <20201207091516.24683-1-mgorman@techsingularity.net> (raw)
This is a minimal series to reduce the amount of runqueue scanning in
select_idle_sibling in the worst case.
Patch 1 removes SIS_AVG_CPU because it's unused.
Patch 2 improves the hit rate of p->recent_used_cpu to reduce the amount
of scanning. It should be relatively uncontroversial
Patch 3-4 scans the runqueues in a single pass for select_idle_core()
and select_idle_cpu() so runqueues are not scanned twice. It's
a tradeoff because it benefits deep scans but introduces overhead
for shallow scans.
Even if patch 3-4 is rejected to allow more time for Aubrey's idle cpu mask
approach to stand on its own, patches 1-2 should be fine. The main decision
with patch 4 is whether select_idle_core() should do a full scan when searching
for an idle core, whether it should be throttled in some other fashion or
whether it should be just left alone.
--
2.26.2
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next reply other threads:[~2020-12-07 9:17 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-07 9:15 Mel Gorman [this message]
2020-12-07 9:15 ` [PATCH 1/4] sched/fair: Remove SIS_AVG_CPU Mel Gorman
2020-12-07 15:05 ` Vincent Guittot
2020-12-08 10:07 ` Dietmar Eggemann
2020-12-08 10:59 ` Mel Gorman
2020-12-08 13:24 ` Vincent Guittot
2020-12-08 13:36 ` Mel Gorman
2020-12-08 13:43 ` Vincent Guittot
2020-12-08 13:53 ` Mel Gorman
2020-12-08 14:47 ` Vincent Guittot
2020-12-08 15:12 ` Mel Gorman
2020-12-08 15:19 ` Vincent Guittot
2020-12-07 9:15 ` [PATCH 2/4] sched/fair: Do not replace recent_used_cpu with the new target Mel Gorman
2020-12-08 9:57 ` Dietmar Eggemann
2020-12-08 11:02 ` Mel Gorman
2020-12-07 9:15 ` [PATCH 3/4] sched/fair: Return an idle cpu if one is found after a failed search for an idle core Mel Gorman
2020-12-07 15:06 ` Vincent Guittot
2020-12-07 9:15 ` [PATCH 4/4] sched/fair: Avoid revisiting CPUs multiple times during select_idle_sibling Mel Gorman
2020-12-07 15:04 ` [RFC PATCH 0/4] Reduce worst-case scanning of runqueues in select_idle_sibling Vincent Guittot
2020-12-07 15:42 ` Mel Gorman
2020-12-08 2:06 ` Li, Aubrey
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