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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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WARNING: multiple messages have this Message-ID (diff)
From: Mel Gorman <mgorman@techsingularity.net>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Aubrey Li <aubrey.li@linux.intel.com>,
	Barry Song <song.bao.hua@hisilicon.com>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Ziljstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Linux-ARM <linux-arm-kernel@lists.infradead.org>,
	Mel Gorman <mgorman@techsingularity.net>
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


             reply	other threads:[~2020-12-07  9:17 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-07  9:15 Mel Gorman [this message]
2020-12-07  9:15 ` [RFC PATCH 0/4] Reduce worst-case scanning of runqueues in select_idle_sibling Mel Gorman
2020-12-07  9:15 ` [PATCH 1/4] sched/fair: Remove SIS_AVG_CPU Mel Gorman
2020-12-07  9:15   ` Mel Gorman
2020-12-07 15:05   ` Vincent Guittot
2020-12-07 15:05     ` Vincent Guittot
2020-12-08 10:07   ` Dietmar Eggemann
2020-12-08 10:07     ` Dietmar Eggemann
2020-12-08 10:59     ` Mel Gorman
2020-12-08 10:59       ` Mel Gorman
2020-12-08 13:24       ` Vincent Guittot
2020-12-08 13:24         ` Vincent Guittot
2020-12-08 13:36         ` Mel Gorman
2020-12-08 13:36           ` Mel Gorman
2020-12-08 13:43           ` Vincent Guittot
2020-12-08 13:43             ` Vincent Guittot
2020-12-08 13:53             ` Mel Gorman
2020-12-08 13:53               ` Mel Gorman
2020-12-08 14:47               ` Vincent Guittot
2020-12-08 14:47                 ` Vincent Guittot
2020-12-08 15:12                 ` Mel Gorman
2020-12-08 15:12                   ` Mel Gorman
2020-12-08 15:19                   ` Vincent Guittot
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
2020-12-07  9:15   ` Mel Gorman
2020-12-08  9:57   ` Dietmar Eggemann
2020-12-08  9:57     ` Dietmar Eggemann
2020-12-08 11:02     ` Mel Gorman
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  9:15   ` Mel Gorman
2020-12-07 15:06   ` Vincent Guittot
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  9:15   ` 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 15:04   ` Vincent Guittot
2020-12-07 15:42   ` Mel Gorman
2020-12-07 15:42     ` Mel Gorman
2020-12-08  2:06     ` Li, Aubrey
2020-12-08  2:06       ` Li, Aubrey

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