linux-kernel - [PATCH 0/4] Reduce scanning of runqueues in select_idle

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Message-Id: <20201208153501.1467-1-mgorman@techsingularity.net>
Date:   Tue,  8 Dec 2020 15:34:57 +0000
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Peter Ziljstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     Aubrey Li <aubrey.li@...ux.intel.com>,
        Barry Song <song.bao.hua@...ilicon.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Valentin Schneider <valentin.schneider@....com>,
        Linux-ARM <linux-arm-kernel@...ts.infradead.org>,
        Mel Gorman <mgorman@...hsingularity.net>
Subject: [PATCH 0/4] Reduce scanning of runqueues in select_idle_sibling

Changelog since v1
o Drop single-pass patch						(vincent)
o Scope variables used for SIS_AVG_CPU					(dietmar)
o Remove redundant assignment						(dietmar

This reduces 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 moves all SIS_PROP-related calculations under SIS_PROP

Patch 3 improves the hit rate of p->recent_used_cpu to reduce the amount
	of scanning. It should be relatively uncontroversial

Patch 4 returns an idle candidate if one is found while scanning for a
	free core.

-- 
2.26.2

Mel Gorman (4):
  sched/fair: Remove SIS_AVG_CPU
  sched/fair: Move avg_scan_cost calculations under SIS_PROP
  sched/fair: Do not replace recent_used_cpu with the new target
  sched/fair: Return an idle cpu if one is found after a failed search
    for an idle core

 kernel/sched/fair.c     | 51 ++++++++++++++++++++---------------------
 kernel/sched/features.h |  1 -
 2 files changed, 25 insertions(+), 27 deletions(-)

-- 
2.26.2