linux-kernel - [PATCH 0/4] sched/fair: Core sched wake up path improvements

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Message-ID: <cover.1758543008.git.sieberf@amazon.com>
Date: Mon, 22 Sep 2025 14:39:21 +0200
From: Fernand Sieber <sieberf@...zon.com>
To: <mingo@...hat.com>, <peterz@...radead.org>
CC: <linux-kernel@...r.kernel.org>, <juri.lelli@...hat.com>,
	<vincent.guittot@...aro.org>, <dietmar.eggemann@....com>,
	<rostedt@...dmis.org>, <bsegall@...gle.com>, <mgorman@...e.de>,
	<bristot@...hat.com>, <vschneid@...hat.com>, <dwmw@...zon.co.uk>,
	<jschoenh@...zon.de>, <liuyuxua@...zon.com>, <graf@...zon.de>
Subject: [PATCH 0/4] sched/fair: Core sched wake up path improvements

This patch series addresses several issues and improvements in the core
scheduling within the fair scheduler's wake-up paths. The overall result
is better task placement reducing force idle.

The main issues addressed are as follows:

Slow path:
1. Fix incorrect cookie matching logic that wrongly discards idle cores
2. Better fallback logic when no cookie matching target is found

Fast path:
3. Add cookie checks in wake affine idle to prevent force idle
4. Enhance task selection in select idle sibling to consider cookies

Fernand Sieber (4):
  sched/fair: Fix cookie check on __select_idle_cpu()
  sched/fair: Still look for the idlest cpu with no matching cookie
  sched/fair: Add cookie checks on wake idle path
  sched/fair: Add more core cookie check in wake up fast path

 kernel/sched/fair.c  | 49 ++++++++++++++++++++++++++++++++------------
 kernel/sched/sched.h | 41 ++++++++++++++++++++----------------
 2 files changed, 59 insertions(+), 31 deletions(-)

--
2.43.0

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