linux-kernel - [RFC PATCH 0/2] Reintroduce NEXT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251021142824.3747201-1-mgorman@techsingularity.net>
Date: Tue, 21 Oct 2025 15:28:22 +0100
From: Mel Gorman <mgorman@...hsingularity.net>
To: linux-kernel@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Juri Lelli <juri.lelli@...hat.com>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Valentin Schneider <vschneid@...hat.com>,
	Chris Mason <clm@...a.com>,
	Mel Gorman <mgorman@...hsingularity.net>
Subject: [RFC PATCH 0/2] Reintroduce NEXT_BUDDY for EEVDF v2

I've been chasing down a number of schedule issues recently like many
others and found they were broadly grouped as

1. Failure to boost CPU frequency with powersave/ondemand governors
2. Processors entering idle states that are too deep
3. Differences in wakeup latencies for wakeup-intensive workloads

Adding topology into account means that there is a lot of
machine-specific behaviour which may explain why some discussions
recently have reproduction problems. Nevertheless, the removal of
LAST_BUDDY and NEXT_BUDDY being disabled has an impact on wakeup
latencies.

This RFC is to determine if this is valid approach to prefer selecting
a wakee if it's eligible to run even though other unrelated tasks are
more eligible.

 kernel/sched/fair.c     | 131 ++++++++++++++++++++++++++++++++++------
 kernel/sched/features.h |   2 +-
 2 files changed, 112 insertions(+), 21 deletions(-)

-- 
2.51.0