linux-kernel - [RFC PATCH v3 0/3] sched: Skip queued wakeups only when L2 is shared

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: <20230822113133.643238-1-mathieu.desnoyers@efficios.com>
Date:   Tue, 22 Aug 2023 07:31:30 -0400
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Ingo Molnar <mingo@...hat.com>,
        Valentin Schneider <vschneid@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Swapnil Sapkal <Swapnil.Sapkal@....com>,
        Aaron Lu <aaron.lu@...el.com>,
        Julien Desfossez <jdesfossez@...italocean.com>, x86@...nel.org
Subject: [RFC PATCH v3 0/3] sched: Skip queued wakeups only when L2 is shared

This series improves performance of scheduler wakeups on large systems
by skipping queued wakeups only when CPUs share their L2 cache, rather
than when they share their LLC.

The speedup mainly reproduces on workloads which have at least *some*
idle time (because it significantly increases the number of migrations,
and thus remote wakeups), *and* it needs to have a sufficient load to
cause contention on the runqueue locks.

Feedback is welcome,

Thanks,

Mathieu

Mathieu Desnoyers (3):
  sched: Rename cpus_share_cache to cpus_share_llc
  sched: Introduce cpus_share_l2c (v3)
  sched: ttwu_queue_cond: skip queued wakeups across different l2 caches

Cc: Ingo Molnar <mingo@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Valentin Schneider <vschneid@...hat.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Ben Segall <bsegall@...gle.com>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Daniel Bristot de Oliveira <bristot@...hat.com>
Cc: Vincent Guittot <vincent.guittot@...aro.org>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: Swapnil Sapkal <Swapnil.Sapkal@....com>
Cc: Aaron Lu <aaron.lu@...el.com>
Cc: Julien Desfossez <jdesfossez@...italocean.com>
Cc: x86@...nel.org

 block/blk-mq.c                 |  2 +-
 include/linux/sched/topology.h | 10 ++++++++--
 kernel/sched/core.c            | 14 +++++++++++---
 kernel/sched/fair.c            |  8 ++++----
 kernel/sched/sched.h           |  2 ++
 kernel/sched/topology.c        | 32 +++++++++++++++++++++++++++++---
 6 files changed, 55 insertions(+), 13 deletions(-)

-- 
2.39.2