linux-kernel - [PATCH v6 0/2] Adjust NUMA imbalance for multiple LLCs

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: <20220208094334.16379-1-mgorman@techsingularity.net>
Date:   Tue,  8 Feb 2022 09:43:32 +0000
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Valentin Schneider <valentin.schneider@....com>,
        Aubrey Li <aubrey.li@...ux.intel.com>,
        Barry Song <song.bao.hua@...ilicon.com>,
        Mike Galbraith <efault@....de>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
        Gautham Shenoy <gautham.shenoy@....com>,
        K Prateek Nayak <kprateek.nayak@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        Mel Gorman <mgorman@...hsingularity.net>
Subject: [PATCH v6 0/2] Adjust NUMA imbalance for multiple LLCs

Changelog sinve v5
o Fix off-by-one error

Changelog since V4
o Scale imbalance based on the top domain that prefers siblings
o Keep allowed imbalance as 2 up to the point where LLCs can be overloaded

Changelog since V3
o Calculate imb_numa_nr for multiple SD_NUMA domains
o Restore behaviour where communicating pairs remain on the same node

Commit 7d2b5dd0bcc4 ("sched/numa: Allow a floating imbalance between NUMA
nodes") allowed an imbalance between NUMA nodes such that communicating
tasks would not be pulled apart by the load balancer. This works fine when
there is a 1:1 relationship between LLC and node but can be suboptimal
for multiple LLCs if independent tasks prematurely use CPUs sharing cache.

The series addresses two problems -- inconsistent logic when allowing a
NUMA imbalance and sub-optimal performance when there are many LLCs per
NUMA node.

 include/linux/sched/topology.h |  1 +
 kernel/sched/fair.c            | 30 ++++++++++---------
 kernel/sched/topology.c        | 53 ++++++++++++++++++++++++++++++++++
 3 files changed, 71 insertions(+), 13 deletions(-)

-- 
2.31.1