linux-kernel - Re: [PATCH v2 3/5] mm: memcg: make stats flushing threshold per-memcg

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

Message-ID: <CALvZod5hKvjm3WVSOGc5PpR9eNHFkt=BDmcrBe5CeWgFzP7jgQ@mail.gmail.com>
Date:   Fri, 20 Oct 2023 10:23:16 -0700
From:   Shakeel Butt <shakeelb@...gle.com>
To:     kernel test robot <oliver.sang@...el.com>
Cc:     Yosry Ahmed <yosryahmed@...gle.com>, oe-lkp@...ts.linux.dev,
        lkp@...el.com, cgroups@...r.kernel.org, linux-mm@...ck.org,
        ying.huang@...el.com, feng.tang@...el.com, fengwei.yin@...el.com,
        Andrew Morton <akpm@...ux-foundation.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Muchun Song <muchun.song@...ux.dev>,
        Ivan Babrou <ivan@...udflare.com>, Tejun Heo <tj@...nel.org>,
        Michal Koutný <mkoutny@...e.com>,
        Waiman Long <longman@...hat.com>, kernel-team@...udflare.com,
        Wei Xu <weixugc@...gle.com>, Greg Thelen <gthelen@...gle.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/5] mm: memcg: make stats flushing threshold per-memcg

On Fri, Oct 20, 2023 at 9:18 AM kernel test robot <oliver.sang@...el.com> wrote:
>
>
>
> Hello,
>
> kernel test robot noticed a -25.8% regression of will-it-scale.per_thread_ops on:
>
>
> commit: 51d74c18a9c61e7ee33bc90b522dd7f6e5b80bb5 ("[PATCH v2 3/5] mm: memcg: make stats flushing threshold per-memcg")
> url: https://github.com/intel-lab-lkp/linux/commits/Yosry-Ahmed/mm-memcg-change-flush_next_time-to-flush_last_time/20231010-112257
> base: https://git.kernel.org/cgit/linux/kernel/git/akpm/mm.git mm-everything
> patch link: https://lore.kernel.org/all/20231010032117.1577496-4-yosryahmed@google.com/
> patch subject: [PATCH v2 3/5] mm: memcg: make stats flushing threshold per-memcg
>
> testcase: will-it-scale
> test machine: 104 threads 2 sockets (Skylake) with 192G memory
> parameters:
>
>         nr_task: 100%
>         mode: thread
>         test: fallocate1
>         cpufreq_governor: performance
>
>
> In addition to that, the commit also has significant impact on the following tests:
>
> +------------------+---------------------------------------------------------------+
> | testcase: change | will-it-scale: will-it-scale.per_thread_ops -30.0% regression |
> | test machine     | 104 threads 2 sockets (Skylake) with 192G memory              |
> | test parameters  | cpufreq_governor=performance                                  |
> |                  | mode=thread                                                   |
> |                  | nr_task=50%                                                   |
> |                  | test=fallocate1                                               |
> +------------------+---------------------------------------------------------------+
>

Yosry, I don't think 25% to 30% regression can be ignored. Unless
there is a quick fix, IMO this series should be skipped for the
upcoming kernel open window.