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References: <20231010032117.1577496-4-yosryahmed@google.com> <202310202303.c68e7639-oliver.sang@intel.com>
In-Reply-To: <202310202303.c68e7639-oliver.sang@intel.com>
From:   Shakeel Butt <shakeelb@google.com>
Date:   Fri, 20 Oct 2023 10:23:16 -0700
Message-ID: <CALvZod5hKvjm3WVSOGc5PpR9eNHFkt=BDmcrBe5CeWgFzP7jgQ@mail.gmail.com>
Subject: Re: [PATCH v2 3/5] mm: memcg: make stats flushing threshold per-memcg
To:     kernel test robot <oliver.sang@intel.com>
Cc:     Yosry Ahmed <yosryahmed@google.com>, oe-lkp@lists.linux.dev,
        lkp@intel.com, cgroups@vger.kernel.org, linux-mm@kvack.org,
        ying.huang@intel.com, feng.tang@intel.com, fengwei.yin@intel.com,
        Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@kernel.org>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Muchun Song <muchun.song@linux.dev>,
        Ivan Babrou <ivan@cloudflare.com>, Tejun Heo <tj@kernel.org>,
        =?UTF-8?Q?Michal_Koutn=C3=BD?= <mkoutny@suse.com>,
        Waiman Long <longman@redhat.com>, kernel-team@cloudflare.com,
        Wei Xu <weixugc@google.com>, Greg Thelen <gthelen@google.com>,
        linux-kernel@vger.kernel.org
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On Fri, Oct 20, 2023 at 9:18=E2=80=AFAM kernel test robot <oliver.sang@inte=
l.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: mem=
cg: 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-everyth=
ing
> patch link: https://lore.kernel.org/all/20231010032117.1577496-4-yosryahm=
ed@google.com/
> patch subject: [PATCH v2 3/5] mm: memcg: make stats flushing threshold pe=
r-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 follow=
ing tests:
>
> +------------------+-----------------------------------------------------=
----------+
> | testcase: change | will-it-scale: will-it-scale.per_thread_ops -30.0% r=
egression |
> | test machine     | 104 threads 2 sockets (Skylake) with 192G memory    =
          |
> | test parameters  | cpufreq_governor=3Dperformance                      =
            |
> |                  | mode=3Dthread                                       =
            |
> |                  | nr_task=3D50%                                       =
            |
> |                  | test=3Dfallocate1                                   =
            |
> +------------------+-----------------------------------------------------=
----------+
>

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.