linux-kernel - Re: [PATCH 0/5] mm: memcg: subtree stats flushing and thresholds

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Date:   Mon, 2 Oct 2023 14:46:58 -0700
From:   Yosry Ahmed <yosryahmed@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Shakeel Butt <shakeelb@...gle.com>,
        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-mm@...ck.org, cgroups@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/5] mm: memcg: subtree stats flushing and thresholds

On Thu, Sep 21, 2023 at 1:11 AM Yosry Ahmed <yosryahmed@...gle.com> wrote:
>
> This series attempts to address shortages in today's approach for memcg
> stats flushing, namely occasionally stale or expensive stat reads. The
> series does so by changing the threshold that we use to decide whether
> to trigger a flush to be per memcg instead of global (patch 3), and then
> changing flushing to be per memcg (i.e. subtree flushes) instead of
> global (patch 5).
>
> Patch 3 & 5 are the core of the series, and they include more details
> and testing results. The rest are either cleanups or prep work.
>
> This series replaces the "memcg: more sophisticated stats flushing"
> series [1], which also replaces another series, in a long list of
> attempts to improve memcg stats flushing. It is not a v2 as it is a
> completely different approach. This is based on collected feedback from
> discussions on lkml in all previous attempts. Hopefully, this is the
> final attempt.
>
> [1]https://lore.kernel.org/lkml/20230913073846.1528938-1-yosryahmed@google.com/
>
> Yosry Ahmed (5):
>   mm: memcg: change flush_next_time to flush_last_time
>   mm: memcg: move vmstats structs definition above flushing code
>   mm: memcg: make stats flushing threshold per-memcg
>   mm: workingset: move the stats flush into workingset_test_recent()
>   mm: memcg: restore subtree stats flushing
>
>  include/linux/memcontrol.h |   8 +-
>  mm/memcontrol.c            | 269 +++++++++++++++++++++----------------
>  mm/vmscan.c                |   2 +-
>  mm/workingset.c            |  37 +++--
>  4 files changed, 181 insertions(+), 135 deletions(-)
>
> --
> 2.42.0.459.ge4e396fd5e-goog
>

Friendly ping for feedback on this approach :)