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Date:   Tue, 10 Oct 2023 03:21:11 +0000
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Message-ID: <20231010032117.1577496-1-yosryahmed@google.com>
Subject: [PATCH v2 0/5] mm: memcg: subtree stats flushing and thresholds
From:   Yosry Ahmed <yosryahmed@google.com>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@kernel.org>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Shakeel Butt <shakeelb@google.com>,
        Muchun Song <muchun.song@linux.dev>,
        Ivan Babrou <ivan@cloudflare.com>, Tejun Heo <tj@kernel.org>,
        "=?UTF-8?q?Michal=20Koutn=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-mm@kvack.org, cgroups@vger.kernel.org,
        linux-kernel@vger.kernel.org, Yosry Ahmed <yosryahmed@google.com>
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Precedence: bulk

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 new version of
the same patchset 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/

v1 -> v2:
- Fixed compilation error reported by the kernel robot in patch 4, also
  added a missing rcu_read_unlock().
- More testing results in the commit message of patch 3.

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            |  42 ++++--
 4 files changed, 185 insertions(+), 136 deletions(-)

-- 
2.42.0.609.gbb76f46606-goog