From mboxrd@z Thu Jan  1 00:00:00 1970
From: Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>
Subject: Re: [PATCH] memcg: async flush memcg stats from perf sensitive
 codepaths
Date: Mon, 28 Feb 2022 19:46:53 +0100
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To: Shakeel Butt <shakeelb@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@kernel.org>, Roman Gushchin <roman.gushchin@linux.dev>, Ivan Babrou <ivan@cloudflare.com>, Cgroups <cgroups@vger.kernel.org>, Linux MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, Daniel Dao <dqminh@cloudflare.com>, stable <stable@vger.kernel.org>

On Fri, Feb 25, 2022 at 05:42:57PM -0800, Shakeel Butt <shakeelb@google.com> wrote:
> Yes, the right fix would be to optimize the flushing code (but that
> would require more work/time). However I still think letting
> performance critical code paths to skip the sync flush would be good
> in general. So, if the current patch is not to your liking we can
> remove mem_cgroup_flush_stats() from workingset_refault().

What about flushing just the subtree of the memcg where the refault
happens?
It doesn't reduce the overall work and there's still full-tree
cgroup_rstat_lock but it should make the chunks of work smaller
durations more regular.


Michal