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Date: Mon, 22 Jan 2024 16:20:31 +0100
From: Michal =?utf-8?Q?Koutn=C3=BD?= <mkoutny@suse.com>
To: Shakeel Butt <shakeelb@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, 
	Jens Axboe <axboe@kernel.dk>, Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>, 
	Jan Kara <jack@suse.cz>, Roman Gushchin <roman.gushchin@linux.dev>, 
	Michal Hocko <mhocko@kernel.org>, Muchun Song <muchun.song@linux.dev>, cgroups@vger.kernel.org, 
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: writeback: ratelimit stat flush from
 mem_cgroup_wb_stats
Message-ID: <jazycqhefxn6oigmt6mitn2cfoonscbdwqxy5g7gs2j74w3ia5@qwcu3v7kmk4h>
References: <20240118184235.618164-1-shakeelb@google.com>
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Hello.

On Thu, Jan 18, 2024 at 06:42:35PM +0000, Shakeel Butt <shakeelb@google.com=
> wrote:
> One of our workloads (Postgres 14) has regressed when migrated from 5.10
> to 6.1 upstream kernel. The regression can be reproduced by sysbench's
> oltp_write_only benchmark.
> It seems like the always on rstat flush in
> mem_cgroup_wb_stats() is causing the regression.

Is the affected benchmark running in a non-root cgroup?

I'm asking whether this would warrant a=20
  Fixes: fd25a9e0e23b ("memcg: unify memcg stat flushing")=20
that introduced the global flush (in v6.1) but it was removed later in=20
  7d7ef0a4686a ("mm: memcg: restore subtree stats flushing")=20
(so v6.8 could be possibly unaffected).

Thanks,
Michal

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