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Date: Thu, 18 Jan 2024 14:19:24 -0500
From: Johannes Weiner <hannes@cmpxchg.org>
To: Shakeel Butt <shakeelb@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Jens Axboe <axboe@kernel.dk>,
	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: <20240118191924.GN939255@cmpxchg.org>
References: <20240118184235.618164-1-shakeelb@google.com>
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In-Reply-To: <20240118184235.618164-1-shakeelb@google.com>

On Thu, Jan 18, 2024 at 06:42:35PM +0000, Shakeel Butt 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. So, rate limit that
> specific rstat flush. One potential consequence would be the dirty
> throttling might be decided on stale memcg stats. However from our
> benchmarks and production traffic we have not observed any change in the
> dirty throttling behavior of the application.
> 
> Signed-off-by: Shakeel Butt <shakeelb@google.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>