linux-kernel - Re: [PATCH] mm/memcontrol: export memcg.swap watermark via sysfs for v2 memcg

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Message-ID: <20230525012103.GA24888@cmpxchg.org>
Date:   Wed, 24 May 2023 21:21:03 -0400
From:   Johannes Weiner <hannes@...xchg.org>
To:     "Lars R. Damerow" <lars@...ar.com>
Cc:     mhocko@...nel.org, roman.gushchin@...ux.dev, shakeelb@...gle.com,
        tj@...nel.org, lizefan.x@...edance.com, corbet@....net,
        muchun.song@...ux.dev, akpm@...ux-foundation.org,
        cgroups@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH] mm/memcontrol: export memcg.swap watermark via sysfs for
 v2 memcg

On Wed, May 24, 2023 at 11:17:33AM -0700, Lars R. Damerow wrote:
> This patch is similar to commit 8e20d4b33266 ("mm/memcontrol: export
> memcg->watermark via sysfs for v2 memcg"), but exports the swap counter's
> watermark.
> 
> We allocate jobs to our compute farm using heuristics determined by memory
> and swap usage from previous jobs. Tracking the peak swap usage for new
> jobs is important for determining when jobs are exceeding their expected
> bounds, or when our baseline metrics are getting outdated.
> 
> Our toolset was written to use the "memory.memsw.max_usage_in_bytes" file
> in cgroups v1, and altering it to poll cgroups v2's "memory.swap.current"
> would give less accurate results as well as add complication to the code.
> Having this watermark exposed in sysfs is much preferred.
> 
> Signed-off-by: Lars R. Damerow <lars@...ar.com>

Looks good to me.

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