From: "T.J. Mercier" <tjmercier@google.com>
To: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Muchun Song <muchun.song@linux.dev>,
Steven Rostedt <rostedt@goodmis.org>,
JP Kobryn <inwardvessel@gmail.com>,
Yosry Ahmed <yosryahmed@google.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org,
Meta kernel team <kernel-team@meta.com>,
Michal Hocko <mhocko@suse.com>,
Muchun Song <songmuchun@bytedance.com>
Subject: Re: [PATCH v2] memcg: add tracing for memcg stat updates
Date: Wed, 16 Oct 2024 10:17:22 -0700 [thread overview]
Message-ID: <CABdmKX3iqmPnmSDi=KCy+0QSws+PjLR1jLs8HL-JjorCARM02A@mail.gmail.com> (raw)
In-Reply-To: <20241015213721.3804209-1-shakeel.butt@linux.dev>
On Tue, Oct 15, 2024 at 2:37 PM Shakeel Butt <shakeel.butt@linux.dev> wrote:
>
> The memcg stats are maintained in rstat infrastructure which provides very
> fast updates side and reasonable read side. However memcg added plethora
> of stats and made the read side, which is cgroup rstat flush, very slow.
> To solve that, threshold was added in the memcg stats read side i.e. no
> need to flush the stats if updates are within the threshold.
>
> This threshold based improvement worked for sometime but more stats were
> added to memcg and also the read codepath was getting triggered in the
> performance sensitive paths which made threshold based ratelimiting
> ineffective. We need more visibility into the hot and cold stats i.e.
> stats with a lot of updates. Let's add trace to get that visibility.
>
> Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
> Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
> Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Muchun Song <songmuchun@bytedance.com>
> Cc: JP Kobryn <inwardvessel@gmail.com>
> Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: T.J. Mercier <tjmercier@google.com>
prev parent reply other threads:[~2024-10-16 17:17 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-15 21:37 Shakeel Butt
2024-10-15 21:52 ` Johannes Weiner
2024-10-16 17:17 ` T.J. Mercier [this message]
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