From: Johannes Weiner <hannes@cmpxchg.org>
To: Yosry Ahmed <yosryahmed@google.com>
Cc: "Tejun Heo" <tj@kernel.org>, "Josef Bacik" <josef@toxicpanda.com>,
"Jens Axboe" <axboe@kernel.dk>,
"Zefan Li" <lizefan.x@bytedance.com>,
"Michal Hocko" <mhocko@kernel.org>,
"Roman Gushchin" <roman.gushchin@linux.dev>,
"Shakeel Butt" <shakeelb@google.com>,
"Muchun Song" <muchun.song@linux.dev>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Michal Koutný" <mkoutny@suse.com>,
"Vasily Averin" <vasily.averin@linux.dev>,
cgroups@vger.kernel.org, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
bpf@vger.kernel.org, "Michal Hocko" <mhocko@suse.com>
Subject: Re: [PATCH v3 5/8] memcg: sleep during flushing stats in safe contexts
Date: Thu, 30 Mar 2023 15:30:13 -0400 [thread overview]
Message-ID: <ZCXjRYASA+Cjomlx@cmpxchg.org> (raw)
In-Reply-To: <20230330191801.1967435-6-yosryahmed@google.com>
On Thu, Mar 30, 2023 at 07:17:58PM +0000, Yosry Ahmed wrote:
> Currently, all contexts that flush memcg stats do so with sleeping not
> allowed. Some of these contexts are perfectly safe to sleep in, such as
> reading cgroup files from userspace or the background periodic flusher.
> Flushing is an expensive operation that scales with the number of cpus
> and the number of cgroups in the system, so avoid doing it atomically
> where possible.
>
> Refactor the code to make mem_cgroup_flush_stats() non-atomic (aka
> sleepable), and provide a separate atomic version. The atomic version is
> used in reclaim, refault, writeback, and in mem_cgroup_usage(). All
> other code paths are left to use the non-atomic version. This includes
> callbacks for userspace reads and the periodic flusher.
>
> Since refault is the only caller of mem_cgroup_flush_stats_ratelimited(),
> change it to mem_cgroup_flush_stats_atomic_ratelimited(). Reclaim and
> refault code paths are modified to do non-atomic flushing in separate
> later patches -- so it will eventually be changed back to
> mem_cgroup_flush_stats_ratelimited().
>
> Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
> Acked-by: Shakeel Butt <shakeelb@google.com>
> Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
next prev parent reply other threads:[~2023-03-30 19:30 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-30 19:17 [PATCH v3 0/8] memcg: avoid flushing stats atomically where possible Yosry Ahmed
2023-03-30 19:17 ` [PATCH v3 1/8] cgroup: rename cgroup_rstat_flush_"irqsafe" to "atomic" Yosry Ahmed
2023-03-30 19:17 ` Yosry Ahmed
2023-03-30 19:17 ` [PATCH v3 2/8] memcg: rename mem_cgroup_flush_stats_"delayed" to "ratelimited" Yosry Ahmed
2023-03-30 19:17 ` [PATCH v3 3/8] memcg: do not flush stats in irq context Yosry Ahmed
2023-03-30 19:17 ` Yosry Ahmed
2023-03-30 19:17 ` [PATCH v3 4/8] memcg: replace stats_flush_lock with an atomic Yosry Ahmed
2023-04-04 16:52 ` Michal Koutný
2023-04-04 16:52 ` Michal Koutný
2023-04-04 17:13 ` Shakeel Butt
2023-04-04 17:13 ` Shakeel Butt
2023-04-04 17:21 ` Shakeel Butt
2023-04-04 17:21 ` Shakeel Butt
2023-04-04 17:32 ` Michal Koutný
2023-03-30 19:17 ` [PATCH v3 5/8] memcg: sleep during flushing stats in safe contexts Yosry Ahmed
2023-03-30 19:30 ` Johannes Weiner [this message]
2023-04-04 15:09 ` Johannes Weiner
2023-03-30 19:17 ` [PATCH v3 6/8] workingset: memcg: sleep when flushing stats in workingset_refault() Yosry Ahmed
2023-04-04 16:53 ` Michal Koutný
2023-04-04 16:53 ` Michal Koutný
2023-04-04 18:09 ` Yosry Ahmed
2023-04-05 8:00 ` Michal Koutný
2023-04-05 8:00 ` Michal Koutný
2023-04-05 8:02 ` Yosry Ahmed
2023-04-05 8:02 ` Yosry Ahmed
2023-03-30 19:18 ` [PATCH v3 7/8] vmscan: memcg: sleep when flushing stats during reclaim Yosry Ahmed
2023-03-30 19:18 ` Yosry Ahmed
2023-03-30 19:18 ` [PATCH v3 8/8] memcg: do not modify rstat tree for zero updates Yosry Ahmed
2023-03-30 19:18 ` Yosry Ahmed
2023-04-04 16:53 ` Michal Koutný
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