Re: [PATCH v3 4/8] memcg: replace stats_flush_lock with an atomic

From: "Michal Koutný" <mkoutny@suse.com>
To: Shakeel Butt <shakeelb@google.com>
Cc: Yosry Ahmed <yosryahmed@google.com>, Tejun Heo <tj@kernel.org>,
	Josef Bacik <josef@toxicpanda.com>, Jens Axboe <axboe@kernel.dk>,
	Zefan Li <lizefan.x@bytedance.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	Muchun Song <muchun.song@linux.dev>,
	Andrew Morton <akpm@linux-foundation.org>,
	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 4/8] memcg: replace stats_flush_lock with an atomic
Date: Tue, 4 Apr 2023 19:32:09 +0200	[thread overview]
Message-ID: <20230404173209.fuw2wdbhbzdgszc6@blackpad> (raw)
In-Reply-To: <CALvZod7Ao-VmB4as+VHsR+awW1jmOA18uVM7qk21mVsXTOYC2A@mail.gmail.com>

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On Tue, Apr 04, 2023 at 10:21:33AM -0700, Shakeel Butt <shakeelb@google.com> wrote:
> > Yes indeed it is. Basically we want to avoid unconditional cache
> > dirtying. This pattern is also used at other places in the kernel like
> > qspinlock.

Thanks for confirmation.

(I remembered the commit 873f64b791a2 ("mm/memcontrol.c: remove the
redundant updating of stats_flush_threshold"). But was slightly confused
why would it be open-coded every time.)

> Oh also take a look at
> https://lore.kernel.org/all/20230404052228.15788-1-feng.tang@intel.com/

Thanks for the link.

Michal

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