linux-kernel - Re: [PATCH] mm/memcg: Skip high limit check in root memcg

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Message-ID: <Y/ThbQNqrdny4+Pf@dhcp22.suse.cz>
Date:   Tue, 21 Feb 2023 16:21:17 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     Haifeng Xu <haifeng.xu@...pee.com>
Cc:     hannes@...xchg.org, shakeelb@...gle.com, muchun.song@...ux.dev,
        akpm@...ux-foundation.org, cgroups@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/memcg: Skip high limit check in root memcg

On Tue 21-02-23 22:21:45, Haifeng Xu wrote:
[...]
> >> The test result show that with or without the patch, the time taken is almost the same.
> > 
> > This is in line with my expectation. So the question is whether the
> > additional check is really worth it. 
> 
> This patch doesn't bring any obvious benifit or harm, but the high
> limit check in root memcg seems a little weird.  Maybe we can add this
> check

Well, I do not see the code to look weird TBH. There is nothing wrong in
doing the check for the root memcg. It is a bit pointless but it is not
incorrect.

> It all depends on your viewpoint.

>From my POV, I prefer changes that either fix something (correctness
issue or a performance issue/improvement) or improve readbility. The
check doesn't fix anything and I am not convinced about an improved
readabilit either.

Thanks for the patch anyway!
-- 
Michal Hocko
SUSE Labs