linux-kernel - Re: [RFC PATCH] mm: fix the inaccurate memory statistics issue for users

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Message-Id: <20250523172305.57843-1-sj@kernel.org>
Date: Fri, 23 May 2025 10:23:05 -0700
From: SeongJae Park <sj@...nel.org>
To: SeongJae Park <sj@...nel.org>
Cc: Baolin Wang <baolin.wang@...ux.alibaba.com>,
	akpm@...ux-foundation.org,
	david@...hat.com,
	shakeelb@...gle.com,
	lorenzo.stoakes@...cle.com,
	Liam.Howlett@...cle.com,
	vbabka@...e.cz,
	rppt@...nel.org,
	surenb@...gle.com,
	mhocko@...e.com,
	linux-mm@...ck.org,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] mm: fix the inaccurate memory statistics issue for users

On Fri, 23 May 2025 10:20:29 -0700 SeongJae Park <sj@...nel.org> wrote:

> On Fri, 23 May 2025 11:16:13 +0800 Baolin Wang <baolin.wang@...ux.alibaba.com> wrote:
> 
> > On some large machines with a high number of CPUs running a 64K kernel,
> 
> What does 64K kernel means?
> 
> > we found that the 'RES' field is always 0 displayed by the top command
> > for some processes, which will cause a lot of confusion for users.
> > 
> >     PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
> >  875525 root      20   0   12480      0      0 R   0.3   0.0   0:00.08 top
> >       1 root      20   0  172800      0      0 S   0.0   0.0   0:04.52 systemd
> > 
> > The main reason is that the batch size of the percpu counter is quite large
> > on these machines, caching a significant percpu value, since converting mm's
> > rss stats into percpu_counter by commit f1a7941243c1 ("mm: convert mm's rss
> > stats into percpu_counter").

Forgot asking this, sorry.  Should we add Fixes: tag and Cc stable@?


Thanks,
SJ

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