linux-kernel - Re: [PATCH v3] mm: optimize stat output for 11% sys time reduce

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Message-ID: <CAJxJ_jgGCL8WcyAO1iyF5Eu+6JtcemAPGs-WMFAaHdaM8V3uDA@mail.gmail.com>
Date: Fri, 23 Jan 2026 09:07:13 +0800
From: Jianyue Wu <wujianyue000@...il.com>
To: Shakeel Butt <shakeel.butt@...ux.dev>
Cc: Andrew Morton <akpm@...ux-foundation.org>, hannes@...xchg.org, mhocko@...nel.org, 
	roman.gushchin@...ux.dev, muchun.song@...ux.dev, linux-mm@...ck.org, 
	cgroups@...r.kernel.org, linux-kernel@...r.kernel.org, inwardvessel@...il.com
Subject: Re: [PATCH v3] mm: optimize stat output for 11% sys time reduce

On Fri, Jan 23, 2026 at 5:12 AM Shakeel Butt <shakeel.butt@...ux.dev> wrote:
>
> On Thu, Jan 22, 2026 at 09:13:51AM -0800, Andrew Morton wrote:
> > On Thu, 22 Jan 2026 19:42:42 +0800 Jianyue Wu <wujianyue000@...il.com> wrote:
> > So the tl;dr here is "vfprintf() is slow".
> >
> > It's quite a large change, although not a complex one.
> >
> > Do we need to change so much?  Would some subset of these changes
> > provide most of the benefit?
> >
> > It does rather uglify things so there's a risk that helpful people will
> > send "cleanups" which switch back to using *printf*.  Explanatory code
> > comments would help prevent that but we'd need a lot of them.
> >
> > I dunno, what do people think?  Does the benefit justify the change?
>
> It does come with significant benefit but there is no urgency and we can
> definitely decrease the ugliness. JP told me he has some ideas to
> improve this.
>
> Andrew, let's skip this patch for the upcoming merge window and you can
> drop it from mm-tree if it is a burden.
>
Agree. This touches a lot of code and increases complexity, which is a
significant
downside. If there are ideas to improve it, that’d be great.
I’m OK with dropping it for the upcoming merge window, and drop it if
it is a burden.