linux-kernel - Re: [linus:master] [fsnotify] a94204f4d4: stress-ng.timerfd.ops_per

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Message-ID: <CAOQ4uxgC_Uaa2XA8vyuDvsio1ysr__9kF6RK3pKcD=Xa1ps8Mg@mail.gmail.com>
Date: Fri, 7 Feb 2025 12:34:03 +0100
From: Amir Goldstein <amir73il@...il.com>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: kernel test robot <oliver.sang@...el.com>, oe-lkp@...ts.linux.dev, lkp@...el.com, 
	linux-kernel@...r.kernel.org, Jan Kara <jack@...e.cz>, linux-fsdevel@...r.kernel.org, 
	Christian Brauner <brauner@...nel.org>
Subject: Re: [linus:master] [fsnotify] a94204f4d4: stress-ng.timerfd.ops_per_sec
 7.0% improvement

On Thu, Feb 6, 2025 at 9:45 PM Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> On Wed, 5 Feb 2025 at 00:09, kernel test robot <oliver.sang@...el.com> wrote:
> >
> > kernel test robot noticed a 7.0% improvement of stress-ng.timerfd.ops_per_sec on:
>
> I have no idea what the heck that benchmark does, but I am happy to
> see that this whole patch series did actually end up improving on the
> whole fsnotify cost that I was ranting about in the original
> submission.
>
> Obviously this load doesn't actually do the new pre-event hooks, so it
> seems to be all just about how fsnotify_file_area_perm() (or some
> other fsnotify hook in the normal read() path) now isn't the
> unconditional pig that it used to be.

Right.
We got this win by slightly modifying semantics of FAN_ACCESS_PERM
events, but I cannot imagine that anyone will care (famous last words).

It's all about the fact that
>
> I don't see how that would be worth 7%, but I'll happily take it.
>

Yeh, I was happy to see that as well :)

Thanks,
Amir.