Re: [fanotify] a8b98c808e: stress-ng.fanotify.ops_per_sec 32.2% improvement

[Amir Goldstein]

On Thu, Jun 3, 2021 at 4:36 AM kernel test robot <oliver.sang@xxxxxxxxx> wrote:
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> Greeting,
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> FYI, we noticed a 32.2% improvement of stress-ng.fanotify.ops_per_sec due to commit:
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> commit: a8b98c808eab3ec8f1b5a64be967b0f4af4cae43 ("fanotify: fix permission model of unprivileged group")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
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>

I guess now we know what caused the reported regression:
https://lore.kernel.org/lkml/20210511124632.GL24154@xxxxxxxxxxxxxx/

I didn't know that capable() is so significant.

FWIW, here is a link to the test code:
https://github.com/ColinIanKing/stress-ng/blob/master/stress-fanotify.c#L474

It creates events in a loop by child process while the parent process
reads the generated events in a loop (on two different fanotify groups).

Thanks,
Amir.