linux-kernel - Re: [fanotify] a8b98c808e: stress-ng.fanotify.ops_per

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Date:   Fri, 4 Jun 2021 07:56:18 +1000
From:   Matthew Bobrowski <repnop@...gle.com>
To:     Jan Kara <jack@...e.cz>
Cc:     Amir Goldstein <amir73il@...il.com>,
        kernel test robot <oliver.sang@...el.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        LKML <linux-kernel@...r.kernel.org>, lkp@...ts.01.org,
        kbuild test robot <lkp@...el.com>, ying.huang@...el.com,
        feng.tang@...el.com, zhengjun.xing@...ux.intel.com,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: [fanotify] a8b98c808e: stress-ng.fanotify.ops_per_sec 32.2%
 improvement

On Thu, Jun 03, 2021 at 10:43:24AM +0200, Jan Kara wrote:
> On Thu 03-06-21 09:57:15, Amir Goldstein wrote:
> > On Thu, Jun 3, 2021 at 4:36 AM kernel test robot <oliver.sang@...el.com> wro
> > > Greeting,
> > >
> > > FYI, we noticed a 32.2% improvement of stress-ng.fanotify.ops_per_sec due to commit:
> > >
> > >
> > > commit: a8b98c808eab3ec8f1b5a64be967b0f4af4cae43 ("fanotify: fix permission model of unprivileged group")
> > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> > >
> > >
> > 
> > I guess now we know what caused the reported regression:
> > https://lore.kernel.org/lkml/20210511124632.GL24154@quack2.suse.cz/
> > 
> > I didn't know that capable() is so significant.
> 
> Yeah, I wouldn't guess either. Interesting.

Indeed, interesting! :)

While on the topic of stress-ng, it reminds me to set this up on my server
so we can perform such regressions before merging fanotify changes into
master.

/M