Re: [PATCH 00/10] Further reduce overhead of fsnotify permission hooks

From: Amir Goldstein <amir73il@gmail.com>
To: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>,
	Christian Brauner <brauner@kernel.org>,
	linux-fsdevel@vger.kernel.org,
	 kernel test robot <oliver.sang@intel.com>
Subject: Re: [PATCH 00/10] Further reduce overhead of fsnotify permission hooks
Date: Thu, 4 Apr 2024 17:41:18 +0300	[thread overview]
Message-ID: <CAOQ4uxiV1Y5ufSVqH4T0xbjwtxLA0ijM=kf9xQMSGZXBjTLFCg@mail.gmail.com> (raw)
In-Reply-To: <20240404143443.zfurlpe27m4mysrs@quack3>

On Thu, Apr 4, 2024 at 5:34 PM Jan Kara <jack@suse.cz> wrote:
>
> On Tue 19-03-24 11:59:11, Amir Goldstein wrote:
> > On Sun, Mar 17, 2024 at 8:42 PM Amir Goldstein <amir73il@gmail.com> wrote:
> > >
> > > Jan,
> > >
> > > Commit 082fd1ea1f98 ("fsnotify: optimize the case of no parent watcher")
> > > has reduced the CPU overhead of fsnotify hooks, but we can further
> > > reduce the overhead of permission event hooks, by avoiding the call to
> > > fsnotify() and fsnotify_parent() altogether when there are no permission
> > > event watchers on the sb.
> > >
> > > The main motivation for this work was to avoid the overhead that was
> > > reported by kernel test robot on the patch that adds the upcoming
> > > per-content event hooks (i.e. FS_PRE_ACCESS/FS_PRE_MODIFY).
> > >
> > > Kernel test robot has confirmed that with this series, the addition of
> > > pre-conent fsnotify hooks does not result in any regression [1].
> > > Kernet test robot has also reported performance improvements in some
> > > workloads compared to upstream on an earlier version of this series, but
> > > still waiting for the final results.
> >
> > FYI, the results are back [1] and they show clear improvement in two
> > workloads by this patch set as expected when the permission hooks
> > are practically being disabled:
>
> Patches are now merged into my tree.

Yay!
If possible, please also push fsnotify branch.

Thanks,
Amir.