From: Jan Kara <jack@suse.cz>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Jan Kara <jack@suse.cz>, Jens Axboe <axboe@kernel.dk>,
Christian Brauner <brauner@kernel.org>,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v3] fsnotify: optimize the case of no parent watcher
Date: Tue, 16 Jan 2024 13:04:34 +0100 [thread overview]
Message-ID: <20240116120434.gsdg7lhb4pkcppfk@quack3> (raw)
In-Reply-To: <20240116113247.758848-1-amir73il@gmail.com>
On Tue 16-01-24 13:32:47, Amir Goldstein wrote:
> If parent inode is not watching, check for the event in masks of
> sb/mount/inode masks early to optimize out most of the code in
> __fsnotify_parent() and avoid calling fsnotify().
>
> Jens has reported that this optimization improves BW and IOPS in an
> io_uring benchmark by more than 10% and reduces perf reported CPU usage.
>
> before:
>
> + 4.51% io_uring [kernel.vmlinux] [k] fsnotify
> + 3.67% io_uring [kernel.vmlinux] [k] __fsnotify_parent
>
> after:
>
> + 2.37% io_uring [kernel.vmlinux] [k] __fsnotify_parent
>
> Reported-and-tested-by: Jens Axboe <axboe@kernel.dk>
> Link: https://lore.kernel.org/linux-fsdevel/b45bd8ff-5654-4e67-90a6-aad5e6759e0b@kernel.dk/
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> ---
>
> Jan,
>
> Considering that this change looks like a clear win and it actually
> the change that you suggested, I cleaned it up a bit and posting for
> your consideration.
Agreed, I like this. What did you generate this patch against? It does not
apply on top of current Linus' tree (maybe it needs the change sitting in
VFS tree - which is fine I can wait until that gets merged)?
> I've kept the wrappers fsnotify_path() and fsnotify_sb_has_watchers()
> although they are not directly related to the optimization, because they
> makes the code a bit nicer IMO.
Yeah, these cleanups are fine. I would have prefered them as a separate
patch (some people might want the performance improvement to be backported
and this makes it unnecessarily more complex) but don't resend just because
of that.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2024-01-16 12:04 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-16 11:32 [PATCH v3] fsnotify: optimize the case of no parent watcher Amir Goldstein
2024-01-16 12:04 ` Jan Kara [this message]
2024-01-16 12:53 ` Amir Goldstein
2024-01-24 16:07 ` Jan Kara
2024-01-24 16:20 ` Amir Goldstein
2024-02-13 19:45 ` Amir Goldstein
2024-02-14 11:23 ` Jan Kara
2024-02-14 13:40 ` Amir Goldstein
2024-02-15 8:36 ` Jan Kara
2024-03-06 14:51 ` Amir Goldstein
2024-03-08 16:00 ` Jan Kara
2024-03-11 13:51 ` Christian Brauner
2024-02-15 15:07 ` Jens Axboe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240116120434.gsdg7lhb4pkcppfk@quack3 \
--to=jack@suse.cz \
--cc=amir73il@gmail.com \
--cc=axboe@kernel.dk \
--cc=brauner@kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).