From: Miklos Szeredi <[email protected]>
To: Jens Axboe <[email protected]>
Cc: "Darrick J. Wong" <[email protected]>,
Christoph Hellwig <[email protected]>,
Bernd Schubert <[email protected]>,
[email protected], [email protected],
[email protected], [email protected],
[email protected]
Subject: Re: [PATCH 1/2] fs: add FMODE_DIO_PARALLEL_WRITE flag
Date: Tue, 18 Apr 2023 14:42:03 +0200 [thread overview]
Message-ID: <CAJfpegvv-SPJRjWrR_+JY-H=xmYq0pnTfAtj-N8kG7AnQvWd=w@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
On Sat, 15 Apr 2023 at 15:15, Jens Axboe <[email protected]> wrote:
> Yep, that is pretty much it. If all writes to that inode are serialized
> by a lock on the fs side, then we'll get a lot of contention on that
> mutex. And since, originally, nothing supported async writes, everything
> would get punted to the io-wq workers. io_uring added per-inode hashing
> for this, so that any punt to io-wq of a write would get serialized.
>
> IOW, it's an efficiency thing, not a correctness thing.
We could still get a performance regression if the majority of writes
still trigger the exclusive locking. The questions are:
- how often does that happen in real life?
- how bad the performance regression would be?
Without first attempting to answer those questions, I'd be reluctant
to add FMODE_DIO_PARALLEL_WRITE to fuse.
Thanks,
Miklos
next prev parent reply other threads:[~2023-04-18 12:42 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-07 17:20 [PATCHSET for-next 0/2] Flag file systems as supporting parallel dio writes Jens Axboe
2023-03-07 17:20 ` [PATCH 1/2] fs: add FMODE_DIO_PARALLEL_WRITE flag Jens Axboe
2023-04-12 13:40 ` Bernd Schubert
2023-04-12 13:43 ` Bernd Schubert
2023-04-13 7:40 ` Miklos Szeredi
2023-04-13 9:25 ` Bernd Schubert
2023-04-14 5:11 ` Christoph Hellwig
2023-04-14 15:36 ` Darrick J. Wong
2023-04-15 13:15 ` Jens Axboe
2023-04-18 12:42 ` Miklos Szeredi [this message]
2023-04-18 12:55 ` Bernd Schubert
2023-04-18 22:13 ` Dave Chinner
2023-04-19 1:28 ` Jens Axboe
2023-04-16 5:54 ` Christoph Hellwig
2023-04-19 1:29 ` Jens Axboe
2023-03-07 17:20 ` [PATCH 2/2] io_uring: avoid hashing O_DIRECT writes if the filesystem doesn't need it Jens Axboe
2023-03-15 17:40 ` [PATCHSET for-next 0/2] Flag file systems as supporting parallel dio writes Jens Axboe
2023-03-16 4:29 ` Darrick J. Wong
2023-03-17 2:53 ` Jens Axboe
2023-04-03 12:24 ` Christian Brauner
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='CAJfpegvv-SPJRjWrR_+JY-H=xmYq0pnTfAtj-N8kG7AnQvWd=w@mail.gmail.com' \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
/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