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From: Chris Mason <clm@fb.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Josef Bacik <jbacik@fb.com>, LKML <linux-kernel@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Dave Chinner <david@fromorbit.com>, Neil Brown <neilb@suse.de>,
	Jan Kara <jack@suse.cz>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug()
Date: Fri, 11 Sep 2015 22:15:29 -0400	[thread overview]
Message-ID: <20150912021529.GD4150@ret.masoncoding.com> (raw)
In-Reply-To: <CA+55aFzsgbAUAFBydnob2zidYT6TW3YAfo2K22duftU+MjCMwQ@mail.gmail.com>

On Fri, Sep 11, 2015 at 05:52:27PM -0700, Linus Torvalds wrote:
> On Fri, Sep 11, 2015 at 4:36 PM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > Are we really ok with waiting synchronously for an inode while holding
> > the plug? No chance of deadlock (waiting for IO that we've plugged)?
> > That issue is true even of the current code, though, and I have _not_
> > really thought that through, it's just a worry.
> 
> Never mind. We still flush the plug on explicit scheduling events.  I
> wonder why I thought we got rid of that. Some kind of "senior moment",

But flushing on schedule is a little different.  It ends up calling
blk_schedule_flush_plug() which will hand off work to kblockd through
blk_run_queue_async()

Not a huge deal, but if we're scheduling to wait for that IO, we should
really run the plug ourselves so that we're not waiting for kblockd too.

-chris

  reply	other threads:[~2015-09-12  2:15 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-11 19:37 [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Chris Mason
2015-09-11 20:02 ` Linus Torvalds
2015-09-11 20:37   ` Linus Torvalds
2015-09-11 20:40     ` Josef Bacik
2015-09-11 21:04       ` Linus Torvalds
2015-09-11 22:06         ` Linus Torvalds
2015-09-11 23:16           ` Chris Mason
2015-09-11 23:36             ` Linus Torvalds
2015-09-12  0:52               ` Linus Torvalds
2015-09-12  2:15                 ` Chris Mason [this message]
2015-09-12  2:27                   ` Linus Torvalds
2015-09-12 23:00               ` Chris Mason
2015-09-12 23:29                 ` Linus Torvalds
2015-09-12 23:46                   ` Chris Mason
2015-09-13 13:12                     ` Chris Mason
2015-09-13 22:56                       ` Dave Chinner
2015-09-13 23:12                 ` Dave Chinner
2015-09-14 20:06                   ` Linus Torvalds
2015-09-16 15:16                     ` Chris Mason
2015-09-16 19:58                       ` Jan Kara
2015-09-16 20:00                         ` Chris Mason
2015-09-16 22:07                           ` Dave Chinner
2015-09-17  0:37                             ` Dave Chinner
2015-09-17  1:12                               ` Linus Torvalds
2015-09-17  2:14                                 ` Dave Chinner
2015-09-17 19:39                                   ` Linus Torvalds
2015-09-17 22:42                                     ` Chris Mason
2015-09-17 23:08                                       ` Linus Torvalds
2015-09-17 23:56                                         ` Chris Mason
2015-09-18  0:37                                           ` Dave Chinner
2015-09-18  1:50                                             ` Linus Torvalds
2015-09-18  5:40                                               ` Dave Chinner
2015-09-18  6:04                                                 ` Linus Torvalds
2015-09-18  6:06                                                   ` Linus Torvalds
2015-09-18 14:21                                                     ` Jens Axboe
2015-09-18 13:16                                                   ` Chris Mason
2015-09-18 14:23                                                     ` Jens Axboe
2015-09-18 15:32                                                       ` Linus Torvalds
2015-09-18 15:59                                                         ` Peter Zijlstra
2015-09-18 16:02                                                           ` Peter Zijlstra
2015-09-18 16:12                                                           ` Linus Torvalds
2015-09-28 14:47                                                             ` Peter Zijlstra
2015-09-28 16:08                                                               ` Linus Torvalds
2015-09-29  7:55                                                                 ` Ingo Molnar
2015-09-18 22:17                                                   ` Dave Chinner
2015-09-21  9:24                                                     ` Jan Kara
2015-09-21 20:21                                                       ` Andrew Morton
2015-09-17 23:03                                   ` Dave Chinner
2015-09-17 23:13                                     ` Linus Torvalds
2015-09-17  3:48                               ` Chris Mason
2015-09-17  4:30                                 ` Dave Chinner
2015-09-17 12:13                                   ` Chris Mason
2015-09-11 23:06         ` Chris Mason
2015-09-11 23:13           ` Linus Torvalds
  -- strict thread matches above, loose matches on Subject: below --
2015-09-09 15:23 Chris Mason
2015-09-11 18:49 ` Jens Axboe

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