linux-mm.kvack.org archive mirror
 help / color / mirror / Atom feed
From: Theodore Ts'o <tytso@mit.edu>
To: Mel Gorman <mgorman@suse.de>
Cc: Jan Kara <jack@suse.cz>,
	linux-ext4@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>, Jiri Slaby <jslaby@suse.cz>
Subject: Re: Excessive stall times on ext4 in 3.9-rc2
Date: Sat, 20 Apr 2013 20:05:22 -0400	[thread overview]
Message-ID: <20130421000522.GA5054@thunk.org> (raw)
In-Reply-To: <20130412094731.GI11656@suse.de>

As an update to this thread, we brought up this issue at LSF/MM, and
there is a thought that we should be able to solve this problem by
having lock_buffer() check to see if the buffer is locked due to a
write being queued, to have the priority of the write bumped up in the
write queues to resolve the priority inversion.  I believe Jeff Moyer
was going to look into this, if I remember correctly.

An alternate solution which I've been playing around adds buffer_head
flags so we can indicate that a buffer contains metadata and/or should
have I/O submitted with the REQ_PRIO flag set.

Adding a buffer_head flag for at least BH_Meta is probably a good
thing, since that way the blktrace will be properly annotated.
Whether we should keep the BH_Prio flag or rely on lock_buffer()
automatically raising the priority is, my feeling is that if
lock_buffer() can do the right thing, we should probably do it via
lock_buffer().  I have a feeling this might be decidedly non-trivial,
though, so perhaps we should just doing via BH flags?

	   	      	     	  	- Ted

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

  reply	other threads:[~2013-04-21  0:05 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-02 14:27 Excessive stall times on ext4 in 3.9-rc2 Mel Gorman
2013-04-02 15:00 ` Jiri Slaby
2013-04-02 15:03 ` Zheng Liu
2013-04-02 15:15   ` Mel Gorman
2013-04-02 15:06 ` Theodore Ts'o
2013-04-02 15:14   ` Theodore Ts'o
2013-04-02 18:19     ` Theodore Ts'o
2013-04-07 21:59       ` Frank Ch. Eigler
2013-04-08  8:36         ` Mel Gorman
2013-04-08 10:52           ` Frank Ch. Eigler
2013-04-08 11:01         ` Theodore Ts'o
2013-04-03 10:19     ` Mel Gorman
2013-04-03 12:05       ` Theodore Ts'o
2013-04-03 15:15         ` Mel Gorman
2013-04-05 22:18       ` Jiri Slaby
2013-04-05 23:16         ` Theodore Ts'o
2013-04-06  7:29           ` Jiri Slaby
2013-04-06  7:37             ` Jiri Slaby
2013-04-06  8:19               ` Jiri Slaby
2013-04-06 13:15             ` Theodore Ts'o
2013-04-10 10:56   ` Mel Gorman
2013-04-10 13:12     ` Theodore Ts'o
2013-04-11 17:04       ` Mel Gorman
2013-04-11 18:35         ` Theodore Ts'o
2013-04-11 21:33           ` Jan Kara
2013-04-12  2:57             ` Theodore Ts'o
2013-04-12  4:50               ` Dave Chinner
2013-04-12 15:19                 ` Theodore Ts'o
2013-04-13  1:23                   ` Dave Chinner
2013-04-22 14:38                   ` Mel Gorman
2013-04-22 22:42                     ` Jeff Moyer
2013-04-23  0:02                       ` Theodore Ts'o
2013-04-23  9:31                       ` Jan Kara
2013-04-23 14:01                       ` Mel Gorman
2013-04-24 19:09                         ` Jeff Moyer
2013-04-25 12:21                           ` Mel Gorman
2013-04-12  9:47               ` Mel Gorman
2013-04-21  0:05                 ` Theodore Ts'o [this message]
2013-04-21  0:07                   ` [PATCH 1/3] ext4: mark all metadata I/O with REQ_META Theodore Ts'o
2013-04-21  0:07                     ` [PATCH 2/3] buffer: add BH_Prio and BH_Meta flags Theodore Ts'o
2013-04-21  0:07                     ` [PATCH 3/3] ext4: mark metadata blocks using bh flags Theodore Ts'o
2013-04-21  6:09                       ` Jiri Slaby
2013-04-21 19:55                         ` Theodore Ts'o
2013-04-21 20:48                           ` [PATCH 3/3 -v2] " Theodore Ts'o
2013-04-22 12:06                     ` [PATCH 1/3] ext4: mark all metadata I/O with REQ_META Zheng Liu
2013-04-23 15:33                   ` Excessive stall times on ext4 in 3.9-rc2 Mel Gorman
2013-04-23 15:50                     ` Theodore Ts'o
2013-04-23 16:13                       ` Mel Gorman
2013-04-12 10:18               ` Tvrtko Ursulin
2013-04-12  9:45           ` Mel Gorman
2013-04-02 23:16 ` Theodore Ts'o
2013-04-03 15:22   ` Mel Gorman

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=20130421000522.GA5054@thunk.org \
    --to=tytso@mit.edu \
    --cc=jack@suse.cz \
    --cc=jslaby@suse.cz \
    --cc=linux-ext4@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mgorman@suse.de \
    /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).