From: Jan Kara <jack@suse.cz>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>, Jan Kara <jack@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mel@linux.vnet.ibm.com>,
Dave Chinner <david@fromorbit.com>,
Trond Myklebust <Trond.Myklebust@netapp.com>,
Itaru Kitayama <kitayama@cl.bb4u.ne.jp>,
Minchan Kim <minchan.kim@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [PATCH 5/6] writeback: try more writeback as long as something was written
Date: Thu, 21 Apr 2011 18:41:54 +0200 [thread overview]
Message-ID: <20110421164154.GC4476@quack.suse.cz> (raw)
In-Reply-To: <20110421060556.GA24232@localhost>
On Thu 21-04-11 14:05:56, Wu Fengguang wrote:
> On Thu, Apr 21, 2011 at 12:39:40PM +0800, Christoph Hellwig wrote:
> > On Thu, Apr 21, 2011 at 11:33:25AM +0800, Wu Fengguang wrote:
> > > I collected the writeback_single_inode() traces (patch attached for
> > > your reference) each for several test runs, and find much more
> > > I_DIRTY_PAGES after patchset. Dave, do you know why there are so many
> > > I_DIRTY_PAGES (or radix tag) remained after the XFS ->writepages() call,
> > > even for small files?
> >
> > What is your defintion of a small file? As soon as it has multiple
> > extents or holes there's absolutely no way to clean it with a single
> > writepage call.
>
> It's writing a kernel source tree to XFS. You can find in the below
> trace that it often leaves more dirty pages behind (indicated by the
> I_DIRTY_PAGES flag) after writing as less as 1 page (indicated by the
> wrote=1 field).
As Dave said, it's probably just a race since XFS redirties the inode on
IO completion. So I think the inodes are just small so they have only a few
dirty pages so you don't have much to write and they are written and
redirtied before you check the I_DIRTY flags. You could use radix tree
dirty tag to verify whether there are really dirty pages or not...
BTW a quick check of kernel tree shows the following distribution of
sizes (in KB):
Count KB Cumulative Percent
257 0 0.9%
13309 4 45%
5553 8 63%
2997 12 73%
1879 16 80%
1275 20 83%
987 24 87%
685 28 89%
540 32 91%
387 36 ...
309 40
264 44
249 48
170 52
143 56
144 60
132 64
100 68
...
Total 30155
And the distribution of your 'wrote=xxx' roughly corresponds to this...
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
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next prev parent reply other threads:[~2011-04-21 16:41 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-19 3:00 [PATCH 0/6] writeback: moving expire targets for background/kupdate works Wu Fengguang
2011-04-19 3:00 ` [PATCH 1/6] writeback: pass writeback_control down to move_expired_inodes() Wu Fengguang
2011-04-19 3:00 ` [PATCH 2/6] writeback: the kupdate expire timestamp should be a moving target Wu Fengguang
2011-04-19 7:02 ` Dave Chinner
2011-04-19 7:20 ` Wu Fengguang
2011-04-19 9:31 ` Jan Kara
2011-04-19 3:00 ` [PATCH 3/6] writeback: sync expired inodes first in background writeback Wu Fengguang
2011-04-19 7:35 ` Dave Chinner
2011-04-19 9:57 ` Jan Kara
2011-04-19 12:56 ` Wu Fengguang
2011-04-19 13:46 ` Wu Fengguang
2011-04-20 1:21 ` Dave Chinner
2011-04-20 2:53 ` Wu Fengguang
2011-04-21 0:45 ` Dave Chinner
2011-04-21 2:06 ` Wu Fengguang
2011-04-21 3:01 ` Dave Chinner
2011-04-21 3:59 ` Wu Fengguang
2011-04-21 4:10 ` Wu Fengguang
2011-04-21 4:36 ` Christoph Hellwig
2011-04-21 6:36 ` Dave Chinner
2011-04-21 16:04 ` Jan Kara
2011-04-22 2:24 ` Wu Fengguang
2011-04-22 21:12 ` Jan Kara
2011-04-26 5:37 ` Wu Fengguang
2011-04-26 14:30 ` Jan Kara
2011-04-20 7:38 ` Wu Fengguang
2011-04-21 1:01 ` Dave Chinner
2011-04-21 1:47 ` Wu Fengguang
2011-04-19 3:00 ` [PATCH 4/6] writeback: introduce writeback_control.inodes_cleaned Wu Fengguang
2011-04-19 9:47 ` Jan Kara
2011-04-19 3:00 ` [PATCH 5/6] writeback: try more writeback as long as something was written Wu Fengguang
2011-04-19 10:20 ` Jan Kara
2011-04-19 11:16 ` Wu Fengguang
2011-04-19 21:10 ` Jan Kara
2011-04-20 7:50 ` Wu Fengguang
2011-04-20 15:22 ` Jan Kara
2011-04-21 3:33 ` Wu Fengguang
2011-04-21 4:39 ` Christoph Hellwig
2011-04-21 6:05 ` Wu Fengguang
2011-04-21 16:41 ` Jan Kara [this message]
2011-04-22 2:32 ` Wu Fengguang
2011-04-22 21:23 ` Jan Kara
2011-04-21 7:09 ` Dave Chinner
2011-04-21 7:14 ` Christoph Hellwig
2011-04-21 7:52 ` Dave Chinner
2011-04-21 8:00 ` Christoph Hellwig
2011-04-19 3:00 ` [PATCH 6/6] NFS: return -EAGAIN when skipped commit in nfs_commit_unstable_pages() Wu Fengguang
2011-04-19 3:29 ` Trond Myklebust
2011-04-19 3:55 ` Wu Fengguang
2011-04-21 4:40 ` Christoph Hellwig
2011-04-19 6:38 ` [PATCH 0/6] writeback: moving expire targets for background/kupdate works Dave Chinner
2011-04-19 8:02 ` Wu Fengguang
2011-04-21 4:34 ` Christoph Hellwig
2011-04-21 5:50 ` Wu Fengguang
2011-04-21 5:56 ` Christoph Hellwig
2011-04-21 6:07 ` Wu Fengguang
2011-04-21 7:17 ` Christoph Hellwig
2011-04-21 10:15 ` Wu Fengguang
-- strict thread matches above, loose matches on Subject: below --
2010-07-22 5:09 [PATCH 0/6] [RFC] writeback: try to write older pages first Wu Fengguang
2010-07-22 5:09 ` [PATCH 5/6] writeback: try more writeback as long as something was written Wu Fengguang
2010-07-23 17:39 ` Jan Kara
2010-07-26 12:39 ` Wu Fengguang
2010-07-26 11:01 ` Mel Gorman
2010-07-26 11:39 ` Wu Fengguang
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