From: Mel Gorman <mel@csn.ul.ie>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Dave Chinner <david@fromorbit.com>, Jan Kara <jack@suse.cz>,
Christoph Hellwig <hch@infradead.org>,
Chris Mason <chris.mason@oracle.com>,
Jens Axboe <jens.axboe@oracle.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 2/6] writeback: the kupdate expire timestamp should be a moving target
Date: Mon, 26 Jul 2010 11:52:00 +0100 [thread overview]
Message-ID: <20100726105200.GK5300@csn.ul.ie> (raw)
In-Reply-To: <20100722061822.630779474@intel.com>
On Thu, Jul 22, 2010 at 01:09:30PM +0800, Wu Fengguang wrote:
> Dynamicly compute the dirty expire timestamp at queue_io() time.
> Also remove writeback_control.older_than_this which is no longer used.
>
> writeback_control.older_than_this used to be determined at entrance to
> the kupdate writeback work. This _static_ timestamp may go stale if the
> kupdate work runs on and on. The flusher may then stuck with some old
> busy inodes, never considering newly expired inodes thereafter.
>
> This has two possible problems:
>
> - It is unfair for a large dirty inode to delay (for a long time) the
> writeback of small dirty inodes.
>
> - As time goes by, the large and busy dirty inode may contain only
> _freshly_ dirtied pages. Ignoring newly expired dirty inodes risks
> delaying the expired dirty pages to the end of LRU lists, triggering
> the very bad pageout(). Neverthless this patch merely addresses part
> of the problem.
>
> CC: Jan Kara <jack@suse.cz>
> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Again, makes sense and I can't see a problem. There are some worth
smithing issues in the changelog such as Dynamicly -> Dynamically and
s/writeback_control.older_than_this used/writeback_control.older_than_this is used/
but other than that.
Acked-by: Mel Gorman <mel@csn.ul.ie>
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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next prev parent reply other threads:[~2010-07-26 10:52 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-22 5:09 [PATCH 0/6] [RFC] writeback: try to write older pages first Wu Fengguang
2010-07-22 5:09 ` [PATCH 1/6] writeback: pass writeback_control down to move_expired_inodes() Wu Fengguang
2010-07-23 18:16 ` Jan Kara
2010-07-26 10:44 ` Mel Gorman
2010-08-01 15:23 ` Minchan Kim
2010-07-22 5:09 ` [PATCH 2/6] writeback: the kupdate expire timestamp should be a moving target Wu Fengguang
2010-07-23 18:17 ` Jan Kara
2010-07-26 10:52 ` Mel Gorman [this message]
2010-07-26 11:32 ` Wu Fengguang
2010-08-01 15:29 ` Minchan Kim
2010-07-22 5:09 ` [PATCH 3/6] writeback: kill writeback_control.more_io Wu Fengguang
2010-07-23 18:24 ` Jan Kara
2010-07-26 10:53 ` Mel Gorman
2010-08-01 15:34 ` Minchan Kim
2010-08-05 14:50 ` Wu Fengguang
2010-08-05 14:55 ` Wu Fengguang
2010-08-05 14:56 ` Minchan Kim
2010-08-05 15:26 ` Wu Fengguang
2010-07-22 5:09 ` [PATCH 4/6] writeback: sync expired inodes first in background writeback Wu Fengguang
2010-07-23 18:15 ` Jan Kara
2010-07-26 11:51 ` Wu Fengguang
2010-07-26 12:12 ` Jan Kara
2010-07-26 12:29 ` Wu Fengguang
2010-07-26 10:57 ` Mel Gorman
2010-07-26 12:00 ` Wu Fengguang
2010-07-26 12:20 ` Jan Kara
2010-07-26 12:31 ` Wu Fengguang
2010-07-26 12:39 ` Jan Kara
2010-07-26 12:47 ` Wu Fengguang
2010-07-26 12:56 ` Wu Fengguang
2010-07-26 12:59 ` Mel Gorman
2010-07-26 13:11 ` Wu Fengguang
2010-07-27 9:45 ` Mel Gorman
2010-08-01 15:15 ` Minchan Kim
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
2010-07-22 5:09 ` [PATCH 6/6] writeback: introduce writeback_control.inodes_written Wu Fengguang
2010-07-26 11:04 ` Mel Gorman
2010-07-23 10:24 ` [PATCH 0/6] [RFC] writeback: try to write older pages first Mel Gorman
2010-07-26 7:18 ` Wu Fengguang
2010-07-26 10:42 ` Mel Gorman
2010-07-26 10:28 ` Itaru Kitayama
2010-07-26 11:47 ` Wu Fengguang
-- strict thread matches above, loose matches on Subject: below --
2011-04-19 3:00 [PATCH 0/6] writeback: moving expire targets for background/kupdate works 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
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