From: Andrew Morton <akpm@linux-foundation.org>
To: Jan Kara <jack@suse.cz>
Cc: linux-fsdevel@vger.kernel.org, hch@infradead.org,
jaxboe@fusionio.com, Wu Fengguang <fengguang.wu@intel.com>
Subject: Re: [PATCH 3/3 v2] mm: Avoid resetting wb_start after each writeback round
Date: Thu, 5 Aug 2010 17:21:07 -0700 [thread overview]
Message-ID: <20100805172107.703ccf77.akpm@linux-foundation.org> (raw)
In-Reply-To: <1281034399-13055-4-git-send-email-jack@suse.cz>
On Thu, 5 Aug 2010 20:53:19 +0200
Jan Kara <jack@suse.cz> wrote:
> WB_SYNC_NONE writeback is done in rounds of 1024 pages so that we don't write
> out some huge inode for too long while starving writeout of other inodes. To
> avoid livelocks, we record time we started writeback in wbc->wb_start and do
> not write out inodes which were dirtied after this time. But currently,
> writeback_inodes_wb() resets wb_start each time it is called thus effectively
> invalidating this logic and making any WB_SYNC_NONE writeback prone to
> livelocks.
data point: that was eight-year-old code that we broke. Five months ago.
How did you discover this? You have test cases which cover this
scenario and things locked up?
next prev parent reply other threads:[~2010-08-06 0:22 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-05 18:53 [PATCH 0/3 v2] Three writeback fixes to stop sync(1) livelocks Jan Kara
2010-08-05 18:53 ` [PATCH 1/3 v2] mm: Stop background writeback if there is other work queued for the thread Jan Kara
2010-08-05 19:38 ` Jens Axboe
2010-08-05 23:45 ` Andrew Morton
2010-08-07 16:04 ` Wu Fengguang
2010-08-08 2:43 ` Jan Kara
2010-08-08 3:10 ` Wu Fengguang
2010-08-08 4:12 ` Dave Chinner
2010-08-08 7:29 ` Wu Fengguang
2010-08-08 11:07 ` Jens Axboe
2010-08-08 13:59 ` Jan Kara
2010-08-08 22:55 ` Wu Fengguang
2010-08-05 18:53 ` [PATCH 2/3 v2] mm: Fix writeback_in_progress() Jan Kara
2010-08-05 19:37 ` Jens Axboe
2010-08-05 23:06 ` Wu Fengguang
2010-08-06 0:10 ` Andrew Morton
2010-08-08 2:25 ` Jan Kara
2010-08-05 18:53 ` [PATCH 3/3 v2] mm: Avoid resetting wb_start after each writeback round Jan Kara
2010-08-05 19:38 ` Jens Axboe
2010-08-06 0:21 ` Andrew Morton [this message]
2010-08-07 22:45 ` Jan Kara
2010-08-06 12:23 ` [PATCH 0/3 v2] Three writeback fixes to stop sync(1) livelocks Christoph Hellwig
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