From: Andrew Morton <akpm@linux-foundation.org>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jan Kara <jack@suse.cz>, Dave Chinner <david@fromorbit.com>,
Christoph Hellwig <hch@infradead.org>,
<linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 02/15] writeback: update dirtied_when for synced inode to prevent livelock
Date: Tue, 7 Jun 2011 16:02:45 -0700 [thread overview]
Message-ID: <20110607160245.9270aa27.akpm@linux-foundation.org> (raw)
In-Reply-To: <20110607213853.635444678@intel.com>
On Wed, 08 Jun 2011 05:32:38 +0800
Wu Fengguang <fengguang.wu@intel.com> wrote:
> Explicitly update .dirtied_when on synced inodes, so that they are no
> longer considered for writeback in the next round.
It sounds like this somewhat answers my questions for [1/15].
But I'm not seeing a description of exactly what caused the livelock.
> We'll do more aggressive "keep writeback as long as we wrote something"
> logic in wb_writeback(). The "use LONG_MAX .nr_to_write" trick in commit
> b9543dac5bbc ("writeback: avoid livelocking WB_SYNC_ALL writeback") will
> no longer be enough to stop sync livelock.
>
> It can prevent both of the following livelock schemes:
>
> - while true; do echo data >> f; done
> - while true; do touch f; done
You're kidding. This livelocks sync(1)? When did we break this?
Why is this? Because the inode keeps on getting rotated to head-of-list?
next prev parent reply other threads:[~2011-06-07 23:03 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-07 21:32 [PATCH 00/15] writeback fixes and cleanups for 3.0 (v5) Wu Fengguang
2011-06-07 21:32 ` [PATCH 01/15] writeback: introduce .tagged_writepages for the WB_SYNC_NONE sync stage Wu Fengguang
2011-06-07 23:02 ` Andrew Morton
2011-06-07 23:24 ` Wu Fengguang
2011-06-07 21:32 ` [PATCH 02/15] writeback: update dirtied_when for synced inode to prevent livelock Wu Fengguang
2011-06-07 23:02 ` Andrew Morton [this message]
2011-06-07 23:51 ` Wu Fengguang
2011-06-07 21:32 ` [PATCH 03/15] writeback: introduce writeback_control.inodes_cleaned Wu Fengguang
2011-06-07 23:03 ` Andrew Morton
2011-06-08 0:10 ` Wu Fengguang
2011-06-07 21:32 ` [PATCH 04/15] writeback: try more writeback as long as something was written Wu Fengguang
2011-06-07 21:32 ` [PATCH 05/15] writeback: the kupdate expire timestamp should be a moving target Wu Fengguang
2011-06-07 21:32 ` [PATCH 06/15] writeback: refill b_io iff empty Wu Fengguang
2011-06-07 21:32 ` [PATCH 07/15] writeback: split inode_wb_list_lock into bdi_writeback.list_lock Wu Fengguang
2011-06-07 23:03 ` Andrew Morton
2011-06-08 0:20 ` Wu Fengguang
2011-06-08 0:35 ` Andrew Morton
2011-06-08 1:36 ` Wu Fengguang
2011-06-07 21:32 ` [PATCH 08/15] writeback: elevate queue_io() into wb_writeback() Wu Fengguang
2011-06-07 21:32 ` [PATCH 09/15] writeback: avoid extra sync work at enqueue time Wu Fengguang
2011-06-07 21:32 ` [PATCH 10/15] writeback: add bdi_dirty_limit() kernel-doc Wu Fengguang
2011-06-07 21:32 ` [PATCH 11/15] writeback: skip balance_dirty_pages() for in-memory fs Wu Fengguang
2011-06-11 13:07 ` Wu Fengguang
2011-06-13 13:42 ` Jan Kara
2011-06-07 21:32 ` [PATCH 12/15] writeback: remove writeback_control.more_io Wu Fengguang
2011-07-11 21:31 ` Hugh Dickins
2011-07-12 6:20 ` Wu Fengguang
2011-07-12 19:50 ` Hugh Dickins
2011-07-13 5:49 ` Hugh Dickins
2011-07-13 10:57 ` Hugh Dickins
2011-07-13 11:19 ` Jan Kara
2011-07-13 15:06 ` Hugh Dickins
2011-07-13 22:07 ` Wu Fengguang
2011-06-07 21:32 ` [PATCH 13/15] writeback: remove .nonblocking and .encountered_congestion Wu Fengguang
2011-06-07 21:32 ` [PATCH 14/15] writeback: trace event writeback_single_inode Wu Fengguang
2011-06-07 21:32 ` [PATCH 15/15] writeback: trace event writeback_queue_io Wu Fengguang
2011-06-07 23:04 ` [PATCH 00/15] writeback fixes and cleanups for 3.0 (v5) Andrew Morton
2011-06-08 2:01 ` Wu Fengguang
2011-06-08 6:21 ` Sedat Dilek
2011-06-08 13:45 ` Wu Fengguang
2011-06-09 1:16 ` Stephen Rothwell
2011-06-09 2:18 ` Wu Fengguang
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