From: Dave Chinner <david@fromorbit.com>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.cz>, Mel Gorman <mel@csn.ul.ie>,
Minchan Kim <minchan.kim@gmail.com>,
Christoph Hellwig <hch@infradead.org>,
linux-fsdevel@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 13/17] writeback: remove writeback_control.more_io
Date: Fri, 13 May 2011 09:04:32 +1000 [thread overview]
Message-ID: <20110512230432.GL19446@dastard> (raw)
In-Reply-To: <20110512140032.289087832@intel.com>
On Thu, May 12, 2011 at 09:57:19PM +0800, Wu Fengguang wrote:
> When wbc.more_io was first introduced, it indicates whether there are
> at least one superblock whose s_more_io contains more IO work. Now with
> the per-bdi writeback, it can be replaced with a simple b_more_io test.
>
> Acked-by: Jan Kara <jack@suse.cz>
> Acked-by: Mel Gorman <mel@csn.ul.ie>
> CC: Minchan Kim <minchan.kim@gmail.com>
> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
> ---
> fs/fs-writeback.c | 9 ++-------
> include/linux/writeback.h | 1 -
> include/trace/events/ext4.h | 6 ++----
> include/trace/events/writeback.h | 5 +----
> 4 files changed, 5 insertions(+), 16 deletions(-)
>
> --- linux-next.orig/fs/fs-writeback.c 2011-05-05 23:30:30.000000000 +0800
> +++ linux-next/fs/fs-writeback.c 2011-05-05 23:30:33.000000000 +0800
> @@ -560,12 +560,8 @@ static int writeback_sb_inodes(struct su
> iput(inode);
> cond_resched();
> spin_lock(&wb->list_lock);
> - if (wbc->nr_to_write <= 0) {
> - wbc->more_io = 1;
> + if (wbc->nr_to_write <= 0)
> return 1;
> - }
> - if (!list_empty(&wb->b_more_io))
> - wbc->more_io = 1;
> }
> /* b_io is empty */
> return 1;
> @@ -707,7 +703,6 @@ static long wb_writeback(struct bdi_writ
> wbc.older_than_this = &oldest_jif;
> }
>
> - wbc.more_io = 0;
> wbc.nr_to_write = write_chunk;
> wbc.pages_skipped = 0;
> wbc.inodes_cleaned = 0;
> @@ -755,7 +750,7 @@ retry:
> /*
> * No more inodes for IO, bail
> */
> - if (!wbc.more_io)
> + if (list_empty(&wb->b_more_io))
> break;
We're not holding the wb->list_lock here, so we need to be careful
here. I think this is safe given that there shuold only be one
flusher thread operating on the list, but when we expand to multiple
flusher threads per-bdi, this coul dbe a nasty landmine. A comment
is probably in order explaining why this is safe to check unlocked
right now...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2011-05-12 23:04 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-12 13:57 [PATCH 00/17] writeback fixes and cleanups for 2.6.40 (v2) Wu Fengguang
2011-05-12 13:57 ` [PATCH 01/17] writeback: introduce .tagged_sync for the WB_SYNC_NONE sync stage Wu Fengguang
2011-05-12 22:40 ` Dave Chinner
2011-05-13 2:56 ` Wu Fengguang
2011-05-13 10:17 ` Christoph Hellwig
2011-05-15 23:43 ` Dave Chinner
2011-05-16 5:39 ` Wu Fengguang
2011-05-19 21:17 ` Wu Fengguang
2011-05-12 13:57 ` [PATCH 02/17] writeback: update dirtied_when for synced inode to prevent livelock Wu Fengguang
2011-05-12 22:42 ` Dave Chinner
2011-05-13 3:08 ` Wu Fengguang
2011-05-19 21:31 ` Wu Fengguang
2011-05-23 13:14 ` Jan Kara
2011-05-24 3:03 ` Wu Fengguang
2011-05-12 13:57 ` [PATCH 03/17] writeback: introduce writeback_control.inodes_cleaned Wu Fengguang
2011-05-12 22:44 ` Dave Chinner
2011-05-13 3:36 ` Wu Fengguang
2011-05-15 23:50 ` Dave Chinner
2011-05-16 10:40 ` Christoph Hellwig
2011-05-16 11:14 ` Wu Fengguang
2011-05-12 13:57 ` [PATCH 04/17] writeback: try more writeback as long as something was written Wu Fengguang
2011-05-12 13:57 ` [PATCH 05/17] writeback: the kupdate expire timestamp should be a moving target Wu Fengguang
2011-05-12 13:57 ` [PATCH 06/17] writeback: sync expired inodes first in background writeback Wu Fengguang
2011-05-12 22:55 ` Dave Chinner
2011-05-16 13:00 ` Wu Fengguang
2011-05-12 13:57 ` [PATCH 07/17] writeback: refill b_io iff empty Wu Fengguang
2011-05-12 13:57 ` [PATCH 08/17] writeback: split inode_wb_list_lock into bdi_writeback.list_lock Wu Fengguang
2011-05-12 13:57 ` [PATCH 09/17] writeback: elevate queue_io() into wb_writeback() Wu Fengguang
2011-05-12 13:57 ` [PATCH 10/17] writeback: avoid extra sync work at enqueue time Wu Fengguang
2011-05-12 13:57 ` [PATCH 11/17] writeback: add bdi_dirty_limit() kernel-doc Wu Fengguang
2011-05-12 13:57 ` [PATCH 12/17] writeback: skip balance_dirty_pages() for in-memory fs Wu Fengguang
2011-05-16 10:43 ` Christoph Hellwig
2011-05-16 10:49 ` Wu Fengguang
2011-05-12 13:57 ` [PATCH 13/17] writeback: remove writeback_control.more_io Wu Fengguang
2011-05-12 14:25 ` Minchan Kim
2011-05-12 23:04 ` Dave Chinner [this message]
2011-05-13 5:03 ` Wu Fengguang
2011-05-15 23:54 ` Dave Chinner
2011-05-12 13:57 ` [PATCH 14/17] writeback: make writeback_control.nr_to_write straight Wu Fengguang
2011-05-12 14:56 ` Jan Kara
2011-05-12 23:18 ` Dave Chinner
2011-05-13 5:28 ` Wu Fengguang
2011-05-16 0:12 ` Dave Chinner
2011-05-16 12:05 ` Wu Fengguang
2011-05-12 13:57 ` [PATCH 15/17] writeback: remove .nonblocking and .encountered_congestion Wu Fengguang
2011-05-12 13:57 ` [PATCH 16/17] writeback: trace event writeback_single_inode Wu Fengguang
2011-05-12 23:20 ` Dave Chinner
2011-05-13 5:37 ` Wu Fengguang
2011-05-16 0:14 ` Dave Chinner
2011-05-16 12:21 ` Wu Fengguang
2011-05-12 13:57 ` [PATCH 17/17] writeback: trace event writeback_queue_io Wu Fengguang
-- strict thread matches above, loose matches on Subject: below --
2011-05-06 3:08 [PATCH 00/17] writeback fixes and cleanups for 2.6.40 Wu Fengguang
2011-05-06 3:08 ` [PATCH 13/17] writeback: remove writeback_control.more_io Wu Fengguang
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