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From: Wu Fengguang <fengguang.wu@intel.com>
To: Jan Kara <jack@suse.cz>
Cc: "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	Dave Chinner <david@fromorbit.com>,
	Christoph Hellwig <hch@infradead.org>,
	Chris Mason <chris.mason@oracle.com>
Subject: Re: [PATCH 2/2] writeback: Replace some redirty_tail() calls with requeue_io()
Date: Sat, 8 Oct 2011 19:52:27 +0800	[thread overview]
Message-ID: <20111008115227.GA17208@localhost> (raw)
In-Reply-To: <20111008040036.GA30069@localhost>

On Sat, Oct 08, 2011 at 12:00:36PM +0800, Wu Fengguang wrote:
> Hi Jan,
> 
> The test results look not good: btrfs is heavily impacted and the
> other filesystems are slightly impacted.
> 
> I'll send you the detailed logs in private emails (too large for the
> mailing list). Basically I noticed many writeback_wait traces that
> never appear w/o this patch. In the btrfs cases that see larger
> regressions, I see large fluctuations in the writeout bandwidth and
> long disk idle periods. It's still a bit puzzling how all these
> happen..

Sorry I find that part of the regressions (about 2-3%) are caused by
change of my test scripts recently. Here are the more fair compares
and they show only regressions in btrfs and xfs:

     3.1.0-rc8-ioless6a+  3.1.0-rc8-ioless6-requeue+
------------------------  ------------------------
                   37.34        +0.8%        37.65  thresh=100M/ext3-10dd-4k-8p-4096M-100M:10-X
                   44.44        +3.4%        45.96  thresh=100M/ext3-1dd-4k-8p-4096M-100M:10-X
                   41.70        +1.0%        42.14  thresh=100M/ext3-2dd-4k-8p-4096M-100M:10-X
                   46.45        -0.3%        46.32  thresh=100M/ext4-10dd-4k-8p-4096M-100M:10-X
                   56.60        -0.3%        56.41  thresh=100M/ext4-1dd-4k-8p-4096M-100M:10-X
                   54.14        +0.9%        54.63  thresh=100M/ext4-2dd-4k-8p-4096M-100M:10-X
                   30.66        -0.7%        30.44  thresh=1G/ext3-100dd-4k-8p-4096M-1024M:10-X
                   35.24        +1.6%        35.82  thresh=1G/ext3-10dd-4k-8p-4096M-1024M:10-X
                   43.58        +0.5%        43.80  thresh=1G/ext3-1dd-4k-8p-4096M-1024M:10-X
                   50.42        -0.6%        50.14  thresh=1G/ext4-100dd-4k-8p-4096M-1024M:10-X
                   56.23        -1.0%        55.64  thresh=1G/ext4-10dd-4k-8p-4096M-1024M:10-X
                   58.12        -0.5%        57.84  thresh=1G/ext4-1dd-4k-8p-4096M-1024M:10-X
                   45.37        +1.4%        46.03  thresh=8M/ext3-1dd-4k-8p-4096M-8M:10-X
                   43.71        +2.2%        44.69  thresh=8M/ext3-2dd-4k-8p-4096M-8M:10-X
                   35.58        +0.5%        35.77  thresh=8M/ext4-10dd-4k-8p-4096M-8M:10-X
                   56.39        +1.4%        57.16  thresh=8M/ext4-1dd-4k-8p-4096M-8M:10-X
                   51.26        +1.5%        52.04  thresh=8M/ext4-2dd-4k-8p-4096M-8M:10-X
                  787.25        +0.7%       792.47  TOTAL

     3.1.0-rc8-ioless6a+  3.1.0-rc8-ioless6-requeue+
------------------------  ------------------------
                   44.53       -18.6%        36.23  thresh=100M/xfs-10dd-4k-8p-4096M-100M:10-X
                   55.89        -0.4%        55.64  thresh=100M/xfs-1dd-4k-8p-4096M-100M:10-X
                   51.11        +0.5%        51.35  thresh=100M/xfs-2dd-4k-8p-4096M-100M:10-X
                   41.76        -4.8%        39.77  thresh=1G/xfs-100dd-4k-8p-4096M-1024M:10-X
                   48.34        -0.3%        48.18  thresh=1G/xfs-10dd-4k-8p-4096M-1024M:10-X
                   52.36        -0.2%        52.26  thresh=1G/xfs-1dd-4k-8p-4096M-1024M:10-X
                   31.07        -1.1%        30.74  thresh=8M/xfs-10dd-4k-8p-4096M-8M:10-X
                   55.44        -0.6%        55.09  thresh=8M/xfs-1dd-4k-8p-4096M-8M:10-X
                   47.59       -31.2%        32.74  thresh=8M/xfs-2dd-4k-8p-4096M-8M:10-X
                  428.07        -6.1%       401.99  TOTAL

     3.1.0-rc8-ioless6a+  3.1.0-rc8-ioless6-requeue+
------------------------  ------------------------
                   58.23       -82.6%        10.13  thresh=100M/btrfs-10dd-4k-8p-4096M-100M:10-X
                   58.43       -80.3%        11.54  thresh=100M/btrfs-1dd-4k-8p-4096M-100M:10-X
                   58.53       -79.9%        11.76  thresh=100M/btrfs-2dd-4k-8p-4096M-100M:10-X
                   56.55       -31.7%        38.63  thresh=1G/btrfs-100dd-4k-8p-4096M-1024M:10-X
                   56.11       -30.1%        39.25  thresh=1G/btrfs-10dd-4k-8p-4096M-1024M:10-X
                   56.21       -18.3%        45.93  thresh=1G/btrfs-1dd-4k-8p-4096M-1024M:10-X
                  344.06       -54.3%       157.24  TOTAL

I'm now bisecting the patches to find out the root cause.

Thanks,
Fengguang

  reply	other threads:[~2011-10-08 11:52 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-09-08  0:44 [PATCH 1/2] writeback: Improve busyloop prevention Jan Kara
2011-09-08  0:44 ` [PATCH 2/2] writeback: Replace some redirty_tail() calls with requeue_io() Jan Kara
2011-09-08  1:22   ` Wu Fengguang
2011-09-08 15:03     ` Jan Kara
2011-09-18 14:07       ` Wu Fengguang
2011-10-05 17:39         ` Jan Kara
2011-10-07 13:43           ` Wu Fengguang
2011-10-07 14:22             ` Jan Kara
2011-10-07 14:29               ` Wu Fengguang
2011-10-07 14:45                 ` Jan Kara
2011-10-07 15:29                   ` Wu Fengguang
2011-10-08  4:00                   ` Wu Fengguang
2011-10-08 11:52                     ` Wu Fengguang [this message]
2011-10-08 13:49                       ` Wu Fengguang
2011-10-09  0:27                         ` Wu Fengguang
2011-10-09  8:44                           ` Wu Fengguang
2011-10-10 11:21                     ` Jan Kara
2011-10-10 11:31                       ` Wu Fengguang
2011-10-10 23:30                         ` Jan Kara
2011-10-11  2:36                           ` Wu Fengguang
2011-10-11 21:53                             ` Jan Kara
2011-10-12  2:44                               ` Wu Fengguang
2011-10-12 19:34                                 ` Jan Kara
2011-09-08  0:57 ` [PATCH 1/2] writeback: Improve busyloop prevention Wu Fengguang
2011-09-08 13:49   ` Jan Kara
  -- strict thread matches above, loose matches on Subject: below --
2011-10-12 20:57 [PATCH 0/2 v4] writeback: Improve busyloop prevention and inode requeueing Jan Kara
2011-10-12 20:57 ` [PATCH 2/2] writeback: Replace some redirty_tail() calls with requeue_io() Jan Kara
2011-10-13 14:30   ` Wu Fengguang

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