From: Wu Fengguang <fengguang.wu@intel.com>
To: "linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>
Cc: Jan Kara <jack@suse.cz>, Li Shaohua <shaohua.li@intel.com>,
LKML <linux-kernel@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
Theodore Ts'o <tytso@mit.edu>
Subject: ext4 data=writeback performs worse than data=ordered now
Date: Wed, 14 Dec 2011 21:34:00 +0800 [thread overview]
Message-ID: <20111214133400.GA18565@localhost> (raw)
Hi,
Shaohua recently found that ext4 writeback mode could perform worse
than ordered mode in some cases. It may not be a big problem, however
we'd like to share some information on our findings.
I tested both 3.2 and 3.1 kernels on normal SATA disks and USB key.
The interesting thing is, data=writeback used to run a bit faster
than data=ordered, however situation get inverted presumably by the
IO-less dirty throttling.
The worst case happens for the USB key, where both old/new kernels
see ~10% worse performance for data=writeback.
wfg@bee /export/writeback% ./compare -g ext4 -c fs snb/JBOD*/*-3.2.0-rc3-pause6+
ext4 ext4:wb
------------------------ ------------------------
216.50 -0.5% 215.50 snb/JBOD-4HDD-thresh=100M/ext4-1dd-1-3.2.0-rc3-pause6+
210.34 -0.5% 209.36 snb/JBOD-4HDD-thresh=1G/ext4-10dd-1-3.2.0-rc3-pause6+
218.92 -0.5% 217.85 snb/JBOD-4HDD-thresh=1G/ext4-1dd-1-3.2.0-rc3-pause6+
218.03 -0.1% 217.72 snb/JBOD-4HDD-thresh=8G/ext4-10dd-1-3.2.0-rc3-pause6+
221.19 -2.0% 216.82 snb/JBOD-4HDD-thresh=8G/ext4-1dd-1-3.2.0-rc3-pause6+
1084.98 -0.7% 1077.26 TOTAL write_bw
wfg@bee /export/writeback% ./compare -g ext4 -c fs fat/*/*-3.2.0-rc3-pause6+
ext4 ext4:wb
------------------------ ------------------------
46.87 -1.9% 45.96 fat/UKEY-HDD/ext4-100dd-1-3.2.0-rc3-pause6+
57.40 -4.9% 54.61 fat/UKEY-HDD/ext4-10dd-1-3.2.0-rc3-pause6+
62.13 -1.2% 61.41 fat/UKEY-HDD/ext4-1dd-1-3.2.0-rc3-pause6+
2.46 -1.0% 2.44 fat/UKEY-thresh=100M/ext4-100dd-1-3.2.0-rc3-pause6+
4.52 -4.3% 4.33 fat/UKEY-thresh=100M/ext4-10dd-1-3.2.0-rc3-pause6+
6.20 -10.6% 5.54 fat/UKEY-thresh=100M/ext4-1dd-1-3.2.0-rc3-pause6+
2.55 +8.7% 2.77 fat/fio/ext4-fio_fat_mmap_randwrite_4k-1-3.2.0-rc3-pause6+
9.60 -4.0% 9.21 fat/fio/ext4-fio_fat_mmap_randwrite_64k-1-3.2.0-rc3-pause6+
53.57 -3.6% 51.61 fat/fio/ext4-fio_fat_rates-1-3.2.0-rc3-pause6+
49.16 -1.3% 48.51 fat/thresh=1000M/ext4-100dd-1-3.2.0-rc3-pause6+
56.20 -1.4% 55.40 fat/thresh=1000M/ext4-10dd-1-3.2.0-rc3-pause6+
57.86 -1.4% 57.07 fat/thresh=1000M/ext4-1dd-1-3.2.0-rc3-pause6+
50.36 -3.2% 48.75 fat/thresh=1000M:990M/ext4-100dd-1-3.2.0-rc3-pause6+
56.46 -1.4% 55.69 fat/thresh=1000M:990M/ext4-10dd-1-3.2.0-rc3-pause6+
57.51 -0.9% 56.97 fat/thresh=1000M:990M/ext4-1dd-1-3.2.0-rc3-pause6+
50.02 -0.8% 49.60 fat/thresh=1000M:999M/ext4-100dd-1-3.2.0-rc3-pause6+
55.56 -1.3% 54.84 fat/thresh=1000M:999M/ext4-10dd-1-3.2.0-rc3-pause6+
56.88 -0.6% 56.52 fat/thresh=1000M:999M/ext4-1dd-1-3.2.0-rc3-pause6+
32.03 -3.3% 30.98 fat/thresh=100M/ext4-100dd-1-3.2.0-rc3-pause6+
46.63 -2.5% 45.47 fat/thresh=100M/ext4-10dd-1-3.2.0-rc3-pause6+
56.67 -2.3% 55.34 fat/thresh=100M/ext4-1dd-1-3.2.0-rc3-pause6+
36.16 -0.9% 35.84 fat/thresh=10M/ext4-10dd-1-3.2.0-rc3-pause6+
56.01 -0.1% 55.98 fat/thresh=10M/ext4-1dd-1-3.2.0-rc3-pause6+
31.45 +0.2% 31.51 fat/thresh=1M/ext4-10dd-1-3.2.0-rc3-pause6+
52.83 -2.3% 51.62 fat/thresh=1M/ext4-1dd-1-3.2.0-rc3-pause6+
1047.06 -1.8% 1027.98 TOTAL write_bw
wfg@bee /export/writeback% ./compare -g ext4 -c fs fat/*/*-3.1.0+
ext4 ext4:wb
------------------------ ------------------------
45.91 +2.2% 46.90 fat/UKEY-HDD/ext4-100dd-1-3.1.0+
54.53 +7.4% 58.54 fat/UKEY-HDD/ext4-10dd-1-3.1.0+
62.18 -3.8% 59.83 fat/UKEY-HDD/ext4-1dd-1-3.1.0+
2.41 -10.7% 2.15 fat/UKEY-thresh=100M/ext4-100dd-1-3.1.0+
4.24 -3.0% 4.11 fat/UKEY-thresh=100M/ext4-10dd-1-3.1.0+
6.25 -11.6% 5.53 fat/UKEY-thresh=100M/ext4-1dd-1-3.1.0+
2.20 +0.6% 2.22 fat/fio/ext4-fio_fat_mmap_randwrite_4k-1-3.1.0+
8.76 -4.2% 8.40 fat/fio/ext4-fio_fat_mmap_randwrite_64k-1-3.1.0+
50.95 +0.4% 51.17 fat/fio/ext4-fio_fat_rates-1-3.1.0+
47.44 +4.1% 49.40 fat/thresh=1000M/ext4-100dd-1-3.1.0+
53.30 +4.3% 55.60 fat/thresh=1000M/ext4-10dd-1-3.1.0+
56.02 +0.8% 56.47 fat/thresh=1000M/ext4-1dd-1-3.1.0+
47.99 +1.3% 48.61 fat/thresh=1000M:990M/ext4-100dd-1-3.1.0+
52.82 +0.3% 53.00 fat/thresh=1000M:990M/ext4-10dd-1-3.1.0+
54.73 +1.9% 55.74 fat/thresh=1000M:990M/ext4-1dd-1-3.1.0+
47.91 -0.6% 47.62 fat/thresh=1000M:999M/ext4-100dd-1-3.1.0+
51.51 +3.0% 53.05 fat/thresh=1000M:999M/ext4-10dd-1-3.1.0+
52.88 +1.6% 53.71 fat/thresh=1000M:999M/ext4-1dd-1-3.1.0+
34.56 -2.3% 33.76 fat/thresh=100M/ext4-100dd-1-3.1.0+
46.44 -1.3% 45.86 fat/thresh=100M/ext4-10dd-1-3.1.0+
54.76 +3.5% 56.65 fat/thresh=100M/ext4-1dd-1-3.1.0+
37.43 +3.4% 38.69 fat/thresh=10M/ext4-10dd-1-3.1.0+
55.21 -0.5% 54.95 fat/thresh=10M/ext4-1dd-1-3.1.0+
40.36 -1.3% 39.83 fat/thresh=1M/ext4-10dd-1-3.1.0+
55.66 -0.1% 55.61 fat/thresh=1M/ext4-1dd-1-3.1.0+
1026.44 +1.1% 1037.40 TOTAL write_bw
Here are the comparison between kernels. As you can see, the ordered
mode is improved slightly by 2% w/ IO-less, while data=writeback sees
-0.9% drop.
wfg@bee /export/writeback% ./compare -g ext4- fat/*/*-3.1.0+ fat/*/*-3.2.0-rc3-pause6+
3.1.0+ 3.2.0-rc3-pause6+
------------------------ ------------------------
45.91 +2.1% 46.87 fat/UKEY-HDD/ext4-100dd-1-3.1.0+
54.53 +5.3% 57.40 fat/UKEY-HDD/ext4-10dd-1-3.1.0+
62.18 -0.1% 62.13 fat/UKEY-HDD/ext4-1dd-1-3.1.0+
2.41 +2.1% 2.46 fat/UKEY-thresh=100M/ext4-100dd-1-3.1.0+
4.24 +6.6% 4.52 fat/UKEY-thresh=100M/ext4-10dd-1-3.1.0+
6.25 -0.9% 6.20 fat/UKEY-thresh=100M/ext4-1dd-1-3.1.0+
2.20 +15.6% 2.55 fat/fio/ext4-fio_fat_mmap_randwrite_4k-1-3.1.0+
8.76 +9.5% 9.60 fat/fio/ext4-fio_fat_mmap_randwrite_64k-1-3.1.0+
50.95 +5.1% 53.57 fat/fio/ext4-fio_fat_rates-1-3.1.0+
47.44 +3.6% 49.16 fat/thresh=1000M/ext4-100dd-1-3.1.0+
53.30 +5.4% 56.20 fat/thresh=1000M/ext4-10dd-1-3.1.0+
56.02 +3.3% 57.86 fat/thresh=1000M/ext4-1dd-1-3.1.0+
47.99 +4.9% 50.36 fat/thresh=1000M:990M/ext4-100dd-1-3.1.0+
52.82 +6.9% 56.46 fat/thresh=1000M:990M/ext4-10dd-1-3.1.0+
54.73 +5.1% 57.51 fat/thresh=1000M:990M/ext4-1dd-1-3.1.0+
47.91 +4.4% 50.02 fat/thresh=1000M:999M/ext4-100dd-1-3.1.0+
51.51 +7.9% 55.56 fat/thresh=1000M:999M/ext4-10dd-1-3.1.0+
52.88 +7.6% 56.88 fat/thresh=1000M:999M/ext4-1dd-1-3.1.0+
34.56 -7.3% 32.03 fat/thresh=100M/ext4-100dd-1-3.1.0+
46.44 +0.4% 46.63 fat/thresh=100M/ext4-10dd-1-3.1.0+
54.76 +3.5% 56.67 fat/thresh=100M/ext4-1dd-1-3.1.0+
37.43 -3.4% 36.16 fat/thresh=10M/ext4-10dd-1-3.1.0+
55.21 +1.5% 56.01 fat/thresh=10M/ext4-1dd-1-3.1.0+
40.36 -22.1% 31.45 fat/thresh=1M/ext4-10dd-1-3.1.0+
55.66 -5.1% 52.83 fat/thresh=1M/ext4-1dd-1-3.1.0+
1026.44 +2.0% 1047.06 TOTAL write_bw
wfg@bee /export/writeback% ./compare -g ext4:wb fat/*/*-3.1.0+ fat/*/*-3.2.0-rc3-pause6+
3.1.0+ 3.2.0-rc3-pause6+
------------------------ ------------------------
46.90 -2.0% 45.96 fat/UKEY-HDD/ext4:wb-100dd-1-3.1.0+
58.54 -6.7% 54.61 fat/UKEY-HDD/ext4:wb-10dd-1-3.1.0+
59.83 +2.7% 61.41 fat/UKEY-HDD/ext4:wb-1dd-1-3.1.0+
2.15 +13.3% 2.44 fat/UKEY-thresh=100M/ext4:wb-100dd-1-3.1.0+
4.11 +5.2% 4.33 fat/UKEY-thresh=100M/ext4:wb-10dd-1-3.1.0+
5.53 +0.2% 5.54 fat/UKEY-thresh=100M/ext4:wb-1dd-1-3.1.0+
2.22 +24.8% 2.77 fat/fio/ext4:wb-fio_fat_mmap_randwrite_4k-1-3.1.0+
8.40 +9.6% 9.21 fat/fio/ext4:wb-fio_fat_mmap_randwrite_64k-1-3.1.0+
51.17 +0.9% 51.61 fat/fio/ext4:wb-fio_fat_rates-1-3.1.0+
49.40 -1.8% 48.51 fat/thresh=1000M/ext4:wb-100dd-1-3.1.0+
55.60 -0.3% 55.40 fat/thresh=1000M/ext4:wb-10dd-1-3.1.0+
56.47 +1.1% 57.07 fat/thresh=1000M/ext4:wb-1dd-1-3.1.0+
48.61 +0.3% 48.75 fat/thresh=1000M:990M/ext4:wb-100dd-1-3.1.0+
53.00 +5.1% 55.69 fat/thresh=1000M:990M/ext4:wb-10dd-1-3.1.0+
55.74 +2.2% 56.97 fat/thresh=1000M:990M/ext4:wb-1dd-1-3.1.0+
47.62 +4.2% 49.60 fat/thresh=1000M:999M/ext4:wb-100dd-1-3.1.0+
53.05 +3.4% 54.84 fat/thresh=1000M:999M/ext4:wb-10dd-1-3.1.0+
53.71 +5.2% 56.52 fat/thresh=1000M:999M/ext4:wb-1dd-1-3.1.0+
33.76 -8.3% 30.98 fat/thresh=100M/ext4:wb-100dd-1-3.1.0+
45.86 -0.8% 45.47 fat/thresh=100M/ext4:wb-10dd-1-3.1.0+
56.65 -2.3% 55.34 fat/thresh=100M/ext4:wb-1dd-1-3.1.0+
38.69 -7.4% 35.84 fat/thresh=10M/ext4:wb-10dd-1-3.1.0+
54.95 +1.9% 55.98 fat/thresh=10M/ext4:wb-1dd-1-3.1.0+
39.83 -20.9% 31.51 fat/thresh=1M/ext4:wb-10dd-1-3.1.0+
55.61 -7.2% 51.62 fat/thresh=1M/ext4:wb-1dd-1-3.1.0+
1037.40 -0.9% 1027.98 TOTAL write_bw
Thanks,
Fengguang
next reply other threads:[~2011-12-14 14:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-14 13:34 Wu Fengguang [this message]
[not found] ` <20111214140025.GA19650@localhost>
2011-12-14 14:03 ` ext4 data=writeback performs worse than data=ordered now Wu Fengguang
2011-12-14 14:30 ` Ted Ts'o
2011-12-14 14:49 ` Wu Fengguang
2011-12-14 14:52 ` Tao Ma
2011-12-14 15:02 ` Wu Fengguang
2011-12-15 1:02 ` Shaohua Li
2011-12-15 1:00 ` Wu Fengguang
2011-12-15 1:27 ` NeilBrown
2011-12-15 1:34 ` Wu Fengguang
2011-12-15 5:02 ` Wu Fengguang
2011-12-15 1:20 ` Darrick J. Wong
2011-12-15 1:42 ` Shaohua Li
2011-12-15 18:10 ` Darrick J. Wong
2011-12-16 1:47 ` Shaohua Li
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20111214133400.GA18565@localhost \
--to=fengguang.wu@intel.com \
--cc=jack@suse.cz \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=shaohua.li@intel.com \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.