On 5/1/2011 10:40 AM, Boyd Stephen Smith Jr. wrote:
In<4dbd0d23.1080...@hardwarefreak.com>, Stan Hoeppner wrote:
Independent Linux filesystem tests performed by an IBM engineer to track
BTRFS performance during development. XFS trounces the others in most
tests:
These results are interesting and useful, but I think "trounces" is a poor
description for what XFS does.
Not using barriers undermines data consistency guarantees, I think it is best
to ignore the 2.6.35-rc5-autokern1-ext3-*-ext3, 2.6.35-rc5-autokern1-ext4-*-
ext4-nobarrier, and 2.6.35-rc5-autokern1-xfs-*-xfx-nobarrier entries.
It would be best for you to state something like "which results are
relevant to you depend on your workload and hardware environment".
Generally, anyone running a server with persistent storage is interested
in the nobarrier results. Those without persistent storage should be
interested in the barrier results. There are exceptions to this general
guideline and I mention at least one below.
Barriers are used to flush storage device cache to avoid data loss due
to a system crash or power loss. Barriers are great for low end systems
lacking persistent storage. However, barriers should never be used with
high performance persistent storage, i.e. RAID/SAN controllers w/
battery or flash backed write cache. Using barriers with such storage
arrays simply costs you between 50-90% of your random write performance,
especially with shared SAN storage and many hosts, as issuing a single
barrier flushes the entire BBWC in the array controller. May enterprise
arrays contain 32GB or more of BBWC.
The nobarrier results are far more relevant than the barrier results,
especially the 16 and 128 thread results, for those SAs with high
performance persistent storage. For desktop users the single thread
barrier results are probably the most relevant. For those running
mdraid all of the barrier results are relevant, and nobarrier if they
trust their kernel and UPS. For those running simulation apps
generating hundreds of gigs or terabytes of non volatile data, either
with mdraid0 or hardware RAID0, the nobarrier results will be of the
most interest.
So that btrfs doesn't remain the only filesystem with 2 entries, I'll also
ignore the 2.6.35-rc5-autokern1-btrfs-*-btrfs-nocow entry, as it is non-
default.
http://btrfs.boxacle.net/repository/raid/2.6.35-rc5/2.6.35-rc5/2.6.35-rc5_La
rge_file_creates_num_threads=1.html
On the graphs, XFS is, respectively:
2nd, 4th, 2nd, 4th
http://btrfs.boxacle.net/repository/raid/2.6.35-rc5/2.6.35-rc5/2.6.35-rc5_La
rge_file_creates_num_threads=16.html
2nd, 1st, 2nd, 1st
http://btrfs.boxacle.net/repository/raid/2.6.35-rc5/2.6.35-rc5/2.6.35-rc5_La
rge_file_creates_num_threads=128.html
1st, 1st, 1st, 1st
http://btrfs.boxacle.net/repository/raid/2.6.35-rc5/2.6.35-rc5/2.6.35-rc5_La
rge_file_random_writes._num_threads=1.html
1st, 4th, 1st, 4th
http://btrfs.boxacle.net/repository/raid/2.6.35-rc5/2.6.35-rc5/2.6.35-rc5_La
rge_file_random_writes._num_threads=16.html
2nd, 1st, 2nd, 2nd
http://btrfs.boxacle.net/repository/raid/2.6.35-rc5/2.6.35-rc5/2.6.35-rc5_La
rge_file_random_writes._num_threads=128.html
2nd, 4th, 2nd, 2nd
http://btrfs.boxacle.net/repository/raid/2.6.35-rc5/2.6.35-rc5/2.6.35-rc5_Ma
il_server_simulation._num_threads=1.html
5th, 1st, 5th, 1st, 3rd
http://btrfs.boxacle.net/repository/raid/2.6.35-rc5/2.6.35-rc5/2.6.35-rc5_Ma
il_server_simulation._num_threads=16.html
5th, 1st, 5th, 5th, 1st
http://btrfs.boxacle.net/repository/raid/2.6.35-rc5/2.6.35-rc5/2.6.35-rc5_Ma
il_server_simulation._num_threads=128.html
4th, 2nd, 4th, 4th, 2nd
I wouldn't say that is a "trouncing", since it doesn't even win in many
categories.
In those test where XFS has the best 'score' it typically beats most
others by a wide margin. In those tests where is does not have the best
'score' it's usually not far below the leader. As I said before, the
key is 'overall' performance. If you compare the XFS results
individually against each other FS, it's apparent it beats them all
handily, overall.
If you could interpret a graph correctly Boyd maybe you'd see it
differently. :) Just taking the last one above as an example, you
listed XFS as 4th place when it's clearly in first place, by a huge
margin over all but JFS. XFS 32k, JFS 30k, EXT4 20k.
The first chart in each set of results in the important one. The others
can pretty much be ignored. If you study this a bit you'll see why
that's the case. As these tests are server centric, retabulate and
count only the nobarrier results and only from the first chart of each test.
--
Stan
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