2012/3/1 Chris Mason [off-list ref]:

On Thu, Mar 01, 2012 at 03:03:53PM +0100, Jacek Luczak wrote:

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2012/3/1 Hillf Danton [off-list ref]:

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On Thu, Mar 1, 2012 at 9:35 PM, Jacek Luczak <difrost.kernel@gmail=

=2Ecom> wrote:

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While I was about to grab acp I've noticed seekwatcher with made =

my day :)

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seekwatcher run of tar cf to eliminate writes (all done on 3.2.7)=

:

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1) btrfs: http://dozzie.jarowit.net/~dozzie/luczajac/tar_btrfs.pn=

g

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2) ext4: http://dozzie.jarowit.net/~dozzie/luczajac/tar_ext4.png
3) both merged: http://dozzie.jarowit.net/~dozzie/luczajac/tar_bt=

rfs_ext4.png

Whoa, seekwatcher makes it pretty clear.

Yep, ext4 is close to my wife's closet.

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I will send acp results soon.

Would you please take reiserfs into account?

As of now not (lack of time) but I'm pretty close to consider XFS in
the game. Whenever I will have more time and there won't be a pressu=

re

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on giving host back to production I will redo same tests for reiserf=

s.

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Now I'm focused on the userspace sorting results.

reiserfs should have results very similar to ext4. =A0The directory
hashing used by reiserfs is going to result in a very random read
pattern.

XFS will probably beat btrfs in this test. =A0Their directory indexes
reflect on disk layout very well.

True, but not that fast on small files.

Except the question I've raised in first mail there's a point in all
those action. We are maintaining host that are used for building
software: random access, lot of small files and dirs (always a co),
heavy parallel IO. We were testing XFS vs ext4 a year ago and XFS was
around 10% slower on build times. We did not - yet - done same on
btrfs. Now we're looking for replacement for ext4 as we suffer from
those issue - but we were not aware of that until stepped into this
issue.

If you would like me to do some specific tests around ext4 and btrfs,
let me know.

-Jacek