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 [off-list ref] wrote:

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While I was about to grab acp I've noticed seekwatcher with made my day :)

seekwatcher run of tar cf to eliminate writes (all done on 3.2.7):
1) btrfs: http://dozzie.jarowit.net/~dozzie/luczajac/tar_btrfs.png
2) ext4: http://dozzie.jarowit.net/~dozzie/luczajac/tar_ext4.png
3) both merged: http://dozzie.jarowit.net/~dozzie/luczajac/tar_btrfs_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 pressure
on giving host back to production I will redo same tests for reiserfs.

Now I'm focused on the userspace sorting results.

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

XFS will probably beat btrfs in this test.  Their 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