Re: getdents - ext4 vs btrfs performance

[Chris Mason]

On Thu, Mar 01, 2012 at 03:03:53PM +0100, Jacek Luczak wrote:
> 2012/3/1 Hillf Danton <dhillf@xxxxxxxxx>:
> > On Thu, Mar 1, 2012 at 9:35 PM, Jacek Luczak <difrost.kernel@xxxxxxxxx> wrote:
> >>
> >> 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.

> >>
> >> 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.

-chris
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