xattr performance and Samba4

[tridge at samba.org]

Mike,

 > There are 2 more experiments that would definitely be worth running:
 > 
 > 1) with the current benchmark config and XFS filesystem, increase the log
 > size to maximum (32768 blocks)
 > 
 > 2) With ext3 and the 400M journal, increase the running time of the
 > benchmark to say 600 secs?

I've combined the results into:

  http://samba.org/~tridge/xattr_results/xfs-ext3-tuning.png

The 3 curves are:

 - the xfs-512 results with default journal size (from an earlier
   graph, included for easy comparison)

 - xfs-512 results with a journal of size 32768 blocks

 - ext3 results with inode size 256 and journal 400M (and the patch to
   allow ext3 to take advantage of large inodes).

The latter two results are with 600 second runs. 

 > Have theory, need confirmation!

The larger journal certainly helps xfs a lot, though not quite as much
as ext3.

Please let me know how well the results match your theory!

Cheers, Tridge