we use XFS for a very I/O-intensive, in-house developed real-time
database application, and whenever we see new or significantly changed
file-systems becoming available, we run a benchmark using this
application on a conserved, fixed real-world data set.
I'm pleased to state that using the experimental "delaylog" mount option
(in vanilla linux-2.6.35) we measured a 17% performance increase
for our benchmark scenario. (Other mount-options in use both before
and after the "delaylog" option: noatime,nodiratime,nobarrier)
That's a lot given that XFS was the fastest performing file-system
for this application already.
It's also a promising result regarding stability, as several other
tests (using e.g. reiser4 or ceph) in the past led to crashes in the
same benchmark scenario.
So thanks to all contributing developers for this significant optimization!