Re: xfs > md 50% write performance drop on .30+ kernel?

On Mon, Oct 12, 2009 at 05:58:20PM +0100, mark delfman wrote:

Hi... in recent tests we are seeing a 50% drop in performance from
XFS>MD on a 2.6.30 kernel (compared to a 2.6.28 kernel)

In short:  Performance to MD0 direct = circa 1.7GBsec (see below), via
xfs circa 850MBsec.  On previous system (2.6.28) there was no drop in
performance (in fact often an increase).

I am hopefully that this is simply a matter of barriers etc on the
newer kernel and MD, but we have tried many options and nothing seems
to change this so would very much appreciate advice.

Did barrier support for RAID0 got introduced in 2.6.30?