[PATCH 6/6] powerpc: Use lwsync for acquire barrier if CPU supports it

[Olof Johansson]

On Tue, Feb 16, 2010 at 03:19:03PM +1100, Benjamin Herrenschmidt wrote:
> On Mon, 2010-02-15 at 22:22 -0600, Olof Johansson wrote:
> > 
> > Turns out this one hurts PA6T performance quite a bit, lwsync seems to be
> > significantly more expensive there. I see a 25% drop in the microbenchmark
> > doing pthread_lock/unlock loops on two cpus.
> > 
> > Taking out the CPU_FTR_LWSYNC will solve it, it's a bit unfortunate since
> > the sync->lwsync changes definitely still can, and should, be done. 
> 
> So we should use a different feature bit. No biggie. If needed we can
> split them more anyways.

Yeah, fine with me.


-Olof