Re: [PATCH 6/6] powerpc: Use lwsync for acquire barrier if CPU supports it
From: Olof Johansson <hidden>
Date: 2010-02-16 06:03:07
From: Olof Johansson <hidden>
Date: 2010-02-16 06:03:07
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:quoted
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