Re: [PATCH v2 0/3] x86: faster mb()+other barrier.h tweaks

From: Michael S. Tsirkin
Date: Wed Jan 27 2016 - 09:18:57 EST

On Wed, Jan 27, 2016 at 03:14:09PM +0100, Peter Zijlstra wrote:
> On Wed, Jan 27, 2016 at 04:07:56PM +0200, Michael S. Tsirkin wrote:
> > mwait_idle is the only one that calls smp_mb and not mb()
> > I couldn't figure out why - original patches did mb()
> > there.
> That probably wants changing. That said, running UP kernels on affected
> hardware is 'unlikely' :-)

OK that's nice. After changing that one place, everyone calls
mb() around clflush so it should be safe to change smp_mb away
from mfence without breaking things.
I'm testing v4 that does this.