Re: [PATCH 4/5] futex: Avoid taking hb lock if nothing to wakeup

Peter Zijlstra
2013-11-25T17:38:28Z

On Mon, Nov 25, 2013 at 06:32:55PM +0100, Thomas Gleixner wrote:
> In that context it would also be helpful to measure the overhead on
> x86 for the !empty case.

Yes, because mfence is by no means a cheap instruction on x86.