Re: [RFC][PATCH] spin loop arch primitives for busy waiting
From: Peter Zijlstra
Date: Fri Apr 07 2017 - 05:44:08 EST
On Thu, Apr 06, 2017 at 10:31:46AM -0700, Linus Torvalds wrote:
> But maybe "monitor" is really cheap. I suspect it's microcoded,
> though, which implies "no".
On my IVB-EP (will also try on something newer):
MONITOR ~332 cycles
MWAIT ~224 cycles (C0, explicitly invalidated MONITOR)
So yes, expensive.