[RFC][PATCH] spin loop arch primitives for busy waiting

Peter Zijlstra peterz at infradead.org
Fri Apr 7 19:43:49 AEST 2017


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.


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