Re: [PATCH] sched,kvm: Fix KVM preempt_notifier usage

From: Peter Zijlstra
Date: Fri Jul 03 2015 - 08:19:23 EST


On Fri, Jul 03, 2015 at 01:12:11PM +0200, Paolo Bonzini wrote:
> In fact you shouldn't have just tested the patch on a case _without_
> preemption notifiers, you should have also benchmarked the impact that
> static keys have _with_ preemption notifiers. In a
> not-really-artificial case (one single-processor guest running on the
> host), the static key patch adds a static_key_slow_inc on a relatively
> hot path for KVM, which is not acceptable.

Spawning the first vcpu is a hot path?
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