Re: [PATCH RFC] KVM: busy-spin detector

Balbir Singh
2010-06-11T14:07:02Z

* Marcelo Tosatti <mtosatti@redhat.com> [2010-06-10 23:25:51]:

>
> The following patch implements a simple busy-spin detector. It considers
> a vcpu as busy-spinning if there are two consecutive exits due to
> external interrupt on the same RIP, and sleeps for 100us in that case.
>
> It is very likely that if the vcpu is making progress it will either
> exit for other reasons or change RIP.
>
> The percentage numbers below represent improvement in kernel build
> time in comparison with mainline (RHEL 5.4 guest).
>

Interesting approach, is there a reason to tie it in with pause loop
exits? Can't we do something more generic or even para-virtish.

--
Three Cheers,
Balbir