Subject: [PATCH 1/2] ARM: KVM: Yield CPU when vcpu executes a WFE

From: [email-masked] (Raghavendra K T)
Date: Tue, 08 Oct 2013 20:32:59 +0530

[...]
>>> +               kvm_vcpu_on_spin(vcpu);
>>
>> Could you also enable CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT for arm and
>> check if ple handler logic helps further?
>> we would ideally get one more optimization folded into ple handler if
>> you enable that.
>
> Just gave it a go, and the results are slightly (but consistently)
> worse. Over 10 runs:
>
> Without RELAX_INTERCEPT: Average run 3.3623s
> With RELAX_INTERCEPT: Average run 3.4226s
>
> Not massive, but still noticeable. Any clue?

Is it  a 4x overcommit? Probably we would have hit the code
overhead if it were small guests.

RELAX_INTERCEPT is worth enabling for large guests with
overcommits.