Re: [PATCH v2 0/4] KVM: optimize the kvm_vcpu_on_spin

[Longpeng (Mike)]

On 2017/8/8 15:41, Cornelia Huck wrote:

> On Tue, 8 Aug 2017 12:05:31 +0800
> "Longpeng(Mike)" <longpeng2@xxxxxxxxxx> wrote:
> 
>> This is a simple optimization for kvm_vcpu_on_spin, the
>> main idea is described in patch-1's commit msg.
> 
> I think this generally looks good now.
> 
>>
>> I did some tests base on the RFC version, the result shows
>> that it can improves the performance slightly.
> 
> Did you re-run tests on this version?


Hi Cornelia,

I didn't re-run tests on V2. But the major difference between RFC and V2
is that V2 only cache result for X86 (s390/arm needn't) and V2 saves a
expensive operation ( 440-1400 cycles on my test machine ) for X86/VMX.

So I think V2's performance is at least the same as RFC or even slightly
better. :)

> 
> I would also like to see some s390 numbers; unfortunately I only have a
> z/VM environment and any performance numbers would be nearly useless
> there. Maybe somebody within IBM with a better setup can run a quick
> test?
> 
> .
> 


-- 
Regards,
Longpeng(Mike)