Re: [Xen-devel] [PATCH RFC V4 0/5] kvm : Paravirt-spinlock support for KVM guests

[Alexander Graf <agraf@xxxxxxx>]

On 16.01.2012, at 15:20, Srivatsa Vaddagiri wrote:

> * Alexander Graf <agraf@xxxxxxx> [2012-01-16 04:57:45]:
> 
>> Speaking of which - have you benchmarked performance degradation of pv 
>> ticket locks on bare metal?
> 
> You mean, run kernel on bare metal with CONFIG_PARAVIRT_SPINLOCKS
> enabled and compare how it performs with CONFIG_PARAVIRT_SPINLOCKS disabled 
> for 
> some workload(s)?

Yup

> 
> In some sense, the 1x overcommitcase results posted does measure the overhead
> of (pv-)spinlocks no? We don't see any overhead in that case for atleast
> kernbench ..
> 
>> Result for Non PLE machine :
>> ============================
> 
> [snip]
> 
>> Kernbench:
>>               BASE                    BASE+patch

What is BASE really? Is BASE already with the PV spinlocks enabled? I'm having 
a hard time understanding which tree you're working against, since the 
prerequisites aren't upstream yet.


Alex

>>               %improvement
>>               mean (sd)               mean (sd)
>> Scenario A:
>> case 1x:      164.233 (16.5506)       163.584 (15.4598       0.39517
> 
> [snip]
> 
>> Result for PLE machine:
>> ======================
> 
> [snip]
>> Kernbench:
>>               BASE                    BASE+patch
>>               %improvement
>>               mean (sd)               mean (sd)
>> Scenario A:
>> case 1x:      161.263 (56.518)        159.635 (40.5621)      1.00953
> 
> - vatsa
> 


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