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

[Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx>]

* 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)?

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
>                %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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