Re: [RFC] para virt interface of perf to support kvm guest os statistics collection in guest os

[Avi Kivity <avi@redhat.com>]

On 06/09/2010 06:30 AM, Zhang, Yanmin wrote:
> From: Zhang, Yanmin<yanmin_zhang@linux.intel.com>
>
> Based on Ingo's idea, I implement a para virt interface for perf to support
> statistics collection in guest os. That means we could run tool perf in guest
> os directly.
>
> Great thanks to Peter Zijlstra. He is really the architect and gave me architecture
> design suggestions. I also want to thank Yangsheng and LinMing for their generous
> help.
>
> The design is:
>
> 1) Add a kvm_pmu whose callbacks mostly just calls hypercall to vmexit to host kernel;
> 2) Create a host perf_event per guest perf_event;
> 3) Host kernel syncs perf_event count/overflows data changes to guest perf_event
> when processing perf_event overflows after NMI arrives. Host kernel inject NMI to guest
> kernel if a guest event overflows.
> 4) Guest kernel goes through all enabled event on current cpu and output data when they
> overflows.
> 5) No change in user space.
>    

Other issues:

- save/restore support for live migration
- some way to limit the number of open handles (comes automatically with 
the table approach I suggested earlier)

-- 
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