Re: [PATCH v7 2/3] KVM: x86: trace mmio begin and complete

[Avi Kivity]

On 08/27/2012 12:51 PM, Dong Hao wrote:
> From: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>
> 
> 'perf kvm stat record/report' will use kvm_exit and kvm_mmio(read...) to
> calculate mmio read emulated time for the old kernel, in order to trace
> mmio read event more exactly, we add kvm_mmio_begin to trace the time when
> mmio read begins, also, add kvm_io_done to trace the time when mmio/pio is
> completed
> 

Why is this so critical?

If a lot of time is spent in in-kernel mmio, then 'perf top' will report
it.  Otherwise the time between kvm_exit and kvm_entry describes the
time spent in the host.  Not all of it is mmio handling, but it is quite
close.

-- 
error compiling committee.c: too many arguments to function
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