Find timing info between two VM exits

Find timing info between two VM exits

[avadh patel]

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Hi All,

I was looking into the source code of kvm and modified qemu and trying to
find the time spent between two VM-exit in kvm.
Is there a way to find this from user-space qemu, without modifying the
kernel module or libkvm?

Thanks,
Avadh

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Re: Find timing info between two VM exits

[Avi Kivity]

avadh patel wrote:
> Hi All,
>
> I was looking into the source code of kvm and modified qemu and trying 
> to find the time spent between two VM-exit in kvm.
> Is there a way to find this from user-space qemu, without modifying 
> the kernel module or libkvm?
>

What do you mean exactly?  Average time between vmexits?  Time between 
vmexit and vmenter?  time between vmenter and vmexit?  Or what code 
executes?

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


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Re: Find timing info between two VM exits

[avadh patel]

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Hi Avi,

Sorry for the wrong question. My revised question is as follows:
How can I find the time spent between vm-enter and vm-exit ?
In other words, How can I find the number of clock ticks spent in execution
of VM's code between vm-enter and vm-exit ?

Thanks,
Avadh


On Dec 24, 2007 2:05 AM, Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote:

> avadh patel wrote:
> > Hi All,
> >
> > I was looking into the source code of kvm and modified qemu and trying
> > to find the time spent between two VM-exit in kvm.
> > Is there a way to find this from user-space qemu, without modifying
> > the kernel module or libkvm?
> >
>
> What do you mean exactly?  Average time between vmexits?  Time between
> vmexit and vmenter?  time between vmenter and vmexit?  Or what code
> executes?
>
> --
> error compiling committee.c: too many arguments to function
>
>

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Re: Find timing info between two VM exits

[Avi Kivity]

avadh patel wrote:
> Hi Avi,
>
> Sorry for the wrong question. My revised question is as follows:
> How can I find the time spent between vm-enter and vm-exit ?
> In other words, How can I find the number of clock ticks spent in 
> execution of VM's code between vm-enter and vm-exit ?

Linux 2.6.24 supports guest time counters in /proc/pid/stat; these sum 
up the amount of real time spent inside the guest.  To get clock tick 
counts, you can add rdtsc calls in vmx_vcpu_run or svm_vcpu_run, before 
and after the big asm block.


-- 
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