Re: [PATCH] lighweight VM Exit

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Dong, Eddie wrote:
> Avi Kivity wrote:
>   
>> Why not use hardware autoloading?  Is it slower than software?
>>     
>
> I believe HW is faster than SW, but the problem is that this kind of
> save/restore is 
> only needed for heavy weight VM Exit in KVM. While HW doesn't provide an
> easy
> way to bypass these MSR save/restore for light weight VM Exit, we have
> to do
> that in SW.
>   

k.

>   
>> Otherwise looks good.  Did you measure performance improvement?  I
>> usually use user/test/vmexit.c from kvm-userspace.git.
>>
>>     
>
> Yes, I tested RHEL5 64 bits guest, in my old Pentium 4 platform, I get
> 4.9% 
> performance increasement using Kernel Builder as workload. In my 4 core
> Clovertown platform (Core 2 Duo), I get 5.4% performance increasement.
> 32 bits guest test didn't show regression either. 
> Further improvement can be made base on this patch such as MSR_EFER
> virtualization.
>
> thx,eddie
>
> A slight revise per Christoph's comments.
>   

You missed my comments regarding coding style.


-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


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