[Xen-devel] RE: [Xen-users] Does vt-x itself have perf. impact on Hypervisor w/o considering HVM?

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Liang Yang
> Sent: 22 January 2007 18:33
> To: Xen devel list; xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-users] Does vt-x itself have perf. impact on 
> Hypervisor w/o considering HVM?
> 
> Hello,
> 
> Suppose I have two different kinds of CPUs which have exactly 
> the same 
> configuration except one supports VT-X while the other does 
> not. If I want 
> to test the I/O performance (or other perf. testing which is not 
> particularly related to I/O) of the both domain0 and 
> Para-Virtualized Guest 
> Domain (HVM domain is not considered), shall I expect to get the same 
> performance results on these two CPUs?

Assuming ALL other aspects are the same, when you're not using HVM,
there should be absolutely zero impact from it (aside from it using up a
few kilobytes of memory, to be precise, HVM (including both VMX and SVM)
takes up 129459 bytes when not used - more memory is allocated
dynamically when it's being used for obvious reasons. For modern
systems, that's so small that it doesn't matter). 

--
Mats
> 
> Thanks,
> 
> Liang
> 
> 
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