Re: [RFC PATCH 0/3] generic hypercall support

[Gregory Haskins <ghaskins@novell.com>]

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Marcelo Tosatti wrote:
> On Fri, May 08, 2009 at 10:55:37AM +0300, Avi Kivity wrote:
>   
>> Marcelo Tosatti wrote:
>>     
>>> Also it would be interesting to see the MMIO comparison with EPT/NPT,
>>> it probably sucks much less than what you're seeing.
>>>   
>>>       
>> Why would NPT improve mmio?  If anything, it would be worse, since the  
>> processor has to do the nested walk.
>>
>> Of course, these are newer machines, so the absolute results as well as  
>> the difference will be smaller.
>>     
>
> Quad-Core AMD Opteron(tm) Processor 2358 SE 2.4GHz:
>
> NPT enabled:
> test 0: 3088633284634 - 3059375712321 = 29257572313
> test 1: 3121754636397 - 3088633419760 = 33121216637
> test 2: 3204666462763 - 3121754668573 = 82911794190
>
> NPT disabled:
> test 0: 3638061646250 - 3609416811687 = 28644834563
> test 1: 3669413430258 - 3638061771291 = 31351658967
> test 2: 3736287253287 - 3669413463506 = 66873789781
>
>   
Thanks for running that.  Its interesting to see that NPT was in fact
worse as Avi predicted.

Would you mind if I graphed the result and added this data to my wiki? 
If so, could you adjust the tsc result into IOPs using the proper
time-base and the test_count you ran with?   I can show a graph with the
data as is and the relative differences will properly surface..but it
would be nice to have apples to apples in terms of IOPS units with my
other run.

-Greg


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