[Xen-devel] RE: [PATCH][RFC]Provide fast write emulation path to release shadow lock

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Tim Deegan [mailto:Tim.Deegan@xxxxxxxxxx] 
>Sent: 2008年1月22日 17:26
>
>At 10:20 +0800 on 22 Jan (1200997253), Tian, Kevin wrote:
>> We also did series of tests on 32/32pae/32e: (host is 32e)
>>                    32       32pae       32e
>> ----Linux----
>> kernel build   +1%    +0.86%    +1.9%
>> Specjbb        +0.9% +1.61%    +0.32%
>> 
>> ----XP----
>> Sysbench     N/A     -0.05%     -0.32%(*)
>> 
>> * Sysbench score is not very stable on 32e guest, with up
>> to 6% variation observed in 5 rounds running. 32pae is
>> stable. 32 XP image was unfortunately corrupted at test 
>> cycle, so not test yet. Don't want to hold here from getting
>> early comments. :-)
>> 
>> I thought the performance gain should be straightforward
>> with this patch, and thus would like to know comment
>> like:
>>      - Is it a right direction?
>
>Looks good to me! 
>
>>      - Is there anything wrong or missed in patch?
>
>Nothing fundamental that I can see by reading through it.  One 
>thing I'd
>change is to avoid introducing "vfn": a virtual address >> PAGE_SIZE is
>just a "page number".

OK.

>
>>      - Any more benchmarks should we test?
>
>Anything and everything. :)  Specially multi-vcpu mixed operations
>(e.g. kernel compile + ltp + network traffic) while doing live migrate.
>Even when they look as clean as this one, changes in the shadow fault
>handler tend to chase out implicit/forgotten assumptions.
>

Agree. I asked the question because the combinations are really too many
and usually we try those tests. So for the case you mentioned when doing
live migrate, can I consider the stability/correctness is the major test goal
since individual score may vary a lot in such complex environment?

Thanks,
Kevin

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