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

  • To: "Tim Deegan" <Tim.Deegan@xxxxxxxxxx>
  • From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
  • Date: Tue, 22 Jan 2008 18:01:33 +0800
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Tue, 22 Jan 2008 02:03:17 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: Achc2T+yqUKvNZgYSRmn99A1xUxE0wAA+Axg
  • Thread-topic: [PATCH][RFC]Provide fast write emulation path to release shadow lock

>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".


>>      - 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?


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