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

  • To: "Tim Deegan" <Tim.Deegan@xxxxxxxxxx>, "Tian, Kevin" <kevin.tian@xxxxxxxxx>
  • From: "Xu, Dongxiao" <dongxiao.xu@xxxxxxxxx>
  • Date: Fri, 25 Jan 2008 09:41:04 +0800
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Thu, 24 Jan 2008 17:42:37 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: Achc2W6lkubPm+D0QWGysocInGUBLACGKs1g
  • Thread-topic: [Xen-devel] Re: [PATCH][RFC]Provide fast write emulation path torelease shadow lock

Hi, Tim and Kevin,
    I did some stability test with and without Kevin's patch: 

First guest (Linux):  kernel build;
Second guest (Linux): network copy;
Third guest (Windows): Sysmark 2007;

In dom0, I did local migration to the three guest.

But I found that even without Kevin's patch, the guest would be blue screen in 
Windows or print some call trace in Linux guest. Have you seen this issue 
before? Thanks!

Best Regards,
Xu Dongxiao

-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Tim Deegan
Sent: 2008年1月22日 17:26
To: Tian, Kevin
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] Re: [PATCH][RFC]Provide fast write emulation path 
torelease shadow lock

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.



Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Citrix Systems (R&D) Ltd.
[Company #02300071, SL9 0DZ, UK.]

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