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Date: Wed, 02 Nov 2011 18:10:03 +0100
From: Fabien Chouteau <chouteau@adacore.com>
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Subject: Re: [Qemu-devel] Multiple instances of Qemu on Windows multicore
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org

On 02/11/2011 17:25, Paolo Bonzini wrote:
> On 11/02/2011 04:38 PM, Fabien Chouteau wrote:
>> Hello fellow Qemu aficionados,
>>
>> On Windows, Qemu sets the affinity mask in order to run all thread on
>> CPU0, with this comment in the code (os-win32.c:182):
>>
>>      /* Note: cpu_interrupt() is currently not SMP safe, so we force
>>         QEMU to run on a single CPU */
>>
>> This was added by Fabrice Bellard in 2006 (git show a8e5ac33d).
>>
>> I can't find/understand any reason for this CPU affinity restriction.
> 
> Have you tried looking for a justification in the mailing lists?

Yes, and I found few mails from Fabrice Bellard and Konrad Schwarz in
the archives:

http://thread.gmane.org/gmane.comp.emulators.qemu/13804

and

http://thread.gmane.org/gmane.comp.emulators.qemu/13831/focus=13805

But it didn't provide more information about the problem.

>
> Also, I suppose you have tested without the affinity mask and it works?
>

Yes I did, it works pretty well. I had 1 unexpected failure among ~6000
tests. But I would like to have a substantial explanation.

>
> Offhand I cannot think of why that would be needed.
>

OK, thanks for your help.


-- 
Fabien Chouteau