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Re: [Xen-devel] [Patch 2 of 2]: PV-domain SMP performance Linux-part

  • To: Jan Beulich <jbeulich@xxxxxxxxxx>
  • From: Juergen Gross <juergen.gross@xxxxxxxxxxxxxxxxxxx>
  • Date: Fri, 19 Dec 2008 11:42:15 +0100
  • Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
  • Delivery-date: Fri, 19 Dec 2008 02:42:40 -0800
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Jan Beulich wrote:
>>>> Juergen Gross <juergen.gross@xxxxxxxxxxxxxxxxxxx> 19.12.08 11:06 >>>
>> Regarding handling this in Xen only: not to deschedule a vcpu in case of
>> interrupts disabled is easy, but how would you deschedule it after interrupts
>> are allowed again?
> It's all the same as with the newly added flag of yours - it requires 
> cooperation
> from the guest (plus the forced de-schedule if it fails to do so). It's just 
> that
> you don't need to set two flags when disabling interrupts, that second flag
> would only be needed when you want to avoid being de-scheduled for
> reasons other than event delivery being disabled.

I just wanted to be independent from the event mechanism. I'm fine with
merging the two features, but it would be more limiting than necessary.
It's like disabling IRQs and avoiding preemption of a thread: you can avoid
preemption by disabling IRQs, but this is not the best way to do it...


Juergen Gross                             Principal Developer
IP SW OS6                      Telephone: +49 (0) 89 636 47950
Fujitsu Siemens Computers         e-mail: juergen.gross@xxxxxxxxxxxxxxxxxxx
Otto-Hahn-Ring 6                Internet: www.fujitsu-siemens.com
D-81739 Muenchen         Company details: www.fujitsu-siemens.com/imprint.html

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