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

[Juergen Gross <juergen.gross@fujitsu-siemens.com>]

Jan Beulich wrote:
>>>> Juergen Gross <juergen.gross@fujitsu-siemens.com> 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

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