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RE: [Xen-devel] event priority

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
Subject: RE: [Xen-devel] event priority
From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
Date: Mon, 10 Apr 2006 23:44:12 +0800
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: [Xen-devel] event priority
>From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx]
>Sent: 2006年4月10日 23:25
>On 10 Apr 2006, at 15:51, Tian, Kevin wrote:
>>>     Seems current event priority is simple by
>>> earlier-alloc-higher-priority style, because event ports are allocated
>>> incrementally from 1 and event dispatcher uses bit search instruction
>>> to walk pending events sequentially. Is there any plan (or benefit) to
>>> add more flexible priority policy, since by current way the priority
>>> is
>>> decided completely by compilation sequence of different drivers?
>> Sorry, I should say driver init sequence here. :-)
>If hardirq 'scheduling' is demonstrated to be an issue then we can
>certainly work on this. There are various possible solutions -- the
>easiest being to simply round-robin scan the event_pending array.
>  -- Keir

OK, seems currently no reports to say it as an issue in the
community, and question is just from my curiosity about possible
ideas. Anyway, event layer provides flexibility and we can always
tune it when really required, like your suggestion. Or even we can
provide guest ability to reserve fixed port range for some higher
priority events, like timer virq though currently it's already the
highest one due to init sequence. :-)


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