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Re: [Xen-devel] RE: The caculation of the credit in credit_scheduler

To: "Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx>, "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>, George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] RE: The caculation of the credit in credit_scheduler
From: Keir Fraser <keir@xxxxxxx>
Date: Fri, 05 Nov 2010 09:45:09 +0000
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Dong, Eddie" <eddie.dong@xxxxxxxxx>
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Thread-topic: [Xen-devel] RE: The caculation of the credit in credit_scheduler
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On 05/11/2010 09:33, "Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx> wrote:

>> Interrupt delivery is a victim of us switching tasklet implementation
>> to work in idle VCPU context instead of in softirq context. It might
>> be sensible to make use of softirqs directly from the
>> interrupt-delivery logic, or introduce a second type of tasklets
>> (built on softirqs), or perhaps we can think of a way to structure
>> interrupt delivery that doesn't need softirq context at all -- that
>> would be nice! What did we need softirq context for in the first
>> place? 
> A dedicated softirq maybe a good choice. In this case,  it needs a Per-CPU
> list structure to record the pending interrupts' destinations(which domains).
> In the softirq callback,  it can check the list and delivery the interrupts to
> guests one by one.

Feel free to code it up. Don't forget the CPU hotplug callback so that
interrupt work can de done immediately, or farmed off to another CPU, when a
CPU is taken offline.

I'd be perfectly happy to implement softirq tasklets as an alternative. I
could do that bit of the implementation. Which do you think would result in
neater code in the interrupt-delivery subsystem?

 -- Keir

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