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[Xen-devel] RE: "monitor"-ed address and IPI reduction

To: Jan Beulich <JBeulich@xxxxxxxxxx>
Subject: [Xen-devel] RE: "monitor"-ed address and IPI reduction
From: "Wei, Gang" <gang.wei@xxxxxxxxx>
Date: Tue, 9 Mar 2010 16:39:13 +0800
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Thread-topic: "monitor"-ed address and IPI reduction
Jan Beulich wrote:
> What is the point of specifying "current" as the address to monitor?

You provide a good point. The original purpose to monitor "current" is to avoid 
accidentally wakeup while relying on ipi for waking up mechanism.

> The memory location of interest really is
> irq_stat[cpu].__softirq_pending, and if that was used it would then
> also be possible to actually avoid sending IPIs when monitor/mwait
> are in use, as is being done on Linux. 

I agree that we can have a try on this. Waking up cpu by mem write should be 
more efficient for monitor/mwait case.

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