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RE: [Xen-devel] Align periodic vpts to reduce timer interrupts and save

To: Gary Grebus <ggrebus@xxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Align periodic vpts to reduce timer interrupts and save power
From: "Wei, Gang" <gang.wei@xxxxxxxxx>
Date: Wed, 11 Feb 2009 08:44:26 +0800
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Cc: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
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Thread-topic: [Xen-devel] Align periodic vpts to reduce timer interrupts and save power
On Tuesday, February 10, 2009 11:56 PM, Gary Grebus wrote:
...
> But the customer using that accounting data won't be happy, even if they
> are saving a couple watts.  Especially since the data is likely to be
> only intermittently wrong.  It sounds like, for correctness, there
> should be more done to avoid having the virtual timers tick in immediate
> succession, not less as you propose.

The customer would be happy if he keeps getting the correct accounting data 
while he want it, meanwhile he have another choice to save more power while he 
don't care the accounting data. That is what we try to do.

> 
> I suppose if there is a configuration parameter, we can deal with it by
> adding one more guest-specific configuration rule.

Good suggestion. The feature would rather fit in guest-specific category, so we 
can consider how to do it well.

Jimmy

> 
>       /gary
> 
>> Second, our solution does not intend to remove this offset. We just tries to
>> provide a power-saving feature via a configurable way. For such feature some
>> side effect may exist but the overall gain is more power efficient. I will
>> make my patch ready soon, and we can do further discussion on the
>> implementation level then.    
>> 
>> Jimmy
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