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RE: [Xen-devel] [PATCH] Deferrable Timer

To: "Dave Winchell" <dwinchell@xxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] [PATCH] Deferrable Timer
From: "Yu, Ke" <ke.yu@xxxxxxxxx>
Date: Fri, 18 Jul 2008 22:37:44 +0800
Cc: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>, "Wei, Gang" <gang.wei@xxxxxxxxx>
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Thread-topic: [Xen-devel] [PATCH] Deferrable Timer
Dave,

Glad to see there is deferrable timer application. Please go ahead with
that. And I will keep you updated if there is finding in my side. 

BTW, Could you please elaborate more on the "guest-handles-missed-tick"
case? Since there is no need to inject missed tick to guest, which timer
would be used as deferrable timer?

Best Regards
Ke 

Dave Winchell wrote:
> Ke,
> 
> One would think that hpet or vpt support for the
> guest-handles-missed-ticks policy would be a good application for a
> deferrable timer. 
> If a deferrable timer were used, then the comparator (cmp) would have
> to 
> be warped to a non-integer multiple of the period. This is because
> Linux reads the comparator register to estimate the delay since the
> interrupt 
> was posted.
> I don't think warping like this will be a problem. At some point, I
> can test this.
> 
> I think we could use the deferrable timer for the
> guest-does-not-handle-missed-ticks
> policy as well.
> 
> Any investigation that you want to do in the platform timer area would
> be fine.
> Or I can do it, but that will probably be after I do the vpt.c/hpet.c
> integration
> work.
> 
> thanks,
> Dave
> 
>> Best Regards
>> Ke
>> 
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-devel


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