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xen-devel
RE: [Xen-devel] [PATCH] Deferrable Timer
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To: |
"Yu, Ke" <ke.yu@xxxxxxxxx>, "Dave Winchell" <dwinchell@xxxxxxxxxxxxxxx> |
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Subject: |
RE: [Xen-devel] [PATCH] Deferrable Timer |
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From: |
"Yu, Ke" <ke.yu@xxxxxxxxx> |
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Date: |
Fri, 18 Jul 2008 23:11:15 +0800 |
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Cc: |
"Tian, Kevin" <kevin.tian@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>, "Wei, Gang" <gang.wei@xxxxxxxxx> |
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[Xen-devel] [PATCH] Deferrable Timer |
Yu, Ke wrote:
> 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?
Oh, I catch your points now, please ignore my previous question. You
actually means that: since guest can handle the missed tick correcty, it
is acceptable that the hpet/vpt timer is defered, so the hpet/vpt timer
itself can be deferrable timer. so is the
"guest-does-not-handle-missed-ticks" case, since xen can handle that by
inject missed tick respectively.
If my understanding is correct, I would say your point is truly good, I
expect this will reduce the timer count much especially when there is
multiple HVMs.
Best Regards
Ke
>
> 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
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
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