WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] Re: Clock Running Fast on Win7 DomU

On Jun 27, 2011, at 8:56 AM, Tim Deegan wrote:

> Hi Tom,
> 
> At 09:18 -0400 on 16 Jun (1308215917), Tom Goetz wrote:
>> We've tracked this down further an it seems to be an issue with the virtual 
>> HPET. Some difference between 3.4.2 and 4.0.1 results in Win7 clock running 
>> fast. The lower the programmed frequency the more accurate the Win7 clock is.
>> 
>> HPET frequency vs time for Win7 clock to tick off 60s:
>> 1ms     60s
>> 10ms   50s
>> 15ms   46s
> 
> Have you been able to reproduce this on 4.1 or 4.2-unstable?  The Win7
> clock seems to be running at the right speed for me on unstable, just by
> booting win7 (sp1, 64-bit) and bringing up the desktop clock.  Or do I
> need to do something in particular to change the granularity to 1ms?
> 
> Tim.
> 
>> In Win7 the 'rate adjustment' column of the HalpHpetClockTable is zero for 
>> all frequencies. Our current working theory is that an issue at startup is 
>> causing the error calibration to fail or not happen resulting in larger 
>> errors at larger frequencies.
>> 

I resolved the issue. Our brand new Qemu from upstream was emitting interrupts 
for the PIC. The extra timer interrupts were making time go faster.

Thanks for replying.

---
Tom Goetz
tom.goetz@xxxxxxxxxxxxxxxxxxx




_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

<Prev in Thread] Current Thread [Next in Thread>