Re: [Xen-devel] Time Skewing on Windows XP

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 12.03.13 at 05:40, Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx> 
>>> wrote:
> While I was investigating the following issue on Windows XP (both 32-bit and 
> 64-bit):
> 
> * AMD NPT performance regression after c/s 24770:7f79475d3de7
>     Reference:http://marc.info/?l=xen-devel&m=135075376805215 
> 
> On the latest source form xen-unstable, I ran into an issue where the timing 
> on the HVM guests skewing about 2x slower than the actual wall clock time.  
> This results in the system time slowing down. This is regardless of the 
> cpufreq governor scaling. (I tried with both ondemand and performance).
> 
> However, I don't see the same behavior on the Win7 HVM guests. Is this a 
> known issue.

While I recall respective reports, the issue should not be present
on current -unstable, so if you do have observations like this they
will need investigation.

> I assume that XP and Win7 uses different mechanism for keeping 
> time (e.g. rdtsc vs. HPET)?

Quite possible, but I don't know. Nor do I know whether there are,
just like for Linux, ways to make Windows pick a different clock
source (for comparison purposes).

Jan


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