Re: [Xen-devel] Big Bug:Time in VM goes slower; foud Solution but demand Judgement! A Interesting Story!

["Jan Beulich" <JBeulich@xxxxxxxx>]

(re-adding xen-devel to Cc)

>>> On 13.08.12 at 18:24, tupeng212 <tupeng212@xxxxxxxxx> wrote:
> I am home sending you this letter,  I can tell the details:
> I only compared the rate setted down with RegA, if same, don't call 
> create_periodic_time, and it is OK.
> but after a while it changed the rate to 152...(normal rate), and it changed 
> back to 97...(high rate), and 
> this action repeated, at this point, VM's time slowed again. so only block 
> the same rate's setting doesn't work.

But in this case the hypervisor has no choice - it has to update
the periodic timer. I don't think we could reliably guess that the
guest might plan on quickly toggling between two rates.

> but when I let pt->scheduled to be static(no changed) when setting regA down, 
> even at the rate's switching I notice above,
> it works very well, bug of time slowing never appear again.

Yeah, likely that solves the problem for you, but as it's not
correct, it's likely to cause problems for others.

Jan


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