Re: [Xen-devel] PV guest timings

[David Vrabel <dvrabel@xxxxxxxxxx>]

On 26/11/2013 15:38, Simon Martin wrote:
> Hi Keir,
>  
>> Are you using the single-shot timer or the periodic timer? 
> I'm using the single-shot timer.
>  
>>  
>> How are you calculating clock time? 
> Copied code in from Mini-OS. To make sure I don't get drift between
> deadlines as this is a single shot timer I read monotonic_clock at
> startup and then calculate every deadline by incrementing this register
> by the period on each timer call.
>  
> As an additional comment. I decided to filter out the samples with
> negative latency. This seems to happen 100 times a second, i.e. the 10
> ms Hypervisor timer event. This improves the timings considerably. So it
> looks like I'm on the right track looking for ways to distinguish
> between timer events.

You should disable the periodic timer if you don't need it.

VCPUOP_stop_periodic_timer

David

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