On 03/13/2014 12:49 AM, Jincheng Miao wrote:
In http://libvirt.org/formatdomain.html#elementsTime , we could find there are three attributes of catchup tickpolicy: limit, threshold and slew.
" The catchup element has three optional attributes, each a positive integer. The attributes are threshold, slew, and limit. " The xml format likes: <clock offset='utc'> <timer name='rtc' tickpolicy='catchup'> <catchup slew='123'/> or <catchup threshold='123'/> or <catchup limit='123'/> </timer> </clock>
But there is no further explanation. Does anyone know what's the meaning of these attributes ?
We ought to copy the documentation that qemu just added: # Policy for handling lost ticks in timer devices. # # @discard: throw away the missed tick(s) and continue with future injection # normally. Guest time may be delayed, unless the OS has explicit # handling of lost ticks # # @delay: continue to deliver ticks at the normal rate. Guest time will be # delayed due to the late tick # # @merge: merge the missed tick(s) into one tick and inject. Guest time # may be delayed, depending on how the OS reacts to the merging # of ticks # # @slew: deliver ticks at a higher rate to catch up with the missed tick. The # guest time should not be delayed once catchup is complete. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org