Re: [libvirt] [RFC][PATCHv1 2/5] libvirt - new API for getting percpu statistics of VM

2011/4/20 KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com&gt;: > On Tue, 19 Apr 2011 12:29:05 +0100 > "Daniel P. Berrange" <berrange(a)redhat.com&gt; wrote: > >> On Fri, Apr 15, 2011 at 04:43:03PM +0900, KAMEZAWA Hiroyuki wrote: >> > On Fri, 15 Apr 2011 09:43:15 +0200 >> > Matthias Bolte <matthias.bolte(a)googlemail.com&gt; wrote: >> > >> > > 2011/4/15 KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com&gt;: >> > > Also do you really need the absolute CPU time? >> > yes, for virt-top -1. >> >> I don't think that is correct. What virt-top ultimately displays >> to the end user is a % utilization. So it would be happy to get >> data in either % util & display that directly, or get absolute >> CPU time and calculate deltas to display % util. >> > > virt-top calculate delta by itself. > > >> I wonder if we could provide an API that could be used to provide >> either per-VCPU or per-PCPU  statistics in one go, so that we >> can finally have an API for cpu time that works well for VMWare. >> > > VMWare ? > VMware can provide various statistics about a virtual machine, but most (actually all, I think) are not provided as absolute values but in 20 sec slots with 1h of history (a vCenter can store longer history). Therefore, it's nearly impossible to get the absolute CPU time of a virtual machine since bootup. In most cases the enduser is not interested in the absolute CPU time but in the current CPU utilization in percent. VMware already calculates the utilization, but libvirt currently has not API to expose that. http://www.vmware.com/support/developer/vc-sdk/visdk41pubs/ApiReference/v... http://www.vmware.com/support/developer/vc-sdk/visdk41pubs/ApiReference/c...