On Fri, Dec 09, 2011 at 07:24:07PM +0800, Fury kerry wrote: > I'm trying to figure out a way to attribute the VM CPU% into individual > physical CPU or at least find out whether it is possible. Based on the FAQ > of virt-top ( http://people.redhat.com/~rjones/virt-top/faq.html#pcpu ) , > it seems currently libvirt don't support it. > > For KVM, attributing VM load into individual physical CPU equals to account > the task cpu times spent at each CPU. Linux kernel export some scheduling > statistics in /proc/<pid>/schedstat and /proc/schedstat, but I can not > find a way to derive or calculate the per CPU task time from there. Do you > guys know how to calculate or *approximate* per CPU task time, ( possiblly > from existing kernel statistics ), can you give me some directions? Or the > task itself e.g. KVM has to maintain such statistics. > > Per the FAQ of virt-top, there are only 2 workaround: > > 1. Pin all your virtual CPUs to physical CPUs. Then there is no > ambiguity. > 2. Assume that CPU affinity works and assume the domain is running on > the '#'-marked CPU(s). > > Workaround #2 seems promising but I'm not sure how accurate it is. The FAQ describes the current situation. There's a open bug which is scheduled to be fixed in the RHEL 6.3 timeframe (next 6 months) to make this work properly using the new virNodeGetCPUStats API in libvirt. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into Xen guests. http://et.redhat.com/~rjones/virt-p2v
