From mboxrd@z Thu Jan 1 00:00:00 1970 From: Karl Rister Subject: cpu utilization monitoring Date: Mon, 11 Sep 2006 14:44:23 -0500 Message-ID: <200609111444.23398.kmr@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Xen Devel List-Id: xen-devel@lists.xenproject.org Currently in the vcpu_runstate_info structure we have fields that contain the time spent when the vcpu is in one of four states. When trying to determine the physical utilization that a vcpu is requiring of the system from libxc we make a domctl operation call to the XEN_DOMCTL_getvcpuinfo command. When processing this command we pull the value for the RUNSTATE_running field and attribute it to the processor that the vcpu is currently running on. I believe that with the new credit scheduler these values are wrong as it is possible that the vcpu has time in RUNSTATE_running that was not actually spent on the currently running processor. Is there a separate path through the libraries and into Xen that retrieves this information in a more correct manner? Given that a vcpu can migrate among several physical processors in the time between samples it seems that a finer grained accounting mechanism is needed to correctly report physical utilization of the hardware resources. -- Karl Rister IBM Linux Performance Team kmr@us.ibm.com