From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 0/2][KVM] guest time accounting Date: Mon, 13 Aug 2007 11:01:05 +0300 Message-ID: <46C00FC1.1070306@qumranet.com> References: <46BC8B39.6050202@bull.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel , linux-kernel , virtualization To: Laurent Vivier Return-path: In-Reply-To: <46BC8B39.6050202-6ktuUTfB/bM@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Laurent Vivier wrote: > The aim of these two patches is to measure the CPU time used by a virtual > machine. All comments are welcome... I'm not sure it's the good way to do that. > > [PATCH 1/2] introduce a new field, "guest", in cpustat to store the time used by > the CPU to run virtual CPU. Modify /proc/stat to display this new field. > > [PATCH 2/2] modify account_system_time() to add cputime to cpustat->guest if we > are running a VCPU. We add this cputime to cpustat->user instead of > cpustat->system because this part of KVM code is in fact user code although it > is executed in the kernel. We duplicate VCPU time between guest and user to > allow an unmodified "top(1)" to display correct value. A modified "top(1)" is > able to display good cpu user time and cpu guest time by subtracting cpu guest > time from cpu user time. > [copying Ingo and Rusty] The patches look good. A couple of comments: - perhaps the new fields should be guarded by a #ifdef CONFIG_HYPERVISOR (selected by CONFIG_KVM)? that way the (minor) additional overhead is only incurred if it can possibly be used. I imagine that our canine cousin will want to use this as well. - I think that there is per-task accounting of user time and system time; that should be extended as well. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/