From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030490AbXALFez (ORCPT ); Fri, 12 Jan 2007 00:34:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1160998AbXALFez (ORCPT ); Fri, 12 Jan 2007 00:34:55 -0500 Received: from mx1.redhat.com ([66.187.233.31]:44005 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030490AbXALFez (ORCPT ); Fri, 12 Jan 2007 00:34:55 -0500 Message-ID: <45A71DEA.9020307@redhat.com> Date: Fri, 12 Jan 2007 00:34:34 -0500 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Thunderbird 1.5.0.7 (X11/20061008) MIME-Version: 1.0 To: Avi Kivity CC: Ingo Molnar , kvm-devel , linux-kernel Subject: Re: kvm & dyntick References: <45A66106.5030608@qumranet.com> In-Reply-To: <45A66106.5030608@qumranet.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Avi Kivity wrote: > dyntick-enabled guest: > - reduce the load on the host when the guest is idling > (currently an idle guest consumes a few percent cpu) You do not need dynticks for this actually. Simple no-tick-on-idle like Xen has works well enough. While you're modifying the timer code, you might also want to add proper accounting for steal time. Time during which your guest had a runnable process, but was not actually running itself, should not be accounted against the currently running process. I wonder if it would be possible to simply copy some of the timer code from Xen. They have the timing quirks worked out very well and their timer_interrupt() is pretty nice code. (Now I need to buy myself another VT box so I can help out with KVM :)) http://virt.kernelnewbies.org/ParavirtBenefits has some other features you may want to have :))) -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: kvm & dyntick Date: Fri, 12 Jan 2007 00:34:34 -0500 Message-ID: <45A71DEA.9020307@redhat.com> References: <45A66106.5030608@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel , linux-kernel Return-path: To: Avi Kivity In-Reply-To: <45A66106.5030608-atKUWr5tajBWk0Htik3J/w@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 Avi Kivity wrote: > dyntick-enabled guest: > - reduce the load on the host when the guest is idling > (currently an idle guest consumes a few percent cpu) You do not need dynticks for this actually. Simple no-tick-on-idle like Xen has works well enough. While you're modifying the timer code, you might also want to add proper accounting for steal time. Time during which your guest had a runnable process, but was not actually running itself, should not be accounted against the currently running process. I wonder if it would be possible to simply copy some of the timer code from Xen. They have the timing quirks worked out very well and their timer_interrupt() is pretty nice code. (Now I need to buy myself another VT box so I can help out with KVM :)) http://virt.kernelnewbies.org/ParavirtBenefits has some other features you may want to have :))) -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic. ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV