From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: Stolen and degraded time and schedulers Date: Fri, 16 Mar 2007 09:53:34 -0700 Message-ID: <45FACB8E.7000505@goop.org> References: <1173816769.22180.14.camel@localhost> <45F70A71.9090205@goop.org> <1173821224.1416.24.camel@dwalker1> <45F71EA5.2090203@goop.org> <45F74515.7010808@vmware.com> <45F77C27.8090604@goop.org> <45F846AB.6060200@vmware.com> <45F84E39.7030507@goop.org> <20070314203826.GA15394@elte.hu> <45F86247.40109@goop.org> <20070316083828.GA22168@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20070316083828.GA22168@elte.hu> Sender: linux-kernel-owner@vger.kernel.org To: Ingo Molnar Cc: Dan Hecht , dwalker@mvista.com, cpufreq@lists.linux.org.uk, Linux Kernel Mailing List , Con Kolivas , Chris Wright , Virtualization Mailing List , john stultz , Thomas Gleixner , paulus@au.ibm.com, schwidefsky@de.ibm.com, Rik van Riel List-Id: virtualization@lists.linuxfoundation.org Ingo Molnar wrote: > i dont understand: how are you separating 'stolen time' drifts from > events generated for absolute timeouts? > I'm not sure what you're asking; I think we're talking past each other. I can extract from Xen how much time was stolen over some real-time interval. If I call do_stolen_accounting() at any two arbitrary points, it will compute the amount of time stolen in the interval. So that means I can call it from time to time to update stolen time. Of course, this accounting will be out of date for a while, but it doesn't matter too much. I call it from the timer interrupt, since it will be called occasionally on idle CPUs and often on busy CPUs, which is what we want. Oh, its worth pointing out that stolen time is accounted against CPUs rather than individual processes, so it doesn't need to be related to process scheduling. Also, none of this is in the patch set I posted; I've implemented it since, and it will be in the next batch. J