Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752546AbaAGOLf (ORCPT ); Tue, 7 Jan 2014 09:11:35 -0500 Received: from merlin.infradead.org ([205.233.59.134]:59219 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752526AbaAGOL0 (ORCPT ); Tue, 7 Jan 2014 09:11:26 -0500 Date: Tue, 7 Jan 2014 15:10:59 +0100 From: Peter Zijlstra To: Vincent Guittot Cc: Dietmar Eggemann , "linux-kernel@vger.kernel.org" , "mingo@kernel.org" , "pjt@google.com" , Morten Rasmussen , "cmetcalf@tilera.com" , "tony.luck@intel.com" , "alex.shi@linaro.org" , "preeti@linux.vnet.ibm.com" , "linaro-kernel@lists.linaro.org" , "paulmck@linux.vnet.ibm.com" , "corbet@lwn.net" , "tglx@linutronix.de" , "len.brown@intel.com" , "arjan@linux.intel.com" , "amit.kucheria@linaro.org" , "james.hogan@imgtec.com" , "schwidefsky@de.ibm.com" , "heiko.carstens@de.ibm.com" Subject: Re: [RFC] sched: CPU topology try Message-ID: <20140107141059.GY3694@twins.programming.kicks-ass.net> References: <20131105222752.GD16117@laptop.programming.kicks-ass.net> <1387372431-2644-1-git-send-email-vincent.guittot@linaro.org> <52B87149.4010801@arm.com> <20140106163123.GN31570@twins.programming.kicks-ass.net> <20140107132220.GZ31570@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140107132220.GZ31570@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 07, 2014 at 02:22:20PM +0100, Peter Zijlstra wrote: I just realized there's two different p's in there. > Ah, another way of looking at it is that the avg without blocked > component is a 'now' picture. It is the load we are concerned with right > now. > > The more blocked we add the further out we look; with the obvious limit > of the entire averaging period. > > So the avg that is runnable is right now, t_0; the avg that is runnable + > blocked is t_0 + p, where p is the avg period over which we expect the > blocked contribution to appear. So the above p for period, is unrelated to the below p which is a probability function. > So something like: > > avg = runnable + p(i) * blocked; where p(i) \e [0,1] > > could maybe be used to replace the cpu_load array and still represent > the concept of looking at a bigger picture for larger sets. Leaving open > the details of the map p. We probably want to assume task wakeup is constant over time, so p (our probability function) should probably be an exponential distribution. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/