Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753959AbbLOMXN (ORCPT ); Tue, 15 Dec 2015 07:23:13 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:45035 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753857AbbLOMXM (ORCPT ); Tue, 15 Dec 2015 07:23:12 -0500 Date: Tue, 15 Dec 2015 13:23:04 +0100 From: Peter Zijlstra To: Luca Abeni Cc: Vincent Guittot , Steve Muckle , Ingo Molnar , linux-kernel , "linux-pm@vger.kernel.org" , Morten Rasmussen , Dietmar Eggemann , Juri Lelli , Patrick Bellasi , Michael Turquette Subject: Re: [RFCv6 PATCH 09/10] sched: deadline: use deadline bandwidth in scale_rt_capacity Message-ID: <20151215122304.GB6357@twins.programming.kicks-ass.net> References: <1449641971-20827-1-git-send-email-smuckle@linaro.org> <1449641971-20827-10-git-send-email-smuckle@linaro.org> <20151214151729.GQ6357@twins.programming.kicks-ass.net> <20151214221231.39b5bc4e@luca-1225C> <566FD446.1080004@unitn.it> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <566FD446.1080004@unitn.it> 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 Content-Length: 1108 Lines: 20 On Tue, Dec 15, 2015 at 09:50:14AM +0100, Luca Abeni wrote: > Strictly speaking, the active utilisation must be updated when a task > wakes up and when a task sleeps/terminates (but when a task sleeps/terminates > you cannot decrease the active utilisation immediately: you have to wait > some time because the task might already have used part of its "future > utilisation"). > The active utilisation must not be updated when a task is throttled: a > task is throttled when its current runtime is 0, so it already used all > of its utilisation for the current period (think about two tasks with > runtime=50ms and period 100ms: they consume 100% of the time on a CPU, > and when the first task consumed all of its runtime, you cannot decrease > the active utilisation). Hehe, this reminds me of the lag tracking in EEVDF/WF2Q/BFQ etc., that had similar issues. -- 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/