From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756845AbcAOJ1u (ORCPT ); Fri, 15 Jan 2016 04:27:50 -0500 Received: from mail-wm0-f41.google.com ([74.125.82.41]:37735 "EHLO mail-wm0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754237AbcAOJ1p (ORCPT ); Fri, 15 Jan 2016 04:27:45 -0500 Date: Fri, 15 Jan 2016 10:27:40 +0100 From: Luca Abeni To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Juri Lelli Subject: Re: [RFC 4/8] Improve the tracking of active utilisation Message-ID: <20160115102740.00068482@luca-1225C> In-Reply-To: <20160114194323.GC6357@twins.programming.kicks-ass.net> References: <1452785094-3086-1-git-send-email-luca.abeni@unitn.it> <1452785094-3086-5-git-send-email-luca.abeni@unitn.it> <20160114194323.GC6357@twins.programming.kicks-ass.net> X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 14 Jan 2016 20:43:23 +0100 Peter Zijlstra wrote: > On Thu, Jan 14, 2016 at 04:24:49PM +0100, Luca Abeni wrote: > > This patch implements a more theoretically sound algorithm for > > thracking the active utilisation: instead of decreasing it when a > > task blocks, use a timer (the "inactive timer", named after the > > "Inactive" task state of the GRUB algorithm) to decrease the > > active utilisaation at the so called "0-lag time". > > See also the large-ish comment in __setparam_dl(). > > If we go do proper 0-lag, as GRUB requires, then we might as well use > it for that. Yes, I initially tried to do this, but I found some issues (I do not remember, but I think they were related to tasks moving from SCHED_DEADLINE to SCHED_OTHER, and then migrating to some other runqueue while SCHED_OTHER but before the 0-lag time) I'll search my notes for this issue in the next days and check again (maybe when I wrote this code I was just misunderstanding something) Luca > > But we need to sort the issue of the task exiting with an armed timer. > The solution suggested there is keeping a task reference with the > timer.