From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755736AbcAOJPh (ORCPT ); Fri, 15 Jan 2016 04:15:37 -0500 Received: from mail-wm0-f46.google.com ([74.125.82.46]:35434 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755524AbcAOJPQ (ORCPT ); Fri, 15 Jan 2016 04:15:16 -0500 Date: Fri, 15 Jan 2016 10:15:11 +0100 From: Luca Abeni To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Juri Lelli Subject: Re: [RFC 5/8] Track the "total rq utilisation" too Message-ID: <20160115101511.726cfe29@luca-1225C> In-Reply-To: <20160115083359.GC3421@worktop> References: <1452785094-3086-1-git-send-email-luca.abeni@unitn.it> <1452785094-3086-6-git-send-email-luca.abeni@unitn.it> <20160114194837.GE6357@twins.programming.kicks-ass.net> <20160115075049.1e24bde8@luca-1225C> <20160115083359.GC3421@worktop> 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 Fri, 15 Jan 2016 09:34:00 +0100 Peter Zijlstra wrote: > On Fri, Jan 15, 2016 at 07:50:49AM +0100, Luca Abeni wrote: > > On Thu, 14 Jan 2016 20:48:37 +0100 > > Peter Zijlstra wrote: > > > > > On Thu, Jan 14, 2016 at 04:24:50PM +0100, Luca Abeni wrote: > > > > This is the sum of the utilisations of tasks that are assigned > > > > to a runqueue, independently from their state (TASK_RUNNING or > > > > blocked) > > > > > > Is it actually used? > > Not in this patchset... > > It is a possible "cheap" (but less accurate) alternative to the > > tracking introduced in patch 4. Or can be used in more advanced > > implementations of multi-processor GRUB, but not in this patchset. > > > > So, it can be removed from the patchset; I added it so that people > > can see all the possible alternative utilization tracking > > strategies. > > OK, so that might've been useful text for the changelog. But given > that, maybe leave it out for now. > > BTW, have you got a paper on smp grub? The one mentioned in the cover letter describes the implementation I posted: http://disi.unitn.it/~abeni/reclaiming/rtlws14-grub.pdf There is also a newer paper, that will be published at ACM SAC 2016 (so, it is not available yet), but is based on this technical report: http://arxiv.org/abs/1512.01984 This second paper describes some more complex algorithms (easily implementable over this patchset) that are able to guarantee hard schedulability for SCHED_DEADLINE tasks with reclaiming on SMP. Luca