Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757496AbcJPTsB (ORCPT ); Sun, 16 Oct 2016 15:48:01 -0400 Received: from mail-lf0-f51.google.com ([209.85.215.51]:35404 "EHLO mail-lf0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756980AbcJPTry (ORCPT ); Sun, 16 Oct 2016 15:47:54 -0400 Date: Sun, 16 Oct 2016 21:40:59 +0200 From: Luca Abeni To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Tommaso Cucinotta , Juri Lelli , Thomas Gleixner , Andrea Parri , giuseppe lipari , Claudio Scordino Subject: Re: About group scheduling for SCHED_DEADLINE Message-ID: <20161016214059.65ac35b6@utopia> In-Reply-To: <20161010110818.GA11311@worktop.programming.kicks-ass.net> References: <20161009213938.3cec05ea@utopia> <20161010101558.GL3568@worktop.programming.kicks-ass.net> <20161010110818.GA11311@worktop.programming.kicks-ass.net> X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.25; x86_64-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 Content-Length: 1216 Lines: 28 On Mon, 10 Oct 2016 13:08:18 +0200 Peter Zijlstra wrote: > On Mon, Oct 10, 2016 at 12:15:58PM +0200, Peter Zijlstra wrote: > > However, I think there's a third alternative. I have memories of a > > paper from UNC (I'd have to dig through the site to see if I can > > still find it) where they argue that for a hierarchical (G-)FIFO > > you should use minimal concurrency, that is run the minimal number > > of (v)cpu servers. > > > > This would mean we give a single CBS parameter and carve out the > > minimal number (of max CBS) (v)cpu that fit in that. > > > > I'm just not sure how the random affinity crap works out for that, > > if we have the (v)cpu servers migratable in the G-EDF and migrate > > to whatever is demanded by the task at runtime it might work, but > > who knows.. Analysis would be needed I think. > > Hurm,.. thinking slightly more on this, this ends up being a DL task > with random affinity, which is problematic IIRC. Yes, there currently is no existing schedulability analysis for multi-processor EDF with random affinities (as far as I know), but I think we can at least have a look at developing this kind of analysis. Giuseppe, what do you think? Luca