From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752608AbcFNOAA (ORCPT ); Tue, 14 Jun 2016 10:00:00 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:50909 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751744AbcFNN77 (ORCPT ); Tue, 14 Jun 2016 09:59:59 -0400 Date: Tue, 14 Jun 2016 15:59:39 +0200 From: Peter Zijlstra To: Juri Lelli Cc: mingo@kernel.org, tglx@linutronix.de, rostedt@goodmis.org, xlpang@redhat.com, linux-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, jdesfossez@efficios.com, bristot@redhat.com, Ingo Molnar Subject: Re: [RFC][PATCH 1/8] rtmutex: Deboost before waking up the top waiter Message-ID: <20160614135939.GA3704@worktop> References: <20160607195635.710022345@infradead.org> <20160607200215.637804442@infradead.org> <20160614090934.GE5981@e106622-lin> <20160614125412.GI30921@twins.programming.kicks-ass.net> <20160614132031.GL5981@e106622-lin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160614132031.GL5981@e106622-lin> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 14, 2016 at 02:20:31PM +0100, Juri Lelli wrote: > On 14/06/16 14:54, Peter Zijlstra wrote: > > On Tue, Jun 14, 2016 at 10:09:34AM +0100, Juri Lelli wrote: > > > I've got only nitpicks for the changelog. Otherwise the patch looks good > > > to me (and yes, without it bw inheritance would be a problem). > > > > So for bw inheritance I'm still not sure how to dead with the faxt that > > the top_pi_waiter, while blocked, can still be running, spin waiting. > > > > You mean for M-BWI (multiprocessor), right? If that's the case, we were > actually discussing this thing with Pisa/Trento folks yesterday. I'm not > sure yet as well, but plan seems to be to get first things right with > current DI code (Luca was saying that there is a BUG somewhere); then > move to implement BWI; and then tackle the M- case (and see what we can > do to work around the theoretical need for spin waiting). We actually > got some ideas a while back, but I need to go there and refresh my mind. > > If the plan sounds reasonable to you, it seems that we can start this > discussion as soon as Luca has his DI fixes ready. What you think? No objections.