From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752630AbcFNNUd (ORCPT ); Tue, 14 Jun 2016 09:20:33 -0400 Received: from foss.arm.com ([217.140.101.70]:58689 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752278AbcFNNUc (ORCPT ); Tue, 14 Jun 2016 09:20:32 -0400 Date: Tue, 14 Jun 2016 14:20:31 +0100 From: Juri Lelli To: Peter Zijlstra 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: <20160614132031.GL5981@e106622-lin> References: <20160607195635.710022345@infradead.org> <20160607200215.637804442@infradead.org> <20160614090934.GE5981@e106622-lin> <20160614125412.GI30921@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160614125412.GI30921@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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?