Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754846AbcKPKkP (ORCPT ); Wed, 16 Nov 2016 05:40:15 -0500 Received: from merlin.infradead.org ([205.233.59.134]:39672 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752195AbcKPKkN (ORCPT ); Wed, 16 Nov 2016 05:40:13 -0500 Date: Wed, 16 Nov 2016 11:40:14 +0100 From: Peter Zijlstra To: Christoph Lameter Cc: Daniel Vacek , Daniel Bristot de Oliveira , Tommaso Cucinotta , LKML , linux-rt-users , Steven Rostedt , Ingo Molnar Subject: Re: your mail Message-ID: <20161116104014.GQ3142@twins.programming.kicks-ass.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 979 Lines: 26 On Tue, Nov 15, 2016 at 02:29:16PM -0600, Christoph Lameter wrote: > > > > There is a deadlock, Peter!!! > > > > Describe please? Also, have you tried disabling RT_RUNTIME_SHARE ? > > > > > The description was given earlier in the the thread and the drawbacks of > using RT_RUNTIME_SHARE as well. I've not seen a deadlock described. It either was an unbounded priority inversion or a starvation issue, both of which are 'design' features of the !rt kernel. Neither things are new, so its not a regression either. And, as stated, I'm not really happy to muck with this known troublesome code and add features for which we must then maintain feature parity when replacing it either. On top of which, the implementation had issues; now I know you're the blinder kind of person that disregards everything not in his immediate interest, but if you'd looked at the patch you'd have seen he'd added code the idle entry path, which will slow down every single to-idle transition.