From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965663AbbEEQbH (ORCPT ); Tue, 5 May 2015 12:31:07 -0400 Received: from www.linutronix.de ([62.245.132.108]:50842 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964916AbbEEQbF (ORCPT ); Tue, 5 May 2015 12:31:05 -0400 Date: Tue, 5 May 2015 18:31:20 +0200 (CEST) From: Thomas Gleixner To: Steven Rostedt cc: Mike Galbraith , Ronny Meeus , LKML , Peter Zijlstra Subject: Re: [PATCH] sched: Handle priority boosted tasks proper in setscheduler() In-Reply-To: <20150505122920.7861907d@gandalf.local.home> Message-ID: References: <20150505122920.7861907d@gandalf.local.home> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 5 May 2015, Steven Rostedt wrote: > I got pulled onto other things so I never finished it, but one thing > that worried me about this fix is this: > > T1 - FIFO policy (prio = 10) > lock(rtmutex); > > T2 (prio = 20) > lock(rtmutex) > boost T1 (prio = 20) > > TI (prio = 20) > sys_sched_setscheduler(prio = 30) > TI (prio = 30) > > T1 (prio = 30) > sys_sched_setscheduler(SCHED_OTHER) > new_effective_prio = 20, oldprio = 30 > > Before the code stopped at the rt_mutex_check_prio(), but now it > continues. Will having the policy change cause problems here? No, because it stays effective in the FIFO domain. Thanks, tglx