Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935784AbcCQLRv (ORCPT ); Thu, 17 Mar 2016 07:17:51 -0400 Received: from www.linutronix.de ([62.245.132.108]:59631 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935760AbcCQLRp (ORCPT ); Thu, 17 Mar 2016 07:17:45 -0400 Date: Thu, 17 Mar 2016 12:16:11 +0100 (CET) From: Thomas Gleixner To: Peter Zijlstra cc: Nicholas Mc Guire , Steven Rostedt , Joel Fernandes , Greg Kroah-Hartman , linux-rt-users@vger.kernel.org, Linux Kernel Mailing List , kernelnewbies , Ingo Molnar Subject: Re: RFC on fixing mutex spinning on owner In-Reply-To: <20160317101823.GQ6344@twins.programming.kicks-ass.net> Message-ID: References: <20160316233530.GA8731@kroah.com> <20160316221751.71816309@grimm.local.home> <20160317073605.GM6344@twins.programming.kicks-ass.net> <20160317080526.GB6679@osadl.at> <20160317101823.GQ6344@twins.programming.kicks-ass.net> 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 Content-Length: 438 Lines: 12 On Thu, 17 Mar 2016, Peter Zijlstra wrote: > Also, maybe the tracer should measure the time from need_resched() > getting true until the next preemption point, instead of the entire time > preemption was disabled. Which would avoid the entire issue altogether. Well, that only gives you the information on a actual preemption, but not information about long preempt disabled regions which can cause a problem eventually. Thanks, tglx