From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752949Ab3FYVUG (ORCPT ); Tue, 25 Jun 2013 17:20:06 -0400 Received: from mail-pa0-f45.google.com ([209.85.220.45]:38175 "EHLO mail-pa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751274Ab3FYVUE (ORCPT ); Tue, 25 Jun 2013 17:20:04 -0400 Message-ID: <51CA0980.8010409@gmail.com> Date: Tue, 25 Jun 2013 15:20:00 -0600 From: David Ahern User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:17.0) Gecko/20130509 Thunderbird/17.0.6 MIME-Version: 1.0 To: Peter Zijlstra CC: Ingo Molnar , LKML Subject: Re: deadlock in scheduler enabling HRTICK feature References: <51CA0622.8010105@gmail.com> <20130625211713.GA18796@laptop.programming.kicks-ass.net> In-Reply-To: <20130625211713.GA18796@laptop.programming.kicks-ass.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/25/13 3:17 PM, Peter Zijlstra wrote: > On Tue, Jun 25, 2013 at 03:05:38PM -0600, David Ahern wrote: >> Peter/Ingo: >> >> I can reliably cause a deadlock in the scheduler by enabling the HRTICK >> feature. I first hit the problem with 2.6.27 but have been able to reproduce >> it with newer kernels. I have not tried top of Linus' tree, so perhaps this >> has been fixed in 3.10. > > Yeah, I know.. its been on the todo list forever but its never been > important. Its disabled by default and all sched debug features are for > those brave enough to keep the pieces ;-) > Not a whole to of pieces to keep. What is the expectation that the feature provides? not a whole lot of documentation on it. I walked down the path wondering if it solved an odd problem we are seeing with the CFS in 2.6.27 kernel. David