From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754383Ab3F0W3C (ORCPT ); Thu, 27 Jun 2013 18:29:02 -0400 Received: from mail-pb0-f41.google.com ([209.85.160.41]:60563 "EHLO mail-pb0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753895Ab3F0W3B (ORCPT ); Thu, 27 Jun 2013 18:29:01 -0400 Message-ID: <51CCBCA9.1000200@gmail.com> Date: Thu, 27 Jun 2013 16:28:57 -0600 From: David Ahern User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:17.0) Gecko/20130620 Thunderbird/17.0.7 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> <51CA0980.8010409@gmail.com> <20130626070533.GA3601@dyad.programming.kicks-ass.net> <51CB1AE9.5090709@gmail.com> <20130627104309.GQ28407@twins.programming.kicks-ass.net> In-Reply-To: <20130627104309.GQ28407@twins.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 6/27/13 4:43 AM, Peter Zijlstra wrote: > On Wed, Jun 26, 2013 at 10:46:33AM -0600, David Ahern wrote: >> On 6/26/13 1:05 AM, Peter Zijlstra wrote: >>>> 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. >>> >>> Its supposed to use hrtimers for slice expiry instead of the regular tick. >> >> So theoretically CPU bound tasks would get preempted sooner? That was my >> guess/hope anyways. > > Doth the below worketh? It doth. Usually make -j 8 for a kernel build in a VM would lock it up pretty quickly. With the patch I was able to run full builds multiple times. As for the solution you are avoiding the nesting by not waking up the softirq daemon. I'll backport to 2.6.27 and see what happens. Thanks for the patch. David