From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757088Ab3LERQA (ORCPT ); Thu, 5 Dec 2013 12:16:00 -0500 Received: from mx1.redhat.com ([209.132.183.28]:13764 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752912Ab3LERP7 (ORCPT ); Thu, 5 Dec 2013 12:15:59 -0500 Date: Thu, 5 Dec 2013 12:15:50 -0500 From: Dave Jones To: "Paul E. McKenney" Cc: Linux Kernel Subject: Re: lots of brief rcu stalls. Message-ID: <20131205171550.GA30002@redhat.com> Mail-Followup-To: Dave Jones , "Paul E. McKenney" , Linux Kernel References: <20131204232838.GA25592@redhat.com> <20131205001614.GI15492@linux.vnet.ibm.com> <20131205012206.GA31349@redhat.com> <20131205164912.GA1585@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131205164912.GA1585@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 05, 2013 at 08:49:12AM -0800, Paul E. McKenney wrote: > But what workload are you running that causes this? The only way I > can think of to make this happen requires that you have at least one > CPU spending more than 21 seconds running continuously in kernel mode. > Is that what you are doing, or have you come up with some other creative > way for this to happen? In the latter case, I would really like to know > about it in case it exposes yet another flaw in my RCU design. ;-) just the regular trinity runs, so it could be anything. (Running a few instances of it, with a couple dozen child processes each to drive up the loadavg) if only I had a trace or something that I could start to guess at what was happening :) Dave