From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756946Ab2DDQH5 (ORCPT ); Wed, 4 Apr 2012 12:07:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43168 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756620Ab2DDQH4 (ORCPT ); Wed, 4 Apr 2012 12:07:56 -0400 Date: Wed, 4 Apr 2012 11:27:27 -0400 From: Josh Boyer To: paulmck@linux.vnet.ibm.com Cc: linux-kernel@vger.kernel.org, kernel-team@fedoraproject.org Subject: RCU related performance regression in 3.3 Message-ID: <20120404152726.GB16299@zod.bos.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline 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 Hi Paul, We've had a few reports of some boot slowdowns with the 3.3 rebase we did in Fedora 16. One of our users volunteered to bisect a vanilla kernel and wound up at "rcu: Permit dyntick-idle with callbacks pending (commit 7cb924990)". You can find more details in the bug [1], but it's been reported on both physical hardware and in virtual machines. Have you seen anything like this in your testing? Given the user used a vanilla 3.3 kernel, I'm wondering if there is a targetted fix that might be backported. If so, it would be good to get that headed to the 3.3.y stable tree. josh [1] https://bugzilla.redhat.com/show_bug.cgi?id=806548