From patchwork Tue May 29 19:42:51 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tim Gardner X-Patchwork-Id: 161792 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from chlorine.canonical.com (chlorine.canonical.com [91.189.94.204]) by ozlabs.org (Postfix) with ESMTP id 9F279B6FD4 for ; Wed, 30 May 2012 05:42:33 +1000 (EST) Received: from localhost ([127.0.0.1] helo=chlorine.canonical.com) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1SZSJ9-0005D1-9y; Tue, 29 May 2012 19:42:19 +0000 Received: from mail.tpi.com ([70.99.223.143]) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1SZSJ6-0005Cv-8S for kernel-team@lists.ubuntu.com; Tue, 29 May 2012 19:42:16 +0000 Received: from [192.168.1.101] (host-174-45-43-11.hln-mt.client.bresnan.net [174.45.43.11]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mail.tpi.com (Postfix) with ESMTP id 6F0C531CC72; Tue, 29 May 2012 12:41:05 -0700 (PDT) Message-ID: <4FC526BB.6080100@canonical.com> Date: Tue, 29 May 2012 13:42:51 -0600 From: Tim Gardner User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 MIME-Version: 1.0 To: Leann Ogasawara Subject: Re: Low latency kernel for Quantal References: <4FC4F595.1010904@canonical.com> In-Reply-To: <4FC4F595.1010904@canonical.com> Cc: kernel-team X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.13 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kernel-team-bounces@lists.ubuntu.com Errors-To: kernel-team-bounces@lists.ubuntu.com On 05/29/2012 10:13 AM, Tim Gardner wrote: > At UDS I committed to adding a low latency flavour to Quantal if we > could collapse generic and virtual. It appears that we've been able to > do so. > > After looking at the lowlatency kernel in Precise > (git://kernel.ubuntu.com/themuso/ubuntu-precise-lowlatency.git) it looks > like the required config changes are: > > CONFIG_HZ=1000 > CONFIG_NO_HZ=n > CONFIG_PREEMPT=y > CONFIG_PREEMPT_RCU=y > > and some other config options that get enabled as a result of the above > changes. > > The only relevant code patch is 'UBUNTU: SAUCE: Made kernel irq-threaded > by default' which changes the default behavior of forced IRQ threads to > enabled, and adds a kernel boot parameter to override the default. I > propose that we _not_ carry this patch in Quantal if the lowlatency > installer can add 'threadirqs' to the grub kernel command line. > > Thoughts? > > rtg And here is a pull request guaranteed to make your builds take longer. The only clash that I see in the Quantal archive is with the lowlatency meta package. I'll have to add some 'Conflicts:' or 'Replaces:' in the mainline kernel meta package. Maybe I can get it removed completely since it was auto-synced. rtg