From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753079Ab3KNKug (ORCPT ); Thu, 14 Nov 2013 05:50:36 -0500 Received: from e7.ny.us.ibm.com ([32.97.182.137]:58399 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752323Ab3KNKud (ORCPT ); Thu, 14 Nov 2013 05:50:33 -0500 Date: Thu, 14 Nov 2013 16:20:17 +0530 From: Srikar Dronamraju To: Peter Zijlstra Cc: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, mikey@neuling.org, linux-tip-commits@vger.kernel.org Subject: Re: [PATCH v2] sched: Check sched_domain before computing group power. Message-ID: <20131114105017.GD543@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <20131112105547.GA27310@linux.vnet.ibm.com> <20131112115736.GO5056@laptop.programming.kicks-ass.net> <20131112164126.GF2559@linux.vnet.ibm.com> <20131113151718.GN21461@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20131113151718.GN21461@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13111410-5806-0000-0000-00002369C5BD Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > + /* > + * build_sched_domains() -> init_sched_groups_power() > + * gets here before we've attached the domains to the > + * runqueues. > + * > + * Use power_of(), which is set irrespective of domains > + * in update_cpu_power(). > + * > + * This avoids power/power_orig from being 0 and > + * causing divide-by-zero issues on boot. > + * > + * Runtime updates will correct power_orig. > + */ > + if (!rq->sd) { Because this condition is only true during boot up, I am now thinking if we should do mark this as unlikely i.e if (unlikely(!rq->sd)) { Peter, Please do let me know if you agree and if you want to spin of a new version? > + power_orig += power_of(cpu); > + power += power_of(cpu); > + continue; > + } > + > + sgp = rq->sd->groups->sgp; > + power_orig += sgp->power_orig; > + power += sgp->power; > } > } else { > /* > -- Thanks and Regards Srikar Dronamraju