Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754840AbbDICj3 (ORCPT ); Wed, 8 Apr 2015 22:39:29 -0400 Received: from g4t3425.houston.hp.com ([15.201.208.53]:49364 "EHLO g4t3425.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753903AbbDICj1 (ORCPT ); Wed, 8 Apr 2015 22:39:27 -0400 Message-ID: <1428547155.3506.42.camel@j-VirtualBox> Subject: Re: sched: Improve load balancing in the presence of idle CPUs From: Jason Low To: Srikar Dronamraju Cc: Preeti U Murthy , Morten Rasmussen , "peterz@infradead.org" , "mingo@kernel.org" , Daniel Lezcano , "riel@redhat.com" , "vincent.guittot@linaro.org" , "pjt@google.com" , "benh@kernel.crashing.org" , "efault@gmx.de" , "linux-kernel@vger.kernel.org" , "iamjoonsoo.kim@lge.com" , "svaidy@linux.vnet.ibm.com" , "tim.c.chen@linux.intel.com" , jason.low2@hp.com Date: Wed, 08 Apr 2015 19:39:15 -0700 In-Reply-To: <20150408111216.GA24645@linux.vnet.ibm.com> References: <1427741729.5694.24.camel@j-VirtualBox> <551A5CCE.70008@linux.vnet.ibm.com> <1427828056.2492.24.camel@j-VirtualBox> <551B9514.80701@linux.vnet.ibm.com> <20150401170418.GX18994@e105550-lin.cambridge.arm.com> <1427954347.2556.43.camel@j-VirtualBox> <551FB5F5.5050906@linux.vnet.ibm.com> <1428449300.2556.79.camel@j-VirtualBox> <1428451666.2556.84.camel@j-VirtualBox> <20150408111216.GA24645@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1010 Lines: 26 On Wed, 2015-04-08 at 16:42 +0530, Srikar Dronamraju wrote: > * Jason Low [2015-04-07 17:07:46]: > > @@ -7687,7 +7700,7 @@ static inline bool nohz_kick_needed(struct rq *rq) > > int nr_busy, cpu = rq->cpu; > > bool kick = false; > > > > - if (unlikely(rq->idle_balance)) > > + if (unlikely(idle_cpu(cpu))) > > return false; > > > The only other place that we use idle_balance is > run_rebalance_domains(). Would it make sense to just use idle_cpu() in > run_rebalance_domains() and remove rq->idle_balance? Hi Srikar, So the idle_balance is used for storing the idle state of the CPU before calling the softirq, for load balancing decisions. In that case, we may need to keep this extra variable in order to store that information. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/