Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933092AbbDGX2c (ORCPT ); Tue, 7 Apr 2015 19:28:32 -0400 Received: from g2t2353.austin.hp.com ([15.217.128.52]:45985 "EHLO g2t2353.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932230AbbDGX21 (ORCPT ); Tue, 7 Apr 2015 19:28:27 -0400 Message-ID: <1428449300.2556.79.camel@j-VirtualBox> Subject: Re: sched: Improve load balancing in the presence of idle CPUs From: Jason Low To: Preeti U Murthy Cc: Morten Rasmussen , "peterz@infradead.org" , "mingo@kernel.org" , Daniel Lezcano , "riel@redhat.com" , "vincent.guittot@linaro.org" , "srikar@linux.vnet.ibm.com" , "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: Tue, 07 Apr 2015 16:28:20 -0700 In-Reply-To: <551FB5F5.5050906@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> 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: 1025 Lines: 25 On Sat, 2015-04-04 at 15:29 +0530, Preeti U Murthy wrote: > Solution 1: As exists in the mainline > Solution 2: nohz_idle_balance(); rebalance_domains() on the ILB CPU > Solution 3: Above patch. > > I observe that Solution 3 is not as aggressive in spreading load as > Solution 2. With Solution 2, the load gets spread within the first 3-4 > seconds, hmm, so 3-4 seconds still sounds like a long time. > while with Solution3, the load gets spread within the first 6-7 > seconds. I think this is because, the above patch decides to further > nohz_idle_load_balance() based on the load on the current ILB CPU which > has most likely pulled just one task. Okay, so perhaps we can also try continuing nohz load balancing if we find that there are overloaded CPUs in the system. -- 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/