From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752719AbbC0CaX (ORCPT ); Thu, 26 Mar 2015 22:30:23 -0400 Received: from mga01.intel.com ([192.55.52.88]:49003 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752141AbbC0CaW (ORCPT ); Thu, 26 Mar 2015 22:30:22 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.11,476,1422950400"; d="scan'208";a="698555223" Date: Fri, 27 Mar 2015 10:12:01 +0800 From: Wanpeng Li To: Preeti U Murthy Cc: peterz@infradead.org, mingo@kernel.org, riel@redhat.com, daniel.lezcano@linaro.org, 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, morten.rasmussen@arm.com, jason.low2@hp.com, Wanpeng Li Subject: Re: [PATCH V2] sched: Improve load balancing in the presence of idle CPUs Message-ID: <20150327021201.GA4491@kernel> Reply-To: Wanpeng Li References: <20150326130014.21532.17158.stgit@preeti.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150326130014.21532.17158.stgit@preeti.in.ibm.com> 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 Preeti, On Thu, Mar 26, 2015 at 06:32:44PM +0530, Preeti U Murthy wrote: > >1. An ILB CPU was chosen from the first numa domain to trigger nohz idle >load balancing [Given the experiment, upto 6 CPUs per core could be >potentially idle in this domain.] > >2. However the ILB CPU would call load_balance() on itself before >initiating nohz idle load balancing. > >3. Given cores are SMT8, the ILB CPU had enough opportunities to pull >tasks from its sibling cores to even out load. > >4. Now that the ILB CPU was no longer idle, it would abort nohz idle >load balancing I don't see abort nohz idle load balancing when ILB CPU was no longer idle in nohz_idle_balance(), could you explain more in details? Regards, Wanpeng Li