From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755193AbaEHSGj (ORCPT ); Thu, 8 May 2014 14:06:39 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:38239 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755115AbaEHSGi convert rfc822-to-8bit (ORCPT ); Thu, 8 May 2014 14:06:38 -0400 Date: Thu, 8 May 2014 20:06:29 +0200 From: Peter Zijlstra To: Jason Low Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, daniel.lezcano@linaro.org, alex.shi@linaro.org, preeti@linux.vnet.ibm.com, efault@gmx.de, vincent.guittot@linaro.org, morten.rasmussen@arm.com, aswin@hp.com Subject: Re: [PATCH 2/2] sched: Fix next_balance logic in rebalance_domains() and idle_balance() Message-ID: <20140508180629.GJ2844@laptop.programming.kicks-ass.net> References: <1398725155-7591-1-git-send-email-jason.low2@hp.com> <1398725155-7591-3-git-send-email-jason.low2@hp.com> <1399568364.2030.9.camel@j-VirtualBox> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: <1399568364.2030.9.camel@j-VirtualBox> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 08, 2014 at 09:59:24AM -0700, Jason Low wrote: > On Mon, 2014-04-28 at 15:45 -0700, Jason Low wrote: > > Currently, in idle_balance(), we update rq->next_balance when we pull_tasks. > > However, it is also important to update this in the !pulled_tasks case too. > > > > When the CPU is "busy" (the CPU isn't idle), rq->next_balance gets computed > > using sd->busy_factor (so we increase the balance interval when the CPU is > > busy). However, when the CPU goes idle, rq->next_balance could still be set > > to a large value that was computed with the sd->busy_factor. > > > > Thus, we need to also update rq->next_balance in idle_balance() in the cases > > where !pulled_tasks too, so that rq->next_balance gets updated without taking > > the busy_factor into account when the CPU is about to go idle. > > > > This patch makes rq->next_balance get updated independently of whether or > > not we pulled_task. Also, we add logic to ensure that we always traverse > > at least 1 of the sched domains to get a proper next_balance value for > > updating rq->next_balance. > > > > Additionally, since load_balance() modifies the sd->balance_interval, we > > need to re-obtain the sched domain's interval after the call to > > load_balance() in rebalance_domains() before we update rq->next_balance. > > > > This patch adds and uses 2 new helper functions, update_next_balance() and > > get_sd_balance_interval() to update next_balance and obtain the sched > > domain's balance_interval. > > > Hi Peter, > > I noticed that patch 1 is in tip, but not this patch 2. I was wondering > what the current status with this [PATCH 2/2] is at the moment. That made a particular .config explode, need to look at it.