From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751371AbaFWEdQ (ORCPT ); Mon, 23 Jun 2014 00:33:16 -0400 Received: from g6t1524.atlanta.hp.com ([15.193.200.67]:2661 "EHLO g6t1524.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751066AbaFWEdO (ORCPT ); Mon, 23 Jun 2014 00:33:14 -0400 Message-ID: <1403497988.2377.21.camel@j-VirtualBox> Subject: Re: [PATCH v2] sched: Fast idling of CPU when system is partially loaded From: Jason Low To: Tim Chen Cc: Ingo Molnar , Peter Zijlstra , Andi Kleen , Michel Lespinasse , Rik van Riel , Peter Hurley , Davidlohr Bueson , linux-kernel@vger.kernel.org Date: Sun, 22 Jun 2014 21:33:08 -0700 In-Reply-To: <1402948127.2970.578.camel@schen9-DESK> References: <1402948127.2970.578.camel@schen9-DESK> 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 On Mon, 2014-06-16 at 12:48 -0700, Tim Chen wrote: > Thanks to the review from Jason and Peter. I've moved the check > of whether load balance is required into fair.c's idle_balance. > > When a system is lightly loaded (i.e. no more than 1 job per cpu), > attempt to pull job to a cpu before putting it to idle is unnecessary and > can be skipped. This patch adds an indicator so the scheduler can know > when there's no more than 1 active job is on any CPU in the system to > skip needless job pulls. > Signed-off-by: Tim Chen Acked-by: Jason Low This change would address one of the main issues I've also been seeing on my test machines with idle_balance where most of the find_busiest_group overhead is not useful due to that issue with no tasks to move.