From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8A4CAC2D0DB for ; Wed, 22 Jan 2020 13:55:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 668DA24688 for ; Wed, 22 Jan 2020 13:55:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726194AbgAVNzN (ORCPT ); Wed, 22 Jan 2020 08:55:13 -0500 Received: from outbound-smtp04.blacknight.com ([81.17.249.35]:42736 "EHLO outbound-smtp04.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725805AbgAVNzN (ORCPT ); Wed, 22 Jan 2020 08:55:13 -0500 Received: from mail.blacknight.com (pemlinmail03.blacknight.ie [81.17.254.16]) by outbound-smtp04.blacknight.com (Postfix) with ESMTPS id 62638981C5 for ; Wed, 22 Jan 2020 13:55:11 +0000 (GMT) Received: (qmail 9722 invoked from network); 22 Jan 2020 13:55:11 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.18.57]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 22 Jan 2020 13:55:11 -0000 Date: Wed, 22 Jan 2020 13:55:09 +0000 From: Mel Gorman To: Srikar Dronamraju Cc: Ingo Molnar , Peter Zijlstra , LKML , Rik van Riel , Thomas Gleixner , Valentin Schneider , Vincent Guittot Subject: Re: [PATCH v2] sched/fair: Optimize select_idle_core Message-ID: <20200122135509.GW3466@techsingularity.net> References: <20191206172422.6578-1-srikar@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20191206172422.6578-1-srikar@linux.vnet.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 06, 2019 at 10:54:22PM +0530, Srikar Dronamraju wrote: > Currently we loop through all threads of a core to evaluate if the core is > idle or not. This is unnecessary. If a thread of a core is not idle, skip > evaluating other threads of a core. Also while clearing the cpumask, bits > of all CPUs of a core can be cleared in one-shot. > > Collecting ticks on a Power 9 SMT 8 system around select_idle_core > while running schbench shows us > > (units are in ticks, hence lesser is better) > Without patch > N Min Max Median Avg Stddev > x 130 151 1083 284 322.72308 144.41494 > > > With patch > N Min Max Median Avg Stddev Improvement > x 164 88 610 201 225.79268 106.78943 30.03% > > > Reviewed-by: Valentin Schneider > Reviewed-by: Vincent Guittot > Signed-off-by: Srikar Dronamraju Acked-by: Mel Gorman I'm a bit surprised to not see this in linux-next or tip. Did this get rejected or did it accidentally get overlooked because the subject is so similar to 60588bfa223f ("sched/fair: Optimize select_idle_cpu") ? -- Mel Gorman SUSE Labs