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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 2C2E5C433DB for ; Tue, 26 Jan 2021 03:07:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DBE5F22EBF for ; Tue, 26 Jan 2021 03:07:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728062AbhAYMaW (ORCPT ); Mon, 25 Jan 2021 07:30:22 -0500 Received: from outbound-smtp35.blacknight.com ([46.22.139.218]:44527 "EHLO outbound-smtp35.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727932AbhAYMTO (ORCPT ); Mon, 25 Jan 2021 07:19:14 -0500 Received: from mail.blacknight.com (pemlinmail02.blacknight.ie [81.17.254.11]) by outbound-smtp35.blacknight.com (Postfix) with ESMTPS id 65F7E15F3 for ; Mon, 25 Jan 2021 11:46:25 +0000 (GMT) Received: (qmail 28150 invoked from network); 25 Jan 2021 11:46:25 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.22.4]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 25 Jan 2021 11:46:25 -0000 Date: Mon, 25 Jan 2021 11:46:23 +0000 From: Mel Gorman To: "Li, Aubrey" Cc: Vincent Guittot , Peter Zijlstra , Ingo Molnar , Qais Yousef , LKML Subject: Re: [PATCH v3 0/5] Scan for an idle sibling in a single pass Message-ID: <20210125114623.GY3592@techsingularity.net> References: <20210119112211.3196-1-mgorman@techsingularity.net> <20210119120220.GS3592@techsingularity.net> <20210122101451.GV3592@techsingularity.net> <20210125090419.GW3592@techsingularity.net> <31300317-89e0-ca5e-d095-920c6cfe8704@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <31300317-89e0-ca5e-d095-920c6cfe8704@linux.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 25, 2021 at 07:37:55PM +0800, Li, Aubrey wrote: > > It's interesting that patch 3 would make any difference on x64 given that > > it's SMT2. The scan depth should have been similar. It's somewhat expected > > that it will not be a universal win, particularly once the utilisation > > is high enough to spill over in sched domains (25%, 50%, 75% utilisation > > being interesting on 4-socket systems). In such cases, double scanning can > > still show improvements for workloads that idle rapidly like tbench and > > hackbench even though it's expensive. The extra scanning gives more time > > for a CPU to go idle enough to be selected which can improve throughput > > but at the cost of wake-up latency, > > aha, sorry for the confusion. Since you and Vincent discussed to drop > patch3, I just mentioned I tested 5 patches with patch3, not patch3 alone. > Ah, that makes more sense. > > > > Hopefully v4 can be tested as well which is now just a single scan. > > > > Sure, may I know the baseline of v4? > 5.11-rc4. -- Mel Gorman SUSE Labs