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,NICE_REPLY_A,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 25529C433DB for ; Tue, 26 Jan 2021 05:54:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C9195229C4 for ; Tue, 26 Jan 2021 05:54:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388925AbhAZFyV (ORCPT ); Tue, 26 Jan 2021 00:54:21 -0500 Received: from mga05.intel.com ([192.55.52.43]:13465 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728042AbhAYMZa (ORCPT ); Mon, 25 Jan 2021 07:25:30 -0500 IronPort-SDR: zyA3LxLwAar/hMzorYlYg9jpS947JK4+e4cTx+y0F/r230M/fhp7NTTDki3Dx8evikoINVmR45 0jgktxZm674Q== X-IronPort-AV: E=McAfee;i="6000,8403,9874"; a="264533815" X-IronPort-AV: E=Sophos;i="5.79,373,1602572400"; d="scan'208";a="264533815" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jan 2021 03:37:57 -0800 IronPort-SDR: bUi0UhEituNXVIKn22FdlQbCetj6F+yqu4xxdp5RBf7c4Og23VaE0khtEwf/LI5xtXYO2Ri4hE x5Y8pLWeD8wA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.79,373,1602572400"; d="scan'208";a="402275159" Received: from cli6-desk1.ccr.corp.intel.com (HELO [10.239.161.125]) ([10.239.161.125]) by fmsmga004.fm.intel.com with ESMTP; 25 Jan 2021 03:37:56 -0800 Subject: Re: [PATCH v3 0/5] Scan for an idle sibling in a single pass To: Mel Gorman Cc: Vincent Guittot , Peter Zijlstra , Ingo Molnar , Qais Yousef , LKML References: <20210119112211.3196-1-mgorman@techsingularity.net> <20210119120220.GS3592@techsingularity.net> <20210122101451.GV3592@techsingularity.net> <20210125090419.GW3592@techsingularity.net> From: "Li, Aubrey" Message-ID: <31300317-89e0-ca5e-d095-920c6cfe8704@linux.intel.com> Date: Mon, 25 Jan 2021 19:37:55 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210125090419.GW3592@techsingularity.net> Content-Type: text/plain; charset=iso-8859-15 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/1/25 17:04, Mel Gorman wrote: > On Mon, Jan 25, 2021 at 12:29:47PM +0800, Li, Aubrey wrote: >>>>> hackbench -l 2560 -g 1 on 8 cores arm64 >>>>> v5.11-rc4 : 1.355 (+/- 7.96) >>>>> + sis improvement : 1.923 (+/- 25%) >>>>> + the patch below : 1.332 (+/- 4.95) >>>>> >>>>> hackbench -l 2560 -g 256 on 8 cores arm64 >>>>> v5.11-rc4 : 2.116 (+/- 4.62%) >>>>> + sis improvement : 2.216 (+/- 3.84%) >>>>> + the patch below : 2.113 (+/- 3.01%) >>>>> >> >> 4 benchmarks reported out during weekend, with patch 3 on a x86 4s system >> with 24 cores per socket and 2 HT per core, total 192 CPUs. >> >> It looks like mid-load has notable changes on my side: >> - netperf 50% num of threads in TCP mode has 27.25% improved >> - tbench 50% num of threads has 9.52% regression >> > > 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. > > Hopefully v4 can be tested as well which is now just a single scan. > Sure, may I know the baseline of v4? Thanks, -Aubrey