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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 48F2CC2BA19 for ; Thu, 16 Apr 2020 01:25:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E91E2076D for ; Thu, 16 Apr 2020 01:25:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731423AbgDPBY7 (ORCPT ); Wed, 15 Apr 2020 21:24:59 -0400 Received: from mga18.intel.com ([134.134.136.126]:55379 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728589AbgDPBYk (ORCPT ); Wed, 15 Apr 2020 21:24:40 -0400 IronPort-SDR: w9j0dUKdfsEKejz45edleyYO38s8QjFEePL/HDTvmi4Pgb9ozgi1HDEJDXBuIKPQmuIo/kCN8f 9PKPchy1Mfeg== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Apr 2020 18:24:39 -0700 IronPort-SDR: AQnTsEyPjDfJLfBwR7ukTNUMbQA3doOQTB0AHlDuA7/jyWZTsHuqs3lNIONfA+48WF41fzdUgG eY/ZdXU7NVuA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,388,1580803200"; d="scan'208";a="253699927" Received: from yhuang-dev.sh.intel.com (HELO yhuang-dev) ([10.239.159.23]) by orsmga003.jf.intel.com with ESMTP; 15 Apr 2020 18:24:36 -0700 From: "Huang\, Ying" To: Peter Zijlstra Cc: Mel Gorman , , , Ingo Molnar , Mel Gorman , Rik van Riel , Daniel Jordan , Tejun Heo , Dave Hansen , Tim Chen , Aubrey Li Subject: Re: [RFC] autonuma: Support to scan page table asynchronously References: <20200414081951.297676-1-ying.huang@intel.com> <20200414120646.GN3818@techsingularity.net> <20200415113226.GE20730@hirez.programming.kicks-ass.net> Date: Thu, 16 Apr 2020 09:24:35 +0800 In-Reply-To: <20200415113226.GE20730@hirez.programming.kicks-ass.net> (Peter Zijlstra's message of "Wed, 15 Apr 2020 13:32:26 +0200") Message-ID: <87o8rsxlws.fsf@yhuang-dev.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter Zijlstra writes: > On Tue, Apr 14, 2020 at 01:06:46PM +0100, Mel Gorman wrote: >> While it's just an opinion, my preference would be to focus on reducing >> the cost and amount of scanning done -- particularly for threads. > > This; I really don't believe in those back-charging things, esp. since > not having cgroups or having multiple applications in a single cgroup is > a valid setup. Technically, it appears possible to back-charge the CPU time to the process/thread directly (not the cgroup). > Another way to reduce latency spikes is to decrease both > sysctl_numa_balancing_scan_delay and sysctl_numa_balancing_scan_size. > Then you do more smaller scans. By scanning more often you reduce the > contrast, by reducing the size you lower the max latency. Yes. This can reduce latency spikes. Best Regards, Huang, Ying > And this is all assuming you actually want numa balancing for this > process.