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=-2.3 required=3.0 tests=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 D579DC10DCE for ; Fri, 6 Mar 2020 18:06:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ADC5D2067C for ; Fri, 6 Mar 2020 18:06:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726633AbgCFSGS (ORCPT ); Fri, 6 Mar 2020 13:06:18 -0500 Received: from mga02.intel.com ([134.134.136.20]:21379 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725935AbgCFSGS (ORCPT ); Fri, 6 Mar 2020 13:06:18 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Mar 2020 10:06:17 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,523,1574150400"; d="scan'208";a="275627704" Received: from schen9-desk.jf.intel.com (HELO [10.54.74.162]) ([10.54.74.162]) by fmsmga002.fm.intel.com with ESMTP; 06 Mar 2020 10:06:16 -0800 To: Aaron Lu , Aubrey Li Cc: Phil Auld , Vineeth Remanan Pillai , Julien Desfossez , Nishanth Aravamudan , Peter Zijlstra , Ingo Molnar , Thomas Gleixner , Paul Turner , Linus Torvalds , Linux List Kernel Mailing , Dario Faggioli , =?UTF-8?B?RnLDqWTDqXJpYyBXZWlzYmVja2Vy?= , Kees Cook , Greg Kerr , Valentin Schneider , Mel Gorman , Pawan Gupta , Paolo Bonzini References: <20200212230705.GA25315@sinkpad> <29d43466-1e18-6b42-d4d0-20ccde20ff07@linux.intel.com> <20200225034438.GA617271@ziqianlu-desktop.localdomain> <20200227020432.GA628749@ziqianlu-desktop.localdomain> <20200227141032.GA30178@pauld.bos.csb> <20200228025405.GA634650@ziqianlu-desktop.localdomain> <20200306024116.GA16400@ziqianlu-desktop.localdomain> From: Tim Chen Autocrypt: addr=tim.c.chen@linux.intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20200306024116.GA16400@ziqianlu-desktop.localdomain> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/5/20 6:41 PM, Aaron Lu wrote: >>> So this appeared to me like a question of: is it desirable to protect/enhance >>> high weight task performance in the presence of core scheduling? >> >> This sounds to me a policy VS mechanism question. Do you have any idea >> how to spread high weight task among the cores with coresched enabled? > > Yes I would like to get us on the same page of the expected behaviour > before jumping to the implementation details. As for how to achieve > that: I'm thinking about to make core wide load balanced and then high > weight task shall spread on different cores. This isn't just about load > balance, the initial task placement will also need to be considered of > course if the high weight task only runs a small period. > I am wondering why this is not happening: When the low weight task group has exceeded its cfs allocation during a cfs period, the task group should be throttled. In that case, the CPU cores that the low weight task group occupies will become idle, and allow load balance from the overloaded CPUs for the high weight task group to migrate over. Tim