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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 1BB36C10DCE for ; Fri, 6 Mar 2020 18:33:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E3E9720675 for ; Fri, 6 Mar 2020 18:33:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="GoH/PZOh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726733AbgCFSdy (ORCPT ); Fri, 6 Mar 2020 13:33:54 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:26510 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726167AbgCFSdy (ORCPT ); Fri, 6 Mar 2020 13:33:54 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1583519632; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=51IIugSwsBjdfy5MvP+PidoijcdiR9fhmf60EnmBLsw=; b=GoH/PZOhEmBdL8Lne3/UVYZJXrWslzYDLeWKdpz1+4dPM/6lq5QEeuQIcGGgtp4ZmrZFjk sUQsrM07KnGjfMsjxnsx6IdBqhdpeq4UDmV9FUggFkAMt1362FBa4+qp29Voaf7TZzYAOo H3UYoM9WM9suc7q07YGKyX1VaryZQD4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-158-Z5xbXSL3NGmQd5kT5e7hnQ-1; Fri, 06 Mar 2020 13:33:48 -0500 X-MC-Unique: Z5xbXSL3NGmQd5kT5e7hnQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 96E5C18C8C00; Fri, 6 Mar 2020 18:33:44 +0000 (UTC) Received: from pauld.bos.csb (dhcp-17-51.bos.redhat.com [10.18.17.51]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9DF555C1B5; Fri, 6 Mar 2020 18:33:42 +0000 (UTC) Date: Fri, 6 Mar 2020 13:33:40 -0500 From: Phil Auld To: Tim Chen Cc: Aaron Lu , Aubrey Li , Vineeth Remanan Pillai , Julien Desfossez , Nishanth Aravamudan , Peter Zijlstra , Ingo Molnar , Thomas Gleixner , Paul Turner , Linus Torvalds , Linux List Kernel Mailing , Dario Faggioli , =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , Kees Cook , Greg Kerr , Valentin Schneider , Mel Gorman , Pawan Gupta , Paolo Bonzini Subject: Re: [RFC PATCH v4 00/19] Core scheduling v4 Message-ID: <20200306183340.GC23145@pauld.bos.csb> References: <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> <98719a4e-f620-dc8c-f29f-fd63c43e1597@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <98719a4e-f620-dc8c-f29f-fd63c43e1597@linux.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 06, 2020 at 10:06:16AM -0800 Tim Chen wrote: > 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. > cpu.shares is not quota. I think it will only get throttled if it has and exceeds quota. Shares are supposed to be used to help weight contention without providing a hard limit. Cheers, Phil > Tim > --