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=-1.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS autolearn=ham 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 39C55ECE562 for ; Tue, 18 Sep 2018 00:34:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CC5B120C0E for ; Tue, 18 Sep 2018 00:34:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="T57v/jbe" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CC5B120C0E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728689AbeIRGD5 (ORCPT ); Tue, 18 Sep 2018 02:03:57 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:57334 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727106AbeIRGD5 (ORCPT ); Tue, 18 Sep 2018 02:03:57 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w8I0U1Us018813; Tue, 18 Sep 2018 00:33:47 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=on63DCus8rOUtOO9jKg8gWmyGWKE66OvvMADvWncgSw=; b=T57v/jbePs13nuyYGQT1mzbOMsUZI87edxT9c9ej5x/0tq8mlRKLVQjaolDXtQXklF+E c8hIdf+cyehpR+fnFKWtl6yqxXs12LhBEbGktA3E4GTT8JvZVStA3nQLGknoUau5uCc0 ZP63L11hVTeldE9SuZ9uKwTw3Xm2Hbul2MgkTESHLffkw7ckY7ziFHUqSvmrERuY1vhY T7rI/QXQg75xIvZAtjS4Rb4O18Os14u34tR2cs/Z7vx+XXl/o9xDfYAbQ9/yPMyWjumN 8ZJrBOHqRAFU0DqRjbxwcVZpKcUZKbC6zuqaFZZ2GnbbsujJZEg9uRWsnvO7eVSMUyon Vg== Received: from aserv0021.oracle.com (aserv0021.oracle.com [141.146.126.233]) by userp2130.oracle.com with ESMTP id 2mgsgthd9p-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 18 Sep 2018 00:33:47 +0000 Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserv0021.oracle.com (8.14.4/8.14.4) with ESMTP id w8I0XkeR028135 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 18 Sep 2018 00:33:46 GMT Received: from abhmp0013.oracle.com (abhmp0013.oracle.com [141.146.116.19]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id w8I0Xjtt023953; Tue, 18 Sep 2018 00:33:45 GMT Received: from [10.132.91.175] (/10.132.91.175) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 17 Sep 2018 17:33:45 -0700 Subject: Re: [RFC 00/60] Coscheduling for Linux To: "=?UTF-8?Q?Jan_H._Sch=c3=b6nherr?=" , Ingo Molnar , Peter Zijlstra Cc: linux-kernel@vger.kernel.org References: <20180907214047.26914-1-jschoenh@amazon.de> From: Subhra Mazumdar Message-ID: <3336974a-38f7-41dd-25a7-df05e077444f@oracle.com> Date: Mon, 17 Sep 2018 17:33:42 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180907214047.26914-1-jschoenh@amazon.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9019 signatures=668708 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1809180003 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/07/2018 02:39 PM, Jan H. Schönherr wrote: > This patch series extends CFS with support for coscheduling. The > implementation is versatile enough to cover many different coscheduling > use-cases, while at the same time being non-intrusive, so that behavior of > legacy workloads does not change. > > Peter Zijlstra once called coscheduling a "scalability nightmare waiting to > happen". Well, with this patch series, coscheduling certainly happened. > However, I disagree on the scalability nightmare. :) > > In the remainder of this email, you will find: > > A) Quickstart guide for the impatient. > B) Why would I want this? > C) How does it work? > D) What can I *not* do with this? > E) What's the overhead? > F) High-level overview of the patches in this series. > > Regards > Jan > > > A) Quickstart guide for the impatient. > -------------------------------------- > > Here is a quickstart guide to set up coscheduling at core-level for > selected tasks on an SMT-capable system: > > 1. Apply the patch series to v4.19-rc2. > 2. Compile with "CONFIG_COSCHEDULING=y". > 3. Boot into the newly built kernel with an additional kernel command line > argument "cosched_max_level=1" to enable coscheduling up to core-level. > 4. Create one or more cgroups and set their "cpu.scheduled" to "1". > 5. Put tasks into the created cgroups and set their affinity explicitly. > 6. Enjoy tasks of the same group and on the same core executing > simultaneously, whenever they are executed. > > You are not restricted to coscheduling at core-level. Just select higher > numbers in steps 3 and 4. See also further below for more information, esp. > when you want to try higher numbers on larger systems. > > Setting affinity explicitly for tasks within coscheduled cgroups is > currently necessary, as the load balancing portion is still missing in this > series. > I don't get the affinity part. If I create two cgroups by giving them only cpu shares (no cpuset) and set their cpu.scheduled=1, will this ensure co-scheduling of each group on core level for all cores in the system? Thanks, Subhra