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=-1.2 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 62AA4C43381 for ; Thu, 21 Feb 2019 18:47:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 345952084F for ; Thu, 21 Feb 2019 18:47:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="aG47AKXF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728457AbfBUSrM (ORCPT ); Thu, 21 Feb 2019 13:47:12 -0500 Received: from aserp2130.oracle.com ([141.146.126.79]:43572 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726265AbfBUSrK (ORCPT ); Thu, 21 Feb 2019 13:47:10 -0500 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x1LIXibo014322; Thu, 21 Feb 2019 18:46:45 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=X31UqoQlWhtMQ2SUdAKjBMYxCxHivK0kaJEvObzQiVo=; b=aG47AKXFOmvUUki/zRRPk/QJ7yuaxspax9c9am/pf/6sf/S5zvTpUWZTHGmm70doZEcQ P04YOFLq5VBX/HhfgwiuU/pMFpfgdhCBYss+QZC+WZFtqI5ghaQKqQHxXshWEGPO/1fd jbwnEBCgEukwNH9hA4Cbs2DJcC64DViP/4Hhx7zqwDcGwkR8GnVaQORrjOSy/LPzi0pj KaOLYEQaRJmLu3ygOKcTt1johVdemelMMM7YH6JlyPEx4EnVeMtLh6zNqyG4HY4CKW33 nbmK3ttt8Nnvzd6Sc6UB7rLFeNoZtMVUvdbXECdsowfOTO5ygj3qxw5slBgVffDQZkYP Kw== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by aserp2130.oracle.com with ESMTP id 2qp81ej5fd-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 21 Feb 2019 18:46:45 +0000 Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id x1LIkiJh023990 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 21 Feb 2019 18:46:44 GMT Received: from abhmp0022.oracle.com (abhmp0022.oracle.com [141.146.116.28]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x1LIkhf5029134; Thu, 21 Feb 2019 18:46:43 GMT Received: from [10.132.91.175] (/10.132.91.175) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 21 Feb 2019 10:46:43 -0800 Subject: Re: [RFC][PATCH 00/16] sched: Core scheduling To: Peter Zijlstra Cc: Linus Torvalds , Ingo Molnar , Thomas Gleixner , Paul Turner , Tim Chen , Linux List Kernel Mailing , =?UTF-8?B?RnLDqWTDqXJpYyBXZWlzYmVja2Vy?= , Kees Cook , kerrnel@google.com References: <20190218165620.383905466@infradead.org> <20190221140348.GR32494@hirez.programming.kicks-ass.net> From: Subhra Mazumdar Message-ID: <7795f178-37a1-0927-a356-c80d1b174423@oracle.com> Date: Thu, 21 Feb 2019 10:44:35 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190221140348.GR32494@hirez.programming.kicks-ass.net> 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=9174 signatures=668684 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902210130 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/21/19 6:03 AM, Peter Zijlstra wrote: > On Wed, Feb 20, 2019 at 06:53:08PM -0800, Subhra Mazumdar wrote: >> On 2/18/19 9:49 AM, Linus Torvalds wrote: >>> On Mon, Feb 18, 2019 at 9:40 AM Peter Zijlstra wrote: >>>> However; whichever way around you turn this cookie; it is expensive and nasty. >>> Do you (or anybody else) have numbers for real loads? >>> >>> Because performance is all that matters. If performance is bad, then >>> it's pointless, since just turning off SMT is the answer. >>> >>> Linus >> I tested 2 Oracle DB instances running OLTP on a 2 socket 44 cores system. >> This is on baremetal, no virtualization. > I'm thinking oracle schedules quite a bit, right? Then you get massive > overhead (as shown). Yes. In terms of idleness we have: Users baseline core_sched 16    67% 70% 24    53% 59% 32    41% 49% So there is more idleness with core sched which is understandable as there can be forced idleness. The other part contributing to regression is most likely overhead. > > The thing with virt workloads is that if they don't VMEXIT lots, they > also don't schedule lots (the vCPU stays running, nested scheduler > etc..). I plan to run some VM workloads. > > Also; like I wrote, it is quite possible there is some sibling rivalry > here, which can cause excessive rescheduling. Someone would have to > trace a workload and check. > > My older patches had a condition that would not preempt a task for a > little while, such that it might make _some_ progress, these patches > don't have that (yet). >