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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47600C07548 for ; Wed, 15 Nov 2023 06:16:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234537AbjKOGQr (ORCPT ); Wed, 15 Nov 2023 01:16:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60872 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229551AbjKOGQo (ORCPT ); Wed, 15 Nov 2023 01:16:44 -0500 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0EC7291 for ; Tue, 14 Nov 2023 22:16:41 -0800 (PST) Received: from pps.filterd (m0356517.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 3AF5u5M2029714; Wed, 15 Nov 2023 06:16:23 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=date : from : to : cc : subject : message-id : reply-to : references : mime-version : content-type : in-reply-to; s=pp1; bh=xFVnnJMTMBmVSpnPgUmA2cq4J7my1IiGxMtUahWzQjA=; b=q973J3jAC/FlW0IHRY9FPaESMMaj8QfkvWXO/2W4CqWzN25dUEKS/9Bfev484Yv0xC60 YlKjrqiG8VaWHakLrw1mSr1Er6EmA4DRiKJq84k8WZoB65unIIMQhl6oiHK4o8amUS0Z qd4dTY7ccp8lOQZVUmwdI1PRZB5VoNU6/MbgGRkFCC3Otv5ZtHE5ToDVbo0SYxcrF1pi Z7FBPFCyJupdBlNDsiWesNt2mC5cqpCLKSBMKI9CfmBUTeFhHJRl2kCalBFqDfzjZsA+ H1jCwziNlLaFAXknfLwEPzl2RoJlFBadwXnBk6QqH30V+0TA0bS3sIlQsqRh/u6bPxDA hg== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3ucr0hgsw1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 15 Nov 2023 06:16:23 +0000 Received: from m0356517.ppops.net (m0356517.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 3AF5u9jx030159; Wed, 15 Nov 2023 06:16:23 GMT Received: from ppma12.dal12v.mail.ibm.com (dc.9e.1632.ip4.static.sl-reverse.com [50.22.158.220]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3ucr0hgsvt-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 15 Nov 2023 06:16:22 +0000 Received: from pps.filterd (ppma12.dal12v.mail.ibm.com [127.0.0.1]) by ppma12.dal12v.mail.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 3AF4Yu5K015498; Wed, 15 Nov 2023 06:16:21 GMT Received: from smtprelay07.fra02v.mail.ibm.com ([9.218.2.229]) by ppma12.dal12v.mail.ibm.com (PPS) with ESMTPS id 3uakxswnhc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 15 Nov 2023 06:16:21 +0000 Received: from smtpav04.fra02v.mail.ibm.com (smtpav04.fra02v.mail.ibm.com [10.20.54.103]) by smtprelay07.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 3AF6GIIE66584852 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 15 Nov 2023 06:16:19 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D9D3F2004D; Wed, 15 Nov 2023 06:16:18 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AE6BF20043; Wed, 15 Nov 2023 06:16:16 +0000 (GMT) Received: from linux.vnet.ibm.com (unknown [9.126.150.29]) by smtpav04.fra02v.mail.ibm.com (Postfix) with SMTP; Wed, 15 Nov 2023 06:16:16 +0000 (GMT) Date: Wed, 15 Nov 2023 11:46:16 +0530 From: Srikar Dronamraju To: "Aneesh Kumar K.V" Cc: Michael Ellerman , Mark Rutland , Valentin Schneider , Vincent Guittot , "Paul E. McKenney" , Peter Zijlstra , linux-kernel@vger.kernel.org, Rohan McLure , Nicholas Piggin , linuxppc-dev , Josh Poimboeuf Subject: Re: [PATCH v4 0/5] powerpc/smp: Topology and shared processor optimizations Message-ID: <20231115061616.dp5id27xip5j3ovl@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <20231109054938.26589-1-srikar@linux.vnet.ibm.com> <87v8a3zhl8.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <87v8a3zhl8.fsf@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-GUID: DSSAV-iQ-3SVHXm6L-w9TZNu66cVgEyZ X-Proofpoint-ORIG-GUID: z_IZwuVAVLgHDS3lQOTvEUUGU-0vSFZX X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.987,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-11-15_04,2023-11-14_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 suspectscore=0 phishscore=0 impostorscore=0 malwarescore=0 lowpriorityscore=0 mlxlogscore=968 mlxscore=0 adultscore=0 bulkscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311060000 definitions=main-2311150046 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Aneesh Kumar K.V [2023-11-15 11:24:59]: > Srikar Dronamraju writes: > > > PowerVM systems configured in shared processors mode have some unique > > challenges. Some device-tree properties will be missing on a shared > > processor. Hence some sched domains may not make sense for shared processor > > systems. > > > > Most shared processor systems are over-provisioned. Underlying PowerVM > > Hypervisor would schedule at a Big Core granularity. The most recent power > > processors support two almost independent cores. In a lightly loaded > > condition, it helps the overall system performance if we pack to lesser > > number of Big Cores. > > > > Is this good to do if the systems are not over-provisioned? What will be > the performance impact in that case with and without the change? > We are consolidating 1 thread per thread group (aka SMT domain). Since each thread-group is suppose to be independent including having a private L1/L2/L3 cache, we expect minimal impact in non over provisioned scenario. In Over utilization scenario, the changes in this patchset will not even kick in. -- Thanks and Regards Srikar Dronamraju