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 8B813C07548 for ; Wed, 15 Nov 2023 05:55:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234548AbjKOFzt (ORCPT ); Wed, 15 Nov 2023 00:55:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52504 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229551AbjKOFzp (ORCPT ); Wed, 15 Nov 2023 00:55:45 -0500 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ABC0CF5 for ; Tue, 14 Nov 2023 21:55:41 -0800 (PST) Received: from pps.filterd (m0353723.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 3AF5OdAW005965; Wed, 15 Nov 2023 05:55:08 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : in-reply-to : references : date : message-id : mime-version : content-type; s=pp1; bh=kWOFJgMHV8zwXBzfSpUP9Gd/VxV9I+l3M6zuOsMenq4=; b=En8kG0KqhGJHkvBNbvqsfhYI910+scv3EfE/t867N/eWI7pNaGGha+uNOm1/A+afsyOf lYNVUC+VM1WY0kNVIWUHkHK3I+vnjVPUKfd/Ogy4heO4eoGEAxtTyNzcVHmK2PZGnmov dpoybQ+0TC9Dt3G/PgXuuh5Gz8X/z268m/ynUB9AwUMmubIpUSGlPpoVDxTZGKwJFNqV 3y/wKH7qsi4/1aywLOA5igKajagZ4VtBygVAzWbsAM5beTM13VbtjfeoLTWgRkvj/HHj d6CPqw6Wa84FpnfOFs3dmtcasQT4wu/fUpjnJQMJIgvST6y/OrMVC99MDlgum4fN7YYU 3A== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3ucqtfrhgf-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 15 Nov 2023 05:55:08 +0000 Received: from m0353723.ppops.net (m0353723.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 3AF5m5ko000607; Wed, 15 Nov 2023 05:55:07 GMT Received: from ppma21.wdc07v.mail.ibm.com (5b.69.3da9.ip4.static.sl-reverse.com [169.61.105.91]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3ucqtfrhg2-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 15 Nov 2023 05:55:07 +0000 Received: from pps.filterd (ppma21.wdc07v.mail.ibm.com [127.0.0.1]) by ppma21.wdc07v.mail.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 3AF4bVVV024394; Wed, 15 Nov 2023 05:55:07 GMT Received: from smtprelay02.dal12v.mail.ibm.com ([172.16.1.4]) by ppma21.wdc07v.mail.ibm.com (PPS) with ESMTPS id 3uamxnd5ee-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 15 Nov 2023 05:55:07 +0000 Received: from smtpav01.wdc07v.mail.ibm.com (smtpav01.wdc07v.mail.ibm.com [10.39.53.228]) by smtprelay02.dal12v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 3AF5t6rg45875604 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 15 Nov 2023 05:55:06 GMT Received: from smtpav01.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0AC7E58065; Wed, 15 Nov 2023 05:55:06 +0000 (GMT) Received: from smtpav01.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DE51658063; Wed, 15 Nov 2023 05:55:01 +0000 (GMT) Received: from skywalker.linux.ibm.com (unknown [9.43.109.250]) by smtpav01.wdc07v.mail.ibm.com (Postfix) with ESMTP; Wed, 15 Nov 2023 05:55:01 +0000 (GMT) X-Mailer: emacs 29.1 (via feedmail 11-beta-1 I) From: "Aneesh Kumar K.V" To: Srikar Dronamraju , Michael Ellerman Cc: Mark Rutland , Valentin Schneider , Vincent Guittot , Srikar Dronamraju , "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 In-Reply-To: <20231109054938.26589-1-srikar@linux.vnet.ibm.com> References: <20231109054938.26589-1-srikar@linux.vnet.ibm.com> Date: Wed, 15 Nov 2023 11:24:59 +0530 Message-ID: <87v8a3zhl8.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-GUID: hvKOsAQHONLGVo8X8W9YuvD3k84XWF1o X-Proofpoint-ORIG-GUID: ZLDSFN33glRK1jnlkXXusXR_MHPvCSaf 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 lowpriorityscore=0 spamscore=0 suspectscore=0 mlxlogscore=891 priorityscore=1501 bulkscore=0 clxscore=1015 phishscore=0 malwarescore=0 impostorscore=0 mlxscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311060000 definitions=main-2311150044 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? -aneesh