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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 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 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Valentin Schneider , Vincent Guittot , Srikar Dronamraju , "Paul E. McKenney" , Peter Zijlstra , linux-kernel@vger.kernel.org, Nicholas Piggin , Rohan McLure , linuxppc-dev , Josh Poimboeuf Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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