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Wed, 15 Nov 2023 05:27:16 GMT Received: from smtpav01.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3D3A658055; Wed, 15 Nov 2023 05:27:16 +0000 (GMT) Received: from smtpav01.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 310EE5804B; Wed, 15 Nov 2023 05:27:11 +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 05:27:10 +0000 (GMT) X-Mailer: emacs 29.1 (via feedmail 11-beta-1 I) From: "Aneesh Kumar K.V" To: Srikar Dronamraju , Michael Ellerman , Nicholas Piggin , Christophe Leroy Subject: Re: [PATCH v4 1/5] powerpc/smp: Enable Asym packing for cores on shared processor In-Reply-To: <20231109054938.26589-2-srikar@linux.vnet.ibm.com> References: <20231109054938.26589-1-srikar@linux.vnet.ibm.com> <20231109054938.26589-2-srikar@linux.vnet.ibm.com> Date: Wed, 15 Nov 2023 10:57:08 +0530 Message-ID: <87y1ezzivn.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-GUID: P9S993U8EmsbsdPVPDifF6fIIErNdZdN X-Proofpoint-ORIG-GUID: 4iz3V3JE1RwOAw2t7jShDz8OuzhJVCYj 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_03,2023-11-14_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 spamscore=0 suspectscore=0 mlxlogscore=865 priorityscore=1501 bulkscore=0 clxscore=1011 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-2311150040 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 , "ndesaulniers@google.com" , linux-kernel@vger.kernel.org, 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: > If there are shared processor LPARs, underlying Hypervisor can have more > virtual cores to handle than actual physical cores. > > Starting with Power 9, a big core (aka SMT8 core) has 2 nearly > independent thread groups. On a shared processors LPARs, it helps to > pack threads to lesser number of cores so that the overall system > performance and utilization improves. PowerVM schedules at a big core > level. Hence packing to fewer cores helps. > > For example: Lets says there are two 8-core Shared LPARs that are > actually sharing a 8 Core shared physical pool, each running 8 threads > each. Then Consolidating 8 threads to 4 cores on each LPAR would help > them to perform better. This is because each of the LPAR will get > 100% time to run applications and there will no switching required by > the Hypervisor. > Will this patch consolidate things to first 8 threads or just the one Big core? /me continues to look at other patches and wonder whether 4/5 should come before this? > > To achieve this, enable SD_ASYM_PACKING flag at CACHE, MC and DIE level > when the system is running in shared processor mode and has big cores. > > Signed-off-by: Srikar Dronamraju -aneesh