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Thu, 29 Jun 2023 14:31:51 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1041A20040; Thu, 29 Jun 2023 14:31:51 +0000 (GMT) Received: from pomme.tlslab.ibm.com (unknown [9.101.4.33]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 29 Jun 2023 14:31:50 +0000 (GMT) From: Laurent Dufour To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v3 0/9] Introduce SMT level and add PowerPC support Date: Thu, 29 Jun 2023 16:31:40 +0200 Message-ID: <20230629143149.79073-1-ldufour@linux.ibm.com> X-Mailer: git-send-email 2.41.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: KnQKqTYL1ux1N6LbZbIv59sbgWflxRND X-Proofpoint-ORIG-GUID: I0FfXe544_ewxmg6_4UIwmxfARBnRcst X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.591,FMLib:17.11.176.26 definitions=2023-06-29_03,2023-06-27_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 adultscore=0 lowpriorityscore=0 clxscore=1015 phishscore=0 spamscore=0 bulkscore=0 mlxlogscore=999 priorityscore=1501 malwarescore=0 suspectscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2305260000 definitions=main-2306290131 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: linux-arch@vger.kernel.org, dave.hansen@linux.intel.com, linux-kernel@vger.kernel.org, mingo@redhat.com, bp@alien8.de, npiggin@gmail.com, tglx@linutronix.de Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" I'm taking over the series Michael sent previously [1] which is smartly reviewing the initial series I sent [2]. This series is addressing the comments sent by Thomas and me on the Michael's one. Here is a short introduction to the issue this series is addressing: When a new CPU is added, the kernel is activating all its threads. This leads to weird, but functional, result when adding CPU on a SMT 4 system for instance. Here the newly added CPU 1 has 8 threads while the other one has 4 threads active (system has been booted with the 'smt-enabled=4' kernel option): ltcden3-lp12:~ # ppc64_cpu --info Core 0: 0* 1* 2* 3* 4 5 6 7 Core 1: 8* 9* 10* 11* 12* 13* 14* 15* This mixed SMT level may confused end users and/or some applications. There is no SMT level recorded in the kernel (common code), neither in user space, as far as I know. Such a level is helpful when adding new CPU or when optimizing the energy efficiency (when reactivating CPUs). When SMP and HOTPLUG_SMT are defined, this series is adding a new SMT level (cpu_smt_num_threads) and few callbacks allowing the architecture code to fine control this value, setting a max and a "at boot" level, and controling whether a thread should be onlined or not. v3: Fix a build error in the patch 6/9 v2: As Thomas suggested, Reword some commit's description Remove topology_smt_supported() Remove topology_smt_threads_supported() Introduce CONFIG_SMT_NUM_THREADS_DYNAMIC Remove switch() in __store_smt_control() Update kernel-parameters.txt [1] https://lore.kernel.org/linuxppc-dev/20230524155630.794584-1-mpe@ellerman.id.au/ [2] https://lore.kernel.org/linuxppc-dev/20230331153905.31698-1-ldufour@linux.ibm.com/ Laurent Dufour (1): cpu/SMT: Remove topology_smt_supported() Michael Ellerman (8): cpu/SMT: Move SMT prototypes into cpu_smt.h cpu/SMT: Move smt/control simple exit cases earlier cpu/SMT: Store the current/max number of threads cpu/SMT: Create topology_smt_thread_allowed() cpu/SMT: Allow enabling partial SMT states via sysfs powerpc/pseries: Initialise CPU hotplug callbacks earlier powerpc: Add HOTPLUG_SMT support powerpc/pseries: Honour current SMT state when DLPAR onlining CPUs .../ABI/testing/sysfs-devices-system-cpu | 1 + .../admin-guide/kernel-parameters.txt | 4 +- arch/Kconfig | 3 + arch/powerpc/Kconfig | 2 + arch/powerpc/include/asm/topology.h | 15 +++ arch/powerpc/kernel/smp.c | 8 +- arch/powerpc/platforms/pseries/hotplug-cpu.c | 30 +++-- arch/powerpc/platforms/pseries/pseries.h | 2 + arch/powerpc/platforms/pseries/setup.c | 2 + arch/x86/include/asm/topology.h | 4 +- arch/x86/kernel/cpu/bugs.c | 3 +- arch/x86/kernel/smpboot.c | 8 -- include/linux/cpu.h | 25 +--- include/linux/cpu_smt.h | 33 +++++ kernel/cpu.c | 118 ++++++++++++++---- 15 files changed, 187 insertions(+), 71 deletions(-) create mode 100644 include/linux/cpu_smt.h Tested-by: Sachin Sant