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Wed, 5 Jul 2023 11:53:11 +0000 (GMT) Message-ID: Date: Wed, 5 Jul 2023 13:53:10 +0200 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH v3 0/9] Introduce SMT level and add PowerPC support Content-Language: en-US To: "Zhang, Rui" , "linuxppc-dev@lists.ozlabs.org" Cc: "npiggin@gmail.com" , "dave.hansen@linux.intel.com" , "bp@alien8.de" , "mingo@redhat.com" , "tglx@linutronix.de" , "christophe.leroy@csgroup.eu" , "linux-kernel@vger.kernel.org" , "mpe@ellerman.id.au" , "linux-arch@vger.kernel.org" References: <20230629143149.79073-1-ldufour@linux.ibm.com> <44bf8b00c960473e37e35571104b5a1b24673142.camel@intel.com> From: Laurent Dufour In-Reply-To: <44bf8b00c960473e37e35571104b5a1b24673142.camel@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: N4P2ig7ddIkXcU9iADb77eI_NafRDr1l X-Proofpoint-GUID: 2jxNtGr7yfx_aCflspM8uTWG1RSqMSor Content-Transfer-Encoding: 8bit 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=2023-07-05_02,2023-07-05_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 suspectscore=0 clxscore=1011 mlxscore=0 malwarescore=0 mlxlogscore=999 lowpriorityscore=0 adultscore=0 phishscore=0 spamscore=0 bulkscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2305260000 definitions=main-2307050102 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 05/07/2023 à 05:04, Zhang, Rui a écrit : > Hi, Laurent, > > I want to test this patch set and found that it does not apply on top > of latest usptream git, because of some changes in this merge window, > so better rebase. Hi Rui, Thanks for your interest for this series. The latest Thomas's changes came into the PowerPC next branch. I'm working on a rebase. Cheers, Laurent. > thanks, > rui > > On Thu, 2023-06-29 at 16:31 +0200, Laurent Dufour wrote: >> 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 >> >