Messages in this thread | | | Date | Wed, 5 Jul 2023 13:53:10 +0200 | Subject | Re: [PATCH v3 0/9] Introduce SMT level and add PowerPC support | From | Laurent Dufour <> |
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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 >> >
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