v2 at https://lore.kernel.org/lkml/20201110183054.15883-1-ggherdovich@xxxxxxx/ Changes wrt v2: - "code golf" on the function function init_freq_invariance_cppc(). Make better use of the "secondary" argument to init_freq_invariance(), which was introduced at b56e7d45e807 ("x86, sched: Don't enable static key when starting secondary CPUs") to deal with CPU hotplug. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Cover Letter from v2: v1 at https://lore.kernel.org/lkml/20201110083936.31994-1-ggherdovich@xxxxxxx/ Changes wrt v1: - made initialization safe under CPU hotplug. The function init_freq_invariance_cppc now lets only the first caller into init_freq_invariance(). - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Cover Letter from v1: This series adds support for frequency invariant accounting on AMD EPYC Zen2 (aka "Rome"). The first patch by Nathan lays out the foundation by querying ACPI infrastructure for the max boost frequency of the system. Specifically, this value is available via the CPPC machinery; the previous EPYC generation, namely Zen aka "Naples", doesn't implement that and frequency invariance won't be supported. The second patch sets the estimate for freq_max to be the midpoint between max_boost and max_P, as that works slightly better in practice. A side effect of this series is to provide, with the invariant schedutil governor, a suitable baseline to evaluate a (still work-in-progress) CPPC-based cpufreq driver for the AMD platform (see https://lore.kernel.org/lkml/cover.1562781484.git.Janakarajan.Natarajan@xxxxxxx if/when it will resubmitted. Giovanni Gherdovich (2): x86, sched: Use midpoint of max_boost and max_P for frequency invariance on AMD EPYC x86: Print ratio freq_max/freq_base used in frequency invariance calculations Nathan Fontenot (1): x86, sched: Calculate frequency invariance for AMD systems arch/x86/include/asm/topology.h | 8 ++++ arch/x86/kernel/smpboot.c | 79 ++++++++++++++++++++++++++++++--- drivers/acpi/cppc_acpi.c | 3 ++ 3 files changed, 85 insertions(+), 5 deletions(-) -- 2.26.2
