linux-kernel - [PATCH 0/3] arch_topology, ACPI: populate cpu capacity from CPPC

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Date:   Fri, 14 May 2021 10:53:36 +0100
From:   Ionela Voinescu <ionela.voinescu@....com>
To:     Sudeep Holla <sudeep.holla@....com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Giovanni Gherdovich <ggherdovich@...e.cz>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Valentin Schneider <valentin.schneider@....com>
Cc:     linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH 0/3] arch_topology, ACPI: populate cpu capacity from CPPC

Hi all,

These are a few trivial patches to populate cpu capacity information
using performance information from ACPI's CPPC.

I've tied this functionality to the existing function
init_freq_invariance_cppc() called in acpi_cppc_processor_probe().
This function is renamed to a more generic arch_init_invariance_cppc().

The patches have been build tested on x86 and more thoroughly tested on
Juno R2 (arm64), which uses the new functionality, with the following
results:


root@...ntu:~# dmesg | grep cpu_capacity
[    2.157494] init_cpu_capacity_cppc: CPU0 cpu_capacity=38300 (raw).
[    2.163699] init_cpu_capacity_cppc: CPU1 cpu_capacity=38300 (raw).
[    2.169899] init_cpu_capacity_cppc: CPU2 cpu_capacity=38300 (raw).
[    2.176098] init_cpu_capacity_cppc: CPU3 cpu_capacity=38300 (raw).
[    2.182296] init_cpu_capacity_cppc: CPU4 cpu_capacity=102400 (raw).
[    2.188581] init_cpu_capacity_cppc: CPU5 cpu_capacity=102400 (raw).
[    2.194867] cpu_capacity: capacity_scale=102400
[    2.199409] cpu_capacity: CPU0 cpu_capacity=383
[    2.203952] cpu_capacity: CPU1 cpu_capacity=383
[    2.208495] cpu_capacity: CPU2 cpu_capacity=383
[    2.213037] cpu_capacity: CPU3 cpu_capacity=383
[    2.217580] cpu_capacity: CPU4 cpu_capacity=1024
[    2.222209] cpu_capacity: CPU5 cpu_capacity=1024
[    2.226886] init_cpu_capacity_cppc: cpu_capacity initialization done

root@...ntu:~# tail -n +1 /sys/devices/system/cpu/cpu*/cpu_capacity
==> /sys/devices/system/cpu/cpu0/cpu_capacity <==
383
==> /sys/devices/system/cpu/cpu1/cpu_capacity <==
383
==> /sys/devices/system/cpu/cpu2/cpu_capacity <==
383
==> /sys/devices/system/cpu/cpu3/cpu_capacity <==
383
==> /sys/devices/system/cpu/cpu4/cpu_capacity <==
1024
==> /sys/devices/system/cpu/cpu5/cpu_capacity <==
1024

All works as expected even if ACPI processor support is built as a
module.

Patches are based on v5.13-rc1.

Let me know what you think!

Thanks,
Ionela.

Ionela Voinescu (3):
  x86, ACPI: rename init_freq_invariance_cppc to
    arch_init_invariance_cppc
  arch_topology: obtain cpu capacity using information from CPPC
  arm64, topology: enable use of init_cpu_capacity_cppc()

 arch/arm64/include/asm/topology.h |  4 ++++
 arch/x86/include/asm/topology.h   |  2 +-
 drivers/acpi/cppc_acpi.c          |  6 ++---
 drivers/base/arch_topology.c      | 39 +++++++++++++++++++++++++++++++
 include/linux/arch_topology.h     |  4 ++++
 5 files changed, 51 insertions(+), 4 deletions(-)

-- 
2.29.2.dirty