[PATCH v4 0/7] consolidate and cleanup CPU capacity

Vincent Guittot
2023-10-27T08:04:09Z

This is the 1st part of consolidating how the max compute capacity is
used in the scheduler and how we calculate the frequency for a level of
utilization.

Fix some unconsistancy when computing frequency for an utilization. There
can be a mismatch between energy model and schedutil.

Next step will be to make a difference between the original
max compute capacity of a CPU and what is currently available when
there is a capping applying forever (i.e. seconds or more).

Changes since v3:
- Split patch 5 cpufreq/cppc
- Fix topology_init_cpu_capacity_cppc()
- Fix init if AMU ratio
- Added some tags

Changes since v2:
- Remove the 1st patch which has been queued in tip
- Rework how to initialize the reference frequency for cppc_cpufreq and
change topology_init_cpu_capacity_cppc() to also set capacity_ref_freq
- Add a RFC to convert AMU to use arch_scale_freq_ref and move the config
of the AMU ratio to be done when intializing cpu capacity and
capacity_ref_freq
- Added some tags

Changes since v1:
- Fix typos
- Added changes in cpufreq to use arch_scale_freq_ref() when calling
arch_set_freq_scale (patch 3).
- arch_scale_freq_ref() is always defined and returns 0 (as proposed
by Ionela) when not defined by the arch. This simplifies the code with
the addition of patch 3.
- Simplify Energy Model which always uses arch_scale_freq_ref(). The
latter returns 0 when not defined by arch instead of last item of the
perf domain. This is not a problem because the function is only defined
for compilation purpose in this case and we don't care about the
returned value. (patch 5)
- Added changes in cppc cpufreq to set capacity_ref_freq (patch 6)
- Added reviewed tag for patch 1 which got a minor change but not for
others as I did some changes which could make previous reviewed tag
no more relevant.

Vincent Guittot (7):
topology: add a new arch_scale_freq_reference
cpufreq: use the fixed and coherent frequency for scaling capacity
cpufreq/schedutil: use a fixed reference frequency
energy_model: use a fixed reference frequency
cpufreq/cppc: move and rename cppc_cpufreq_{perf_to_khz|khz_to_perf}
cpufreq/cppc: set the frequency used for computing the capacity
arm64/amu: use capacity_ref_freq to set AMU ratio

arch/arm/include/asm/topology.h | 1 +
arch/arm64/include/asm/topology.h | 1 +
arch/arm64/kernel/topology.c | 26 +++---
arch/riscv/include/asm/topology.h | 1 +
drivers/acpi/cppc_acpi.c | 93 +++++++++++++++++++++
drivers/base/arch_topology.c | 55 ++++++++----
drivers/cpufreq/cppc_cpufreq.c | 134 ++++--------------------------
drivers/cpufreq/cpufreq.c | 4 +-
include/acpi/cppc_acpi.h | 2 +
include/linux/arch_topology.h | 8 ++
include/linux/cpufreq.h | 9 ++
include/linux/energy_model.h | 14 +++-
kernel/sched/cpufreq_schedutil.c | 26 +++++-
13 files changed, 221 insertions(+), 153 deletions(-)

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2.34.1