linux-kernel - Re: [PATCH v6 0/7] consolidate and cleanup CPU capacity

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Message-ID: <00ce01bf-1612-46cd-926d-ac283cfddff9@arm.com>
Date:   Fri, 10 Nov 2023 09:30:47 +0100
From:   Pierre Gondois <pierre.gondois@....com>
To:     Vincent Guittot <vincent.guittot@...aro.org>,
        linux@...linux.org.uk, catalin.marinas@....com, will@...nel.org,
        paul.walmsley@...ive.com, palmer@...belt.com,
        aou@...s.berkeley.edu, sudeep.holla@....com,
        gregkh@...uxfoundation.org, rafael@...nel.org, mingo@...hat.com,
        peterz@...radead.org, juri.lelli@...hat.com,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, bristot@...hat.com, vschneid@...hat.com,
        viresh.kumar@...aro.org, lenb@...nel.org, robert.moore@...el.com,
        lukasz.luba@....com, ionela.voinescu@....com,
        beata.michalska@....com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-pm@...r.kernel.org, linux-acpi@...r.kernel.org
Cc:     conor.dooley@...rochip.com, suagrfillet@...il.com,
        ajones@...tanamicro.com, lftan@...nel.org
Subject: Re: [PATCH v6 0/7] consolidate and cleanup CPU capacity

For a CPPC platform + EM/EAS (but without AMU):
Tested-by: Pierre Gondois <pierre.gondois@....com>

On 11/9/23 11:14, Vincent Guittot wrote:
> 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 v5:
> - remove useless return in freq_inv_set_max_ratio()
> - Add tags
> 
> Changes since v4:
> - Capitalize the verb in subject
> - Remove usless parentheses in cppc_get_dmi_max_khz()
> - Use freq_ref pattern everywhere
> - Fix MHz / kHz units conversion for cppc_cpufreq
> - Move default definition of arch_scale_freq_ref() in
>    include/linux/sched/topology.h beside arch_scale_cpu_capacity
>    which faces similar default declaration behavior. This location covers
>    all cases with arch and CONFIG_* which was not the case with previous
>    attempts.
> 
> 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          | 104 ++++++++++++++++++++++
>   drivers/base/arch_topology.c      |  56 ++++++++----
>   drivers/cpufreq/cppc_cpufreq.c    | 139 ++++--------------------------
>   drivers/cpufreq/cpufreq.c         |   4 +-
>   include/acpi/cppc_acpi.h          |   2 +
>   include/linux/arch_topology.h     |   8 ++
>   include/linux/cpufreq.h           |   1 +
>   include/linux/energy_model.h      |   6 +-
>   include/linux/sched/topology.h    |   8 ++
>   kernel/sched/cpufreq_schedutil.c  |  26 +++++-
>   14 files changed, 224 insertions(+), 159 deletions(-)
>