linux-kernel - [PATCH V5 0/2] cpufreq: cppc: Add support for frequency invariance

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Date:   Mon,  1 Mar 2021 12:21:16 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Rafael Wysocki <rjw@...ysocki.net>,
        Ben Segall <bsegall@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Mel Gorman <mgorman@...e.de>,
        Peter Zijlstra <peterz@...radead.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Will Deacon <will@...nel.org>
Cc:     linux-pm@...r.kernel.org,
        Ionela Voinescu <ionela.voinescu@....com>,
        linux-acpi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH V5 0/2] cpufreq: cppc: Add support for frequency invariance

Hello,

CPPC cpufreq driver is used for ARM servers and this patch series tries
to provide counter-based frequency invariance support for them in the
absence for architecture specific counters (like AMUs).

This is tested by:
- /me with some hacks on Hikey, as I didn't have access to the right
  hardware.

- Vincent Guittot on ThunderX2, only initial testing done.

- Ionela Voinescu on Juno R2, though she tested a previous version of
  this.


This is based of 5.12-rc1.

Changes since V4:
- Move some code to policy specific initialization for cppc driver.
- Initialize kthread specific stuff only once in cppc driver.
- Added a kerneldoc comment in cppc driver and improved changelog as
  well.

Changes since V3:
- rebuild_sched_domains_energy() stuff moved from arm64 to drivers/base.
- Added Reviewed/Tested-by Ionela for the first patch.
- Remove unused max_freq field from structure in cppc driver.
- s/cppc_f_i/cppc_freq_inv.
- Fix an per-cpu access, there was a bug in earlier version.
- Create a single kthread which can run on any CPU and takes care of
  work from all the CPUs.
- Do the whole FIE thing under a new CONFIG option for cppc driver.
- Few minor improvements.

Changes since V2:
- Not sending as an RFC anymore.
- Several renames, reordering of code in 1/2 based on Ionela's comments.
- Several rebase changes for 2/2.
- The freq_scale calculations are optimized a bit.
- Better overall commenting and commit logs.

Changes since V1:
- The interface for setting the callbacks is improved, so different
  parts looking to provide their callbacks don't need to think about
  each other.

- Moved to per-cpu storage for storing the callback related data, AMU
  counters have higher priority with this.

--
viresh

Viresh Kumar (2):
  topology: Allow multiple entities to provide sched_freq_tick()
    callback
  cpufreq: CPPC: Add support for frequency invariance

 arch/arm64/include/asm/topology.h |  10 +-
 arch/arm64/kernel/topology.c      | 105 +++++--------
 drivers/base/arch_topology.c      |  85 ++++++++++-
 drivers/cpufreq/Kconfig.arm       |   9 ++
 drivers/cpufreq/cppc_cpufreq.c    | 244 ++++++++++++++++++++++++++++--
 include/linux/arch_topology.h     |  15 +-
 kernel/sched/core.c               |   1 +
 7 files changed, 377 insertions(+), 92 deletions(-)


base-commit: fe07bfda2fb9cdef8a4d4008a409bb02f35f1bd8
-- 
2.25.0.rc1.19.g042ed3e048af