linux-kernel - [PATCH 0/6] arm, arm64: frequency- and cpu-invariant accounting support for task scheduler

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Date:   Thu,  8 Jun 2017 08:55:07 +0100
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-pm@...r.kernel.org, linux@....linux.org.uk,
        linux-arm-kernel@...ts.infradead.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Juri Lelli <juri.lelli@....com>,
        Vincent Guittot <vincent.guittot@...aor.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Morten Rasmussen <morten.rasmussen@....com>
Subject: [PATCH 0/6] arm, arm64: frequency- and cpu-invariant accounting support for task scheduler

For a more accurate (i.e. frequency- and cpu-invariant) load-tracking
the task scheduler needs a frequency-scaling and on a heterogeneous
system a cpu-scaling correction factor.

This patch-set implements a Frequency Invariance Engine (FIE)
(topology_get_freq_scale()) in drivers/base/arch_topology.c to provide
a frequency-scaling correction factor.

The Cpu Invariance Engine (CIE) (topology_get_cpu_scale()) providing a
cpu-scaling correction factor was already introduced by the "Fix issues
and factorize arm/arm64 capacity information code" patch-set [1].

This patch-set also enables the frequency- and cpu-invariant accounting
support. Enabling here means to associate (wire) the task scheduler
cname arch_scale_freq_capacity and arch_scale_cpu_capacity with the FIE
and CIE function names from drivers/base/arch_topology.c. This replaces
the task scheduler's default FIE and CIE in kernel/sched/sched.h.

Patch high level description:

 [   01/06] Rework cpufreq policy notifier for frequency-invariant
            accounting support
 [   02/06] Frequency Invariance Engine (FIE)
 [03,04/06] Enable frequency- and cpu-invariant accounting support on
            arm
 [05,06/06] Enable frequency- and cpu-invariant accounting support on
            arm64

The patch-set is based on top of linux-next/master (tag: next-20170607)
and it is also available from:

 git://linux-arm.org/linux-de.git upstream/freq_and_cpu_inv

It has been tested on TC2 (arm) and JUNO (arm64) by running a ramp-up
rt-app task pinned to a cpu with the ondemand cpufreq governor and
checking the load-tracking signals of this task.

[1] https://marc.info/?l=linux-kernel&m=149625018223002&w=2

Dietmar Eggemann (6):
  drivers base/arch_topology: prepare cpufreq policy notifier for
    frequency-invariant load-tracking support
  drivers base/arch_topology: frequency-invariant load-tracking support
  arm: wire frequency-invariant accounting support up to the task
    scheduler
  arm: wire cpu-invariant accounting support up to the task scheduler
  arm64: wire frequency-invariant accounting support up to the task
    scheduler
  arm64: wire cpu-invariant accounting support up to the task scheduler

 arch/arm/include/asm/topology.h   |  8 +++++
 arch/arm/kernel/topology.c        |  1 -
 arch/arm64/include/asm/topology.h |  8 +++++
 arch/arm64/kernel/topology.c      |  1 -
 drivers/base/arch_topology.c      | 64 ++++++++++++++++++++++++++++++++++-----
 include/linux/arch_topology.h     |  2 ++
 6 files changed, 75 insertions(+), 9 deletions(-)

-- 
2.11.0