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
