This series demonstrates cpu frequency scaling via a simple policy
driven by the scheduler. Specifically the policy evaluates cpu frequency
when cpu utilization is updated from enqueue_task_fair and
dequeue_task_fair. The policy itself uses a simple up/down threshold
scheme using the same 80%/20% cpu utilization boundaries that are used
by default in the ondemand cpufreq governor.
This series is not intended for merging, but instead to ignite some
discussion around scheduler-driven cpu frequency selection. Of
particular interest to me is the policy itself and how it might
integrate with task placement in CFS's load_balance. Additionally I'd
like to ask the scheduler experts about which call sites in CFS are
right for evaluating cpu frequency selection; maybe
{en,de}queue_task_fair are not such a good idea?
The messiest part of this series is the cpumask stuff, where I tried to
track which cpus have updated statistics in the case of a sched_entity
which contains several other sched_entities that are spread across cpus.
As discussed at Linux Plumbers Conference 2014, I will replace this
complexity with simpler logic that ignores scheduler cgroups in the next
version. In any case I am posting the code I have now.
This code is experiemental and bugs are Guaranteed.
These patches are based on the scale invariance series from Morten[0].
The variables names in this RFC will doubtless change once that work is
rebased onto Vincent's series[1].
[0]
http://lkml.kernel.org/r/<1411403047-32010-1-git-send-email-morten.rasmus...@arm.com>
[1]
http://lkml.kernel.org/r/<1412684017-16595-1-git-send-email-vincent.guit...@linaro.org>
Mike Turquette (6):
sched: cfs: declare capacity_of in sched.h
sched: fair: add usage_util_of helper
cpufreq: add per-governor private data
sched: cfs: cpu frequency scaling arch functions
sched: cfs: cpu frequency scaling based on task placement
sched: energy_model: simple cpu frequency scaling policy
Morten Rasmussen (1):
sched: Make energy awareness a sched feature
drivers/cpufreq/Kconfig | 21 +++
include/linux/cpufreq.h | 6 +
kernel/sched/Makefile | 1 +
kernel/sched/energy_model.c | 341 ++++++++++++++++++++++++++++++++++++++++++++
kernel/sched/fair.c | 69 ++++++++-
kernel/sched/features.h | 6 +
kernel/sched/sched.h | 3 +
7 files changed, 445 insertions(+), 2 deletions(-)
create mode 100644 kernel/sched/energy_model.c
--
1.8.3.2
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