[PATCH 0/2] cpufreq: Use sorted frequency tables

[Viresh Kumar <viresh.kumar@linaro.org>]

Hi Guys,

This work in inspired by some of the concerns raised by Steve in one of
his patchset.

Currently, the cpufreq drivers aren't required to provide a sorted list
of frequencies to the cpufreq-core and so traversing that list match a
target frequency is very inefficient.

This is not bearable by, for example, the fast-switch path of schedutil
governor and so we have moved the traversing logic local to the
acpi-cpufreq driver for now. That is better handled in the core, but it
has to be efficient.

OTOH, even for traditional governors without a fast-switch path, it
would be much better to be able to traverse this table quickly.

The ideal solution would be to keep a single freq-table in struct
cpufreq_policy, that will be sorted as well. But there are few
dependencies due to which it can't be done today (Hint: cpufreq drivers
are abusing the 'index' passed to them, to refer to multiple arrays).

And so for now, lets create a separate table local to the cpufreq-core
only.

To use that, another API cpufreq_find_target_index() is created as well
and few users are migrated to it.

Lightly tested on Exynos board, frequencies were getting selected as
expected.

--
viresh

Viresh Kumar (2):
  cpufreq: Store sorted frequency table
  cpufreq: Implement cpufreq_find_target_index() to traverse sorted list

 drivers/cpufreq/acpi-cpufreq.c |  18 ++--
 drivers/cpufreq/cpufreq.c      |  48 ++++++-----
 drivers/cpufreq/freq_table.c   | 191 +++++++++++++++++++++++++++++++++++++++++
 include/linux/cpufreq.h        |   7 ++
 4 files changed, 231 insertions(+), 33 deletions(-)

-- 
2.7.1.410.g6faf27b