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(-)