Re: [PATCH v4 0/7] cpufreq:boost: CPU Boost mode support

Lukasz Majewski
2013-06-26T07:48:23Z

Hi Viresh,

> This patch series introduces support for CPU overclocking technique
> called Boost.
>
> It is a follow up of a LAB governor proposal. Boost is a LAB
> component:
> http://thread.gmane.org/gmane.linux.kernel/1484746/match=cpufreq
>
> Boost unifies hardware based solution (e.g. Intel Nehalem) with
> software oriented one (like the one done at Exynos).
> For this reason cpufreq/freq_table code has been reorganized to
> include common code.
>
> Important design decisions:
>
> - Boost related code is compiled-in unconditionally and disabled by
> default The cpufreq_driver is responsibile for setting
> boost_supported flag and providing enable_boost callback(if HW
> support is needed)
>
> - struct cpufreq_driver has been extended with boost related fields:
> -- boost_supported - when driver supports boosting
> -- enable_boost - callback to function, which is necessary to
> enable boost in the processor (like it is done at Intel)
>
> - Boost sysfs attribute (/sys/devices/system/cpu/cpufreq/boost) is
> always provided.
> It will be read only, until either cpufreq_driver defines
> boost_supported flag or device tree's cpufreq "boost_mode" attribute
> is defined. It is consistent with legacy acpi API.
>
> - No special spin_lock for Boost was created. The one from cpufreq
> core was reused.
>
> - All available policies are now stored in a list.
>
> - The Boost code doesn't rely on any policy. When boost state is
> changed, then the policy list is iterated and proper adjustements are
> done.
>
> - Number of busy cpus (with load > 90%) is calculated and exported as
> a global sysfs attribute.
>
> - The SW based boost can be only enabled when up to one core is
> regarded as a "busy" one. For safety reasons boost is disabled when
> more cores comes into play.
>
> - To improve safety level, the thermal framework is also extended to
> disable software boosting, when thermal trip point is reached.
>
> New patches for v4:
> cpufreq: Store cpufreq policies in a list
> cpufreq: Calculate number of busy CPUs
> cpufreq: Enable software boost only when up to one busy core is
> running thermal:boost: Disable boost when trip point is reached
>
> Tested at: HW:
> Exynos 4412 3.10 linux
> Exynos 4210 3.10 linux
> Compile tested x86_64 defconfig (acpi) - help with HW (Intel Nehalem)
> test needed
>

If this is not a problem, I'd like to kindly ask You to review those
patches.

Rafael has expressed his opinion about "boost" attribute clearly at the
other mail (as a response to v4 patches):
"Simple: Export it only when supported."

Despite the change about the "boost" attribute visibility there were
many other changes, which deserve maintainer's look.

>
> Lukasz Majewski (7):
> cpufreq: Store cpufreq policies in a list
> cpufreq: Add boost frequency support in core
> cpufreq:acpi:x86: Adjust the acpi-cpufreq.c code to work with common
> boost solution
> cpufreq:exynos:Extend Exynos cpufreq driver to support boost
> framework
> cpufreq: Calculate number of busy CPUs
> cpufreq: Enable software boost only when up to one busy core is
> running
> thermal:boost: Disable boost when trip point is reached
>
> drivers/cpufreq/acpi-cpufreq.c | 61 ++++++-----------
> drivers/cpufreq/cpufreq.c | 132
> ++++++++++++++++++++++++++++++++++++
> drivers/cpufreq/cpufreq_governor.c | 4 ++
> drivers/cpufreq/exynos-cpufreq.c | 4 ++
> drivers/cpufreq/freq_table.c | 43 ++++++++++--
> drivers/thermal/cpu_cooling.c | 3 +
> include/linux/cpufreq.h | 15 ++++ 7 files changed, 215
> insertions(+), 47 deletions(-)
>

--
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group