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linux/drivers/cpufreq/Kconfig
Steve Muckle 6bc6115c16 BACKPORT: cpufreq: schedutil: New governor based on scheduler utilization data 
Add a new cpufreq scaling governor, called "schedutil", that uses
scheduler-provided CPU utilization information as input for making
its decisions.

Doing that is possible after commit 34e2c55 (cpufreq: Add
mechanism for registering utilization update callbacks) that
introduced cpufreq_update_util() called by the scheduler on
utilization changes (from CFS) and RT/DL task status updates.
In particular, CPU frequency scaling decisions may be based on
the the utilization data passed to cpufreq_update_util() by CFS.

The new governor is relatively simple.

The frequency selection formula used by it depends on whether or not
the utilization is frequency-invariant.  In the frequency-invariant
case the new CPU frequency is given by

	next_freq = 1.25 * max_freq * util / max

where util and max are the last two arguments of cpufreq_update_util().
In turn, if util is not frequency-invariant, the maximum frequency in
the above formula is replaced with the current frequency of the CPU:

	next_freq = 1.25 * curr_freq * util / max

The coefficient 1.25 corresponds to the frequency tipping point at
(util / max) = 0.8.

All of the computations are carried out in the utilization update
handlers provided by the new governor.  One of those handlers is
used for cpufreq policies shared between multiple CPUs and the other
one is for policies with one CPU only (and therefore it doesn't need
to use any extra synchronization means).

The governor supports fast frequency switching if that is supported
by the cpufreq driver in use and possible for the given policy.
In the fast switching case, all operations of the governor take
place in its utilization update handlers.  If fast switching cannot
be used, the frequency switch operations are carried out with the
help of a work item which only calls __cpufreq_driver_target()
(under a mutex) to trigger a frequency update (to a value already
computed beforehand in one of the utilization update handlers).

Currently, the governor treats all of the RT and DL tasks as
"unknown utilization" and sets the frequency to the allowed
maximum when updated from the RT or DL sched classes.  That
heavy-handed approach should be replaced with something more
subtle and specifically targeted at RT and DL tasks.

The governor shares some tunables management code with the
"ondemand" and "conservative" governors and uses some common
definitions from cpufreq_governor.h, but apart from that it
is stand-alone.

Change-Id: I03876e622768e4b3ee4dc28682af7cce771f2f4c
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
(cherry-picked from 9bdcb44e39)
[ Backport the schedutil cpufreq governor from 4.9. Some cpufreq
  tunable infrastructure as well as the resolve_freq API is also
  backported as those are dependencies]
Signed-off-by: Steve Muckle <smuckle@linaro.org>
[trivial cherry-picking fixes]
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
[fixed default governor machinery]
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
2017-06-02 08:01:50 -07:00

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menu "CPU Frequency scaling"
config CPU_FREQ
bool "CPU Frequency scaling"
select SRCU
help
CPU Frequency scaling allows you to change the clock speed of
CPUs on the fly. This is a nice method to save power, because
the lower the CPU clock speed, the less power the CPU consumes.
Note that this driver doesn't automatically change the CPU
clock speed, you need to either enable a dynamic cpufreq governor
(see below) after boot, or use a userspace tool.
For details, take a look at <file:Documentation/cpu-freq>.
If in doubt, say N.
if CPU_FREQ
config CPU_FREQ_GOV_COMMON
bool
config CPU_FREQ_BOOST_SW
bool
depends on THERMAL
config CPU_FREQ_STAT
tristate "CPU frequency translation statistics"
default y
help
This driver exports CPU frequency statistics information through sysfs
file system.
To compile this driver as a module, choose M here: the
module will be called cpufreq_stats.
If in doubt, say N.
config CPU_FREQ_STAT_DETAILS
bool "CPU frequency translation statistics details"
depends on CPU_FREQ_STAT
help
This will show detail CPU frequency translation table in sysfs file
system.
If in doubt, say N.
choice
prompt "Default CPUFreq governor"
default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1100_CPUFREQ || ARM_SA1110_CPUFREQ
default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
help
This option sets which CPUFreq governor shall be loaded at
startup. If in doubt, select 'performance'.
config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
bool "performance"
select CPU_FREQ_GOV_PERFORMANCE
help
Use the CPUFreq governor 'performance' as default. This sets
the frequency statically to the highest frequency supported by
the CPU.
config CPU_FREQ_DEFAULT_GOV_POWERSAVE
bool "powersave"
select CPU_FREQ_GOV_POWERSAVE
help
Use the CPUFreq governor 'powersave' as default. This sets
the frequency statically to the lowest frequency supported by
the CPU.
config CPU_FREQ_DEFAULT_GOV_USERSPACE
bool "userspace"
select CPU_FREQ_GOV_USERSPACE
help
Use the CPUFreq governor 'userspace' as default. This allows
you to set the CPU frequency manually or when a userspace
program shall be able to set the CPU dynamically without having
to enable the userspace governor manually.
config CPU_FREQ_DEFAULT_GOV_ONDEMAND
bool "ondemand"
select CPU_FREQ_GOV_ONDEMAND
select CPU_FREQ_GOV_PERFORMANCE
help
Use the CPUFreq governor 'ondemand' as default. This allows
you to get a full dynamic frequency capable system by simply
loading your cpufreq low-level hardware driver.
Be aware that not all cpufreq drivers support the ondemand
governor. If unsure have a look at the help section of the
driver. Fallback governor will be the performance governor.
config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
bool "conservative"
select CPU_FREQ_GOV_CONSERVATIVE
select CPU_FREQ_GOV_PERFORMANCE
help
Use the CPUFreq governor 'conservative' as default. This allows
you to get a full dynamic frequency capable system by simply
loading your cpufreq low-level hardware driver.
Be aware that not all cpufreq drivers support the conservative
governor. If unsure have a look at the help section of the
driver. Fallback governor will be the performance governor.
config CPU_FREQ_DEFAULT_GOV_INTERACTIVE
bool "interactive"
select CPU_FREQ_GOV_INTERACTIVE
help
Use the CPUFreq governor 'interactive' as default. This allows
you to get a full dynamic cpu frequency capable system by simply
loading your cpufreq low-level hardware driver, using the
'interactive' governor for latency-sensitive workloads.
config CPU_FREQ_DEFAULT_GOV_SCHED
bool "sched"
select CPU_FREQ_GOV_SCHED
help
Use the CPUfreq governor 'sched' as default. This scales
cpu frequency using CPU utilization estimates from the
scheduler.
config CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
bool "schedutil"
depends on SMP
select CPU_FREQ_GOV_SCHEDUTIL
select CPU_FREQ_GOV_PERFORMANCE
help
Use the 'schedutil' CPUFreq governor by default. If unsure,
have a look at the help section of that governor. The fallback
governor will be 'performance'.
endchoice
config CPU_FREQ_GOV_PERFORMANCE
tristate "'performance' governor"
help
This cpufreq governor sets the frequency statically to the
highest available CPU frequency.
To compile this driver as a module, choose M here: the
module will be called cpufreq_performance.
If in doubt, say Y.
config CPU_FREQ_GOV_POWERSAVE
tristate "'powersave' governor"
help
This cpufreq governor sets the frequency statically to the
lowest available CPU frequency.
To compile this driver as a module, choose M here: the
module will be called cpufreq_powersave.
If in doubt, say Y.
config CPU_FREQ_GOV_USERSPACE
tristate "'userspace' governor for userspace frequency scaling"
help
Enable this cpufreq governor when you either want to set the
CPU frequency manually or when a userspace program shall
be able to set the CPU dynamically, like on LART
<http://www.lartmaker.nl/>.
To compile this driver as a module, choose M here: the
module will be called cpufreq_userspace.
For details, take a look at <file:Documentation/cpu-freq/>.
If in doubt, say Y.
config CPU_FREQ_GOV_ONDEMAND
tristate "'ondemand' cpufreq policy governor"
select CPU_FREQ_GOV_COMMON
help
'ondemand' - This driver adds a dynamic cpufreq policy governor.
The governor does a periodic polling and
changes frequency based on the CPU utilization.
The support for this governor depends on CPU capability to
do fast frequency switching (i.e, very low latency frequency
transitions).
To compile this driver as a module, choose M here: the
module will be called cpufreq_ondemand.
For details, take a look at linux/Documentation/cpu-freq.
If in doubt, say N.
config CPU_FREQ_GOV_INTERACTIVE
bool "'interactive' cpufreq policy governor"
help
'interactive' - This driver adds a dynamic cpufreq policy governor
designed for latency-sensitive workloads.
This governor attempts to reduce the latency of clock
increases so that the system is more responsive to
interactive workloads.
For details, take a look at linux/Documentation/cpu-freq.
If in doubt, say N.
config CPU_FREQ_GOV_CONSERVATIVE
tristate "'conservative' cpufreq governor"
depends on CPU_FREQ
select CPU_FREQ_GOV_COMMON
help
'conservative' - this driver is rather similar to the 'ondemand'
governor both in its source code and its purpose, the difference is
its optimisation for better suitability in a battery powered
environment. The frequency is gracefully increased and decreased
rather than jumping to 100% when speed is required.
If you have a desktop machine then you should really be considering
the 'ondemand' governor instead, however if you are using a laptop,
PDA or even an AMD64 based computer (due to the unacceptable
step-by-step latency issues between the minimum and maximum frequency
transitions in the CPU) you will probably want to use this governor.
To compile this driver as a module, choose M here: the
module will be called cpufreq_conservative.
For details, take a look at linux/Documentation/cpu-freq.
If in doubt, say N.
config CPU_FREQ_GOV_SCHED
bool "'sched' cpufreq governor"
depends on CPU_FREQ
depends on SMP
select CPU_FREQ_GOV_COMMON
help
'sched' - this governor scales cpu frequency from the
scheduler as a function of cpu capacity utilization. It does
not evaluate utilization on a periodic basis (as ondemand
does) but instead is event-driven by the scheduler.
If in doubt, say N.
config CPU_FREQ_GOV_SCHEDUTIL
bool "'schedutil' cpufreq policy governor"
depends on CPU_FREQ && SMP
select CPU_FREQ_GOV_ATTR_SET
select IRQ_WORK
help
This governor makes decisions based on the utilization data provided
by the scheduler. It sets the CPU frequency to be proportional to
the utilization/capacity ratio coming from the scheduler. If the
utilization is frequency-invariant, the new frequency is also
proportional to the maximum available frequency. If that is not the
case, it is proportional to the current frequency of the CPU. The
frequency tipping point is at utilization/capacity equal to 80% in
both cases.
If in doubt, say N.
comment "CPU frequency scaling drivers"
config CPUFREQ_DT
tristate "Generic DT based cpufreq driver"
depends on HAVE_CLK && OF
# if CPU_THERMAL is on and THERMAL=m, CPUFREQ_DT cannot be =y:
depends on !CPU_THERMAL || THERMAL
select PM_OPP
help
This adds a generic DT based cpufreq driver for frequency management.
It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
systems which share clock and voltage across all CPUs.
If in doubt, say N.
if X86
source "drivers/cpufreq/Kconfig.x86"
endif
if ARM || ARM64
source "drivers/cpufreq/Kconfig.arm"
endif
if PPC32 || PPC64
source "drivers/cpufreq/Kconfig.powerpc"
endif
if AVR32
config AVR32_AT32AP_CPUFREQ
bool "CPU frequency driver for AT32AP"
depends on PLATFORM_AT32AP
default n
help
This enables the CPU frequency driver for AT32AP processors.
If in doubt, say N.
endif
if IA64
config IA64_ACPI_CPUFREQ
tristate "ACPI Processor P-States driver"
depends on ACPI_PROCESSOR
help
This driver adds a CPUFreq driver which utilizes the ACPI
Processor Performance States.
For details, take a look at <file:Documentation/cpu-freq/>.
If in doubt, say N.
endif
if MIPS
config LOONGSON2_CPUFREQ
tristate "Loongson2 CPUFreq Driver"
help
This option adds a CPUFreq driver for loongson processors which
support software configurable cpu frequency.
Loongson2F and it's successors support this feature.
For details, take a look at <file:Documentation/cpu-freq/>.
If in doubt, say N.
config LOONGSON1_CPUFREQ
tristate "Loongson1 CPUFreq Driver"
help
This option adds a CPUFreq driver for loongson1 processors which
support software configurable cpu frequency.
For details, take a look at <file:Documentation/cpu-freq/>.
If in doubt, say N.
endif
if SPARC64
config SPARC_US3_CPUFREQ
tristate "UltraSPARC-III CPU Frequency driver"
help
This adds the CPUFreq driver for UltraSPARC-III processors.
For details, take a look at <file:Documentation/cpu-freq>.
If in doubt, say N.
config SPARC_US2E_CPUFREQ
tristate "UltraSPARC-IIe CPU Frequency driver"
help
This adds the CPUFreq driver for UltraSPARC-IIe processors.
For details, take a look at <file:Documentation/cpu-freq>.
If in doubt, say N.
endif
if SUPERH
config SH_CPU_FREQ
tristate "SuperH CPU Frequency driver"
help
This adds the cpufreq driver for SuperH. Any CPU that supports
clock rate rounding through the clock framework can use this
driver. While it will make the kernel slightly larger, this is
harmless for CPUs that don't support rate rounding. The driver
will also generate a notice in the boot log before disabling
itself if the CPU in question is not capable of rate rounding.
For details, take a look at <file:Documentation/cpu-freq>.
If unsure, say N.
endif
config QORIQ_CPUFREQ
tristate "CPU frequency scaling driver for Freescale QorIQ SoCs"
depends on OF && COMMON_CLK && (PPC_E500MC || ARM)
select CLK_QORIQ
help
This adds the CPUFreq driver support for Freescale QorIQ SoCs
which are capable of changing the CPU's frequency dynamically.
endif
endmenu
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