diff options
Diffstat (limited to 'Documentation/admin-guide')
-rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 5 | ||||
-rw-r--r-- | Documentation/admin-guide/pm/cpufreq.rst | 6 | ||||
-rw-r--r-- | Documentation/admin-guide/pm/intel_pstate.rst | 17 |
3 files changed, 24 insertions, 4 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index d35fd3ced0db..9e74ffd377f0 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -703,6 +703,11 @@ cpufreq.off=1 [CPU_FREQ] disable the cpufreq sub-system + cpufreq.default_governor= + [CPU_FREQ] Name of the default cpufreq governor or + policy to use. This governor must be registered in the + kernel before the cpufreq driver probes. + cpu_init_udelay=N [X86] Delay for N microsec between assert and de-assert of APIC INIT to start processors. This delay occurs diff --git a/Documentation/admin-guide/pm/cpufreq.rst b/Documentation/admin-guide/pm/cpufreq.rst index 0c74a7784964..368e612145d2 100644 --- a/Documentation/admin-guide/pm/cpufreq.rst +++ b/Documentation/admin-guide/pm/cpufreq.rst @@ -147,9 +147,9 @@ CPUs in it. The next major initialization step for a new policy object is to attach a scaling governor to it (to begin with, that is the default scaling governor -determined by the kernel configuration, but it may be changed later -via ``sysfs``). First, a pointer to the new policy object is passed to the -governor's ``->init()`` callback which is expected to initialize all of the +determined by the kernel command line or configuration, but it may be changed +later via ``sysfs``). First, a pointer to the new policy object is passed to +the governor's ``->init()`` callback which is expected to initialize all of the data structures necessary to handle the given policy and, possibly, to add a governor ``sysfs`` interface to it. Next, the governor is started by invoking its ``->start()`` callback. diff --git a/Documentation/admin-guide/pm/intel_pstate.rst b/Documentation/admin-guide/pm/intel_pstate.rst index 39d80bc29ccd..40d481cca368 100644 --- a/Documentation/admin-guide/pm/intel_pstate.rst +++ b/Documentation/admin-guide/pm/intel_pstate.rst @@ -431,6 +431,17 @@ argument is passed to the kernel in the command line. supported in the current configuration, writes to this attribute will fail with an appropriate error. +``energy_efficiency`` + This attribute is only present on platforms, which have CPUs matching + Kaby Lake or Coffee Lake desktop CPU model. By default + energy efficiency optimizations are disabled on these CPU models in HWP + mode by this driver. Enabling energy efficiency may limit maximum + operating frequency in both HWP and non HWP mode. In non HWP mode, + optimizations are done only in the turbo frequency range. In HWP mode, + optimizations are done in the entire frequency range. Setting this + attribute to "1" enables energy efficiency optimizations and setting + to "0" disables energy efficiency optimizations. + Interpretation of Policy Attributes ----------------------------------- @@ -554,7 +565,11 @@ somewhere between the two extremes: Strings written to the ``energy_performance_preference`` attribute are internally translated to integer values written to the processor's Energy-Performance Preference (EPP) knob (if supported) or its -Energy-Performance Bias (EPB) knob. +Energy-Performance Bias (EPB) knob. It is also possible to write a positive +integer value between 0 to 255, if the EPP feature is present. If the EPP +feature is not present, writing integer value to this attribute is not +supported. In this case, user can use + "/sys/devices/system/cpu/cpu*/power/energy_perf_bias" interface. [Note that tasks may by migrated from one CPU to another by the scheduler's load-balancing algorithm and if different energy vs performance hints are |