diff options
Diffstat (limited to 'Documentation/admin-guide/pm')
| -rw-r--r-- | Documentation/admin-guide/pm/cpufreq.rst | 6 | ||||
| -rw-r--r-- | Documentation/admin-guide/pm/intel-speed-select.rst | 4 | ||||
| -rw-r--r-- | Documentation/admin-guide/pm/intel_pstate.rst | 19 |
3 files changed, 22 insertions, 7 deletions
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-speed-select.rst b/Documentation/admin-guide/pm/intel-speed-select.rst index b2ca601c21c6..219f1359aac7 100644 --- a/Documentation/admin-guide/pm/intel-speed-select.rst +++ b/Documentation/admin-guide/pm/intel-speed-select.rst @@ -114,7 +114,7 @@ base performance profile (which is performance level 0). Lock/Unlock status ~~~~~~~~~~~~~~~~~~ -Even if there are multiple performance profiles, it is possible that that they +Even if there are multiple performance profiles, it is possible that they are locked. If they are locked, users cannot issue a command to change the performance state. It is possible that there is a BIOS setup to unlock or check with your system vendor. @@ -883,7 +883,7 @@ To enable Intel(R) SST-TF, execute:: enable:success In this case, the option "-a" is optional. If set, it enables Intel(R) SST-TF -feature and also sets the CPUs to high and and low priority using Intel Speed +feature and also sets the CPUs to high and low priority using Intel Speed Select Technology Core Power (Intel(R) SST-CP) features. The CPU numbers passed with "-c" arguments are marked as high priority, including its siblings. diff --git a/Documentation/admin-guide/pm/intel_pstate.rst b/Documentation/admin-guide/pm/intel_pstate.rst index 39d80bc29ccd..9db924904d2c 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 @@ -708,7 +723,7 @@ core (for the policies with other scaling governors). The ``ftrace`` interface can be used for low-level diagnostics of ``intel_pstate``. For example, to check how often the function to set a -P-state is called, the ``ftrace`` filter can be set to to +P-state is called, the ``ftrace`` filter can be set to :c:func:`intel_pstate_set_pstate`:: # cd /sys/kernel/debug/tracing/ |