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| author | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2015-09-08 01:01:14 -0300 |
|---|---|---|
| committer | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2015-09-08 01:01:14 -0300 |
| commit | e5fd91f1ef340da553f7a79da9540c3db711c937 (patch) | |
| tree | b11842027dc6641da63f4bcc524f8678263304a3 /Documentation/cpu-freq/intel-pstate.txt | |
| parent | 2a9b0348e685a63d97486f6749622b61e9e3292f (diff) | |
Linux-libre 4.2-gnu
Diffstat (limited to 'Documentation/cpu-freq/intel-pstate.txt')
| -rw-r--r-- | Documentation/cpu-freq/intel-pstate.txt | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/Documentation/cpu-freq/intel-pstate.txt b/Documentation/cpu-freq/intel-pstate.txt index 655750743..be8d4006b 100644 --- a/Documentation/cpu-freq/intel-pstate.txt +++ b/Documentation/cpu-freq/intel-pstate.txt @@ -3,24 +3,25 @@ Intel P-state driver This driver provides an interface to control the P state selection for SandyBridge+ Intel processors. The driver can operate two different -modes based on the processor model legacy and Hardware P state (HWP) +modes based on the processor model, legacy mode and Hardware P state (HWP) mode. -In legacy mode the driver implements a scaling driver with an internal -governor for Intel Core processors. The driver follows the same model -as the Transmeta scaling driver (longrun.c) and implements the -setpolicy() instead of target(). Scaling drivers that implement -setpolicy() are assumed to implement internal governors by the cpufreq -core. All the logic for selecting the current P state is contained -within the driver; no external governor is used by the cpufreq core. +In legacy mode, the Intel P-state implements two internal governors, +performance and powersave, that differ from the general cpufreq governors of +the same name (the general cpufreq governors implement target(), whereas the +internal Intel P-state governors implement setpolicy()). The internal +performance governor sets the max_perf_pct and min_perf_pct to 100; that is, +the governor selects the highest available P state to maximize the performance +of the core. The internal powersave governor selects the appropriate P state +based on the current load on the CPU. In HWP mode P state selection is implemented in the processor itself. The driver provides the interfaces between the cpufreq core and the processor to control P state selection based on user preferences and reporting frequency to the cpufreq core. In this mode the -internal governor code is disabled. +internal Intel P-state governor code is disabled. -In addtion to the interfaces provided by the cpufreq core for +In addition to the interfaces provided by the cpufreq core for controlling frequency the driver provides sysfs files for controlling P state selection. These files have been added to /sys/devices/system/cpu/intel_pstate/ |