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author | Tony Lindgren <tony@atomide.com> | 2015-07-06 15:33:17 +0300 |
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committer | Tony Lindgren <tony@atomide.com> | 2015-07-06 15:33:17 +0300 |
commit | ae745302c0a3e2b5b768690f631fc14db44467e7 (patch) | |
tree | 1db4d210a7419286b447dc09fa7400a561d55f42 /Documentation/cpu-freq/intel-pstate.txt | |
parent | e3abe2556b2a689b28926cd1581f0b97e9d2afa4 (diff) | |
parent | 22a5dc10e3f8fb8370748ea19dc4e3e1620d8296 (diff) | |
download | linux-ae745302c0a3e2b5b768690f631fc14db44467e7.tar.xz |
Merge branch 'fixes-rc1' into omap-for-v4.2/fixes
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 655750743fb0..be8d4006bf76 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/ |