Based on kernel version 3.15.4. Page generated on 2014-07-07 09:00 EST.
1 Intel P-state driver 2 -------------------- 3 4 This driver implements a scaling driver with an internal governor for 5 Intel Core processors. The driver follows the same model as the 6 Transmeta scaling driver (longrun.c) and implements the setpolicy() 7 instead of target(). Scaling drivers that implement setpolicy() are 8 assumed to implement internal governors by the cpufreq core. All the 9 logic for selecting the current P state is contained within the 10 driver; no external governor is used by the cpufreq core. 11 12 Intel SandyBridge+ processors are supported. 13 14 New sysfs files for controlling P state selection have been added to 15 /sys/devices/system/cpu/intel_pstate/ 16 17 max_perf_pct: limits the maximum P state that will be requested by 18 the driver stated as a percentage of the available performance. 19 20 min_perf_pct: limits the minimum P state that will be requested by 21 the driver stated as a percentage of the available performance. 22 23 no_turbo: limits the driver to selecting P states below the turbo 24 frequency range. 25 26 For contemporary Intel processors, the frequency is controlled by the 27 processor itself and the P-states exposed to software are related to 28 performance levels. The idea that frequency can be set to a single 29 frequency is fiction for Intel Core processors. Even if the scaling 30 driver selects a single P state the actual frequency the processor 31 will run at is selected by the processor itself. 32 33 New debugfs files have also been added to /sys/kernel/debug/pstate_snb/ 34 35 deadband 36 d_gain_pct 37 i_gain_pct 38 p_gain_pct 39 sample_rate_ms 40 setpoint