nto_power_range

Values for load threshold and delay for changing CPU frequency (operating point)

Synopsis:

#include <sys/neutrino.h>
struct nto_power_range {
    _Uint16t load;
    _Uint16t duration;
};

Data:

load
The load threshold, expressed as a percentage of maximum load at the current frequency, at which the kernel will move a CPU cluster to a different frequency.
duration
The number of milliseconds a CPU cluster must be at or beyond the threshold specified by load before the kernel will move it to a different frequency and deliver a sigevent to the power-management process.

Library:

libc

Description:

The nto_power_range data structure is meaningful only if the nto_power_parameter parameter_type member is set to _NTO_PPT_DEFINE_FREQ.

The value for load differs, depending on whether it is used for nto_power_parameter.u.freq.low or nto_power_parameter.u.freq.high:

  • low — the threshold at which the kernel will move the CPU cluster to a lower frequency, if possible, and deliver a sigevent to inform the power-management process of the operating point change.
  • high — the threshold at which the kernel will move the CPU cluster to a higher frequency, if possible, and deliver a sigevent to inform the power-management process of the operating point change.
Note:

For the purposes of power management (and, therefore, in this documentation) a CPU cluster isn't necessarily equivalent to a CPU cluster as defined in the SoC documentation for your board. It is simply a set of CPUs you create so you can manage their power characteristics together. A CPU cluster may include only a single CPU or multiple CPUs.

For more information, see Power Management in the Programmer's Guide.

Page updated: