APERF(4)

NAME
aperf - driver measuring effective CPU frequency via APERF/MPERF MSRs

SYNOPSIS
To compile this driver into the kernel, place the following lines in your kernel configuration file:

device aperf

Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):

    aperf_load="YES"

DESCRIPTION
The aperf driver provides support for measuring the effective CPU frequency, using the APERF and MPERF MSRs. The values are exposed through the HW_SENSORS sysctl(3) tree. For example:

    % sysctl hw.sensors
    hw.sensors.cpu0.freq0: 2684298000 Hz (cpu0 freq)
    hw.sensors.cpu1.freq0: 1418960000 Hz (cpu1 freq)
    hw.sensors.cpu2.freq0: 1234898000 Hz (cpu2 freq)
    hw.sensors.cpu3.freq0: 1242533000 Hz (cpu3 freq)

HARDWARE
The aperf driver supports all AMD and Intel CPUs which provide the APERF and MPERF MSRs:

•   Most AMD CPUs starting at Family 10h
•   Most Intel CPUs starting from Core series and Atom respectively.

SEE ALSO
systat(1), sysctl(3), sensorsd(8), sysctl(8)

HISTORY
The aperf driver first appeared in DragonFly 4.3.

AUTHORS
-nosplit The aperf driver was written by Imre Vadasz <imre@vdsz.com>.