CPU(4)                OpenBSD Programmer's Manual (AMD64)               CPU(4)

NAME
     cpu - Central Processing Unit

SYNOPSIS
     cpu0 at mainbus?
     cpu* at mainbus?

DESCRIPTION
     Several processor models have additional features that extend their base
     functionality, such as power and frequency control or thermal monitoring.

FREQUENCY CONTROL
     The sysctl(3) hw.cpuspeed will return the current operating frequency of
     the processor (on some processors this value may be an approximation).
     If possible, speed may be adjusted by altering hw.setperf from 0 to 100,
     representing percentage of maximum speed.  There are several possible im-
     plementations for setperf, all transparent to the user.

     EST         Enhanced SpeedStep found on Intel processors, offers frequen-
                 cy scaling with numerous positions.

     PowerNow    Found on various AMD processors.  Currently only supports a
                 limited set of models in the K8 families.

THERMAL MONITORING
     The sysctl(3) hw.sensors.cpu*.temp0 will return the current temperature
     reported by the processor.

SEE ALSO
     sysctl(8)

BUGS
     Due to the way in which thermal information is reported on Intel proces-
     sors, the temperature may be off by exactly +/-15 degrees C.

     For multiprocessor kernels with more than one CPU sensor, processors will
     report identical temperatures since the temperature is taken from the
     processor running the sensors update.

OpenBSD 4.7                      July 13, 2009                               1
