Central Processing Unit
cpu0 at mainbus?
cpu* at mainbus?
Several processor models have additional features that extend their base
functionality, such as power and frequency control or thermal monitoring.
The sysctl(2) hw.cpuspeed returns the current
operating frequency of the processor, though on some processors this value may
be only 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 implementations for setperf, all transparent to the user:
The presence of extended instruction sets can be determined by the sysctl
- Enhanced SpeedStep found on Intel and VIA processors, offering frequency
scaling with numerous positions.
- Found on various AMD processors. It currently only supports a limited set
of models in the K8 families.
The sysctl(2) hw.sensors.cpu*.temp0 returns
the current temperature reported by the processor.
Due to the way in which thermal information is reported on Intel processors, the
temperature may be off by exactly +/-15 degrees C.
- Supports the VIA AES encryption instruction set. If this is supported, the
libcrypto EVP AES functions automatically use this support.
For multiprocessor kernels with more than one CPU sensor,
processors report identical temperatures since the temperature is taken from
the processor running the sensors update.