cpu —
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. In systems with more than one control capability, they are preferred in
the order given:
-
-
- LongRun
- Found on Transmeta Crusoe processors, offering frequency scaling with
numerous positions. The processor dynamically adjusts frequency in
response to load; the setperf value is interpreted as the maximum.
-
-
- EST
- Enhanced SpeedStep found on Intel Pentium M processors, offering frequency
scaling with numerous positions.
-
-
- SpeedStep
- Found on some Intel Pentium 3 and newer mobile chips, it is capable of
adjusting frequency between a low and high value. It is only enabled on
some chipsets.
-
-
- TCC
- Thermal Control Circuit found on Intel Pentium 4 and newer processors, it
can adjust processor duty cycle in 12.5 percent increments.
-
-
- PowerNow
- Found on various AMD processors. It currently only supports a limited set
of models in the K6, K7, and K8 families.
The presence of extended instruction sets can be determined by the sysctl
machdep.
-
-
- osfxsr
- Supports the fxsave instruction.
-
-
- sse
- Supports the SSE instruction set.
-
-
- sse2
- Supports the SSE2 instruction set.
-
-
- xcrypt
- Supports the VIA AES encryption instruction set. If this is supported, the
libcrypto EVP AES functions automatically use this support.
The
sysctl(2)
hw.sensors.cpu*.temp0 returns the current temperature reported by the
processor.
sysctl(8)
Due to the way in which thermal information is reported on Intel processors, the
temperature may be off by exactly +/-15 degrees C.
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.
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