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CPU(4)		    FreeBSD/amd64 Kernel Interfaces Manual		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(2) hw.cpuspeed returns the current operating frequency of the
     processor,	though on some processors this value may be only an approxima-
     tion.  If possible, speed may be adjusted by altering hw.setperf from 0
     to	100, representing percentage of	maximum	speed.	There are several pos-
     sible implementations for setperf,	all transparent	to the user:

     EST	 Enhanced SpeedStep found on Intel and VIA processors, offer-
		 ing frequency scaling with numerous positions.

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

INSTRUCTION SET	EXTENSIONS
     The presence of extended instruction sets can be determined by the	sysctl
     machdep.

     xcrypt	 Supports the VIA AES encryption instruction set.  If this is
		 supported, the	libcrypto EVP AES functions automatically use
		 this support.

THERMAL	MONITORING
     The sysctl(2) hw.sensors.cpu*.temp0 returns the current temperature re-
     ported 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 re-
     port identical temperatures since the temperature is taken	from the pro-
     cessor running the	sensors	update.

FreeBSD	13.0			 July 15, 2018			  FreeBSD 13.0

NAME | SYNOPSIS | DESCRIPTION | FREQUENCY CONTROL | INSTRUCTION SET EXTENSIONS | THERMAL MONITORING | SEE ALSO | BUGS

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