NAME    [Toc]    [Back]

     cpu - Central Processing Unit

SYNOPSIS    [Toc]    [Back]

     option I386_CPU
     option I486_CPU
     option I586_CPU
     option I686_CPU

DESCRIPTION    [Toc]    [Back]

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

FREQUENCY CONTROL    [Toc]    [Back]

     The sysctl(3) hw.cpuspeed will return the current  operating
frequency of
     the processor.  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, offers
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, offers
  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.
                 Only enabled on some chipsets.

     TCC         Thermal Control Circuit found on Intel Pentium 4
and newer
                 processors, adjusts processor duty cycle in 12.5
percent increments.


     PowerNow    Found on various AMD processors.  Currently only
supports
                 some models in the K6 family.

INSTRUCTION SET EXTENSIONS    [Toc]    [Back]

     The  presence of extended instruction sets can be determined
by sysctl
     machdep.

     osfxsr      Supports the fxsave instruction.

     sse         Supports the SSE instruction set.

     sse2        Supports the SSE2 instruction set.

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

SEE ALSO    [Toc]    [Back]

     ichpcib(4), npx(4), sysctl(8)

OpenBSD     3.6                          March      15,      2004