1.\" $OpenBSD: cpu.4,v 1.8 2018/07/15 18:04:37 fcambus Exp $ 2.\" 3.\" Copyright (c) 2004 Ted Unangst 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25.\" 26.Dd $Mdocdate: July 15 2018 $ 27.Dt CPU 4 amd64 28.Os 29.Sh NAME 30.Nm cpu 31.Nd Central Processing Unit 32.Sh SYNOPSIS 33.Cd "cpu0 at mainbus?" 34.Cd "cpu* at mainbus?" 35.Sh DESCRIPTION 36Several processor models have additional features that extend their base 37functionality, such as power and frequency control or thermal monitoring. 38.Sh FREQUENCY CONTROL 39The 40.Xr sysctl 2 41hw.cpuspeed returns the current operating frequency of the processor, 42though on some processors this value may be only an approximation. 43If possible, speed may be adjusted by altering hw.setperf from 0 to 100, 44representing percentage of maximum speed. 45There are several possible implementations for setperf, all transparent 46to the user: 47.Bl -tag -width tenletters 48.It EST 49Enhanced SpeedStep found on Intel and VIA processors, 50offering frequency scaling with numerous positions. 51.It PowerNow 52Found on various AMD processors. 53It currently only supports a limited set of models in the K8 families. 54.El 55.Sh INSTRUCTION SET EXTENSIONS 56The presence of extended instruction sets can be determined by the 57sysctl machdep. 58.Bl -tag -width "tenletters" 59.It xcrypt 60Supports the VIA AES encryption instruction set. 61If this is supported, 62the libcrypto EVP AES functions automatically use this support. 63.El 64.Sh THERMAL MONITORING 65The 66.Xr sysctl 2 67hw.sensors.cpu*.temp0 returns the current temperature reported by the 68processor. 69.Sh SEE ALSO 70.Xr sysctl 8 71.Sh BUGS 72Due to the way in which thermal information is reported on Intel processors, 73the temperature may be off by exactly +/-15 degrees C. 74.Pp 75For multiprocessor kernels with more than one CPU sensor, 76processors report identical temperatures 77since the temperature is taken from the processor running the sensors update. 78