1.\" $OpenBSD: acpicpu.4,v 1.6 2013/07/16 16:05:48 schwarze Exp $ 2.\" 3.\" Copyright (c) 2006 Michael Knudsen <mk@openbsd.org> 4.\" 5.\" Permission to use, copy, modify, and distribute this software for any 6.\" purpose with or without fee is hereby granted, provided that the above 7.\" copyright notice and this permission notice appear in all copies. 8.\" 9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16.\" 17.Dd $Mdocdate: July 16 2013 $ 18.Dt ACPICPU 4 19.Os 20.Sh NAME 21.Nm acpicpu 22.Nd ACPI processor power and performance state 23.Sh SYNOPSIS 24.Cd "acpicpu* at acpi?" 25.Sh DESCRIPTION 26The 27.Nm 28driver provides support for extracting processor power and performance 29levels from ACPI tables. 30This information can be used to throttle processor speed to reduce 31power usage and extend battery life through the 32.Va hw.setperf 33.Xr sysctl 3 34mechanism. 35.Sh SEE ALSO 36.Xr sysctl 3 , 37.Xr acpi 4 , 38.Xr cpu 4 , 39.Xr intro 4 , 40.Xr apmd 8 , 41.Xr sysctl 8 42.Sh HISTORY 43The 44.Nm 45driver first appeared in 46.Ox 3.9 . 47.Sh AUTHORS 48.An -nosplit 49The 50.Nm 51driver was written by 52.An Marco Peereboom Aq Mt marco@openbsd.org . 53