bin/120490: powerd should let me specify desired frequencies

[Nate Eldredge]

>Number:         120490
>Category:       bin
>Synopsis:       powerd should let me specify desired frequencies
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Sun Feb 10 05:40:02 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Nate Eldredge
>Release:        6.2-RELEASE-p8
>Organization:
>Environment:
FreeBSD vulcan.lan 6.2-RELEASE-p8 FreeBSD 6.2-RELEASE-p8 #24: Thu Nov 29 09:52:48 PST 2007     nate at vulcan.lan:/usr/obj/usr/src/sys/VULCAN  amd64
>Description:
powerd(8) in adaptive mode adjusts the CPU frequency based on the list from dev.cpu.0.freq_levels, it gradually moves through all available frequencies.  However, in my case this is not desirable; only two of the available frequencies are actually useful.  The CPU's full speed is 1800 MHz; powernow also has a 1000 MHz setting that saves about 20W.  But there are a bunch of other frequencies that apparently come from ACPI.  They do slow down the CPU, but based on my tests the machine's power consumption does not actually change, so there is not much point in using them.  Furthermore, the ACPI frequencies include some really low ones (250MHz or so) which crash the machine if selected.  So I really just want powerd to switch between 1800 and 1000.

It would be useful for powerd to have an option to manually specify a list of desired frequencies.
>How-To-Repeat:

>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: