bin/120490: powerd should let me specify desired frequencies

[Nate Eldredge]

The following reply was made to PR bin/120490; it has been noted by GNATS.

From: Nate Eldredge <neldredge at math.ucsd.edu>
To: Kris Kennaway <kris at FreeBSD.org>
Cc: Nate Eldredge <neldredge at ucsd.edu>, freebsd-gnats-submit at FreeBSD.org
Subject: Re: bin/120490: powerd should let me specify desired frequencies
Date: Sat, 15 Mar 2008 08:52:55 -0700 (PDT)

 On Sun, 17 Feb 2008, Kris Kennaway wrote:
 
 > Nate Eldredge wrote:
 >
 >> 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.
 >
 > Just disable the services that are providing the alternate frequencies. 
 > Probably acpi_throttle.
 
 Just to follow up: that worked.  I put hint.acpi_throttle.0.disabled="1" 
 in /boot/device.hints.  Thanks!
 
 -- 
 
 Nate Eldredge
 neldredge at math.ucsd.edu