Date: Tue, 22 Jan 2008 14:58:13 +1100 (EST) From: Ian Smith <smithi@nimnet.asn.au> To: Tijl Coosemans <tijl@ulyssis.org> Cc: Andreas Davour <ante@update.uu.se>, Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>, freebsd-questions@freebsd.org Subject: Re: Throttle the CPU when the system is idle Message-ID: <Pine.BSF.3.96.1080122135102.3948A-100000@gaia.nimnet.asn.au> In-Reply-To: <20080121180417.5841A16A468@hub.freebsd.org>
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On Mon, 21 Jan 2008 17:54:44 +0100 Tijl Coosemans <tijl@ulyssis.org> wrote:
> On Monday 21 January 2008 16:13:36 Andreas Davour wrote:
> > On Mon, 21 Jan 2008, Tijl Coosemans wrote:
> >> Throttling still made a huge difference on my systems.
On my old two-speed Thinkpad, powerd nearly halves total power drawn!
> > Many different opionions here. How did you do it then?
>
> In /etc/sysctl.conf:
> debug.cpufreq.lowest=400
>
> In /etc/rc.conf:
> economy_cx_lowest="LOW"
> performance_cx_lowest="LOW"
> powerd_enable="YES"
> powerd_flags="-i 92 -r 65 -p 200"
The documentation on all of this could use a little expansion for those
unable to locate/read the code. The BUGS section of powerd(8) states:
"If powerd is used with power_profile, they may override each other."
without saying what might be done about that. /etc/rc.d/power_profile
is called by default (on ACPI laptops) in /etc/devd.conf like so:
# Switch power profiles when the AC line state changes.
notify 10 {
match "system" "ACPI";
match "subsystem" "ACAD";
action "/etc/rc.d/power_profile $notify";
};
A browse of power_profile shows that using the below /etc/rc.conf
values will prevent it from messing with dev.cpu.0.freq when using
powerd (with notes from rc.conf on my Thinkpad T23 at 6.1-RELEASE):
# 27/9/6 powerd manages cpu freq nicely, but not (yet?) CX states
powerd_enable="YES" # default flags seem ok for T23
# disable power_profile management of cpu freq (fights w/ powerd)
performance_cpu_freq="NONE" # Online CPU frequency
economy_cpu_freq="NONE" # Offline CPU frequency
# 24/9/6 power_profile still manages on/offline lowest CX state
# 13/10/6 LOW value C2|C3 depends on whether booted on or offline?
performance_cx_lowest="HIGH" # Online CPU idle state
economy_cx_lowest="LOW" # Offline CPU idle state
Andreas: Tijl's value of -p 200 (ie poll online status and idle
percentage every 200ms instead of default 500ms) should help with
concerns about how fast powerd ramps up frequency when load occurs.
Copying Wojciech as well, as he seemed to be possibly? unaware of the
difference using cx_lowest values (ie which method of halting the CPU)
other than C1 can make to power consumption, and thus CPU temperature.
HTH, Ian
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