system power profile

Kevin Oberman oberman at
Thu Aug 7 09:35:28 PDT 2003

> From: Andreas Kohn <andreas.kohn at>
> Date: Thu, 07 Aug 2003 14:06:46 +0200
> Sender: owner-freebsd-mobile at
> --=-shZJTKcNhhtCBRJjaz1l
> Content-Type: text/plain
> Content-Transfer-Encoding: quoted-printable
> Am Thu, 2003-08-07 um 06.23 schrieb Chris Collins:
> > Hello
> >=20
> > I have been running 5.1-stable on my Vaio 505GL for about a week now and
> > things are working great. I am still trying to figure out a few things th=
> at
> > hopefully some of you can help me with.
> >=20
> > I have noticed that when my laptop boots is selects a system power profil=
> e
> > 'economy' and I have also noticed a few times it has changed to profile
> > 'performance'.  My question is how can I define what these profiles are a=
> nd
> > how can I select them manually myself.=20
> The economy profile is selected when your laptop runs on battery power,
> the performance profile when it is running on AC. (Some BIOS may allow
> to select the profile preference also)
> You can use the hw.acpi.cpu.economy_speed and .performance_speed sysctl
> to select the amount of CPU throttling. The hw.acpi.cpu.current_speed
> contains the current speed :) and .max_speed contains the highest
> possible value.
> Select the profile by unplugging/plugging-in your AC connector *g

But don't assume that the CPU is actually changing in response to the
change. I have seen multiple reports that some (many...all) systems
don't actually change CPU speed when this changes.

I use gkrellm's gkx86info plug-in to monitor the CPU speed. The speed
on my system (and others from multiple vendors) is set by power status
at boot time and never changes until the system is re-booted. this is
true for both ACPI and APM.
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at			Phone: +1 510 486-8634

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