Laptop ACPI question

[Kevin Oberman]

> Date: Sun, 2 May 2004 01:22:51 -0400
> From: James Snow <snow at teardrop.org>
> 
> On Sat, May 01, 2004 at 02:05:36PM -0700, Kevin Oberman wrote:
> > 
> > Actually, ACPI will greatly improve battery life soon, but not yet. The
> > bits and pieces are being fed into CURRENT and I suspect that SpeedStep
> > support will be coming soon.
> > In the meantime, you can use sysctls to manually adjust CPU performance
> > to enhance battery life.
> > 
> > Look at:
> > hw.acpi.cpu.throttle_max: 8
> > hw.acpi.cpu.throttle_state: 8
> > hw.acpi.cpu.cx_supported: C1/0 C2/1 C3/85
> > hw.acpi.cpu.cx_lowest: 0
> > hw.acpi.cpu.cx_history: 1453705/0 0/0 0/0
> 
> Hmm. In 5.2.1-p5, I don't have anything under hw.acpi.cpu
> labeled .throttle*. I do, however, have these:
> 
> hw.acpi.cpu.max_speed: 8
> hw.acpi.cpu.current_speed: 1
> hw.acpi.cpu.performance_speed: 8
> hw.acpi.cpu.economy_speed: 1
> 
> acpi(4) seems to suggest that these will alter CPU speed,
> and presumably battery life as well. Is this not the case?

I suspect that this simply indicates differences between systems. These
settings look a lot like the older, less granular APM controlled
services. I'd certainly try adjusting hw.acpi.cpu.current_speed and see
what effect it has, but it looks to me like it's running at its economy
mode, already.