LaptopMode

[David Zeuthen]

Hi,

Sorry for jumping into this thread a bit late,

On Wed, 2005-09-14 at 16:05 +0100, Richard Hughes wrote:
> Should we be doing:
> 
> echo 1 > /proc/sys/vm/laptop_mode
> 
> For SystemPowerManagement.SetPowerSave if 
> 
> smbios.chassis.type == Notebook 
> 
> Do you want a patch?

I think the layers above hal should figure out itself whether to invoke
SetPowerSave(), e.g. in gnome-power-manager you would probably use
system.formfactor (is more generic, e.g. all boxes don't have a SMBIOS)
on the hal device object representing the computer. 

Btw, I think of this as a non-issue - on non-laptops, it would be a bug
if software on the level of gnome-power-manager (wrt HAL) ever did a
SetPowerSave() method invocation because it should be able to figure out
that the system doesn't have any hal device objects of capability
'ac_adapter' or 'ups', e.g. there is no way to for the system to run on
a battery source.

What I'm trying to say is this: HAL should provide the mechanism for
enforcing policy, but we should never enforce policy. Yes, this means
software can do things that doesn't make sense, like calling
SetPowerSave() on a machine without battery sources, but what I'm trying
to argue is that such software is broken. 

Of course, we also want to reduce power consumption on servers with AC
power sources (in the litterature this is called "runtime power
management") but from what I can tell this is all to be implemented in
the kernel (at least on Linux, check out linux-pm at osdl.org) with
optional e.g. sysfs knobs to control to e.g. control USB device state
transition timeouts.

Cheers,
David