[ltp] Aggressive Powersaving

Pedro Ribeiro linux-thinkpad@linux-thinkpad.org
Tue, 9 Feb 2010 21:22:12 +0000

On 9 February 2010 17:43, Henrique de Moraes Holschuh <hmh@hmh.eng.br> wrote:
> On Tue, 09 Feb 2010, Pedro Ribeiro wrote:
>> I read somewhere (forgot where) that sata power management shouldn't
>> be messed with in hot swappable devices. But maybe that is not true on
>> later kernels?
> The link might not come up by itself on hotplug, but you do have a hook to
> know when you need to kick it back up in this case, as the ACPI layer will
> send an event about the hotplug.
>> Actually now that I think about it, since I use the DVD drive quite
>> sparingly, do you think it is a bad idea to have it on min_power all
>> the time? Will it affect my ability to watch DVD's etc?

Apparently this is a very bad idea. I was getting hard lockups after a
few minutes for no apparent reason. Tried an earlier kernel I had
installed and it also crashed when I set ALPM to min_power on the

It seems that it does not affect power consumption though. Using
tp_smapi I can get very accurate power readings and the only thing
that reduced power consumption was powering off ultrabay - messing
with the SATA ALPM on the ultrabay didn't seem to make any difference.


PS: I'm getting INSANE battery life with the 2.6.33 kernel! In my T400
without wired or wireless internet, I get 8w consumption = 5h30 of
battery life! With wired I get 10w and with wireless 12w. This is
compared to 10/12/13.5 in 2.6.32.