[ltp] what to use to save battery

[Florian Reitmeir]

On Die, 05 Sep 2006, Martin Aumueller wrote:

> These suggestions all seem very interesting. However, could you please 
> elaborate on some of them a little bit more?
sure

> > - a SD Card for the home directory
this is easy, just buy one, use the newst kernel and put your home on it.

> > - use the busybox syslog daemon instead of syslogd and klogd
The busybox syslogd is nice, it uses a memory buffer for logs. On my laptop
there is no need for longterm logfiles. Under debian just install busybox.
then use some startup script like:

/etc/init.d/sysklogd stop
/etc/init.d/klogd stop
busybox klogd
busybox syslogd -C 16

now you can use the command "busybox logread" to get the last 16kb of logs.

> > - disable the internal USB bus for bluetooth and the fingerprint reader so
> > 	the laptop always can use C3/C4 even if the uhci_hcd is loaded (this can
> > be done with unbind in the sysfs)

http://lwn.net/Articles/143397/

in my thinkpad and X60s there is an internal USBV1 bus, and the kernel
activate that bus, because there is the fingerprint reader on it (and
bluetooth).

just unbind the usb host controller, and the cpu can use C3/C4. To use
bluetooth it should fairly simple to script the "bluetooth" button to first
bind the bus.. 

> > - dim the display
thats included in the ibm_acpi kernel module

> > - use cpufreq
there are normaly 2 drivers
acpi cpufreq
centrino cpufreq

if you want to use undervolting .. you have to disable the acpi cpufreq in
your kernel build.

> > - use a blank screensaver which disables the display correctly
xscreensaver does this correct, i test it always in a dark room. if the
screensaver successfully disabled the back-light the display is really dark,
if its only blank you can see the back-light.

> > - don't use postfix/exim use ssmtp instead
postfix/exim do periodic scans of the mail spool. normally i don't need a
mailqueue on my notebook. ssmtp is a very simple and direkt MTA which is only
active if i send a mail.

> > - under gnome, disable beagle
if you want to diable your disk when the laptop goes idle, it really is a bad
idea to enable beagle .. it becomes active when the disk should spin down..

> > - use a 2.6.18-rcX kernel and enable alsa-power management
the new 2.6.18 kernels have the nice feature for alsa and e1000 modules to
disable power until the sound device is open / a network cable is detected.

for alsa its an compile time option (in the -mm tree)
for e1000 its an kernel module option

> How do I enable alsa power management? I didn't find a kernel config option.
> 
> > - use a 2.6.18-rcX kernel and use the new e1000 module for more powersaving
> 
> What does 'new' mean? The one e1000 module that is included with 2.6.18-rc6 or 
> is there another module with a different name?

the kernel docu isn't updated yet, but there is a module option:

2.6.18-rc4/drivers/net/e1000/e1000_param.c

/* Enable Smart Power Down of the PHY
  *
  * Valid Range: 0, 1
  *
  * Default Value: 0 (disabled)
  */
E1000_PARAM(SmartPowerDownEnable, "Enable PHY smart power down");

> > - enable wireless powersaving
there are more the one way of enabling this..
normally i use "iwpriv" for the intel 2200 or 3495 and just try a bit for the
right power mode.

> Thank you very much for clarifying this,
np

-- 
Florian Reitmeir