[ltp] battery life on X60 Kubuntu vs XP

[Igor V. Rafienko]

on May 18, 2007, 19:52, Uwe Brauer wrote:

> > * Are you measuring XP and Kubuntu with roughly the same workload? (e.g.
> >   idle with no powerhungry services running)
>
> I think that is the case, I am just logging in.


You have to check which services are running. Otherwise a comparison is
meaningless.


> > * Regardless of what XP and Kubuntu are telling you, what is the *exact*
> >   power draw given that same workload? (on linux, tp-smapi is your
> >   friend. Check the stats in /sys/devices/platform/smapi/BAT0/power_now
>
> tp-smapi: it seems that it is not installed, and I can't find it via
> apt-cache search


Then compile your own (just for testing -- you can remove that afterwards)
If you do not want to/are unable to, try /proc/acpi/battery/BAT0/*, which
should provide approximately the same info. Unsure how to proceed? Check 
the thinkwiki.

Unfortunately I have no idea where windows keeps this info.

[ ... ]


> > * Is the CPU in the lowest possible C-state on battery? (C4, I believe).
>
> I am not sure, in debian I could set the scaling of the processor down.


/proc/acpi/processor/CPU/* has the information you need.


> > * Are you using the powersave governor when on battery?
>
> Again no idea


Well then, *check* it:

$ cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor


> > * Is USB (uhci_hcd primarily) preventing the cpu from reaching
> >   C4?
>
> How do I check


First you check if the cpu is in C4 (see above), then (if it is not while
you are on battery) you can remove uhci_hcd and see if it makes a
difference.


> > * Which frequency is the cpu running on? Is the second core active? (not
> >   sure that the latter makes a difference, though)
>
> Well first is on 1000 but the second on full 1600 MgH that is with power
> and with battery no idea how to change it.


That's interesting -- there is no reason for the second core to be running
at full speed when the laptop is idling.

- Check the governor for that core (see above for the recipe)
- Force the powersave governor:

   echo powersave > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
   echo powersave > /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor

Does it make a difference now?


> I am sorry that I can't give more information, I wish I could.


Ah, but you can -- <URL: http://www.thinkwiki.org/>





ivr
-- 
VB, by comparison, treats you like a secretary pecking on MS Office.
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