The great battery experiment

Richard A. Smith richard at
Wed Oct 15 03:56:45 EDT 2008

As I reported in my report that went to community news I'm looking for 
power use and battery life information.

Here's a modified version of what I sent in for community news:

Richard would like to call for help from the G1G1, developer, and 
testing community.  Gathering large amount of data to establish a good 
power baseline is a very time consuming task.  Repeated power runs tests 
take  around 6 hours to run.  Richard would like to request that all the
developers, G1G1 users, and testers that are active do a power testing 
run and send the resulting log file to Richard.

If a large amount of people run 1 or 2 logs then Richard will have a 
wealth of data to process.

The steps:  (Please follow these steps as close as possible so the data
is apples to apples)

1) Download the latest olpc-pwr-log:


2) Copy this into your XO where you can run it from a VT.

VT in this case means Virtual Terminal.  A VT is the text console that 
you get to by pressing the Ctrl-Alt-F1 key.  F1 in the XO case is the 
mesh key which is to the right of the magnifying glass.  For more 
information on the VT:

3) Fully charge the battery of your XO and leave the external power
plugged in.

3a) Please remove _all_ external devices connected to the XO.  This 
includes SD cards, USB keyboards, USB disks, etc.  External devices will 
  skew the power readings and create situations where the CPU will not 
go idle.
I'm not really concerned with what your network is doing.  Thats one of 
the things I want to see is how much variability there is in the 
readings.  So association to an access point or running mesh is fine. 
However, please don't disable the WLAN with the extreme power magement 

If you wish to record a brief note on what you had the network doing you 
can do so by adding a message after './olpc-pwr-log' It will be copied 
into the log file as a note.  See 5)

4) Switch to a VT and cd to where the olpc-pwr-log script is.  Running
from a VT is very important.  The output on the VT console will prevent
the system from going into idle-suspend if you have that enabled.

5) ./olpc-pwr-log [message]

[message] is any descriptive text you want to provide about this log. 
Useful info would be if you were connected to an AP or in the mesh.  Its 
not required though.

6) The moment you see the first line of log output (ie right after it 
says it found a battery and a series of numbers displays) pull the 
external power.  The status should go from 'Full' to  'Discharging' on 
the next print which should be in about 15 seconds.

7) Let the system run untouched until it dies.  Do not switch back into
sugar.  If you go back into sugar the DPMS power saving will kick in in
20 minutes and turn off the dcon.

After a while of inactivity the console screen blanker will kick in and 
the text on the screen will go a bit screwy. Don't worry its a known 
bug.  Just ignore it.  If however your screen goes dark and gray (No 
backlight and looks just like the powered is off) then DPMS screen saver 
has kicked in and turned off your DCON.  Please review the earlier steps 
and try to figure out why DPMS activated.  If you have to you can 
disable DPMS with by using xset:

  "xset -dpms"

8) Mail the logs or any questions you have to richard at or find 
me on IRC in the devel room.

Richard Smith  <richard at>
One Laptop Per Child

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