Author: Patrick

Got my chinese driving license

or: part two of How to apply for a driving license in Shanghai (for foreigners with a foreign driving license)

I went in there with my pamphlet containing the 100 questions, of which 90 must be answered correctly to get the license. Being 20 minutes early, I had to take a seat in the waiting hall of room 200, building 8. A few minutes after the the test should have begun, I heard a woman calling my chinese name, so I walked in there. They asked me to take a seat on one of six computer terminals. The screen asked me to press the enter key when ready, after which the test began. The questions were exactly those from the pamphlet, but in another order. If I remember correctly, the choices to each answer were in the same order as in the pamphlet though 😉
After about 15 minutes I had completed 97 questions after which the screen suddenly told me that I passed with a score of 97. A clerk at the right counter called me, and printed my result. With the result I had to go to the left counter, where the guy compiled some other papers and put everything into a small bag. On the bag I found instructions on what to do next: Go to the first floor, pay 55 Yuan, then go back to the second floor, counter 16 and draw a number.
After waiting for some minutes, I got my driving license freshly printed from counter 16 and could go home 🙂 That’s it! Wasn’t that hard 😉

Now I may officially drive in China! 🙂

Intel’s “powertop” gives hints on how to save power

I discovered this small ncurses based tool just yesterday… Just start it as root and it will spit out info on how often the CPU must return from C3 sleep mode to a more power consuming mode, and what the reasons are. It will also show various hints on how to reduce power consumption on your system. The tool is intended for computers with Intel mobile CPUs. It’s available through portage (sys-power/powertop).

Nice work, Intel!

Laptop battery consumption / learning gnuplot

Today I tested how long my laptop’s battery can last when I just keep it on the table, idling. Running Linux and a bunch of applications, the TFT set to the lowest brightness setting. Wireless activated.

After the laptop switched off, I plotted the power consumption curve with gnuplot, which I wanted to get to know for a long time already 😉 The data file (fed from /proc/acpi/battery/BAT1/state) contained 1678 data points (ten samples per minute). The gnuplot session looks like this:

gnuplot> set terminal png picsize 800 600
Terminal type set to 'png'
Options are 'small color picsize 800 600 '
gnuplot> set output "test.png"
gnuplot> plot "powerlog3" using 1:2 title 'Power consumption (W) over time (min)' with lines, "powerlog3" using 1:3 title 'Remaining (%) over time (min)' with lines smooth unique

You can see the result here:
Plot of my laptop’s power consumption, tested on 2007-06-10, plotted with gnuplot

In the beginning I finished something I was working on, so you can see some spikes in the power consumption when I launched programs and such… After 60 minutes the monitor switched off, so the consumption drops. I guess I hit the table at minute 144 or so, because then the monitor seems to have switched on again, don’t remember though 😉

I’ll do the test running Windows at a later time – but there I will only get one number – the total runtime. I have no idea how I could get statistics like that in Windows, and I’m not willing to try 10 shareware programs until I get a suitable result 😉

UPDATE (2007-06-11):
I got around running the test in Windows. I tried to produce about the same conditions: display switches off automatically after 60 minutes, no automatic standby and stuff. I also remembered to switch on the display again after ~70 minutes of being switched off, so the results should really be comparable. One of the apps I kept running on the otherwise idle system was a PuTTY window. Therein I ran a shell script on my server, which touched a file every ten seconds, so I just would have to check the modification date of that file to know when the box went down. I started the test at 11:01 local time, which means 3:01 UTC. The file’s modification date is: 2007-06-11 05:22 (UTC). –> The laptop was shutdown automatically after 2:21h.

So it’s definitely not true that there is some energy wasting going on when Linux is running on a computer, as I have been told (and which eventually caused me conducting this experiment 😉 ). If anything, Windows lost here, as usual.

P.S.: Some information about the two software environments:
Linux: Kernel 2.6.21-gentoo-r2, (for details, have a look at my current configuration). On top of it, running Xorg, KDE with Beryl as window manager, there are usually about 150 processes in the task list.
Windows: Windows Vista Business, everything left quite to the default (I never use it…). No special services running or anything.