mupuf.org // we are octopimupuf.org

An Arduino-based Frontend to My Audio-player (CMus)

CMus is so far my favourite audio player. It is gapless, powerful, scriptable and console-based.

The latter is both an advantage and an inconvenient. Indeed, when procrastinating by browsing the web, I often find myself willing to watch flash-based videos. So, I need to find what console runs CMus to stop the music. I usually launch it in the first console of yakuake, a quake-like terminal for KDE, but stopping the music requires multiples actions.

I could have used KDE’s global keyboard accelerators to send a pause/unpause request to CMus, but I’m far more geeky than that. Instead, I decided to build a remote control to physically add a physical giant button.

While this idea was appealing for the sake of it, I wasn’t fully satisfied. So long for just sending commands, what about receiving data from the computer too? What about displaying visual information to a screen too?

As I know you like videos, here is the video of the current state of the project:

H2G2: Another Attempt at Finding the Ultimate Question

I’m currently an intern at Bordeaux I, working on the security of sensor networks.

Today, I wondered how many articles I read in the last 3 months.

$ find papers/ | wc -l
42

The result was a bit puzzling and hence, I found the following question could be a great candidate to the ultimate question:

How many articles one should read before writing a research article?

If you don’t understand what I’m talking about, google is your friend.

Suspend2RAM, the Init Process and SSHFS

I’ve had a very boring problem for the last couple months, that I could never find the time to diagnose, till two days ago it finally got over my head. My computer would, sometimes, with no apparent reason, refuse to suspend (or actually, it would begin and then, after twenty seconds, interrupt the suspend procedure, breaking all my internet connections, and making the CPU and fans overwork).

This has been going on for a while, and even though I thought that it was linked to a VM I was working on in VirtualBox, I had no clue how to diagnose. Actually, the problem came from defunct processes trying to read a SSHFS share that was a directory in the VM. When the VM would reboot or be shut down, the SSHFS share became invalid. Having a cp process (and probably others like Thunar and ls) trying to connect to it would suffice to trigger the bug. The process would hang up, and killing it would often result in it being stuck as defunct (don’t ask me why, I don’t have the faintest idea).

So, how did this prevent Suspend2RAM from suspending my computer? Well, Suspend2RAM asks applications doing I/O activities to freeze, and it will not suspend if one of the tasks did not answer within 20 seconds, writing this message in dmesg instead :

Freezing of tasks failed after 20.01 seconds (1 tasks refusing to freeze, wq_busy=0): 

This is because the defunct process, that is still considered as currently doing I/O, is of course not able to respond to a signal. Now, this bug is annoying from a layman’s point of view and it’s pretty hard to figure out why such a behaviour can not be avoided. As far as I’m concerned, two design mistakes made this possible:

Idle: Make Your KDE Snappier

If there is something I really expect out of today’s computer, it is performance.

I’ve been a KDE4 user since the version 4.3 and there are a lot of performance improvements to be made. As I usually like bleeding edge/unstable (call it the way you prefer) software,

As it is super easy on ArchLinux, I have been testing kde 4.6 since the beta 1’s release. Apart from some graphical glitches, I was very pleased with it, especially from a performance point of view.

And then came the Release Candidate 1. The system became unresponsive as the performance dropped to an insanely poor level!

Merry Christmas and Happy New Year :)

The MùPùF.org devs wish you a merry Christmas and a happy new year!

We truly hope to deliver you more articles this year (such as how to make a stuffed toy tux or how the Linux graphic stack roughly works).

This year being the end of most of us’s master degree, we should have some more time to work personal projects like the Arduide, PPassKeeper or the reverse engineering of nVidia cards ;) We’ll keep you up to date with that!

As for the 2011 wishes, we let each dev write his own article :)

Please tell us if what you would expect from us, we highly value any comment!

Benchmarking Btrfs on Linux 2.6.37-rc3

Before reinstalling all the operating systems of my laptop, I was wondering if Btrfs would be a good fit for my unstable/development OS.

I wouldn’t have cared that much about the fs if my lappy’s hdd wasn’t slow as hell. I wondered if the built-in compression support of Btrfs could help me get a little more performance out of it. Also, as I tend to deal with loads and loads of ridiculously small files, the fact that Btrfs stores them in the extent of the directory inode should lower the seeking time.

Before reinstalling everything based on the assumption that Btrfs would actually be faster, I wanted to see some benchmarks on simple tasks like extracting, compiling a kernel and removing files. So far, I haven’t been able to find benchmarks for a recent kernel (read, at least linux 2.6.36) except the one from phoronix which doesn’t tell you how much CPU is being used and doesn’t test the compress mount option.