Android Emulator Quick Boot

The first time I tried starting the android emulator, I quit it and never used it again. Starting up took about 5 minutes already and it wasn't too responsive afterwards. Now Matthew Casperson posted a nice howto for using the snapshot feature of the android emulator to start it up quickly. Now all I need is a trick to have it running faster as well... But that's not going to happen as long as it relies on qemu to first translate everything from x86 to arm code.  ;)

Being based on Java, you'd think it would be possible to create a much faster emulator by just leaving out the arm cpu emulation. And it seems some people have done that with youwave. Unfortunately, that's windows-only.

Another line of improvements would be to speed up the graphics, as reportedly displayed with impressive results at Google I/O 2011.

Enabling the Integrated Flash and Plugin Blocker in Google Chrome

If this is not available for you out of the box in the settings page (details, content, plug-ins), you can enable it in about:flags, "click-to-play". You have to restart Chrome for it to take effect. As before, I really don't know why they removed it from the settings page in the first place.

In that same flags page you can also disallow the reading of third party cookies.

Correcting a Misaligned VGA Image on your Monitor or TV in Xorg, e.g. when you see a black border or frame, the image badly aligned to one side of the screen

When I wanted to connect my TV via VGA out to my netbook, the image displayed started with a black frame on the left side and was missing a part on the right side. It only occurred in FullHD resolution (1920x1080), during boot and in other resolutions it was fine. Just for fun I contacted the TV manufacturer, but of course they didn't know any help but "try to install the newest driver for your graphics card".

Segfaults in Google Chrome

I've notice several times that despite the elaborate architecture, Google Chrome does reproducibly crash completely sometimes. But this time way really funny, because of the website I was trying to access:
[23706.661053] chrome[6256]: segfault at 5 ip 087ee261 sp bff2ad80 error 4 in chrome[8048000+2c05000]
[23732.024794] chrome[10876]: segfault at 0 ip (null) sp bff6db4c error 4 in[3bf0000+ec000]

Youtube complains of a lack of local storage? Try this...

It seems youtube would really like you to (aka forces you to) enable enable flash storage for third parties and enable at least 10 kg storage for everybody by default. This is most certainly not a technical necessity, but to make advertizing work better. Otherwise you can't save your youtube 3d settings. But once you've saved your 3d settings, you can switch third party storage back off. ;)

The coming big 3.0 Kernel - First Impresions

After running the 3.0-rc2 for a few days I can say that I notice a higher responsiveness. I'm not sure right now what causes them, but something's definitely improved. On the downside my intel i965 chipset crashes even more. This started in 2.6.39 with video playback, but it's gotten worse now and includes switching to the framebuffer console and back - and a very hard freeze that is, too...

Optimizing Code for Small Size

Many people know the -Os flag of gcc to reduce the code size. Now a while ago Benno posted some tipps to reduce the size of a compiled program for ARM, which give a good hint what to look for in any case. His Summary
"Compile to Thumb instructions.
Use -Os to optimise for space.
Look for unnecessary code.
Look for examples of registers used in the wrong place."

Fixing USB Playback Issues for Video Files on LG, Samsung and other TVs - e.g. "Invalid File" [updated 2017]

If your file won't play and the TV reports "Invalid file", the thumbnail is not created instead a one with a warning arrow, then your TV won't eat the file. Since this post gets a lot of hits and is easily found, I've updated the information a bit.

The problem is likely one of these issues:
1. unsupported video format (check the supported list, e.g. LG)
- especially note the restriction of 30 fps for FullHD
- video codecs are usually divx and h264 (up to profile 4.1), no GMC
- audio codecs are usually mp3, ac3, aac.
2. Badly muxed file or unsupported file type
3. Mkv with header compression

Putting a Group of Processes into a CPU and Memory Jail -- First Steps with Control Groups in Linux

Control groups are really, really great. They can effectively make your system act as if it were two or more systems in one. It's like virtualization without all the overhead and much more efficient than e.g. renicing. (Just a little overhead... and no hard cpu limit yet, but still great!) You can lock a process into a jail that is only as fast as e.g. 10% of your cpu and has only 10 % of your memory and 10 % of your disk speed. Pretty much whatever it does, it won't be able to really annoy you. This means that e.g. big compiles in the backgroud *really* don't affect your browsing *at all*. Here are some presentation slides about cgroups. So let's see how we take the first steps to get there. I will show you how to do it manually step by step so you can learn how it works.

Common Issues with Linux Control Groups - e.g. Lack of Space, Device Busy/Mount Problems, Subgroup can't be deleted, no cpu shares file

Problem: The group will e.g. not let you echo PIDs into its "tasks" file and complain about a lack of space.

Guess the Size of an Lrzip Archive of all Linux Kernel Sources Since 1.0

I've reported before about the efficiency of Lrzip. Now Con did a useful and fun thing: He created an lrzip archive of all the sources of all 2.6 linux kernels. And guess how much space it took? Update: Guess how big an archive of *all* Linux sources since 1.0 is.
A few hints:
- All sources in a tar are 10.3 GB.
- The kernel is 73 MB as a tar.bz2 archive.
- Now it would be less, because the first kernel was smaller (just 32 MB).
- So taking the average (73+32=105/2=52.5) times 39 would be just 2GB (compressed!).

- 19,617,064,960 bytes linux-1.0-2.6.39.tar
- 11,067,473,920 bytes linux-2.6.0-2.6.39.tar

- ( 2,000,000,000 bytes estimate
-   1,535,618,848 bytes linux-2.6.0-2.6.39.tar.xz 13.8%

With heavy, slow IO it took less than an hour to compress, and lrzip was more than twice as fast as xz.

Now that I gave you all these numbers let's see how much it really is... (make a guess an click the link)

Learn Flashcards Efficiently - Tips and How to get OpenCards Running in Linux - Slow Opening of Files in Openoffice and LibreOffice

OpenCards is a great, optimized memorizing software that ensures you need as little time as possible to learn your flashcards.
What you get
  • As it's based on Openoffice, you can make full featured flash cards including diagrams, mind maps and everything else supported in Impress.
  • Focus on learning. As it logs your progress and automatically schedules the next time to question you, you can learn without organizing what to learn when.
  • The repetition schedule is based on modern psychological research. The Leitner system is "a widely used method to efficiently use flashcards that was proposed by the German science journalist Sebastian Leitner in the 1970s. It is a simple implementation of the principle of spaced repetition, where cards are reviewed at increasing interval." (Wikipedia)

Kernel Shark (trace-cmd/ftrace GUI) presentation by Steve Rostedt

There's a nice (WebM) video of Steve presenting the gui to trace-cmd and it's output of ftrace's work.