January 2010 Archives

I wrote a very simple (one function) C++ wrapper class around libcurl, which one can use to download web page data into a C++ string. The class is called WebPageRetriever and is available here:

http://indicium.us/cgi-bin/pages/get?view=scripts

What does your Linux system do when it completely runs out of memory? When even virtual memory is exausted?

As a last resort, Linux turns your processes over to a dark angel known as the OOM Killer. The OOM Killer has the grisly job of picking which process needs to die in order to get your system back to a manageable state. It actually follows a rather precise formula, endeavoring to make a decision which will be most convenient to the user and fair to the running processes.

The details are available here:

http://linux-mm.org/OOM_Killer

And now, a stunning compiling tip from Captain Obvious:

If you are ever compiling the Linux kernel on any system with 500 Mhz of processing power or less, make sure to remove all the driver and filesystem options your don't need. As I'm finding out the hard way, it takes around 5+ minutes to compile the modules for each file system on a computer this slow. I feel especially silly because I am only actually using one disk file system on the machine (xfs).

Probably should have known this before now, but in any case: I found out that you can continuously monitor the output of a file using the "tail" command. In other words, if you use the command

tail -f <filename>

the program will output the last 10 lines of the file, and then it will continue output additional data as the file grows.  This is really handy, I found, when I needed to watch the output of genkernel.log while I was compiling my gentoo kernel.

Saw this on gentoo.org today. Impressive. The inventor used Gentoo as the guitar's OS.

http://www.misadigital.com/

I'm trying to start up a new project in which I will create a small computer cluster out of old PCs in my apartment. This is mainly for the learning experience, and I do not expect to impress anyone with my networked array of Pentium III's. But it should be an interesting project anyway.

I'm planning to use Gentoo, and I am going to start with the official documentation for creating HPC clusters under Gentoo:

http://www.gentoo.org/doc/en/hpc-howto.xml

First step, though, is to actually get the old PCs working. I just got one 10 year old Pentium to boot into the Gentoo minimal install disk, which involved an odd ritual of moving the CD-ROM in and out of the tray a couple of times during boot.

I also only have two spare PCs at the moment, so I'm checking to see if my friends have any junk they want to get rid of. (hint, hint)

1. Define the macro:
   C-x (
   <Do your macro>
   C-x )

2. Give the macro a name:
  M-x name-last-kbd-macro RETURN
  <enter a new name> RETURN

3. Save it in your .emacs file
  C-x C-f
  <put "~/.emacs" in the open file dialog> RETURN
  <move to the end of the file>
  M-x insert-kbd-macro RETURN
  <enter name of the defined macro> RETURN
  C-x C-s

http://indicium.us/cgi-bin/pages/get?view=unsung

I said that I had shut down this blog for good. That was a lie. Okay, not a lie, but in any case I intend to move my blogging back to this site. Enjoy!