Best OS ever

2008-04-25T00:00:00Z

If you are reading this on a box that does not have an impressive amount of RAM (say, 512 MB or less) and is running a fairly recent Linux, then for goodness sake, drop everything you are doing right now and follow the instructions in this entry. I’m going to show you how to make your system use the memory in a more efficient way, yielding an effect almost equivalent to increasing its amount — with no expenses whatsoever! Sounds good? Read on.

You see, there’s this Linux kernel module for kernels 2.6.17 and up (that’s what the phrase fairly recent in the previous paragraph macroexpands to), called Compcache. It works by slicing out a contiguous chunk of your RAM (25% by default, but it’s settable, of course) and setting it up as a swap space with highmost priority. The trick is that pages that are swapped out to this area are compressed using the LZO algorithm, which provides very fast compression/decompression while maintaining a decent compression ratio. In this way, more unused pages can fit in memory, and less of them are swapped out to disk, which can considerably cut down disk swap usage. I’ve enabled it in my system and it doesn’t seem to cause any problems, while providing a visible efficiency boost. Here’s how I did it on a freshly-installed Ubuntu Hardy:

I installed the Ubuntu package build-essential, then downloaded Compcache from its site, extracted it, entered its directory and compiled it by saying make. So far, so easy.
Unfortunately, one cannot say make install — creating a flexible cross-distro install target is admittedly hard. So I installed it by hand, ensuring that my system enables it automatically on boot-up.
I created a directory /lib/modules/2.6.24-16-generic/ubuntu/compcache/ and copied the four kernel modules (compcache.ko, lzo1x_compress.ko, lzo1x_decompress.ko, and tlsf.ko) created by the compilation to that directory.
Next, I ran depmod -a to make the modules loadable by modprobe.
I edited the file /etc/modules and added a line at the end, containing the single word compcache.
I copied the shell scripts use_compcache.sh and unuse_compcache.sh that come with compcache to /usr/local/bin.
I created an executable script /etc/init.d/compcache with the following contents:

#!/bin/sh
case "$1" in
  start)
    /usr/local/bin/use_compcache.sh ;;
  stop)
    /usr/local/bin/unuse_compcache.sh ;;
esac

The last step was to create a symlink /etc/rc2.d/S02compcache pointing to that script.

I then rebooted the system and verified that the new swapspace is in use:

nathell@chamsin:~$ cat /proc/swaps
Filename        Type        Size    Used    Priority
/dev/sdb2       partition   996020  0       -1
/dev/ramzswap0  partition   128896  111396  100

With the final release of Hardy installed on my main box and compcache optimizing its memory usage, I do not hesitate to call this combo the best OS I have ever had installed.

And no, I don’t own a Mac. :-/

Ubuntu post-installation tricks

2008-04-07T00:00:00Z

Yesterday, my level of frustration with my old operating system at work exceeded a critical point, and I installed a fresh daily build of the not-yet-released Ubuntu 8.04 in place of it. Then, in addition to usual post-installation chores like setting up mail, hardware, etc., I performed a couple of steps to make the system more pleasurable to use. Here’s what I did, just in case someone finds this useful.

First, I tweaked the font rendering. This was one area that has long been a PITA for Linux users (at least for me, since 2000 or so), but as far as Ubuntu is concerned, they introduced a change to Freetype somewhere along the way between Feisty and Gutsy which, when set up properly, makes the font rendering on LCD displays far superior for me to that of, say, Windows XP, in particular at small font sizes. The way to enable it is to enable sub-pixel rendering, and set the hinting level to “slight.” This results in a rendering very close to what the author of Texts Rasterization Exposures managed to achieve.
I installed the package msttcorefonts to get Microsoft’s free-as-in-beer set of core TrueType fonts, including Times New Roman, Arial, Georgia, etc. There are very many sites out there on the Web that were designed with these fonts in mind, and this is one of the few areas Microsoft doesn’t completely suck at.
Next I enabled bitmap fonts. The way to do this is to become root, cd to /etc/fonts/conf.d, remove the symlink named 70-no-bitmaps.conf, and make a symlink pointing to /etc/fonts/conf.avail/70-yes-bitmaps.conf instead. This would come in handy in the next step.
Which was installing my favourite console font. Unfortunately, it doesn’t come preinstalled with the Gnome-based Ubuntu, but it was no big deal. The font is named console8x16 and it comes with Kubuntu’s (and KDE’s) default terminal emulator, Konsole. So I downloaded an appropriate package (manually, without the help of APT, because all I wanted was the font, not the package itself). I then installed Midnight Commander (which I use a lot, if only for its great vfs feature, which allows to access, inter alia, Debian/Ubuntu packages as if they were directories), grabbed the file console8x16.pcf.gz, installed it in /usr/share/fonts/X11/misc, changed to that directory, ran mkfontdir and mkfontscale, logged out and restarted the X server.

The last step was to use this font for Emacs, too. So I installed Emacs, created the file ~/.Xdefaults containing the single line

Emacs*font: -misc-console-medium-r-normal--16-160-72-72-c-80-iso10646-1

and ran xrdb ~/.Xdefaults.

Then I got round to configuring Emacs itself. But that’s a story for another post.

Daniel Janus – Ubuntu

Best OS ever

Ubuntu post-installation tricks