Posts tagged 'linux'

Random Efficiency Tips


You probably know the feeling when software you use daily gets in your way rather than assisting you. To me Emacs has been such an offender for a long time - in that it creates backup and semantic.cache files in every directory you edit files in. Obviously, this makes it often impossible to find the file you are looking for in a directory listing.

Last week I had enough and searched for a solution. I found one to the backup files problem in Xah Lee's Advanced Emacs Tips and got rid of semantic.cache by following a suggestion in the ECB FAQ to set semanticdb-default-save-directory. In both cases the functionality in question is not disabled, but the corresponding files are created in a directory somewhere in ~/.emacs.d/ which makes me a happy Emacs user again.

Another huge annoyance is the long time it takes current Linux distributions to boot. I remember how my old 350MHz Pentium II with its by today's standards dead slow harddisks booted in about 20 seconds from the Lilo prompt to the KDM/GDM login screen. Out of the box the Debian installation on my 2.4GHz Core 2 Duo workstation with its 7200RPM disks needs about twice as much time to get me to a graphical (GDM) login. After getting rid of a bunch of unnecessary init scripts I got that figure down to slightly less than 30 seconds. So, it's definitely worth the effort to review what init scripts are run and whether you really need them. I still don't find the result very satisfactory though.

Last but not least I'd like to recommend the tips over at Even if you don't have a recent enough kernel and userspace to benefit from CONFIG_NO_HZ etc. it's worth going through their Tips & Tricks section and looking for potential power savings. Personally, I found the suggestion to mount filesystems with the noatime option enabled very useful, not necessarily because it saves power, but because it significantly speeds up things like apt-cache search, access to the dpkg database, and loading all the .desktop files.

Linux Kernel in a Nutshell

When someone pointed me to Greg K-H's book Linux Kernel in a Nutshell my initial reaction was: Building a kernel isn't exactly rocket science. Why would I want to read a book about it?

Well, it seems I was wrong. I skimmed through the PDF version today and noticed a very useful feature of make menuconfig: Hit / and it allows you to search the CONFIG_ strings.

Kernel Hacking for Fun and Credit Points one of the things I'll be doing at university this semester (although I don't actually need the credit points). There are various other interesting courses, but I haven't made a final decision on which of them to take. Anyways. Good times :)