Saturday, February 08, 2014

A Faster System

I'm always looking for ways to speed up my computer, especially when it comes to the boot process and loading applications. A good overall discussion or improving system performance is at https://wiki.archlinux.org/index.php/Maximizing_Performance, just remember that it focuses on the ArchLinux distro, not the Mandriva distro I use.


READAHEAD
A useful utility is readahead. According to its manpage, readahead populates the page cache with data from a file so that subsequent reads from that file will not block on disk I/O. On my Mandriva 2101.2 system, the default installation of readahead places a default file at /var/lib/readahead/default.early. To create custom files based on your system, you should reboot the system and pause the GRUB menu and add the following to the command line.

init=/sbin/readahead-collector

This will examine your system as it boots and create a list of what files are to be loaded in the order that they are loaded.

The configuration file is found at /etc/readahead.conf and this is where you can turn on debugging if you're experiencing problems and can add excluded directories.

NOTE: READAHEAD is deprecated on newer systems.


PRELINK
Next is the prelink utility. According to the man page, prelink is a program that modifies ELF shared libraries and ELF dynamically linked binaries in such a way that the time needed for the dynamic linker to perform relocations at startup significantly decreases. Due to fewer relocations, the run-time memory consumption decreases as well (especially the number of un-sharable pages).

The file /etc/prelink.conf contains a list of files and directories that prelink uses to determine where it should look and what files to avoid. Prepending -l (or -h if on a networked filesystem) to a path makes prelink search that directory for ELF binaries or shared libraries. You can prepend -b to blacklist a directory or a file to avoid which will speed up the search or deliberately avoid prelinking certain binaries.

Mandriva provides a directory to keep your customizations separate at /etc/prelink.conf.d/; just create a file there ending in .conf and your customizations will be included. The general invocation is

# prelink -a

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