As far as performance, Ubuntu 8.04 isn’t bad out of the box. However, the developers had to make some performance sacrifices in order to remain compatible with older machines. If you have a newer machine with at least 512MB RAM, enabling these tweaks will significantly speed up your Ubuntu experience. There’s a lot of copy and paste blog posts out there on Feisty, and a lot of so-called tweaks that I feel are unnecessary. Where I aim to differentiate this post is to specialize on tweaks relevant to 8.04, and to cover only the 80/20 rule of performance – 20% of the work done tweaking will net you 80% of the speed boost. There’s a lot more that you can tweak, but it really won’t net you that much gain. Here’s what I use on all my desktop Ubuntu installs.
1. Start your services in parallel at boot.
Instead of starting one service at a time, let’s start them all as fast as possible, and in parallel. This will actually slow down older, single core machines, but faster P4’s, and multiple core CPU machines will benefit from this. Run this command, and reboot:
sudo perl -i -pe 's/CONCURRENCY=none/CONCURRENCY=shell/' /etc/init.d/rc
2. Utilize preload to speed up application startup time.
If you have some extra RAM, look into preload. From the preload website:
preload is an adaptive readahead daemon. It monitors applications that users run, and by analyzing this data, predicts what applications users might run, and fetches those binaries and their dependencies into memory for faster startup times.
You can read all about how it does it and how it can be tweaked on this article on techthrob.com, but you can just “set it and forget it” and it will be fine. Run the following command:
sudo apt-get install preload
and bask in the glory of the speed boost!
3. Swappiness != Happiness.
If you have enough RAM, you shouldn’t ever need to use swap. Heck, RAM is cheap. If you’re short on RAM, stop reading this article and go buy some.
My best guess is that the Ubuntu devs do this for folks running on older systems with less RAM, but it doesn’t help any on systems with 512MB or more RAM. Swappiness basically controls the tendency of the kernel to page memory out to disk. You can read the gory details over at kerneltrap.org, or just run the following commands:
sudo sysctl vm.swappiness=5 sudo su -c 'echo vm.swappiness=5 >> /etc/sysctl.conf'
4. Profile your boot process.
This has got to be one of the most undocumented features in Ubunutu. I found many sites saying to “do this”, but none said why. A forum post on the Ubuntu site pointed me in the right direction.
Basically, the second thing to start during boot in Ubuntu is readahead. The init script is at /etc/rcS.d/S01readahead. It preloads all the libs that you might need during bootup. The list of files that this service will load is contained in /etc/readahead/boot (and /etc/readahead/desktop). It’s good to do this once, then repeat it after you do a major upgrade such as a dist-upgrade, or significantly change your startup services. Please note that it will slow the boot process during the profile step, as it’s recording what’s needed at boot time. Your next boot will be much faster.
To start profiling, do the following on bootup:
- At the bootup menu (GRUB), select your default kernel. You may need to press ESC to see this menu.
- Press e for edit.
- Choose the first line (it should start with “kernel”). Press e again.
- Move to the end of the line, then add the word profile. Press enter.
- Press b to boot.
- Let the system boot to the login screen, and wait for all disk activity to stop. Remember, during this one bootup, you’ve told Ubuntu to keep track of all disk activity going on, in order to build that list. Don’t be surprised if it’s significantly slower than your ordinary bootups – that’s why it’s not activated by default, remember?
- Reboot your system, and enjoy the results.
5. Don’t start unneeded services.
Don’t start services that you don’t need or use. They eat up RAM, and consume CPU cycles. The purpose of this post isn’t to define all these services (that may make a nice post in and of itself), it’s to show you how to turn them off.
If you like command line/curses interfaces:
sudo apt-get install sysv-rc-conf && sudo sysv-rc-conf
If you want a GUI:
sudo apt-get install bum && gksudo bum
I run a lot of stuff on my laptop, so I couldn’t disable too many things, but here’s what I did disable: rsync, nfs-kernel-server, apmd, apport, and avahi-daemon.
Many of the other posts out there will have you tweaking your own kernel. While I’m not against this (it makes you learn a lot about how Linux works), doing it for performance reasons isn’t the way to go. You might speed things up a bit, but if you’re that much of a tweaker, look into Gentoo Linux.
Another item left off the list is the tweaking of the ext3 mount options in /etc/fstab. For the most part, Hardy comes out of the box with decent mount options. The one possible exception is the use of noatime. noatime disables the logging of the last access time of the files, and if you’re absolutely sure there’s nothing you use that needs this, then you are okay to replace any occurrence of ‘relatime’ with ‘noatime’ in /etc/fstab. However, if you look at the man page for mount, you’ll see that relatime is a nice compromise between full access time logging and none at all.
Well, that about wraps it up. If you have your own tweaks you’d like to share, post it in the comments!