Ubuntu Performance
Introduction
Some things you can do to tweak better performance from Ubuntu Linux. Some tips may apply to other distributions and/or Gnome installations as well.
In general it is better to use Xubuntu if you want good desktop performance, it runs the XFCE window manager which is much leaner on memory resources than Gnome, KDE or Unity.
Other bloated applications (pre-installed) can also be found... gnome-terminal measuring in at 34M of Virtual memory. My systems tend to have <= 512MB of RAM, so by following the guidelines below one can make a leaner, meaner Ubuntu.
Use the "top" performance tool
Run the command top and examine the output. Here is what it looks like on my desktop...
top - 21:56:34 up 2 days, 12:11, 6 users, load average: 0.80, 0.40, 0.55 Tasks: 99 total, 1 running, 96 sleeping, 0 stopped, 2 zombie Cpu(s): 23.2% us, 1.0% sy, 0.0% ni, 75.8% id, 0.0% wa, 0.0% hi, 0.0% si Mem: 256320k total, 243756k used, 12564k free, 4320k buffers Swap: 498004k total, 91412k used, 406592k free, 83952k cached
The load is not bad (.80) but there is over 90M of swap being used! This is due to running too many processes, most of which are doing NOTHING but eating cycles and precious memory. It is noticable when new commands are launched and they take three times longer to appear than expected. Our goal is eliminate the swap usage and cut the number of running tasks (also called processes) by half.
Yes I could go out and buy more memory but it is cheaper and more rewarding to tweak it.
Turn of gdm (or kdm)
All this program really buys you is a fancy (graphical) login screen. It is a glorified version of xdm. The substitute (and equally effective) way to start an X session is to use an .xinitrc file that launches your window manager of choice. Assuming Gnome is your preferred manager, simply put:
exec gnome-session
into your $HOME/.xinitrc file and disable gdm. You can do this from System->Services but be warned, you WILL kill your X session if you started if from gdm. An alternate way is to bring up a shell and type sudo update-rc.d -f gdm remove and then reboot.
Once rebooted, you can login and type startx to initiate your X session.
Turn off unnecessary services
Suggestions of services to turn off (at your own risk of course) and their memory footprint (estimate).
- anacron 2936K (unless you turn your computer off at night)
- atd 1764K (not many people use at to schedule jobs)
- samba - piggy! (7756K)
- inetd 1548K
- avahi-daemon 980K
Remove locate
locate (or mlocate) runs from cron to build an index of all the files in your filesystem. It is a nasty thing and you problem don't need it unless you run the locate command. When it rebuilds the index (the so-called updatedb process) it basically chew up all your I/O capacity. (Recent updates add ionice to the cron, but ionice only works with certain CPU schedulers)
sudo aptitude purge locate
Don't run evolution, thunderbird or firefox
These are heavyweight apps that cost you ALOT of memory, same goes for gnome-terminal.
If you must run these, do so one at a time to avoid hitting swap. Use a leaner e-mail client like Mutt or even Sylpheed. A good lightweight web browser is Chromium, based on Google Chrome.
Don't run gnome-terminal
This beast weighs in at almost 40M of memory! Try a lighter-weight shell instead - I recommend mrxvt.
Don't run gedit (gnome-editor)
This program takes about 22M of RAM. A similarly useful program is nedit and only takes up half of that.
Get back getty!
No I'm not talking about Geddy Lee of Rush fame, but the getty program which sits and waits for incoming terminal connections. Ask yourself, if you are running an X session, how many TTYs do you really need? One should be good enough, that being tty1.
sudo initctl stop tty2 sudo initctl stop tty3 sudo initctl stop tty4 sudo initctl stop tty5 sudo initctl stop tty6 sudo rm /etc/init/tty[23456].conf
Turn off xscreensaver
System->Preferences->Screensaver and choose Disable Screen Saver from the dropdown. Then do File->Kill Daemon (feels good).
Turn off your background
Is it really necessary? I just use a plain brown background. Adjust with System->Preferences->Desktop Background
Adjust systcls
These values can be put in /etc/sysctl.conf and even set while running by using sysctl -w
vm.swappiness = 10