Here are a few things I have done last night to improve boot time. Some may or may not apply to you. I am running Kubuntu 9.04 Jaunty. Hopefully, you might even suggest more improvements.
Bootchart
First, to analyze booting time, install bootchart. It is a wonderful service that renders
a graph of how startup scripts and services are run. It might add a little overhead to your load time, but it will also tell you exactly where and how time is spent. On Ubuntu: apt-get install bootchart. Mine has been there for months, but if you are just installing then boot your linux once so you get at least one chart: check out /var/log/bootchart -- a PNG image and few reports in a .tgz are created. See the image for an example: my boot took 46 seconds.I am going to list a couple of things I did to cut boot time:
Remove services: You can see in the chart there are a LOT of services being started. I use many of them; I stopped using a few of them and others I seldom use. So I could remove some of them from my startup -- with the risk of having a few things stop working. In other cases, I will just know they are stopped, and will start it when I needed (For example: For work, there are weeks were I use a local apache2 daily; but there are periods where I don't use it -- In this case I am going to start it manually when needed). To remove a process from the startup, run (every command listed here is to be run as root): update-rc.d -f
- apache2: I don't use it daily
- mysql (3 services starting with 'mysql'): I don't use it daily, either
- tomcat5.5: the same
- bluetoothd: I don't have bluetooth hardware!
- kdm-kde4: This is a leftover from last year (was it in Gutsy? Hardy?) that I installed a KDE4 pre-release, and had the option to choose between KDE 3.x and 4.x. The service for my desktop manager is "kdm" (it appears in the chart), not "kdm-kde4" which just gives an error while running.
- winbindd: used for samba if I am correct - I had a samba server, but not anymore
- firestarted: a software firewall. I am behind a firewalling router already. Sometimes I use firestarter for specific things... let's start it manually when needed.
- exim4: a mail server? I have never used it.
- timidity: a daemon for MIDI emulation... I think I installed it and used it once in a year.
- virtualbox-ose: Another leftover -- I used to run VirtualBox OSE (Open Source Edition), but now I am using the "closed" one. The latter has "vboxdrv" and "vboxnet" services; but virtualbox-ose is some leftover from the older virtualbox.
- apport: A tool for crash reports. I don't know if I should removed this... but I have never filled a crash report.
- avahi-daemon: "discovers network resources".... uhm, I don't know what this is about. I removed it, and will re-add it if needed.
- wclientd: this is for a VPN client I have stopped using some time ago. I have other vpn services (agn*) running, this one is not needed.
View and remove services, graphically: There is a nice tool that lists your startup services, and you can choose to start/stop them for current session or remove them from startup sequence: "BUM", Boot Up Manager. I mostly listed manually my /etc/rc?.d directories and viewed bootchart graphs, but this one is also useful too (and it allows to remove services with a click).
Readahead
Since a few versions ago "readahead" is included by default in ubuntu installs. It is meant to read in advance all or most the files needed to boot, in the best order to maximize disk access speed, and avoid too many random seeks in the hard disk as services are started. In most installes, it uses a prebuilt list of files that are read --in a default ubuntu install--, but if you have upgraded versions, installed packages, or just let your install grow up with time, this list will be likely outdated.To update the readahead-list, do the following: Boot your machine, and in the GRUB menu press "e" to edit the kernel parameters. Select your kernel, press "e" again and append the word "profile" (separated with a space from the last parameter written there), press Enter to accept this change and press "b" to boot. This boot will take MUCH longer than usual; it will record all disk activity. The good thing is that all the files will be listed to file /etc/readahead/boot, sorted for optimal access. Once linux booted, just reboot (you don't need to change anything in grub, the "profile" thing was a setting for boot only one time).
The original process is shown in the example chart, as taking about 10 seconds. This is actually good: if we don't do this, it would most likely take even more time to read all files needed for services to load. After profiling my boot, this time increased to about 15 seconds. But the overall time was down to 30s! (From the about 36s before readahead). This is because after the length readahead-list operation, all services load much faster.
Note that some people get benefit from readahead, and others do not. You can check if it works for you by disabling it, just emptying the file /var/readahead/boot. Measure the next load to see if readahead is useful for you. For me, it was!
Summary
I just did the two things above: removing services I don't need, and re-profiling to customize my readahead-list. This made my linux boot in 30s, from the 46s that was using -- a big gain! Yet, I am not completely happy - I know it can be done better. So I would love to hear if you have more tips!Also, once you are done with bootchart you might want to remove it from boot. (I would not uninstall the package, you may want to use it from time to time). Just do "update-rc.d -f bootchart remove" and "update-rc.d -f stop-bootchart remove". To re-add it, you may re-install the package or add it to runlevels 2-3-4-5: update-rc.d stop-bootchart start 99 2 3 4 5
For a couple of alternatives:
- Some people report that the splash screen (with the progress bar, while linux loads) can be expensive and slow down things. You can remove the "splash" parameter from your kernel boot (try it out in the same way "profile" was added, as described above) and see if it helps. It did not help in my case. If it does for you, then you need to go change your "defoptions" in /boot/grub/menu.lst and reinstall grub to get the 'splash' parameter removed permanently.
- There is an endless thread (3 years old already) here with information about readahead, and if you read it thoroughly, with a lot of information and other tips.
