Improving boot time has been a focus of Ubuntu developers in recent releases, with the goal of a ten-second startup set for Ubuntu 10.4.  To test progress thus far, I compared boot performance for Ubuntu 8.04, 9.04 and 9.10.  Below are the results, which demonstrate the impressive strides that have been made thus far towards a faster boot.

Tests were completed using the i386 builds of Ubuntu 8.04.2, 9.04 and the second alpha of 9.10, which was released yesterday.  Each operating system was installed with the default options to a virtual disk image, and was run in KVM, using identical virtualized hardware for each test.  Boot time was measured from the point at which grub initialized the kernel to the appearance of the GDM login screen.

As a disclaimer, I will mention that the boot times recorded below may be a bit faster than those that can be expected on normal desktops and laptops, since my KVM testing environment runs on server-class hardware, with multiple processor cores and high-speed disks powering the virtual machines.  Nonetheless, the tests provide a standardized basis for comparing boot performance between Ubuntu releases.

The numbers

The averages of several tests gave the following results for boot time, in seconds, between the three Ubuntu releases:
  • 9.10 (Karmic) alpha: 12.94
  • 9.04 (Jaunty): 17.06
  • 8.04.2 (Hardy): 25.07
The numbers speak for themselves.  Ubuntu's boot time has improved enormously since the release of 8.04 in April 2008, with the Karmic alpha build starting up almost twice as fast as Hardy.

This progress can be attributed in part to the use of the faster ext4 file system as the default in Karmic.  But since Jaunty, which uses the older ext3, also demonstrates significant improvement over Hardy, it's clear that there's more to the advancement than file systems alone.  Ubuntu developers' focus on optimizing the boot progress, and the replacement of the ancient System V init daemon with upstart, have also been major contributors to the performance increases.

Does it matter?

My inital reaction to discussion about Ubuntu boot time is to wonder who really cares these days how fast a computer can start up.  Personally, I shut down and reboot my computers very rarely, preferring instead to suspend or hibernate them when idle.  I get the sense that most other computer users do the same, if they power down their machines at all when they walk away (which they should, because electricity doesn't grow on trees).

That said, I'm sure there are some users--like those whose machines still won't suspend properly--who have to reboot their computers often, and who benefit considerably from faster boot time.  In addition, having the fastest boot of modern operating systems provides Ubuntu with some bragging rights, and demonstrates that its developers take usability seriously.

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