Ubuntu 9.10 boot optimizations: 5 second startup with an SSD

Canonical has announced the availability of Ubuntu 9.10 alpha 6, the final alpha release before the transition to beta testing. Ubuntu 9.10, codenamed Karmic Koala, introduces a number of important architectural improvements and also improves boot performance, especially on computers with solid state hard drives.

Earlier this year, Canonical revealed plans to significantly optimize boot performance. It aims to deliver 10-second startups for the Ubuntu 10.04 release, which is due in 2010. In the latest Karmic alpha, the team has already taken some important steps toward achieving this goal. Their roadmap indicates that 25 seconds is the target for Karmic, and the reference device used to benchmark progress is the Dell Mini 9 netbook. We did some testing of our own to see how the OS is coming along.

I installed Ubuntu 9.10 alpha 6 on a Dell Inspiron 1420n, the Ubuntu laptop that I reviewed in 2007. I conducted extensive startup performance testing and used the bootchart utility to measure the results. My average boot time was 22 seconds, with Xorg starting roughly 13 seconds into the boot process.

Users with solid state drives will see a far more dramatic improvement in boot performance. Canonical external developer relations coordinator Jorge Castro (a former Ars Linux contributor) supplied us with a boot chart from his computer, which has an SSD and boots Karmic alpha 6 in only five seconds. If you examine his chart, you will see that Xorg comes up in only two seconds.

One of the most significant technical factors contributing to awesome SSD boot performance is the inclusion of sreadahead, a system service that uses prefetching to load data that is used by the boot process before it is needed. It will also cache the prefetched data and store it so that it can be used during subsequent boots, but it's less effective on conventional hard disks where seek latency introduces some challenges. Ubuntu developer Scott James Remnant explained some of the technical nuances in a mailing list post a few months ago.

In Ubuntu 6.10, which was released several years ago, Canonical introduced a new event-based boot daemon called Upstart to replace the traditional System-V init. One of the primary advantages of Upstart is that it is highly conducive to parallelizing the boot process. In previous versions of Ubuntu, Upstart has largely been used with traditional init scripts. Karmic is the first version where it's really being used to its full potential. On an interesting side note, Upstart has been gaining a whole lot of traction in the mobile space and is used in both the Palm Pre and Nokia's upcoming N900.

Not just boot time

In addition to the improvements to boot performance, a number of other significant enhancements are also featured in Ubuntu 9.10. This is the first Ubuntu version to use GRUB2 and Ext4 by default. Another major change is the adoption of DeviceKit, which will displace HAL, the previous hardware abstraction layer. Pidgin has been replaced in favor of Empathy, a new instant messaging client built on the Telepathy framework that has been adopted by the GNOME community. Client software for Canonical's Ubuntu One cloud storage service is also included by default for the first time.

Ubuntu 9.10 alpha 6 is available for download from the Ubuntu web site. According to the release schedule, the first beta is due on October 1, and the final release is coming on October 29.