To get a faster boot on our live systems, we need to get a boot profile (the access order to files contained in loopback). This will avoid CD drives to spin back-and-forth to get files that could have been nearer on the CD medium.

Some solutions

Readahead only (no need to regenerate the loopback)

• sort the access filelist according to their position in the compressed loopback
• drop this sorted filelist next to the loopback
• add a service that readaheads the loopback-position-sorted filelist

Loopback sort (and readahead)

This method adds optimization even if readahead is disabled (preferable on low-memory systems).

• regenerate loopback according to file access order
• optionnally do readahead, using the access-ordered filelist

What others are doing

Ubuntu

They use inotify in their readahead-watch profiling program, but this requires to add a watch for all existing directories, and it maybe lose early events since it isn't run at startup.

• http://packages.ubuntulinux.org/dapper/admin/readahead
• readahead-list
• Faster Boot Time and Optional Persistence

Accelerated Knoppix

Accelerated Knoppix patched the cloop module to add profiling code, which can be controlled using /proc.

Couriousous

echo 1 > /proc/sys/vm/block_dump

gnome-startup (my favorite approach)

• Analyzing and Improving GNOME Startup Time
• syscall hijacking (catch all read events)
• Sysprof

Other tools

• systrace
• inotify-tools
• Linux audit