ureadahead is not optimal

[hdante]

This forum post:

http://ubuntuforums.org/showthread.php?t=1434502

Describes ureadahead as efficiently loading all boot files at once, resulting in a faster boot time, which is correct from the point of view of the I/O. However viewing a bootchart with ureadahead running shows that no other process is started while it's running and cpu utilization is close to zero.

See attached picture which exemplifies this behavior.

In the picture it's possible to see that first process executed after ureadahead is "mountall". However it's very probable that mountall was loaded somewhere in the middle of execution of ureadahead and could have been executed much earlier, resulting in both I/O and processing being used as efficiently as possible. The only possible reason for an optimal implementation to result in the above picture is when "mountall" is the last file that ureadahead loads, which I don't believe is the case.

In the optimal situation, the remaining execution time of the whole boot process after ureadahead should be minimal, mostly dependent on the organization of the files on disk.

[D J Gardner (djgardner)]

I'm not convinced you should be starting fsck while loading stuff into cache - that would surely be a conflict. Both are disk-intensive, after all.