Comment 16 for bug 577763

I've done some testing and the results are shown in the attached bootcharts.

To disable ureadahead I modified /etc/init/ureadahead.conf so that
exec /sbin/ureadahead --daemon
was changed to
#exec /sbin/ureadahead --daemon
(this applies to bootcharts 1, 4 and 10). This was reversed to re-enable it for other steps.

Before bootchart 5 I modified /etc/init/ureadahead.conf so that
start on starting mountall
was changed to
start on started udev
. This changed remained for all later bootcharts.

Before bootchart 8 I added the attachment 10-ssd.rules to /etc/udev/rules.d/ . This change remained for all later boot charts.

Here's a summary of times and the settings used to make the bootcharts:
1 - Time 25.57. Boot with disabled readahead.
2 - Time 25.68. Boot performing profiling. ureadahead.conf is starting mountall. Pack generated is pack-rotational-1 .
3 - Time 27.57. Boot with readahead.
4 - Time 27.01. Boot with disabled readahead.
5 - Time 27.35. Boot with readahead. ureadahead.conf modified to started udev . (Pack used is pack-rotational-1 as made in 2)
6 - Time 25.68. Boot performing profiling. Pack generated is pack-rotational-2 .
7 - Time 27.25. Boot with readahead.
8 - Time 25.57. Boot performing profiling. 10-ssd.rules added to /etc/udev/rules.d/. Pack generated is pack-ssd-1 .
9 - Time 24.47. Boot with readahead.
10 - Time 25.51. Boot with disabled readahead.