[Bug 1074428] [NEW] ureadahead is not optimal

[hdante]

Public bug reported:

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.

** Affects: ureadahead (Ubuntu)
     Importance: Undecided
         Status: New

** Attachment added: "bootchart.png"
   https://bugs.launchpad.net/bugs/1074428/+attachment/3421865/+files/bootchart.png

** Description changed:

  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 with exemplifies this behavior.
+ 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.

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https://bugs.launchpad.net/bugs/1074428

Title:
  ureadahead is not optimal

Status in “ureadahead” package in Ubuntu:
  New

Bug description:
  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.

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