[Bug 1074428] Re: ureadahead is not optimal
D J Gardner
somloieater at gmail.com
Tue Jan 29 17:36:43 UTC 2013
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.
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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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