ureadahead slows down bootup with SSD
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
ureadahead (Ubuntu) |
New
|
Undecided
|
Unassigned |
Bug Description
Binary package hint: ureadahead
I felt like bootup had slowed down in 10.04 and one thing that stood out in bootchart was ureadahead, so I measured its performance according to the instructions at http://
One thing I must note is that my main filesystem is on a SSD while various HDD and USB disks are used to store data.
I've included 5 bootcharts:
*1.no-ureadahea
*2.main-
*3.profiling.png -> Deleted the "pack" file so that ureadahead could reprofile.
*4.all-packs.png -> Booting with ureadahead "optimization", slowest of all boots; 24+ seconds until gdm startup.
*5.minus-
So it seems to me that by trying to cache data for all disks in one go, ureadahead brings performance down to the lowest common denominator, in my case a USB disk.
ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: ureadahead 0.100.0-4.1.2
ProcVersionSign
Uname: Linux 2.6.32-
NonfreeKernelMo
Architecture: i386
Date: Wed Sep 22 08:27:50 2010
PackDump: Error: command ['ureadahead', '--dump'] failed with exit code 4: ureadahead:
PackDumpDat: Error: command ['ureadahead', '--dump'] failed with exit code 4: ureadahead:
PackDumpMnt.
PackDumpMnt.
ProcEnviron:
LC_TIME=
LANGUAGE=en_CA:en
PATH=(custom, user)
LANG=en_CA.utf8
SHELL=/bin/bash
SourcePackage: ureadahead
Hmm, readahead() blocks until the specified data has been read, so if ureadahead is a single threaded process, that's probably the problem that you're running in to.