"readahead" shortens CD boot time
"readahead" shortened KNOPPIX CD boot time by 60sec on our machine (Celeron 2.0 Ghz, 768MB, 24X CD).
readahead HP http://blog.drinsama.de/erich/en/lin...readahead.html
"readahead" populates the page cache with data from files so that subsequent reads from these files will not block on disk I/O. /etc/init.d/readahead is a script to cache files which is reburied at KNOPPIX boot process. We made KNOPPIX with readahead to make quick boot on KNOPPIX. The performance is measured by bootchart (http://www.bootchart.org/). The result is shown at the following figures.
The detail is written in the following HP. iso file of "KNOPPIX wih readahead" is downloadable. You can check performance on your machine. Have fun.
http://unit.aist.go.jp/itri/knoppix/.../index-en.html
Target Machine: NotePC Sharp Mebius PC-GP-D7E
CPU: Celeron 2.0 Ghz, Memory: 768MB, CD Drive: Matsushita DVD-RAM UJ-810
kernel2.6 + readahead (time: 150sec)
http://unit.aist.go.jp/itri/knoppix/...eadahead-q.png
Original full size figure http://unit.aist.go.jp/itri/knoppix/..._readahead.png
kernel 2.6 (time: 210sec)
http://unit.aist.go.jp/itri/knoppix/...hart-2.6-q.png
Original full size figure http://unit.aist.go.jp/itri/knoppix/...tchart-2.6.png
"readahead" requires much memory
Dear,
Thank you, lilsirecho. I'm happy if I can contibute original KNOPPIX.
But we have to know the effcect of "readahead".
We check the performance when memory size is changed on our machine(Celeron 2.0 Ghz, 768MB, 24X CD).
The results is not welcome. The detail is shown at the following URL.
http://unit.aist.go.jp/itri/knoppix/.../index-en.html
Memory, kenel2.6, kernel2.6+readahead (minutes:second). Red number means slower case.
128MB, 7:18, 8:14
160MB, 4:55, 6:00
192MB, 4:04, 4:34
256MB, 3:48, 4:07
384MB, 3:49, 3:16
512MB, 3:48, 2:45
768MB, 3:33, 2:33
"Normal kernel2.6" with less than 256MB memory was faster than "kernel2.6+readahead". "kernel2.6+readahead" became faster if there was more than 384MB memory.
However these results don't show the feature of "readahead". The performance depends on the files which are cached by "readahead". In this case we designate most files which is required till KDE
We have to find the cached files which are suitalbe for memory size.
compared the boottime to normal knoppix
Hello,
I'm wondering what else is so different with: knoppix_v3.7_20041208-20050107+bootchart.iso
because booting takes on my testbox (XP1800, 512 MB ram, DVD drive) 154 sec
with readahead 127 sec
But the normal Knoppix 3.7 just takes 99 sec.
Are there any other special things in this version that are making it slow?