"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

Suzaki;

I downloaded the readahead .iso of Knoppix3.7 and ran it twice to examine the boot time.

The boot without readahead was 4 minutes and 20 seconds.

The boot with readahead was 3 minutes and 20 seconds.

I suggest for completeness that you modify your instructions for booting to include the standard entry....knoppix26...then the readahead and lang=us and myconfig=scan...., etcetra

The download was a 2 hour download and performs as advertised.

On the subject of Klik. The atekon.de server seems to be down.

I would like to try Klik with this download because I think my original Knoppix3.7 has bugs.

I get USB mixer on this download but not on my original download.

I am in readahead Knoppix3.7 at this time.

Good show! :D

I am now running in ...toram.. and haven't yet timed it with and without readahead.

My system has 3GB of ram athlon 1900+ in knoppix3.7

The time to boot with toram stayed constant at 3 minutes and 30 seconds with or without the readahead.

I didn't expect it to be any different, just verified it. Approx 2 minutes to load the ram files in each case.

lilsirecho,

"readahead" may NOT be effective for "toram" option, because "readahead" bridges gaps with slow device read.

"readahead" is not effective for small memory PC, because data cached by "readadata" will be got rid of before it is used. I guess 128MB memory is small.

P.S.
The KNOPPIX with "readahead" and "bootchart" is brought in the bootchart home page.
http://www.bootchart.org/samples.html#Knoppix

P.P.S.
Google of "knoppix readahead bootchart" was 0 yesterday(2005/01/14).
It is 2 today(2005/01/15). There are my home page. :-)

Suzaki;

Your system brought to the attention of Klaus Knopper by e-mail. He shows interest. Perhaps you can provide a patch for his review to enhance his understanding of the feature.

I have hopes the system will provide readahead for DVD installs as well. Klaus plans to release the upcoming version in DVD and CD.

I would expect that Klaus would include this system in the DVD version only to allow CD users minimum ram if I read your post correctly.

I would encourage you to apply the same idea to PCLINUXOSv pre8 if you have the time to try it.

The boot time is longer on that system. It responds to Klik.

I am disappointed that atekon.de is not reachable. Wanted to test more OS's with klik.

I previously reported that SFSKNOPPIX performed well with Klik.

Best to you....

The atekon.de wget installed the Klik file.

I was able to download files of firefox, kaffeine, gcalendar and kwikdisk from the website of berlios.de.

The downloads from atekon.de are not responding at this time (other than the wget).

The only source for apps is therefore the berlios.de . It is referenced at the Klik forum.

I find the klik system to operate correctly in the aist download of Knoppix3.7 in kernel26 with readahead boot utilized.

I am going to try other OS'es.

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.

Suzaki;

Interesting results for the memory sizes. It does put a damper on the idea but perhaps a clue can be derived from examining the effect of cache size.

My computer is athlon 1900+ and I have 2100Ram with 3GB installed. I am running Knoppix3.7 booted with readahead obtained from your download. I am using Firefox installed through Klik and am running in TORAM mode.

I have operated Klik in Knoppix3.7, SFSKNOPPIX, PCLinuxOSv7, and PCLinuxOS pre8.

The server site was down due to too many "hits" and has been slower downloading since coming back on-line.

Please consider sending "patch" data to Klaus Knopper who expressed interest in the boot method.

"Googling" reveals other systems utilizing the readahead idea and they may have observations about the effects of ram on the performance.

One thought....large ram systems use "highmem" which might be enabled early during boot time and would affect the results.

When loading "TORAM" the time for KDE to load is greatly reduced along with the X params. This suggests that the ram tie-in could affect the CD boot time.

My system is somewhat slower clock speed than yours and the boot time I reported was about one minute longer than the 150 secs you reported. In fact, the boot time I received was the 210 secs that yours took without readahead.

This suggests that my large ram slows my boot time since the same program is being loaded on each system.

The handling of boot cache size might well be worthy of attention.

Best of luck with your project!

Ran a series of readahead tests on 512, 1000,2000, and 3000MB of ram. All timed with lang=us and myconfig=scan using watch timing to Desktop start in KDE(x and KDE very slow in normal boot)

Readahead with 3GB ram time 3:14
Normal boot 3GB time 4:11

Readahead with 2GB ram time3:27

Readahead with 1GB ram time 3:14

Readahead with 512MB Ram time 3:12
Normal boot with 512MB ram time 4:05

I suggest you use another other computer's operating data for lesser ram which I do not have available.

It shows that the large X and KDE installs are much improved in loading time.

Perhaps someone on the net can perform the comparison on a different set of hardware.

Good luck!

Suzaki;

Operations performed after Xinstall are multiple KDE installs and take a good amount of time in the boot sequence.

I would wonder if the klik .cmg file system might be initiated in X to reduce the size of the CD install of KDE(due to compression of .cmg files of KDE) and complete the install of KDE with .cmg files previously entered by isolinux. This should permit faster boot loading because the KDE file to load would be reduced in size by 50% and may in fact load faster with cramfs which decompresses the .cmg files.

Perhaps the cramfs file system is not available, however, at the install of X. It may however be ready soon thereafter?

But then, also, .cmg files may not be compatible with isolinux .iso system.

It may also be possible to provide KDE entirely in .cmg files to be called by the user as required.

This would not be an auto load of KDE but a fast boot to X followed by a selective KDE loading process by the user using .cmg files in X.

Or it could be automated.

Have a good day!

Readahead should benefit from utilizing klik .cmg technique.

The .cmg files for KDE could be utilized in the boot sequence to reduce the size of the boot if the .cmg files can be handled by mkisofs in preparing the .iso.

This procedure would cut the size of the KDE material by 50% before mkisofs is applied.

Further, after boot more .cmg files could be downloaded to utilize seldom used KDE files which means less KDE in the boot process. This would eliminate the requirement for loading .cmg files via mkisofs as well as the seldom used KDE files in one approach.

In any event, the boot time should improve with the added .cmg capability for readahead. These files are typically 50% compressed.

If .cmg is compatible with mkisofs, most all files could be .cmg prepped for the boot, those not immediately needed to desktop being de-compressed thereafter????

This might be called double-dipping!

================================================== =============================

Asking might get you knowwhere!

Quote:

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Originally Posted by lilsirecho

In any event, the boot time should improve with the added .cmg capability for readahead. These files are typically 50% compressed.

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The main body of data on a Knoppix cd is already compressed (the KNOPPIX/KNOPPIX file on the cd is a compressed cloop image) so using trying to put cmg files inside this compressed image will lead to no space savings or very very little.

FYI,
readahead will be used in Feather Linux 0.7.2 automatically for systems with 512Mb RAM and above.

Thanks,
Rob

typhoonmentat

Very good. I am sure it will reduce boot time for that release esp. if KDE.

My diatribe about readahead includes using .cmg files after the X boot is completed. Then select the KDE .cmg files to be loaded perhaps even automate the install from .cmg. This means less boot time to useful material and less boot files to load. Perhaps not elegant but certainly should work and only catch is download time if from internet but could be loaded via flash USB.

Best of luck with that new release!

Suzaki;

I understand that the primary cause for response of low ram systems is that the minirt.gz requires ram for execution in the boot process.

CDRom elements at boot time do not require ram to install.

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?