I tried prelink the first time Texstar told us about it, in my Openbox install. I found it strange and bothering to hear the noise of the hard drive when cron restarted prelinking, and running all of a sudden about 2 minutes each night. So at that time I uninstalled it and didn't think about it anymore.
Then recently, the PCLinuxOS Education (non official not supported) in French has been tested by a French user at another forum, and he said Gcompris icon on the desktop, in the Live CD, didn't work.
Does not work I wondered ? How come it does not work ? In fact it was working, but you could have eaten a whole meal before the display starts. So I thought first I would leave the configuration files in the system, home of school, and in /etc/skel, but it appeared not to be doing the trick. I thought that there are too many libs necessary to run it, so I thought I would try prelink. I installed prelink, used the command as root "prelink -avmR", and remastered again. It was better, but yet it was still taking 27 seconds in the LIve CD, which is very very long, when you are demonstrating and getting people to try.
Then I looked at the links in the present threads, seeking for options. At the end, I went to google and found a nice tutorial, here: http://crast.us/james/articles/prelink.phpI did 4 more remasters for tests and came to this
It is possible to prelink only one or a few programs;
After I prelinked only gcompris, the /etc/prelink.cache fell from about 364 KB to 5.5 KB;
The following remaster was able to let me launch Gcompris, from the icon on the desktop, in the Live CD : in 3 seconds only !!!
To switch from the full prelinking to only one, I was not sure and first uninstalled, then found I could use as root "prelink -au" which unprelinks all, then do a "rm -f" on the file /etc/prelink.cache (but this may not be useful), then "prelink -vmR /usr/bin/gcompris". I had thoughts about the "-m" option, tried without and with it, found that it seems to work better with it. (fixed address for memory, if I understood well the man and the howto).I have a question :
I thought it is not necessary for it to be run each day : I moved /etc/cron.daily/prelink to /etc/cron.weekly : is that enough to make it run only once a week ?
In the file /etc/sysconfig/prelink I changed this part:
# How often should full prelink be run (in days)
# Normally, prelink will be run in quick mode, every
# $PRELINK_FULL_TIME_INTERVAL days it will be run
# in normal mode. Comment it out if it should be run
# in normal mode always.
# PRELINK_FULL_TIME_INTERVAL=14I have one more question :
The above comments look to me like it says if the "PRELINK_FULL_TIME_INTERVAL=14" was commented, then it would be run on quick mode only : have I understood correctly ?
So to sum up : prelinking all makes Gcompris start in 27 seconds (same machine, with a Live CD), prelink only the heavy Gcompris allows getting it to start in 3 seconds.
Other tests I tried :
* in a full Openbox, I tried to prelink Libreoffice. That didn't work, it ended with messages saying that some of the related libs could not be prelinked due to some other lib missing, or something like that;
* In my personal Openbox install, (a Nec M160 which has a small celeron 1.46 Ghz and 1 GB ram, quite slow for some apps) I prelinked Firefox and Inkscape only. It seems to help them start faster, but not instant.
And last trick about prelink : if only one or a few programs are prelinked, and we want to prelink one more later, it is possible to do so, just by running the command for one program (prelink -options /path/to/program), and the program and list of libs is added to the /etc/prelink.cache file.
Now in my personal machine, the cache file has gone from 11 kb to 12 kb after I tried to add another program to the list. The option -p allows displaying the content of the prelink.cache file : "prelink -p".
I don't know yet how to un prelink only one program. Maybe something such as ? "prelink -vu /path/to/program" ?
So, for the PCLinuxOS Education, prelink is adopted.
Thanks if you have answers to the 2 questions I asked.