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Yes, you are correct. Using separate executables, with different INODE
numbers, Linux has no idea that the code pages are the same. The benefit
I enumerated will NOT be seen. The only benefit will indeed be in
the shared library routines, and this can be very limited as you point
out. The libraries are "re-entrant", so this benefit will be
seen even if separate executables are invoked.<br><br>
I should have mentioned that the invocation of the executable MUST be the
same INODE to obtain the maximum memory advantage to which I
referred. (Every file in Linux is known by it's INODE number, not
it's name). So if it is a different INODE, Linux has no idea that the
code pages are the same.<br><br>
One simple way to so this is by making a Symbolic link. Do NOT copy them,
but<br>
instead, for each file in the original file structure, make a symbolic
link.<br><br>
Instead of cp $home/cod/cod_linuxex $home/cod2/<br><br>
perform a symbolic link:<br><br>
ln -s $home/cod/cod_linuxex $home/cod2/cod_linuxex<br><br>
If you now check the two files, you will see one points at the
other.<br><br>
ls -li $home/cod/cod_linuxex<br><br>
and <br><br>
ls -li $home/cod2/cod_linuxex<br><br>
The INODE number will be the first value listed. They should be the
same. This means the<br>
invocation from $home/cod and $home/cod2 will use the SAME
executable.<br><br>
****Note, you can not symbolic link across filesystems. If you do,
Linux will make<br>
a copy. So if the /usr directory is a different filesystem than the
/gaming directory,<br>
Linux will make a copy. Make sure for all servers you plan to
execute, they are on the<br>
same filesystem, and they will all be one executable. (Note that the
symbolic link only<br>
takes a few blocks of disk space)... yea... just another side
benefit...<br><br>
Have fun.<br><br>
Thank you Joe for making this very critical observation!<br><br>
MD<br><br>
<br><br>
At 02:07 PM 5/15/2004, Joe Brown wrote:<br>
<blockquote type=cite class=cite cite>Hi Mark,<br><br>
Thanks for sharing your knowledge and taking your time to explain these
technical details in a language I can understand. <br>
One of the reasons this thread started: I mentioned to a colleague, I
prefer to run servers from one install of a game server, to allow the OS
to make use of shared libraries. Althought I think the advantages
are somewhat minor, there are still system performance issues that will
be realized.<br><br>
For a server instance, some ppl have a tendency to make a copy of all the
game server files in seperate home directories for each server
instance. Because these files are a copies, not linked or the same
physical file image, I'm working on the assumption the OS has no means to
identify that the same executable is being run mutiple times, because
it's executing from seperate copies.<br><br>
There are a couple of issues in system performance, I don't care for,
when this happens.<br>
1st, any file caching benifits are out the window. I don't believe
system performace will take a very noticable hit on this, it's effects
are fairly well hidden and hard to observe. But it is
there.<br><br>
2nd, I suspect more memory will be consumed by running game servers from
seperate copies, because shared libraries won't be shared as they could
be. <- I'm in the dark about the accuracy of this statement
tho.<br><br>
I'm a performance junkie. If I can make things perform better, I'll
go the distance to make it so. But when a guy tells me he can't see
a difference in one method vs. another and I cannot refute that with
tangible details, I find myself in bit of a quandery.<br><br>
I would appreciate if you could elaborate on these issues, my technical
knowledge is far less intimate with the internals of the
kernel.<br><br>
<br>
Thanks Again,<br><br>
-Joe<br><br>
</blockquote>
<x-sigsep><p></x-sigsep>
<tt>-------------------------------------------------------------------------------<br>
Mark J.
DeFilippis
defilm@acm.org<br>
defilm@ieee.org<br><br>
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