static vs shared vs modules

[Bob Friesenhahn]

Mikhail Teterin requested that I forward this tidbit of info to the 
list.  The GraphicsMagick build currently distributed with FreeBSD 7.0 
uses shared libraries but not loadable modules.  Some testing I did 
today shows that FreeBSD is much slower at starting GraphicsMagick as 
a large static executable (with shared lib dependencies) than it is 
for a shared library, which itself much slower than the case where 
parts of the needed code are loaded using modules.  This may imply 
that FreeBSD is abnormally slow at initializing large applications 
(e.g. Solaris 10 does not exhibit this anomaly since timings vary only 
by a few percent).

For the timings below, I execute the command using this simple shell 
script:

#!/bin/bash
i=1
count=1000
time while test $i -lt $count
do
   eval "$@"
   let i=i+1
done

Here is the original email content sent to Mikhail Teterin:

I performed some timings for executing a minimal GraphicsMagick command 'gm 
convert -size 1x1 'xc:#F00' null:' 1000 times.  This is under FreeBSD.

Static build:
real    0m39.558s
user    0m24.825s
sys     0m14.853s

Shared build:
real    0m27.828s
user    0m18.367s
sys     0m9.728s

Modules build:
real    0m11.041s
user    0m4.785s
sys     0m6.737s

I find it interesting that FreeBSD is not very efficient at starting large 
(mostly) static programs.  Solaris is a lot better at this. Probably much of 
the difference in performance has to do with how the run-time linker works, and 
the amount of initialized data which needs to be set.

With the static build I can push the generated image size to to 500x500 without 
much impact on the total run time.  The execution overhead is that great.

These differences may seem small but if gm is invoked from a simple shell 
script, it can make the difference between processing 25 small images per 
second or 90 images per second.  Also, the consumed user and system time is 
dramatically less.

Bob
======================================
Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/