Linux c++ opmization--- linux runs at half the speed of windows?

["Shane R" <crazguy22@hotmail.com>]

Hi,

I hope this is the appropriate forum. Please direct me to the correct one if 
it is not.

I am trying to optimize a c++ application that I ported from a windows 
system to Linux.
The app is a terminal based application that does some one time file io at 
the start then runs completely in memory. After the one time io the app runs 
successive timed epochs on the same data in Windows as Linux. The app is a 
program that runs some code for doing non-linear optmization (math stuff).

The reason why I am posting is that I timed the time it takes for the 
application to complete an epoch. It take twice as long in Linux as 
windows?!?!

My system is an Intel Centrino Duo with 2gigs of ram. The application is 
only using a fraction of available memory in windows and linux. The 
application is single-threaded in both.

I am using Visual Studio 2003 in Windows and when I type gcc -v I get:
Target: i486-linux-gnu
Configured with: ../src/configure -v 
--enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr 
--enable-shared --with-system-zlib --libexecdir=/usr/lib 
--without-included-gettext --enable-threads=posix --enable-nls 
--program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu 
--enable-libstdcxx-debug --enable-mpfr --enable-checking=release 
i486-linux-gnu
Thread model: posix
gcc version 4.1.2 20060928 (prerelease) (Ubuntu 4.1.1-13ubuntu5)



I am currently using these g++ options:

CFLAGS = -o3 -O3 -march=pentium4 -ffast-math  -funroll-loops -Wall 
-Wno-return-type

But I have tried every permutation of the above options to virtually no 
effect

The average run time of an epoch in windows is about 3000 milliseconds while 
the average run time of an epoch in Linux is 6000!

I don't know if it matters but I am doing calls to the rand() function in 
both my windows and linux apps.

On another note does anyone have any experience with the Intel drop in 
replacement for GCC?

Thanks in advance for any help,

Shane

_________________________________________________________________
Match.com - Click Here To Find Singles In Your Area Today!  
http://match.engb.msn.com/