Is your windows compiler doing automatic parallelization by chance? Twice as fast on a dual core processor is a bit too coincidental. :-) On 3/8/07, Shane R <crazguy22@xxxxxxxxxxx> wrote:
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/
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