Hi, Have you tried using the -ffast-math option?
/Magnus On Wed, 21 Feb 2007 20:47:50 +0100 Patrice Bouchand <[EMAIL PROTECTED]> wrote: > > FYI, I got the following answer on mplayer mailing list: > > > Apparently -mcpu=440fp is the one. However, it's possible, that GCC > > "optimizations" actually make the code slower. > > Can someone confirme this possiblity ? > > Any answer would be greatly appreciated ;) > > > Patrice Bouchand > > > > Hello, > > > > I was searching for the best mcpu option for amcc440, compiling and > > running a small program you can find here: > > http://magnux.free.fr/gcc/mandelbrot.c. My distro is a ppc fedora core > > 6, and results are obviously the same using DENX4.0. > > > > -------------------- > > -bash-3.00# gcc -O2 ./mandelbrot.c -o ./mandelbrot && > > time ./mandelbrot && rm -f ./mandelbrot > > > > real 1m15.059s > > user 1m14.996s > > sys 0m0.060s > > -bash-3.00# gcc -O2 -mcpu=440 ./mandelbrot.c -o ./mandelbrot && > > time ./mandelbrot && rm -f ./mandelbrot > > > > real 0m39.606s > > user 0m39.552s > > sys 0m0.028s > > -bash-3.00# gcc -O2 -mcpu=440fp ./mandelbrot.c -o ./mandelbrot && > > time ./mandelbrot && rm -f ./mandelbrot > > > > real 1m15.016s > > user 1m14.988s > > sys 0m0.024s > > -bash-3.00# gcc -O2 -msoft-float ./mandelbrot.c -o ./mandelbrot && > > time ./mandelbrot && rm -f ./mandelbrot > > > > real 0m39.577s > > user 0m39.544s > > sys 0m0.032s > > -------------------- > > > > * I do not explain why not using FPU gives better results ? > > > > * I did also a test with bzip2.c > > ( http://pag.csail.mit.edu/~smcc/projects/single-file-programs/bzip2.c ). > > > > ---------------------- > > -bash-3.00# gcc -O2 ./bzip2.c -o ./bzip2 && time ./bzip2 ./oggenc.c > > && ./bzip2 -d ./oggenc.c.bz2 && rm ./bzip2 > > > > real 0m18.478s > > user 0m18.216s > > sys 0m0.152s > > -bash-3.00# gcc -O2 -mcpu=440 ./bzip2.c -o ./bzip2 && > > time ./bzip2 ./oggenc.c && ./bzip2 -d ./oggenc.c.bz2 && rm ./bzip2 > > > > real 0m18.786s > > user 0m18.544s > > sys 0m0.128s > > -bash-3.00# gcc -O2 -mcpu=440fp ./bzip2.c -o ./bzip2 && > > time ./bzip2 ./oggenc.c && ./bzip2 -d ./oggenc.c.bz2 && rm ./bzip2 > > > > real 0m18.811s > > user 0m18.548s > > sys 0m0.144s > > -bash-3.00# gcc -O2 -mcpu=G3 ./bzip2.c -o ./bzip2 && > > time ./bzip2 ./oggenc.c && ./bzip2 -d ./oggenc.c.bz2 && rm ./bzip2 > > > > real 0m18.871s > > user 0m18.644s > > sys 0m0.104s > > ---------------------- > > > > * mcpu option seems to not have any effect ? > > > > * My third test was to compile and run mplayer. > > - With default options (no mcpu specified), my test mpeg was smooth. > > - With mcpu=440fp, my test mpeg was not smooth. > > > > Can anybody bring me some lights about the right gcc mcpu option for > > amcc440 ? > > > > Best regards, > > > > Patrice Bouchand > > > > > > > > > > ______________________________________________________________________ > > Découvrez une nouvelle façon d'obtenir des réponses à toutes vos > > questions ! Profitez des connaissances, des opinions et des > > expériences des internautes sur Yahoo! Questions/Réponses. > > _______________________________________________ > > Linuxppc-embedded mailing list > > [email protected] > > https://ozlabs.org/mailman/listinfo/linuxppc-embedded > > _______________________________________________ > Linuxppc-embedded mailing list > [email protected] > https://ozlabs.org/mailman/listinfo/linuxppc-embedded _______________________________________________ Linuxppc-embedded mailing list [email protected] https://ozlabs.org/mailman/listinfo/linuxppc-embedded
