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
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