From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from postfix1-g20.free.fr (postfix1-g20.free.fr [212.27.60.42]) by ozlabs.org (Postfix) with ESMTP id 91084DDD09 for ; Thu, 22 Feb 2007 06:47:57 +1100 (EST) Received: from smtp8-g19.free.fr (smtp8-g19.free.fr [212.27.42.65]) by postfix1-g20.free.fr (Postfix) with ESMTP id C92ACA5D2BC for ; Wed, 21 Feb 2007 20:47:55 +0100 (CET) Received: from [88.167.113.175] (unknown [88.167.113.175]) by smtp8-g19.free.fr (Postfix) with ESMTP id 8001E16702 for ; Wed, 21 Feb 2007 20:47:51 +0100 (CET) Subject: Re: mcpu options for AMCC440 with fpu From: Patrice Bouchand To: linuxppc-embedded@ozlabs.org In-Reply-To: <600461.55072.qm@web23412.mail.ird.yahoo.com> References: <600461.55072.qm@web23412.mail.ird.yahoo.com> Content-Type: text/plain; charset=UTF-8 Date: Wed, 21 Feb 2007 20:47:50 +0100 Message-Id: <1172087270.3018.18.camel@localhost.localdomain> Mime-Version: 1.0 Reply-To: pb_fwd_list@yahoo.fr List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 > Linuxppc-embedded@ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-embedded