From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29147 invoked by alias); 16 Nov 2007 22:23:42 -0000 Received: (qmail 28385 invoked by uid 48); 16 Nov 2007 22:23:29 -0000 Date: Fri, 16 Nov 2007 22:23:00 -0000 Subject: [Bug libfortran/34128] New: slow gfortran 4.x (library?) compared to g77 3.4 X-Bugzilla-Reason: CC Message-ID: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "mnoble at space dot mit dot edu" Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2007-11/txt/msg01570.txt.bz2 The following codes (compiled as demo1.f and demo2.f) PROGRAM demo1 PROGRAM demo2 integer i integer i double precision result double precision result do i=1,8000000 do i=1,500000000 result = sin(i*3.14159) result = i*3.14159 enddo enddo print*,'result = ',result print*,'result = ',result END END reveal marked performance disparities between g77 and gfortran on an x86_64 Debian Linux 4.0 machine with 4 AMD Opteron cores: vendor_id : AuthenticAMD cpu family : 15 model : 65 model name : Dual-Core AMD Opteron(tm) Processor 2216 stepping : 2 cpu MHz : 2400.452 Sample timings are given below, comparing the Debian binary package of g77 3.4.6 against both gfortran 4.1.2 (Debian binary package) & gfortran 4.2.1 (locally built from source). Perhaps a gfortran library issue? Regards, Michael S. Noble -------------------------------------------------------------------- % uname -a Linux rabble 2.6.18-5-amd64 #1 SMP Tue Oct 2 20:37:02 UTC 2007 x86_64 GNU/Linux which g77 && g77 -v /usr/bin/g77 Reading specs from /usr/lib/gcc/x86_64-linux-gnu/3.4.6/specs Configured with: ../src/configure -v --enable-languages=c,c++,f77,pascal --prefix=/usr --libexecdir=/usr/lib --with-gxx-include-dir=/usr/include/c++/3.4 --enable-shared --with-system-zlib --enable-nls --without-included-gettext --program-suffix=-3.4 --enable-__cxa_atexit --enable-clocale=gnu --enable-libstdcxx-debug x86_64-linux-gnu Thread model: posix gcc version 3.4.6 (Debian 3.4.6-5) g77 -o demo1-g77 -O2 demo1.f time ./demo1-g77 result = -0.690680921 real 0m0.562s g77 -o demo2-g77 -O2 demo2.f time ./demo2-g77 result = 1.57079501E+09 real 0m0.041s which gfortran && gfortran -v /usr/bin/gfortran Using built-in specs. Target: x86_64-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 x86_64-linux-gnu Thread model: posix gcc version 4.1.2 20061115 (prerelease) (Debian 4.1.1-21) gfortran -o demo1-gfortran -O2 demo1.f time ./demo1-gfortran result = -0.690680921077728 real 0m7.681s gfortran -o demo2-gfortran -O2 demo2.f time ./demo2-gfortran result = 1570795008.00000 real 0m2.085s \rm demo?-gfortran PATH=/usr/local/bin:$PATH which gfortran && gfortran -v /usr/local/bin/gfortran Using built-in specs. Target: x86_64-unknown-linux-gnu Configured with: ./configure --prefix=/usr/local --enable-languages=c,c++,fortran Thread model: posix gcc version 4.2.1 gfortran -o demo1-gfortran -O2 demo1.f -L/usr/local/lib -Wl,-R/usr/local/lib time ./demo1-gfortran result = -0.690680921077728 real 0m7.672s gfortran -o demo2-gfortran -O2 demo2.f -L/usr/local/lib -Wl,-R/usr/local/lib time ./demo2-gfortran result = 1570795008.00000 real 0m2.085s -- Summary: slow gfortran 4.x (library?) compared to g77 3.4 Product: gcc Version: 4.1.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libfortran AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: mnoble at space dot mit dot edu GCC build triplet: x86_64-unknown-linux-gnu GCC host triplet: x86_64-unknown-linux-gnu GCC target triplet: x86_64-unknown-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34128