Hello all, I guess there is something wrong with gcc 4.3.1 + openmp. Here how it went with me
Well on this page : http://www.kallipolis.com/openmp/1.html I tried taylor.c and taylor_mp.c compiler options as follows: gcc -O3 taylor.c -o taylor_gcc icc -O3 taylor.c -o taylor_icc gcc -O3 -fopenmp taylor_mp.c -o taylor_mp_gcc icc -O3 -openmp taylor_mp.c -o taylor_mp_icc Results summarized: Only gcc + openmp gave different result, which was wrong according to the web page. Of course there was no speedup. Reason might be due to the number of steps. Being low, so that synchronization of threads was costly. taylor_gcc : Values: e*pi = 8.539734 Total elapsed time: 5500.000 seconds taylor_icc : Values: e*pi = 8.539734 Total elapsed time: 2920.000 seconds ** taylor_mp_gcc: ** Values: e*pi = 8.940247 ** Total elapsed time: 8170.000 seconds taylor_mp_icc: Values: e*pi = 8.539734 Total elapsed time: 6020.000 seconds My system summary : OS : OpenSUSE 11.0 Linux 64 bit + kernel 2.6.25.9-0.2-default gcc version : gcc (SUSE Linux) 4.3.1 20080507 (prerelease) [gcc-4_3-branch revision 135036] CPU : Intel quad core Q6600 (G0 stepping) on ASUS P5K SE icc version : icc (ICC) 10.1 20080312 Let me know if you need more detail. God bless your work! PS: I saw this bug(!) on another web page too!!! Kemal Kilic [EMAIL PROTECTED] -- Summary: OpenMP issue in gcc vs icc Product: gcc Version: 4.3.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: kemalihsan dot 1 at gmail dot com http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36869
