Hi, I noticed that profiling data are wrong if OpenMp is used via -fopenmp.
I have only two #pragma omp parallel statements in a class and the calling statistic of this class contructor is completly wrong (gprof tells me this constructor is called far too often). I found bug http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29935 related to OpenMP and profiling but it seems to be a different issue. I tried to reproduce it on a minimal example but could not get very wrong results. Nevertheless I have a simple example which results in different profiling data depending on the -fopenmp option: #include <vector> class VectorStuff { public: VectorStuff() { } void AddVectors(int n, const double *x1, const double *x2, double *y); }; void VectorStuff::AddVectors(int n, const double *x1, const double *x2, double *y) { y = new double[n]; #pragma omp parallel for for (int i=0; i<n; ++i) y[i] = x1[i] + x2[i]; } int main() { VectorStuff vec; const int n = 1000; std::vector<double> x1(n, -2), x2(n, 2); double *y; vec.AddVectors(n, &x1[0], &x2[0], y); return 0; } Comparig the output of g++-4.2svn -pg -g -fopenmp main.cpp; ./a.out; gprof ./a.out > ./a.out.gprof1 g++-4.2svn -pg -g main.cpp; ./a.out; gprof ./a.out > ./a.out.gprof2 results in --- a.out.gprof1 2007-07-17 10:47:04.000000000 +0200 +++ a.out.gprof2 2007-07-17 10:47:13.000000000 +0200 @@ -37,7 +37,6 @@ 0.00 0.00 0.00 2 0.00 0.00 void std::_Destroy<double*, double>(double*, double*, std::allocator<double>) 0.00 0.00 0.00 1 0.00 0.00 VectorStuff::AddVectors(int, double const*, double const*, double*) 0.00 0.00 0.00 1 0.00 0.00 VectorStuff::VectorStuff() - 0.00 0.00 0.00 1 0.00 0.00 main % the percentage of the total running time of the time program used by this function. I agree that this is not very critical for this example, but for other programs profiling is just useless. $ c++-4.2svn --version c++-4.2svn (GCC) 4.2.1 20070713 (prerelease) -- Summary: Profiling not possible with -fopenmp Product: gcc Version: 4.2.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libgomp AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: jensseidel at users dot sf dot net 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=32789
