Sturla Molden <sturla.mol...@gmail.com> wrote: > OpenMP has a flush pragma for synchronizing shared variables. This means > that OpenMP is not restricted to shared memory hardware. A "pragma omp > flush" can just as well invoke some IPC mechanism, even network > communication.
By the way, while this is the case for C and Fortran, it is certainly not the case for Cython. In a Cython prange block, a shared variable is accessed by dereferencing its address. This requires shared memory. Pure OpenMP in C does not, because shared variables are not accessed through pointers, but are rather normal variables that are synchronized with a pragma. Cython actually requires that there is a shared address space, and it invokes something that strictly speaking has undefined behavior under the OpenMP standard. So thus, a prange block in Cython is expected to work correctly on a laptop with a multicore processor, but it is not expected to work correctly on a cluster. IIRC, Intel's cluster OpenMP is based on MPI, which means the compiler will internally translate code with OpenMP pragmas into equivalent code that calls MPI functions. A program written for OpenMP can then run on any cluster that provides an MPI implementation. _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org https://mail.scipy.org/mailman/listinfo/numpy-discussion
