Dear Bill, Dear All,
after using MPIR successfully for some time, I am looking for a faster
execution of my code and though of a parallel version. Is there a way to do
it?
I tried OpenMP by doing the following: In a toy example, I included
<omp.h>, gcc’ed with "–fopenmp", and along the following non-MPIR code:
int i, nloops, thread_id=0, N = 1000000;
#pragma omp parallel private(thread_id, nloops)
{
nloops=0;
#pragma omp for
for (i=0; i<N; i++) {
nloops++;
}
thread_id = omp_get_thread_num();
printf("Thread %d performed %d iterations of
the loop.\n", thread_id, nloops );
}
which resulted in the output:
Thread 3 performed 250000 iterations of the loop.
Thread 0 performed 250000 iterations of the loop.
Thread 2 performed 250000 iterations of the loop.
Thread 1 performed 250000 iterations of the loop.
I then tried an MPIR version:
int i, nloops, thread_id=0, N = 1000000;
mpf_t a, b; mpf_inits(a, b, 0);
#pragma omp parallel private(thread_id, nloops, a, b)
{
mpf_set_d(a, 0.0);
mpf_set_d(b, 1.0);
#pragma omp for
for (i=0; i<N; i++) {
mpf_add(a, a, b);
}
thread_id = omp_get_thread_num();
gmp_printf("Thread %d performed %.*Ff
iterations of the loop.\n", thread_id, 10, a );
}
mpf_clears(a, b, 0);
which compiled without errors but resulted in an error (“program … stopped
working during execution”) at runtime.
Is it at all possible to run it in parallel with MPIR – and is there a
mistake in the implementation?
Tests: It runs through without error if the “mpf_add” inside the “#pragma
for” loop is erased and b is set not after but before the “#pragma omp
parallel” statement (but not if the “mpf_add” command is erased and b is
declared as above).
I am using gcc and MinGW on a 64-bit (2 cores) Windows 7 machine.
Thanks and best regards!
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