int divide_parallel_processes(int numgroups)
{
#ifdef HAVE_MPI
end_divide_parallel();
if (numgroups > count_processors()) abort("numgroups > count_processors");
int mygroup = (my_rank() * numgroups) / count_processors();
MPI_Comm_split(MPI_COMM_WORLD, mygroup, my_rank(), &mycomm);
return mygroup;
#else
if (numgroups != 1) abort("cannot divide processes in non-MPI mode");
return 0;
#endif
}
int
start_threads(vg_context_t *vcp, int nthreads)
{
pthread_t thread;
if (nthreads <= 0) {
/* Determine the number of threads */
nthreads = count_processors();
if (nthreads <= 0) {
fprintf(stderr,
"ERROR: could not determine processor count\n");
nthreads = 1;
}
}
if (vcp->vc_verbose > 1) {
fprintf(stderr, "Using %d worker thread(s)\n", nthreads);
}
while (--nthreads) {
if (pthread_create(&thread, NULL, vg_thread_loop, vcp))
return 0;
}
vg_thread_loop(vcp);
return 1;
}
void fields::boundary_communications(field_type ft) {
// Communicate the data around!
#if 0 // This is the blocking version, which should always be safe!
for (int noti=0;noti<num_chunks;noti++)
for (int j=0;j<num_chunks;j++) {
const int i = (noti+j)%num_chunks;
const int pair = j+i*num_chunks;
DOCMP {
send(chunks[j]->n_proc(), chunks[i]->n_proc(),
comm_blocks[ft][pair], comm_size_tot(ft,pair));
}
}
#endif
#ifdef HAVE_MPI
const int maxreq = num_chunks*num_chunks;
MPI_Request *reqs = new MPI_Request[maxreq];
MPI_Status *stats = new MPI_Status[maxreq];
int reqnum = 0;
int *tagto = new int[count_processors()];
for (int i=0;i<count_processors();i++) tagto[i] = 0;
for (int noti=0;noti<num_chunks;noti++)
for (int j=0;j<num_chunks;j++) {
const int i = (noti+j)%num_chunks;
const int pair = j+i*num_chunks;
const int comm_size = comm_size_tot(ft,pair);
if (comm_size > 0) {
if (chunks[j]->is_mine() && !chunks[i]->is_mine())
MPI_Isend(comm_blocks[ft][pair], comm_size,
MPI_REALNUM, chunks[i]->n_proc(),
tagto[chunks[i]->n_proc()]++,
mycomm, &reqs[reqnum++]);
if (chunks[i]->is_mine() && !chunks[j]->is_mine())
MPI_Irecv(comm_blocks[ft][pair], comm_size,
MPI_REALNUM, chunks[j]->n_proc(),
tagto[chunks[j]->n_proc()]++,
mycomm, &reqs[reqnum++]);
}
}
delete[] tagto;
if (reqnum > maxreq) abort("Too many requests!!!\n");
if (reqnum > 0) MPI_Waitall(reqnum, reqs, stats);
delete[] reqs;
delete[] stats;
#else
(void) ft; // unused
#endif
}
