hybrid_distr_arg.cpp

#include <algorithm>
#include <cstdlib>
#include <iostream>
#include <mpi.h>
#include <omp.h>

int calculate_start(int worker_id, int workers, int finish, int begin)
{
	int range = finish - begin;
	return begin + worker_id * (range / workers) + std::min(worker_id, range % workers);
}

int calculate_finish(int worker_id, int workers, int finish, int begin)
{
	return calculate_start(worker_id + 1, workers, finish, begin);
}

int main(int argc, char* argv[])
{
	MPI_Init(&argc, &argv);
	
	int my_rank = -1;
	int process_count = -1;
	
	MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
	MPI_Comm_size(MPI_COMM_WORLD, &process_count);
	
	char hostname[MPI_MAX_PROCESSOR_NAME];
	int hostname_length = -1;
	MPI_Get_processor_name(hostname, &hostname_length);
	
	if ( argc == 3 )
	{
		const int global_start = atoi(argv[1]);
		const int global_finish = atoi(argv[2]);
		
		const int my_start = calculate_start( my_rank, process_count, global_finish, global_start);
		const int my_finish = calculate_finish( my_rank, process_count, global_finish, global_start);
		const int my_width = my_finish - my_start;
		
		// hostname1:0: range [3, 12[ size 9
		std::cout << hostname << ":" << my_rank << ": range [" << my_start 
			<< ", " << my_finish << "[ size " << my_width << std::endl;

		#pragma omp parallel default(none) shared(my_rank, hostname, std::cout)
		{
			int my_thread_start = 0;
			int my_thread_finish = 0;
			
			#pragma omp for
			for ( int index = my_start; index < my_finish; ++index )
			{
				if ( my_thread_start == 0 )
					my_thread_start = index;
				my_thread_finish = index;
			}
			
			const int my_thread_width = ++my_thread_finish - my_thread_start;
			
			// hostname1:0.0: range [3,6[ size 3
			#pragma omp critical(stdout)
			std::cout << '\t' << hostname << ":" << my_rank << ":" << omp_get_thread_num() << ": range ["
				<< my_thread_start << "," << my_thread_finish << "[ size " << my_thread_width << std::endl;
		}
	}
	else
		std::cerr << "usage: hybrid_distr_arg min max" << std::endl;
	
	MPI_Finalize();
}