Return trivial timing when transfer is trivial

src/core/perfmodel/perfmodel_bus.c

@@ -2989,6 +2989,9 @@ double starpu_transfer_latency(unsigned src_node, unsigned dst_node)
 /* (in µs) */
 double starpu_transfer_predict(unsigned src_node, unsigned dst_node, size_t size)
 {
+	if (src_node == dst_node)
+		return 0;
+
 	double bandwidth = bandwidth_matrix[src_node][dst_node];
 	double latency = latency_matrix[src_node][dst_node];
 	struct _starpu_machine_topology *topology = &_starpu_get_machine_config()->topology;