moved cartesian communicator creation to world.c

cellular_automaton/wireworld_c/README.md

@@ -19,11 +19,10 @@ The code sample is structured as follows:
  * `configuration.c`, `configuration.h`: Command line parsing and basic logging facilities.
  * `io.c`, `io.h`: Collective I/O of the cellular automaton state.
  * `main.c`: The main program
-   * `broadcast_configuration`: Broadcasting the parsed command line arguments.
-   * `create_cart_comm`: Creation of the MPI Cartesian communicator.
  * `mpitypes.c`, `mpitypes.h`: Creation of MPI datatypes.
  * `simulation.c`, `simulation.h`: Demonstration of 6 approaches for implementing a Wireworld cellular automaton.
  * `world.c`, `world.h`: Initialization of the cellular automaton and associated MPI objects.
+   * `create_cart_comm`: Creation of the MPI Cartesian communicator.
    * `world_init`: Domain decomposition and buffer allocation.
    * `world_init_io_type`: Creation of the MPI subarray datatype for I/O.
    * `world_init_neighborhood`: Identification of neighboring processes, creation of MPI graph communicator.

cellular_automaton/wireworld_c/main.c

@@ -13,8 +13,6 @@ void broadcast_configuration(conf_t *c);
 
 void read_input(const conf_t *c, world_t *world);
 
-void create_cart_comm(const conf_t *c, MPI_Comm *cart_comm);
-
 void iterate(const conf_t *c, world_t *world);
 
 void print_avg_timings(const conf_t *c, double total_time, double sim_time, double io_time);
@@ -94,40 +92,13 @@ void read_input(const conf_t *c, world_t *world) {
       header_length, global_sizes[0], global_sizes[1]
    );
    // Initialize cells (determine local tile, allocate memory)
-   create_cart_comm(c, &cart_comm);
-   world_init(world, cart_comm, global_sizes, c);
-   MPI_Comm_free(&cart_comm);
+   world_init(world, global_sizes, c);
 
    // Collectively read cell data
    file_read_world(file, world, header_length);
    MPI_File_close(&file);
 }
 
-void create_cart_comm(const conf_t *c, MPI_Comm *cart_comm)
-{
-   const int periods[] = {0, 0}; // non-periodic boundaries
-
-   const int allow_reorder = 1;
-   int comm_world_rank, new_rank;
-   int local_ranks_different, ranks_reordered;
-
-   if(debug_enabled(c)) printf("Creating Cartesian communicator...\n");
-   MPI_Cart_create(MPI_COMM_WORLD, 2, c->nprocs, periods, allow_reorder, cart_comm);
-
-   MPI_Comm_rank(MPI_COMM_WORLD, &comm_world_rank);
-   MPI_Comm_rank(*cart_comm, &new_rank);
-
-   local_ranks_different = comm_world_rank != new_rank;
-   MPI_Allreduce(
-      &local_ranks_different, &ranks_reordered, 1, MPI_INT,
-      MPI_LOR, MPI_COMM_WORLD
-   );
-
-   if(debug_enabled(c)) printf(
-       "INFO: MPI reordered ranks: %s\n", ranks_reordered ? "YES" : "NO"
-   );
-}
-
 void iterate(const conf_t *c, world_t *world)
 {
    const int  n_it  = c->n_iterations;

cellular_automaton/wireworld_c/world.c

@@ -2,6 +2,7 @@
 
 #include "world.h"
 
+void create_cart_comm(const conf_t *c, MPI_Comm *cart_comm);
 
 void world_init_io_type(world_t *world);
 void world_free_io_type(world_t *world);
@@ -12,13 +13,42 @@ void world_free_neighborhood(world_t *world);
 void world_init_persistent_requests(world_t *world, const conf_t *c);
 void world_free_persistent_requests(world_t *world);
 
-void world_init(world_t *world, MPI_Comm cart_comm, size_t *global_size, const conf_t *c)
+// --------------------------------------------------------------------------
+
+void create_cart_comm(const conf_t *c, MPI_Comm *cart_comm)
+{
+   const int periods[] = {0, 0}; // non-periodic boundaries
+
+   const int allow_reorder = 1;
+   int comm_world_rank, new_rank;
+   int local_ranks_different, ranks_reordered;
+
+   if(debug_enabled(c)) printf("Creating Cartesian communicator...\n");
+   MPI_Cart_create(MPI_COMM_WORLD, 2, c->nprocs, periods, allow_reorder, cart_comm);
+
+   MPI_Comm_rank(MPI_COMM_WORLD, &comm_world_rank);
+   MPI_Comm_rank(*cart_comm, &new_rank);
+
+   local_ranks_different = comm_world_rank != new_rank;
+   MPI_Allreduce(
+      &local_ranks_different, &ranks_reordered, 1, MPI_INT,
+      MPI_LOR, MPI_COMM_WORLD
+   );
+
+   if(debug_enabled(c)) printf(
+       "INFO: MPI reordered ranks: %s\n", ranks_reordered ? "YES" : "NO"
+   );
+}
+
+void world_init(world_t *world, size_t *global_size, const conf_t *c)
 {
    int dim, lo, hi;
    int nprocs[2], periods[2], proc_coord[2];
    char *buffer;
    size_t storage_size;
+   MPI_Comm cart_comm;
 
+   create_cart_comm(c, &cart_comm);
    MPI_Cart_get(cart_comm, 2, nprocs, periods, proc_coord);
 
    for(dim = 0; dim < 2; dim++) {
@@ -40,6 +70,8 @@ void world_init(world_t *world, MPI_Comm cart_comm, size_t *global_size, const c
    world_init_neighborhood(world, cart_comm, nprocs, proc_coord, c);
    world_init_persistent_requests(world, c);
 
+   MPI_Comm_free(&cart_comm);
+
    if(trace_enabled(c)) {
       int rank;
       MPI_Comm_rank(MPI_COMM_WORLD, &rank);

cellular_automaton/wireworld_c/world.h

@@ -32,7 +32,7 @@ typedef struct
    transfer_t transfer;
 } world_t;
 
-void world_init(world_t *world, MPI_Comm cart_comm, size_t *global_size, const conf_t *c);
+void world_init(world_t *world, size_t *global_size, const conf_t *c);
 
 size_t world_get_storage_size(const world_t *world);