Move collective algorithms to separate folders

[simgrid.git] / src / smpi / colls / allgather / allgather-rhv.cpp

diff --git a/src/smpi/colls/allgather/allgather-rhv.cpp b/src/smpi/colls/allgather/allgather-rhv.cpp
new file mode 100644 (file)
index 0000000..8e7f44b
--- /dev/null
+++ b/src/smpi/colls/allgather/allgather-rhv.cpp
@@ -0,0 +1,105 @@
+/* Copyright (c) 2013-2014. The SimGrid Team.
+ * All rights reserved.                                                     */
+
+/* This program is free software; you can redistribute it and/or modify it
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
+#include "../colls_private.h"
+
+// now only work with power of two processes
+
+int
+smpi_coll_tuned_allgather_rhv(void *sbuf, int send_count,
+                              MPI_Datatype send_type, void *rbuf,
+                              int recv_count, MPI_Datatype recv_type,
+                              MPI_Comm comm)
+{
+  MPI_Status status;
+  MPI_Aint s_extent, r_extent;
+
+  // local int variables
+  int i, dst, send_base_offset, recv_base_offset, send_chunk, recv_chunk,
+      send_offset, recv_offset;
+  int tag = COLL_TAG_ALLGATHER;
+  unsigned int mask;
+  int curr_count;
+
+  // get size of the communicator, followed by rank 
+  unsigned int num_procs = comm->size();
+
+  if((num_procs&(num_procs-1)))
+    THROWF(arg_error,0, "allgather rhv algorithm can't be used with non power of two number of processes ! ");
+
+  unsigned int rank = comm->rank();
+
+  // get size of single element's type for send buffer and recv buffer
+  s_extent = send_type->get_extent();
+  r_extent = recv_type->get_extent();
+
+  // multiply size of each element by number of elements to send or recv
+  send_chunk = s_extent * send_count;
+  recv_chunk = r_extent * recv_count;
+
+  if (send_chunk != recv_chunk) {
+    XBT_WARN("MPI_allgather_rhv use default MPI_allgather.");  
+    smpi_mpi_allgather(sbuf, send_count, send_type, rbuf, recv_count,
+                              recv_type, comm);
+    return MPI_SUCCESS;        
+  }
+
+  // compute starting offset location to perform local copy
+  int size = num_procs / 2;
+  int base_offset = 0;
+  mask = 1;
+  while (mask < num_procs) {
+    if (rank & mask) {
+      base_offset += size;
+    }
+    mask <<= 1;
+    size /= 2;
+  }
+
+  //  printf("node %d base_offset %d\n",rank,base_offset);
+
+  //perform a remote copy
+
+  dst = base_offset;
+  Request::sendrecv(sbuf, send_count, send_type, dst, tag,
+               (char *)rbuf + base_offset * recv_chunk, recv_count, recv_type, dst, tag,
+               comm, &status);
+
+
+  mask >>= 1;
+  i = 1;
+  int phase = 0;
+  curr_count = recv_count;
+  while (mask >= 1) {
+    // destination pair for both send and recv
+    dst = rank ^ mask;
+
+    // compute offsets
+    send_base_offset = base_offset;
+    if (rank & mask) {
+      recv_base_offset = base_offset - i;
+      base_offset -= i;
+    } else {
+      recv_base_offset = base_offset + i;
+    }
+    send_offset = send_base_offset * recv_chunk;
+    recv_offset = recv_base_offset * recv_chunk;
+
+    //  printf("node %d send to %d in phase %d s_offset = %d r_offset = %d count = %d\n",rank,dst,phase, send_base_offset, recv_base_offset, curr_count);
+
+    Request::sendrecv((char *)rbuf + send_offset, curr_count, recv_type, dst, tag,
+                (char *)rbuf + recv_offset, curr_count, recv_type, dst, tag,
+                 comm, &status);
+
+
+    curr_count *= 2;
+    i *= 2;
+    mask >>= 1;
+    phase++;
+  }
+
+  return MPI_SUCCESS;
+}