Move collective algorithms to separate folders

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

diff --git a/src/smpi/colls/allgather/allgather-NTSLR.cpp b/src/smpi/colls/allgather/allgather-NTSLR.cpp
new file mode 100644 (file)
index 0000000..5191e85
--- /dev/null
+++ b/src/smpi/colls/allgather/allgather-NTSLR.cpp
@@ -0,0 +1,56 @@
+/* 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"
+
+// Allgather-Non-Topoloty-Scecific-Logical-Ring algorithm
+int
+smpi_coll_tuned_allgather_NTSLR(void *sbuf, int scount, MPI_Datatype stype,
+                                void *rbuf, int rcount, MPI_Datatype rtype,
+                                MPI_Comm comm)
+{
+  MPI_Aint rextent, sextent;
+  MPI_Status status;
+  int i, to, from, rank, size;
+  int send_offset, recv_offset;
+  int tag = COLL_TAG_ALLGATHER;
+
+  rank = comm->rank();
+  size = comm->size();
+  rextent = rtype->get_extent();
+  sextent = stype->get_extent();
+
+  // irregular case use default MPI fucntions
+  if (scount * sextent != rcount * rextent) {
+    XBT_WARN("MPI_allgather_NTSLR use default MPI_allgather.");  
+    smpi_mpi_allgather(sbuf, scount, stype, rbuf, rcount, rtype, comm);
+    return MPI_SUCCESS;    
+  }
+
+  // topo non-specific
+  to = (rank + 1) % size;
+  from = (rank + size - 1) % size;
+
+  //copy a single segment from sbuf to rbuf
+  send_offset = rank * scount * sextent;
+
+  Request::sendrecv(sbuf, scount, stype, rank, tag,
+               (char *)rbuf + send_offset, rcount, rtype, rank, tag,
+               comm, &status);
+
+
+  //start sending logical ring message
+  int increment = scount * sextent;
+  for (i = 0; i < size - 1; i++) {
+    send_offset = ((rank - i + size) % size) * increment;
+    recv_offset = ((rank - i - 1 + size) % size) * increment;
+    Request::sendrecv((char *) rbuf + send_offset, scount, stype, to, tag + i,
+                 (char *) rbuf + recv_offset, rcount, rtype, from, tag + i,
+                 comm, &status);
+  }
+
+  return MPI_SUCCESS;
+}