From: Augustin Degomme <degomme@idpann.imag.fr>
Date: Mon, 8 Jul 2013 13:01:53 +0000 (+0200)
Subject: quick and naive implementation of the MPI_Exscan collective
X-Git-Tag: v3_9_90~187
X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/commitdiff_plain/cd701c7e68bbf6598c9350e19389c0b6952bdeef

quick and naive implementation of the MPI_Exscan collective
---

diff --git a/src/smpi/instr_smpi.c b/src/smpi/instr_smpi.c
index 2aa3d53f0c..dca11e4f44 100644
--- a/src/smpi/instr_smpi.c
+++ b/src/smpi/instr_smpi.c
@@ -38,6 +38,7 @@ static const char *smpi_colors[] ={
     "reduce",        "0 1 0",
     "reducescatter", "0.52 1 0.52",
     "scan",          "1 0.58 0.23",
+    "exscan",          "1 0.54 0.25",
     "scatterv",      "0.52 0 0.52",
     "scatter",       "1 0.74 0.54",
     "computing",     "0 1 1",
diff --git a/src/smpi/private.h b/src/smpi/private.h
index 1e2a3c2142..52b9ed8cc2 100644
--- a/src/smpi/private.h
+++ b/src/smpi/private.h
@@ -255,6 +255,8 @@ void smpi_mpi_allreduce(void *sendbuf, void *recvbuf, int count,
                         MPI_Datatype datatype, MPI_Op op, MPI_Comm comm);
 void smpi_mpi_scan(void *sendbuf, void *recvbuf, int count,
                    MPI_Datatype datatype, MPI_Op op, MPI_Comm comm);
+void smpi_mpi_exscan(void *sendbuf, void *recvbuf, int count,
+                   MPI_Datatype datatype, MPI_Op op, MPI_Comm comm);
 
 void nary_tree_bcast(void *buf, int count, MPI_Datatype datatype, int root,
                      MPI_Comm comm, int arity);
diff --git a/src/smpi/smpi_base.c b/src/smpi/smpi_base.c
index 73fe79ad64..8afbcae3cb 100644
--- a/src/smpi/smpi_base.c
+++ b/src/smpi/smpi_base.c
@@ -1298,3 +1298,56 @@ void smpi_mpi_scan(void *sendbuf, void *recvbuf, int count,
   xbt_free(tmpbufs);
   xbt_free(requests);
 }
+
+void smpi_mpi_exscan(void *sendbuf, void *recvbuf, int count,
+                   MPI_Datatype datatype, MPI_Op op, MPI_Comm comm)
+{
+  int system_tag = 888;
+  int rank, size, other, index;
+  MPI_Aint lb = 0, dataext = 0;
+  MPI_Request *requests;
+  void **tmpbufs;
+  int recvbuf_is_empty=1;
+  rank = smpi_comm_rank(comm);
+  size = smpi_comm_size(comm);
+
+  // FIXME: check for errors
+  smpi_datatype_extent(datatype, &lb, &dataext);
+
+  // Send/Recv buffers to/from others;
+  requests = xbt_new(MPI_Request, size - 1);
+  tmpbufs = xbt_new(void *, rank);
+  index = 0;
+  for(other = 0; other < rank; other++) {
+    // FIXME: possibly overkill we we have contiguous/noncontiguous data
+    // mapping...
+    tmpbufs[index] = xbt_malloc(count * dataext);
+    requests[index] =
+      smpi_irecv_init(tmpbufs[index], count, datatype, other, system_tag,
+                      comm);
+    index++;
+  }
+  for(other = rank + 1; other < size; other++) {
+    requests[index] =
+      smpi_isend_init(sendbuf, count, datatype, other, system_tag, comm);
+    index++;
+  }
+  // Wait for completion of all comms.
+  smpi_mpi_startall(size - 1, requests);
+  for(other = 0; other < size - 1; other++) {
+    index = smpi_mpi_waitany(size - 1, requests, MPI_STATUS_IGNORE);
+    if(index == MPI_UNDEFINED) {
+      break;
+    }
+    if(index < rank) {
+      if(recvbuf_is_empty)  smpi_datatype_copy(tmpbufs[index], count, datatype, recvbuf, count, datatype);
+      // #Request is below rank: it's a irecv
+      else smpi_op_apply(op, tmpbufs[index], recvbuf, &count, &datatype);
+    }
+  }
+  for(index = 0; index < rank; index++) {
+    xbt_free(tmpbufs[index]);
+  }
+  xbt_free(tmpbufs);
+  xbt_free(requests);
+}
diff --git a/src/smpi/smpi_pmpi.c b/src/smpi/smpi_pmpi.c
index 25acf31d7e..df6074bdbd 100644
--- a/src/smpi/smpi_pmpi.c
+++ b/src/smpi/smpi_pmpi.c
@@ -2013,6 +2013,34 @@ int PMPI_Scan(void *sendbuf, void *recvbuf, int count,
   return retval;
 }
 
+int PMPI_Exscan(void *sendbuf, void *recvbuf, int count, MPI_Datatype datatype,
+                MPI_Op op, MPI_Comm comm){
+  int retval;
+
+  smpi_bench_end();
+#ifdef HAVE_TRACING
+  int rank = comm != MPI_COMM_NULL ? smpi_process_index() : -1;
+  TRACE_smpi_computing_out(rank);
+  TRACE_smpi_collective_in(rank, -1, __FUNCTION__);
+#endif
+  if (comm == MPI_COMM_NULL) {
+    retval = MPI_ERR_COMM;
+  } else if (datatype == MPI_DATATYPE_NULL) {
+    retval = MPI_ERR_TYPE;
+  } else if (op == MPI_OP_NULL) {
+    retval = MPI_ERR_OP;
+  } else {
+    smpi_mpi_exscan(sendbuf, recvbuf, count, datatype, op, comm);
+    retval = MPI_SUCCESS;
+  }
+#ifdef HAVE_TRACING
+  TRACE_smpi_collective_out(rank, -1, __FUNCTION__);
+  TRACE_smpi_computing_in(rank);
+#endif
+  smpi_bench_begin();
+  return retval;
+}
+
 int PMPI_Reduce_scatter(void *sendbuf, void *recvbuf, int *recvcounts,
                        MPI_Datatype datatype, MPI_Op op, MPI_Comm comm)
 {
@@ -2686,11 +2714,6 @@ int PMPI_Alltoallw( void *sendbuf, int *sendcnts, int *sdispls, MPI_Datatype *se
   NOT_YET_IMPLEMENTED
 }
 
-int PMPI_Exscan(void *sendbuf, void *recvbuf, int count, MPI_Datatype datatype,
-                MPI_Op op, MPI_Comm comm){
-  NOT_YET_IMPLEMENTED
-}
-
 int PMPI_Comm_set_name(MPI_Comm comm, char* name){
   NOT_YET_IMPLEMENTED
 }