Carpet*: generalise the comm_state class for collective buffer communications

CarpetLib's comm_state class (actually, it's still just a struct) has been
extended to handle collective buffer communications for all possible C datatypes
at the same time. This makes it unnecessary for the higher-level communication
routines to loop over each individual datatype separately.

darcs-hash:20050815150023-776a0-dddc1aca7ccaebae872f9f451b2c3595cd951fed.gz

1 files changed, 77 insertions, 68 deletions

diff --git a/Carpet/CarpetLib/src/commstate.cc b/Carpet/CarpetLib/src/commstate.cc
index be3e485a2..1bd9a2a8c 100644
--- a/Carpet/CarpetLib/src/commstate.cc
+++ b/Carpet/CarpetLib/src/commstate.cc
@@ -10,54 +10,61 @@
 
 
 // Communication state control
-comm_state::comm_state (int vartype_) : vartype(vartype_)
+comm_state::comm_state ()
 {
-  // If this comm state is created with a valid (ie. non-negative) CCTK vartype
-  // then it is assumed to be used in collective communications for that type
-  // later on, ie. it will step through
+  // If CarpetLib::use_collective_communication_buffers is set to true,
+  // this comm_state object will use collective communications,
+  // ie. it will step through
   //   state_get_buffer_sizes
   //   state_fill_send_buffers
   //   state_empty_recv_buffers
-  // This path needs the size of the vartype, the corresponding MPI datatype
-  // and the collective communication buffers initialized also.
   //
-  // If this comm state is created with a negative vartype then individual
-  // communications on single components are used by stepping through
+  // If CarpetLib::use_collective_communication_buffers is false
+  // then individual communications on single components are used
+  // by stepping through
   //   state_post
   //   state_wait
 
   DECLARE_CCTK_PARAMETERS;
 
-  uses_collective_communication_buffers =
-    use_collective_communication_buffers && vartype >= 0;
+  thestate = use_collective_communication_buffers ?
+             state_get_buffer_sizes : state_post;
 
-  if (uses_collective_communication_buffers) {
-    vartypesize = CCTK_VarTypeSize (vartype);
-    assert (vartypesize > 0);
-
-    thestate = state_get_buffer_sizes;
-    switch (vartype) {
-#define TYPECASE(N,T)                                                     \
-      case  N: { T dummy; datatype = dist::datatype(dummy); } break;
-#include "carpet_typecase.hh"
-#undef TYPECASE
-      default: assert (0 && "invalid datatype");
-    }
-    collbufs.resize (dist::size());
-    rrequests.resize (dist::size(), MPI_REQUEST_NULL);
-    srequests.resize (dist::size(), MPI_REQUEST_NULL);
-    recvbuffers_ready.resize (dist::size());
+  typebufs.resize (dist::c_ndatatypes());
+  for (int type = 0; type < typebufs.size(); type++) {
+    typebufs[type].procbufs.resize(dist::size());
+  }
 
-  } else {
-    thestate = state_post;
+#define INSTANTIATE(T)                                                 \
+  {                                                                    \
+    T dummy;                                                           \
+    int type = dist::c_datatype (dummy);                               \
+    typebufs.at(type).datatypesize = sizeof (dummy);                   \
+    typebufs.at(type).mpi_datatype = dist::datatype (dummy);           \
   }
+#include "instantiate"
+#undef INSTANTIATE
+
+  recvbuffers_ready.resize (dist::c_ndatatypes() * dist::size());
+  srequests.resize (dist::c_ndatatypes() * dist::size(), MPI_REQUEST_NULL);
+  rrequests.resize (dist::c_ndatatypes() * dist::size(), MPI_REQUEST_NULL);
 }
 
+
 void comm_state::step ()
 {
   assert (thestate != state_done);
-  if (uses_collective_communication_buffers) {
-    switch (thestate) {
+  switch (thestate) {
+    case state_post:
+      // After all sends/recvs have been posted in 'state_post'
+      // now wait for their completion in 'state_wait'.
+      thestate = state_wait;
+      break;
+
+    case state_wait:
+      thestate = state_done;
+      break;
+
     case state_get_buffer_sizes:
       // The sizes of the collective communication buffers are known
       // so now allocate them.
@@ -65,21 +72,33 @@ void comm_state::step ()
       // (a clever MPI layer may take advantage of such early posting).
       num_posted_recvs = num_completed_recvs = 0;
 
-      for (size_t i = 0; i < collbufs.size(); i++) {
-        collbufs[i].sendbufbase = new char[collbufs[i].sendbufsize*vartypesize];
-        collbufs[i].recvbufbase = new char[collbufs[i].recvbufsize*vartypesize];
-        collbufs[i].sendbuf = collbufs[i].sendbufbase;
-        collbufs[i].recvbuf = collbufs[i].recvbufbase;
+      for (int type = 0; type < typebufs.size(); type++) {
+
+        // skip unused datatype buffers
+        if (not typebufs[type].in_use) {
+          continue;
+        }
 
-        if (collbufs[i].recvbufsize > 0) {
-          MPI_Irecv (collbufs[i].recvbufbase, collbufs[i].recvbufsize,
-                     datatype, i, MPI_ANY_TAG, dist::comm, &rrequests[i]);
-          num_posted_recvs++;
+        int& datatypesize = typebufs[type].datatypesize;
+        for (int proc = 0; proc < typebufs[type].procbufs.size(); proc++) {
+          procbufdesc& procbuf = typebufs[type].procbufs[proc];
+
+          procbuf.sendbufbase = new char[procbuf.sendbufsize*datatypesize];
+          procbuf.recvbufbase = new char[procbuf.recvbufsize*datatypesize];
+          procbuf.sendbuf = procbuf.sendbufbase;
+          procbuf.recvbuf = procbuf.recvbufbase;
+
+          if (procbuf.recvbufsize > 0) {
+            MPI_Irecv (procbuf.recvbufbase, procbuf.recvbufsize,
+                       typebufs[type].mpi_datatype, proc, type,
+                       dist::comm, &rrequests[dist::size()*type + proc]);
+            num_posted_recvs++;
+          }
         }
       }
 
       // Now go and get the send buffers filled with data.
-      // Once a buffer is full it will get posted right away
+      // Once a buffer is full it will be posted right away
       // (see gdata::copy_into_sendbuffer() and
       //  gdata::interpolate_into_sendbuffer()).
       thestate = state_fill_send_buffers;
@@ -92,14 +111,16 @@ void comm_state::step ()
 
     case state_empty_recv_buffers:
       // Finish (at least one of) the posted communications
-      if (! AllPostedCommunicationsFinished ()) {
+      if (not AllPostedCommunicationsFinished ()) {
         // No state change if there are still outstanding communications;
         // do another comm_state loop iteration.
       } else {
         // Everything is done so release the collective communication buffers.
-        for (size_t i = 0; i < collbufs.size(); i++) {
-          delete[] collbufs[i].sendbufbase;
-          delete[] collbufs[i].recvbufbase;
+        for (int type = 0; type < typebufs.size(); type++) {
+          for (int proc = 0; proc < typebufs[type].procbufs.size(); proc++) {
+            delete[] typebufs[type].procbufs[proc].sendbufbase;
+            delete[] typebufs[type].procbufs[proc].recvbufbase;
+          }
         }
         thestate = state_done;
       }
@@ -107,33 +128,23 @@ void comm_state::step ()
 
     default:
       assert (0 && "invalid state");
-    }
-  } else {
-    switch (thestate) {
-    case state_post:
-      // After all sends/recvs have been posted in 'state_post'
-      // now wait for their completion in 'state_wait'.
-      thestate = state_wait;
-      break;
-    case state_wait:
-      thestate = state_done;
-      break;
-    default:
-      assert (0 && "invalid state");
-    }
   }
 }
 
+
 bool comm_state::done ()
 {
   return thestate == state_done;
 }
 
+
 comm_state::~comm_state ()
 {
-  assert (thestate == state_done ||
-          thestate == uses_collective_communication_buffers ?
-                      state_get_buffer_sizes : state_post);
+  DECLARE_CCTK_PARAMETERS;
+
+  assert (thestate == state_done or
+          thestate == (use_collective_communication_buffers ?
+                       state_get_buffer_sizes : state_post));
   assert (requests.empty());
 }
 
@@ -141,14 +152,14 @@ comm_state::~comm_state ()
 // wait for completion of posted collective buffer sends/receives
 //
 // Depending on the parameter CarpetLib::use_waitall, this function will wait
-// for all at once (true) or at least one (false) of the
-// posted receive operations to finish.
+// for all (true) or at least one (false) of the posted receive operations
+// to finish.
 //
 // It returns true if all posted communications have been completed.
 bool comm_state::AllPostedCommunicationsFinished ()
 {
   DECLARE_CCTK_PARAMETERS;
-  
+ 
   // check if all outstanding receives have been completed already
   if (num_posted_recvs == num_completed_recvs) {
     // finalize the outstanding sends in one go
@@ -158,13 +169,11 @@ bool comm_state::AllPostedCommunicationsFinished ()
   }
 
   // reset completion flag for all receive buffers
-  for (size_t i = 0; i < recvbuffers_ready.size(); i++) {
-    recvbuffers_ready[i] = false;
-  }
+  recvbuffers_ready.assign (recvbuffers_ready.size(), false);
 
   if (use_waitall) {
     // mark all posted recveive buffers as ready
-    for (size_t i = 0; i < rrequests.size(); i++) {
+    for (size_t i = 0; i < recvbuffers_ready.size(); i++) {
       recvbuffers_ready[i] = rrequests[i] != MPI_REQUEST_NULL;
     }