X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/6efc4db71d869ae5af39d17eeeff2a615aba3ccf..292a2a9b6a68f7b9bd620b8222d20ea91fe3bcf9:/src/smpi/smpi_base.c

diff --git a/src/smpi/smpi_base.c b/src/smpi/smpi_base.c
index 2e192a05ae..5192ca3be9 100644
--- a/src/smpi/smpi_base.c
+++ b/src/smpi/smpi_base.c
@@ -2,116 +2,211 @@
  * 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. */
+ * under the terms of the license (GNU LGPL) which comes with this package. */
 
 #include "private.h"
-#include "xbt/time.h"
+#include "xbt/virtu.h"
+#include "mc/mc.h"
+#include "xbt/replay.h"
+#include <errno.h>
+#include "simix/smx_private.h"
+#include "surf/surf.h"
 
-XBT_LOG_NEW_DEFAULT_SUBCATEGORY(smpi_base, smpi,
-                                "Logging specific to SMPI (base)");
-XBT_LOG_EXTERNAL_CATEGORY(smpi_base);
-XBT_LOG_EXTERNAL_CATEGORY(smpi_bench);
-XBT_LOG_EXTERNAL_CATEGORY(smpi_kernel);
-XBT_LOG_EXTERNAL_CATEGORY(smpi_mpi);
-XBT_LOG_EXTERNAL_CATEGORY(smpi_mpi_dt);
-XBT_LOG_EXTERNAL_CATEGORY(smpi_coll);
-XBT_LOG_EXTERNAL_CATEGORY(smpi_receiver);
-XBT_LOG_EXTERNAL_CATEGORY(smpi_sender);
-XBT_LOG_EXTERNAL_CATEGORY(smpi_util);
 
-#define EAGER_LIMIT 65536
-#define RDV_TAG     (-10)
+XBT_LOG_NEW_DEFAULT_SUBCATEGORY(smpi_base, smpi, "Logging specific to SMPI (base)");
 
-void smpi_process_init(int* argc, char*** argv) {
-  int index;
-  smpi_process_data_t data;
-  smx_process_t proc;
 
-  proc = SIMIX_process_self();
-  index = atoi((*argv)[1]);
-  data = smpi_process_remote_data(index);
-  SIMIX_process_set_data(proc, data);
-  if (*argc > 2) {
-    free((*argv)[1]);
-    memmove(&(*argv)[1], &(*argv)[2], sizeof(char *) * (*argc - 2));
-    (*argv)[(*argc) - 1] = NULL;
-  }
-  (*argc)--;
-  DEBUG2("<%d> New process in the game: %p", index, proc);
-}
+static int match_recv(void* a, void* b, smx_action_t ignored) {
+   MPI_Request ref = (MPI_Request)a;
+   MPI_Request req = (MPI_Request)b;
+   XBT_DEBUG("Trying to match a recv of src %d against %d, tag %d against %d",ref->src,req->src, ref->tag, req->tag);
 
-void smpi_process_destroy(void) {
-  int index = smpi_process_index();
+  xbt_assert(ref, "Cannot match recv against null reference");
+  xbt_assert(req, "Cannot match recv against null request");
+  return (ref->src == MPI_ANY_SOURCE || req->src == ref->src)
+    && (ref->tag == MPI_ANY_TAG || req->tag == ref->tag);
+}
 
-  DEBUG1("<%d> Process left the game", index);
+static int match_send(void* a, void* b,smx_action_t ignored) {
+   MPI_Request ref = (MPI_Request)a;
+   MPI_Request req = (MPI_Request)b;
+   XBT_DEBUG("Trying to match a send of src %d against %d, tag %d against %d",ref->src,req->src, ref->tag, req->tag);
+   xbt_assert(ref, "Cannot match send against null reference");
+   xbt_assert(req, "Cannot match send against null request");
+   return (req->src == MPI_ANY_SOURCE || req->src == ref->src)
+          && (req->tag == MPI_ANY_TAG || req->tag == ref->tag);
 }
 
-static MPI_Request build_request(void* buf, int count, MPI_Datatype datatype, int src, int dst, int tag, MPI_Comm comm, unsigned flags) {
+static MPI_Request build_request(void *buf, int count,
+                                 MPI_Datatype datatype, int src, int dst,
+                                 int tag, MPI_Comm comm, unsigned flags)
+{
   MPI_Request request;
 
+  void *old_buf = NULL;
+
   request = xbt_new(s_smpi_mpi_request_t, 1);
+
+  s_smpi_subtype_t *subtype = datatype->substruct;
+
+  if(datatype->has_subtype == 1){
+    // This part handles the problem of non-contignous memory
+    old_buf = buf;
+    buf = malloc(count*smpi_datatype_size(datatype));
+    if (flags & SEND) {
+      subtype->serialize(old_buf, buf, count, datatype->substruct);
+    }
+  }
+
   request->buf = buf;
+  // This part handles the problem of non-contignous memory (for the
+  // unserialisation at the reception)
+  request->old_buf = old_buf;
+  request->old_type = datatype;
+
   request->size = smpi_datatype_size(datatype) * count;
   request->src = src;
   request->dst = dst;
   request->tag = tag;
   request->comm = comm;
-  request->rdv = NULL;
-  request->pair = NULL;
-  request->complete = 0;
-  request->match = MPI_REQUEST_NULL;
+  request->action = NULL;
   request->flags = flags;
-  if(request->size < EAGER_LIMIT) {
-    request->ack = MPI_REQUEST_NULL;
-  } else {
-    request->ack = xbt_new(s_smpi_mpi_request_t, 1);
-    request->ack->buf = NULL;
-    request->ack->size = 0;
-    request->ack->src = dst;
-    request->ack->dst = src;
-    request->ack->tag = RDV_TAG;
-    request->ack->comm = comm;
-    request->ack->rdv = NULL;
-    request->ack->pair = NULL;
-    request->ack->complete = 0;
-    request->ack->match = MPI_REQUEST_NULL;
-    request->ack->flags = NON_PERSISTENT | ((request->flags & RECV) == RECV ? SEND : RECV);
-    smpi_mpi_start(request->ack);
-  }
+  request->detached = 0;
+#ifdef HAVE_TRACING
+  request->send = 0;
+  request->recv = 0;
+#endif
   return request;
 }
 
+
+void smpi_empty_status(MPI_Status * status) {
+  if(status != MPI_STATUS_IGNORE) {
+      status->MPI_SOURCE=MPI_ANY_SOURCE;
+      status->MPI_TAG=MPI_ANY_TAG;
+      status->count=0;
+  }
+}
+
+void smpi_action_trace_run(char *path)
+{
+  char *name;
+  xbt_dynar_t todo;
+  xbt_dict_cursor_t cursor;
+
+  action_fp=NULL;
+  if (path) {
+    action_fp = fopen(path, "r");
+    xbt_assert(action_fp != NULL, "Cannot open %s: %s", path,
+               strerror(errno));
+  }
+
+  if (!xbt_dict_is_empty(action_queues)) {
+    XBT_WARN
+      ("Not all actions got consumed. If the simulation ended successfully (without deadlock), you may want to add new processes to your deployment file.");
+
+
+    xbt_dict_foreach(action_queues, cursor, name, todo) {
+      XBT_WARN("Still %lu actions for %s", xbt_dynar_length(todo), name);
+    }
+  }
+
+  if (path)
+    fclose(action_fp);
+  xbt_dict_free(&action_queues);
+  action_queues = xbt_dict_new_homogeneous(NULL);
+}
+
+static void smpi_mpi_request_free_voidp(void* request)
+{
+  MPI_Request req = request;
+  smpi_mpi_request_free(&req);
+}
+
 /* MPI Low level calls */
-MPI_Request smpi_mpi_send_init(void* buf, int count, MPI_Datatype datatype, int dst, int tag, MPI_Comm comm) {
-  MPI_Request request = build_request(buf, count, datatype, smpi_comm_rank(comm), dst, tag, comm, PERSISTENT | SEND);
+MPI_Request smpi_mpi_send_init(void *buf, int count, MPI_Datatype datatype,
+                               int dst, int tag, MPI_Comm comm)
+{
+  MPI_Request request =
+    build_request(buf, count, datatype, smpi_comm_rank(comm), dst, tag,
+                  comm, PERSISTENT | SEND);
 
   return request;
 }
 
-MPI_Request smpi_mpi_recv_init(void* buf, int count, MPI_Datatype datatype, int src, int tag, MPI_Comm comm) {
-  MPI_Request request = build_request(buf, count, datatype, src, smpi_comm_rank(comm), tag, comm, PERSISTENT | RECV);
+MPI_Request smpi_mpi_recv_init(void *buf, int count, MPI_Datatype datatype,
+                               int src, int tag, MPI_Comm comm)
+{
+  MPI_Request request =
+    build_request(buf, count, datatype, src, smpi_comm_rank(comm), tag,
+                  comm, PERSISTENT | RECV);
 
   return request;
 }
 
-void smpi_mpi_start(MPI_Request request) {
-  xbt_assert0(request->complete == 0, "Cannot start a non-finished communication");
-  if(request->size >= EAGER_LIMIT) {
-    print_request("RDV ack", request->ack);
-    smpi_mpi_wait(&request->ack, MPI_STATUS_IGNORE);
-  }
-  if((request->flags & RECV) == RECV) {
-    smpi_process_post_recv(request);
+void smpi_mpi_start(MPI_Request request)
+{
+  smx_rdv_t mailbox;
+
+  xbt_assert(!request->action,
+             "Cannot (re)start a non-finished communication");
+  if(request->flags & RECV) {
     print_request("New recv", request);
-    request->pair = SIMIX_network_irecv(request->rdv, request->buf, &request->size);
+    if (request->size < surf_cfg_get_int("smpi/async_small_thres"))
+      mailbox = smpi_process_mailbox_small();
+    else
+      mailbox = smpi_process_mailbox();
+
+    // FIXME: SIMIX does not yet support non-contiguous datatypes
+    request->action = simcall_comm_irecv(mailbox, request->buf, &request->size, &match_recv, request);
   } else {
-    smpi_process_post_send(request->comm, request); // FIXME
+
+    int receiver = smpi_group_index(smpi_comm_group(request->comm), request->dst);
+/*    if(receiver == MPI_UNDEFINED) {*/
+/*      XBT_WARN("Trying to send a message to a wrong rank");*/
+/*      return;*/
+/*    }*/
     print_request("New send", request);
-    request->pair = SIMIX_network_isend(request->rdv, request->size, -1.0, request->buf, request->size, NULL);
+    if (request->size < surf_cfg_get_int("smpi/async_small_thres")) { // eager mode
+      mailbox = smpi_process_remote_mailbox_small(receiver);
+    }else{
+      XBT_DEBUG("Send request %p is not in the permanent receive mailbox (buf: %p)",request,request->buf);
+      mailbox = smpi_process_remote_mailbox(receiver);
+    }
+    if (request->size < 64*1024 ) { //(FIXME: this limit should be configurable)
+      void *oldbuf = NULL;
+      if(request->old_type->has_subtype == 0){
+        oldbuf = request->buf;
+        request->detached = 1;
+        if (oldbuf){
+          request->buf = malloc(request->size);
+          memcpy(request->buf,oldbuf,request->size);
+        }
+      }
+      XBT_DEBUG("Send request %p is detached; buf %p copied into %p",request,oldbuf,request->buf);
+    }
+
+    request->action =
+      simcall_comm_isend(mailbox, request->size, -1.0,
+                         request->buf, request->size,
+                         &match_send,
+                         &smpi_mpi_request_free_voidp, // how to free the userdata if a detached send fails
+                         request,
+                         // detach if msg size < eager/rdv switch limit
+                         request->detached);
+
+#ifdef HAVE_TRACING
+    /* FIXME: detached sends are not traceable (request->action == NULL) */
+    if (request->action)
+      simcall_set_category(request->action, TRACE_internal_smpi_get_category());
+#endif
+
   }
+
 }
 
-void smpi_mpi_startall(int count, MPI_Request* requests) {
+void smpi_mpi_startall(int count, MPI_Request * requests)
+{
   int i;
 
   for(i = 0; i < count; i++) {
@@ -119,57 +214,82 @@ void smpi_mpi_startall(int count, MPI_Request* requests) {
   }
 }
 
-void smpi_mpi_request_free(MPI_Request* request) {
+void smpi_mpi_request_free(MPI_Request * request)
+{
   xbt_free(*request);
   *request = MPI_REQUEST_NULL;
 }
 
-MPI_Request smpi_isend_init(void* buf, int count, MPI_Datatype datatype, int dst, int tag, MPI_Comm comm) {
-  MPI_Request request = build_request(buf, count, datatype, smpi_comm_rank(comm), dst, tag, comm, NON_PERSISTENT | SEND);
+MPI_Request smpi_isend_init(void *buf, int count, MPI_Datatype datatype,
+                            int dst, int tag, MPI_Comm comm)
+{
+  MPI_Request request =
+    build_request(buf, count, datatype, smpi_comm_rank(comm), dst, tag,
+                  comm, NON_PERSISTENT | SEND);
 
   return request;
 }
 
-MPI_Request smpi_mpi_isend(void* buf, int count, MPI_Datatype datatype, int dst, int tag, MPI_Comm comm) {
-  MPI_Request request = smpi_isend_init(buf, count, datatype, dst, tag, comm);
+MPI_Request smpi_mpi_isend(void *buf, int count, MPI_Datatype datatype,
+                           int dst, int tag, MPI_Comm comm)
+{
+  MPI_Request request =
+    smpi_isend_init(buf, count, datatype, dst, tag, comm);
 
   smpi_mpi_start(request);
   return request;
 }
 
-MPI_Request smpi_irecv_init(void* buf, int count, MPI_Datatype datatype, int src, int tag, MPI_Comm comm) {
-  MPI_Request request = build_request(buf, count, datatype, src, smpi_comm_rank(comm), tag, comm, NON_PERSISTENT | RECV);
-
+MPI_Request smpi_irecv_init(void *buf, int count, MPI_Datatype datatype,
+                            int src, int tag, MPI_Comm comm)
+{
+  MPI_Request request =
+    build_request(buf, count, datatype, src, smpi_comm_rank(comm), tag,
+                  comm, NON_PERSISTENT | RECV);
   return request;
 }
 
-MPI_Request smpi_mpi_irecv(void* buf, int count, MPI_Datatype datatype, int src, int tag, MPI_Comm comm) {
-  MPI_Request request = smpi_irecv_init(buf, count, datatype, src, tag, comm);
+MPI_Request smpi_mpi_irecv(void *buf, int count, MPI_Datatype datatype,
+                           int src, int tag, MPI_Comm comm)
+{
+  MPI_Request request =
+    smpi_irecv_init(buf, count, datatype, src, tag, comm);
 
   smpi_mpi_start(request);
   return request;
 }
 
-void smpi_mpi_recv(void* buf, int count, MPI_Datatype datatype, int src, int tag, MPI_Comm comm, MPI_Status* status) {
+void smpi_mpi_recv(void *buf, int count, MPI_Datatype datatype, int src,
+                   int tag, MPI_Comm comm, MPI_Status * status)
+{
   MPI_Request request;
-
   request = smpi_mpi_irecv(buf, count, datatype, src, tag, comm);
   smpi_mpi_wait(&request, status);
 }
 
-void smpi_mpi_send(void* buf, int count, MPI_Datatype datatype, int dst, int tag, MPI_Comm comm) {
+
+
+void smpi_mpi_send(void *buf, int count, MPI_Datatype datatype, int dst,
+                   int tag, MPI_Comm comm)
+{
   MPI_Request request;
 
   request = smpi_mpi_isend(buf, count, datatype, dst, tag, comm);
   smpi_mpi_wait(&request, MPI_STATUS_IGNORE);
 }
 
-void smpi_mpi_sendrecv(void* sendbuf, int sendcount, MPI_Datatype sendtype, int dst, int sendtag, void* recvbuf, int recvcount, MPI_Datatype recvtype, int src, int recvtag, MPI_Comm comm, MPI_Status* status) {
+void smpi_mpi_sendrecv(void *sendbuf, int sendcount, MPI_Datatype sendtype,
+                       int dst, int sendtag, void *recvbuf, int recvcount,
+                       MPI_Datatype recvtype, int src, int recvtag,
+                       MPI_Comm comm, MPI_Status * status)
+{
   MPI_Request requests[2];
   MPI_Status stats[2];
 
-  requests[0] = smpi_isend_init(sendbuf, sendcount, sendtype, dst, sendtag, comm);
-  requests[1] = smpi_irecv_init(recvbuf, recvcount, recvtype, src, recvtag, comm);
+  requests[0] =
+    smpi_isend_init(sendbuf, sendcount, sendtype, dst, sendtag, comm);
+  requests[1] =
+    smpi_irecv_init(recvbuf, recvcount, recvtype, src, recvtag, comm);
   smpi_mpi_startall(2, requests);
   smpi_mpi_waitall(2, requests, stats);
   if(status != MPI_STATUS_IGNORE) {
@@ -178,157 +298,341 @@ void smpi_mpi_sendrecv(void* sendbuf, int sendcount, MPI_Datatype sendtype, int
   }
 }
 
-static void finish_wait(MPI_Request* request, MPI_Status* status) {
+int smpi_mpi_get_count(MPI_Status * status, MPI_Datatype datatype)
+{
+  return status->count / smpi_datatype_size(datatype);
+}
+
+static void finish_wait(MPI_Request * request, MPI_Status * status)
+{
+  MPI_Request req = *request;
+  // if we have a sender, we should use its data, and not the data from the receive
+  //FIXME : mail fail if req->action has already been freed, the pointer being invalid
+  if((req->action)&&
+     (req->src==MPI_ANY_SOURCE || req->tag== MPI_ANY_TAG))
+    req = (MPI_Request)SIMIX_comm_get_src_data((*request)->action);
+
   if(status != MPI_STATUS_IGNORE) {
-    status->MPI_SOURCE = (*request)->src;
-    status->MPI_TAG = (*request)->tag;
+    status->MPI_SOURCE = req->src;
+    status->MPI_TAG = req->tag;
+    //if((*request)->action && ((MPI_Request)SIMIX_comm_get_src_data((*request)->action))->size == (*request)->size)
     status->MPI_ERROR = MPI_SUCCESS;
+    //else status->MPI_ERROR = MPI_ERR_TRUNCATE;
+    // this handles the case were size in receive differs from size in send
+    // FIXME: really this should just contain the count of receive-type blocks,
+    // right?
+    status->count = req->size;
   }
-  print_request("finishing wait", *request);
-  if((*request)->complete == 1) {
-    SIMIX_rdv_destroy((*request)->rdv);
-  } else {
-    (*request)->match->complete = 1;
-    (*request)->match->match = MPI_REQUEST_NULL;
+  req = *request;
+
+  print_request("Finishing", req);
+  MPI_Datatype datatype = req->old_type;
+  if(datatype->has_subtype == 1){
+      // This part handles the problem of non-contignous memory
+      // the unserialization at the reception
+    s_smpi_subtype_t *subtype = datatype->substruct;
+    if(req->flags & RECV) {
+      subtype->unserialize(req->buf, req->old_buf, req->size/smpi_datatype_size(datatype) , datatype->substruct);
+    }
+    if(req->detached == 0) free(req->buf);
   }
-  if(((*request)->flags & NON_PERSISTENT) == NON_PERSISTENT) {
+
+  if(req->flags & NON_PERSISTENT) {
     smpi_mpi_request_free(request);
   } else {
-    (*request)->rdv = NULL;
-    (*request)->pair = NULL;
+    req->action = NULL;
   }
 }
 
-int smpi_mpi_test(MPI_Request* request, MPI_Status* status) {
-  int flag = (*request)->complete;
+int smpi_mpi_test(MPI_Request * request, MPI_Status * status) {
+  int flag;
 
+  //assume that request is not MPI_REQUEST_NULL (filtered in PMPI_Test or smpi_mpi_testall before)
+  if ((*request)->action == NULL)
+    flag = 1;
+  else
+    flag = simcall_comm_test((*request)->action);
   if(flag) {
-    SIMIX_communication_destroy((*request)->pair);
     finish_wait(request, status);
+  }else{
+    smpi_empty_status(status);
   }
   return flag;
 }
 
-int smpi_mpi_testany(int count, MPI_Request requests[], int* index, MPI_Status* status) {
-  int i, flag;
+int smpi_mpi_testany(int count, MPI_Request requests[], int *index,
+                     MPI_Status * status)
+{
+  xbt_dynar_t comms;
+  int i, flag, size;
+  int* map;
 
   *index = MPI_UNDEFINED;
   flag = 0;
-  for(i = 0; i < count; i++) {
-    if(requests[i] != MPI_REQUEST_NULL && requests[i]->complete) {
-      SIMIX_communication_destroy(requests[i]->pair);
-      finish_wait(&requests[i], status);
-      *index = i;
-      flag = 1;
-      break;
+  if(count > 0) {
+    comms = xbt_dynar_new(sizeof(smx_action_t), NULL);
+    map = xbt_new(int, count);
+    size = 0;
+    for(i = 0; i < count; i++) {
+      if((requests[i]!=MPI_REQUEST_NULL) && requests[i]->action) {
+         xbt_dynar_push(comms, &requests[i]->action);
+         map[size] = i;
+         size++;
+      }
+    }
+    if(size > 0) {
+      i = simcall_comm_testany(comms);
+      // not MPI_UNDEFINED, as this is a simix return code
+      if(i != -1) {
+        *index = map[i];
+        finish_wait(&requests[*index], status);
+        flag = 1;
+      }
+    }else{
+        //all requests are null or inactive, return true
+        flag=1;
+        smpi_empty_status(status);
     }
+    xbt_free(map);
+    xbt_dynar_free(&comms);
   }
+
   return flag;
 }
 
-void smpi_mpi_wait(MPI_Request* request, MPI_Status* status) {
-  print_request("wait", *request);
-  // data is null if receiver waits before sender enters the rdv
-  if((*request)->complete) {
-    SIMIX_communication_destroy((*request)->pair);
-  } else {
-    SIMIX_network_wait((*request)->pair, -1.0);
+
+int smpi_mpi_testall(int count, MPI_Request requests[],
+                     MPI_Status status[])
+{
+  MPI_Status stat;
+  MPI_Status *pstat = status == MPI_STATUSES_IGNORE ? MPI_STATUS_IGNORE : &stat;
+  int flag=1;
+  int i;
+  for(i=0; i<count; i++){
+    if(requests[i]!= MPI_REQUEST_NULL){
+      if (smpi_mpi_test(&requests[i], pstat)!=1){
+        flag=0;
+      }
+    }else{
+      smpi_empty_status(pstat);
+    }
+    if(status != MPI_STATUSES_IGNORE) {
+      memcpy(&status[i], pstat, sizeof(*pstat));
+    }
+  }
+  return flag;
+}
+
+void smpi_mpi_probe(int source, int tag, MPI_Comm comm, MPI_Status* status){
+  int flag=0;
+  //FIXME find another wait to avoid busy waiting ?
+  // the issue here is that we have to wait on a nonexistent comm
+  while(flag==0){
+    smpi_mpi_iprobe(source, tag, comm, &flag, status);
+    XBT_DEBUG("Busy Waiting on probing : %d", flag);
+    if(!flag) {
+      simcall_process_sleep(0.0001);
+    }
   }
-  finish_wait(request, status);
 }
 
-int smpi_mpi_waitany(int count, MPI_Request requests[], MPI_Status* status) {
+void smpi_mpi_iprobe(int source, int tag, MPI_Comm comm, int* flag, MPI_Status* status){
+  MPI_Request request =build_request(NULL, 0, MPI_CHAR, source, smpi_comm_rank(comm), tag,
+            comm, NON_PERSISTENT | RECV);
+
+  // behave like a receive, but don't do it
+  smx_rdv_t mailbox;
+
+  print_request("New iprobe", request);
+  // We have to test both mailboxes as we don't know if we will receive one one or another
+    if (surf_cfg_get_int("smpi/async_small_thres")>0){
+        mailbox = smpi_process_mailbox_small();
+        XBT_DEBUG("trying to probe the perm recv mailbox");
+        request->action = simcall_comm_iprobe(mailbox, request->src, request->tag, &match_recv, (void*)request);
+    }
+    if (request->action==NULL){
+	mailbox = smpi_process_mailbox();
+        XBT_DEBUG("trying to probe the other mailbox");
+        request->action = simcall_comm_iprobe(mailbox, request->src, request->tag, &match_recv, (void*)request);
+    }
+
+  if(request->action){
+    MPI_Request req = (MPI_Request)SIMIX_comm_get_src_data(request->action);
+    *flag = 1;
+    if(status != MPI_STATUS_IGNORE) {
+      status->MPI_SOURCE = req->src;
+      status->MPI_TAG = req->tag;
+      status->MPI_ERROR = MPI_SUCCESS;
+      status->count = req->size;
+    }
+  }
+  else *flag = 0;
+  smpi_mpi_request_free(&request);
+
+  return;
+}
+
+void smpi_mpi_wait(MPI_Request * request, MPI_Status * status)
+{
+  print_request("Waiting", *request);
+  if ((*request)->action != NULL) { // this is not a detached send
+    simcall_comm_wait((*request)->action, -1.0);
+    finish_wait(request, status);
+  }
+  // FIXME for a detached send, finish_wait is not called:
+}
+
+int smpi_mpi_waitany(int count, MPI_Request requests[],
+                     MPI_Status * status)
+{
   xbt_dynar_t comms;
   int i, size, index;
-  int* map;
+  int *map;
 
   index = MPI_UNDEFINED;
   if(count > 0) {
-    // First check for already completed requests
+    // Wait for a request to complete
+    comms = xbt_dynar_new(sizeof(smx_action_t), NULL);
+    map = xbt_new(int, count);
+    size = 0;
+    XBT_DEBUG("Wait for one of");
     for(i = 0; i < count; i++) {
-      if(requests[i] != MPI_REQUEST_NULL && requests[i]->complete) {
-        index = i;
-        SIMIX_communication_destroy(requests[index]->pair); // always succeeds (but cleans the simix layer)
-        break;
+      if((requests[i] != MPI_REQUEST_NULL) && (requests[i]->action != NULL)) {
+        print_request("Waiting any ", requests[i]);
+        xbt_dynar_push(comms, &requests[i]->action);
+        map[size] = i;
+        size++;
       }
     }
-    if(index == MPI_UNDEFINED) {
-      // Otherwise, wait for a request to complete
-      comms = xbt_dynar_new(sizeof(smx_comm_t), NULL);
-      map = xbt_new(int, count);
-      size = 0;
-      DEBUG0("Wait for one of");
-      for(i = 0; i < count; i++) {
-        if(requests[i] != MPI_REQUEST_NULL && requests[i]->complete == 0) {
-          print_request("   ", requests[i]);
-          xbt_dynar_push(comms, &requests[i]->pair);
-          map[size] = i;
-          size++;
-        }
-      }
-      if(size > 0) {
-        index = SIMIX_network_waitany(comms);
-        index = map[index];
+    if(size > 0) {
+      i = simcall_comm_waitany(comms);
+
+      // not MPI_UNDEFINED, as this is a simix return code
+      if (i != -1) {
+        index = map[i];
+        finish_wait(&requests[index], status);
       }
-      xbt_free(map);
-      xbt_dynar_free(&comms);
-    }
-    if(index != MPI_UNDEFINED) {
-      finish_wait(&requests[index], status);
     }
+    xbt_free(map);
+    xbt_dynar_free(&comms);
   }
+
+  if (index==MPI_UNDEFINED)
+    smpi_empty_status(status);
+
   return index;
 }
 
-void smpi_mpi_waitall(int count, MPI_Request requests[],  MPI_Status status[]) {
-  int index;
+int smpi_mpi_waitall(int count, MPI_Request requests[],
+                      MPI_Status status[])
+{
+  int  index, c;
   MPI_Status stat;
-
-  while(count > 0) {
-    index = smpi_mpi_waitany(count, requests, &stat);
-    if(index == MPI_UNDEFINED) {
-      break;
+  MPI_Status *pstat = status == MPI_STATUSES_IGNORE ? MPI_STATUS_IGNORE : &stat;
+  int retvalue=MPI_SUCCESS;
+  //tag invalid requests in the set
+  for(c = 0; c < count; c++) {
+    if(requests[c]==MPI_REQUEST_NULL || requests[c]->dst == MPI_PROC_NULL ){
+      if(status != MPI_STATUSES_IGNORE)
+        smpi_empty_status(&status[c]);
+    }else if(requests[c]->src == MPI_PROC_NULL ){
+      if(status != MPI_STATUSES_IGNORE) {
+        smpi_empty_status(&status[c]);
+        status[c].MPI_SOURCE=MPI_PROC_NULL;
+      }
     }
-    if(status != MPI_STATUS_IGNORE) {
-      memcpy(&status[index], &stat, sizeof(stat));
+  }
+
+  for(c = 0; c < count; c++) {
+      if(MC_is_active()) {
+        smpi_mpi_wait(&requests[c], pstat);
+        index = c;
+      } else {
+        index = smpi_mpi_waitany(count, requests, pstat);
+        if(index == MPI_UNDEFINED) {
+          break;
+       }
+      if(status != MPI_STATUSES_IGNORE) {
+        memcpy(&status[index], pstat, sizeof(*pstat));
+        if(status[index].MPI_ERROR==MPI_ERR_TRUNCATE)retvalue=MPI_ERR_IN_STATUS;
+
+      }
     }
-    // FIXME: check this -v
-    // Move the last request to the found position
-    requests[index] = requests[count - 1];
-    requests[count - 1] = MPI_REQUEST_NULL;
-    count--;
   }
+  return retvalue;
 }
 
-int smpi_mpi_waitsome(int incount, MPI_Request requests[], int* indices, MPI_Status status[]) {
-  int i, count;
+int smpi_mpi_waitsome(int incount, MPI_Request requests[], int *indices,
+                      MPI_Status status[])
+{
+  int i, count, index;
+  MPI_Status stat;
+  MPI_Status *pstat = status == MPI_STATUSES_IGNORE ? MPI_STATUS_IGNORE : &stat;
 
   count = 0;
-  for(i = 0; i < incount; i++) {
-    if(requests[i] != MPI_REQUEST_NULL && requests[i]->complete) {
-      SIMIX_communication_destroy(requests[i]->pair);
-      finish_wait(&requests[i], status != MPI_STATUS_IGNORE ? &status[i] : MPI_STATUS_IGNORE);
-      indices[count] = i;
+  for(i = 0; i < incount; i++)
+  {
+    index=smpi_mpi_waitany(incount, requests, pstat);
+    if(index!=MPI_UNDEFINED){
+      indices[count] = index;
       count++;
+      if(status != MPI_STATUSES_IGNORE) {
+        memcpy(&status[index], pstat, sizeof(*pstat));
+      }
+    }else{
+      return MPI_UNDEFINED;
     }
   }
   return count;
 }
 
-void smpi_mpi_bcast(void* buf, int count, MPI_Datatype datatype, int root, MPI_Comm comm) {
+int smpi_mpi_testsome(int incount, MPI_Request requests[], int *indices,
+                      MPI_Status status[])
+{
+  int i, count, count_dead;
+  MPI_Status stat;
+  MPI_Status *pstat = status == MPI_STATUSES_IGNORE ? MPI_STATUS_IGNORE : &stat;
+
+  count = 0;
+  count_dead = 0;
+  for(i = 0; i < incount; i++) {
+    if((requests[i] != MPI_REQUEST_NULL)) {
+      if(smpi_mpi_test(&requests[i], pstat)) {
+         indices[count] = i;
+         count++;
+         if(status != MPI_STATUSES_IGNORE) {
+            memcpy(&status[i], pstat, sizeof(*pstat));
+         }
+      }
+    }else{
+      count_dead++;
+    }
+  }
+  if(count_dead==incount)return MPI_UNDEFINED;
+  else return count;
+}
+
+void smpi_mpi_bcast(void *buf, int count, MPI_Datatype datatype, int root,
+                    MPI_Comm comm)
+{
   // arity=2: a binary tree, arity=4 seem to be a good setting (see P2P-MPI))
   nary_tree_bcast(buf, count, datatype, root, comm, 4);
 }
 
-void smpi_mpi_barrier(MPI_Comm comm) {
+void smpi_mpi_barrier(MPI_Comm comm)
+{
   // arity=2: a binary tree, arity=4 seem to be a good setting (see P2P-MPI))
   nary_tree_barrier(comm, 4);
 }
 
-void smpi_mpi_gather(void* sendbuf, int sendcount, MPI_Datatype sendtype, void* recvbuf, int recvcount, MPI_Datatype recvtype, int root, MPI_Comm comm) {
+void smpi_mpi_gather(void *sendbuf, int sendcount, MPI_Datatype sendtype,
+                     void *recvbuf, int recvcount, MPI_Datatype recvtype,
+                     int root, MPI_Comm comm)
+{
   int system_tag = 666;
-  int rank, size, src, index, sendsize, recvsize;
-  MPI_Request* requests;
+  int rank, size, src, index;
+  MPI_Aint lb = 0, recvext = 0;
+  MPI_Request *requests;
 
   rank = smpi_comm_rank(comm);
   size = smpi_comm_size(comm);
@@ -336,16 +640,19 @@ void smpi_mpi_gather(void* sendbuf, int sendcount, MPI_Datatype sendtype, void*
     // Send buffer to root
     smpi_mpi_send(sendbuf, sendcount, sendtype, root, system_tag, comm);
   } else {
-    sendsize = smpi_datatype_size(sendtype);
-    recvsize = smpi_datatype_size(recvtype);
+    // FIXME: check for errors
+    smpi_datatype_extent(recvtype, &lb, &recvext);
     // Local copy from root
-    memcpy(&((char*)recvbuf)[root * recvcount * recvsize], sendbuf, sendcount * sendsize * sizeof(char));
+    smpi_datatype_copy(sendbuf, sendcount, sendtype,
+                       (char *)recvbuf + root * recvcount * recvext, recvcount, recvtype);
     // Receive buffers from senders
     requests = xbt_new(MPI_Request, size - 1);
     index = 0;
     for(src = 0; src < size; src++) {
       if(src != root) {
-        requests[index] = smpi_irecv_init(&((char*)recvbuf)[src * recvcount * recvsize], recvcount, recvtype, src, system_tag, comm);
+        requests[index] = smpi_irecv_init((char *)recvbuf + src * recvcount * recvext,
+                                          recvcount, recvtype,
+                                          src, system_tag, comm);
         index++;
       }
     }
@@ -356,10 +663,14 @@ void smpi_mpi_gather(void* sendbuf, int sendcount, MPI_Datatype sendtype, void*
   }
 }
 
-void smpi_mpi_gatherv(void* sendbuf, int sendcount, MPI_Datatype sendtype, void* recvbuf, int* recvcounts, int* displs, MPI_Datatype recvtype, int root, MPI_Comm comm) {
+void smpi_mpi_gatherv(void *sendbuf, int sendcount, MPI_Datatype sendtype,
+                      void *recvbuf, int *recvcounts, int *displs,
+                      MPI_Datatype recvtype, int root, MPI_Comm comm)
+{
   int system_tag = 666;
-  int rank, size, src, index, sendsize;
-  MPI_Request* requests;
+  int rank, size, src, index;
+  MPI_Aint lb = 0, recvext = 0;
+  MPI_Request *requests;
 
   rank = smpi_comm_rank(comm);
   size = smpi_comm_size(comm);
@@ -367,15 +678,20 @@ void smpi_mpi_gatherv(void* sendbuf, int sendcount, MPI_Datatype sendtype, void*
     // Send buffer to root
     smpi_mpi_send(sendbuf, sendcount, sendtype, root, system_tag, comm);
   } else {
-    sendsize = smpi_datatype_size(sendtype);
+    // FIXME: check for errors
+    smpi_datatype_extent(recvtype, &lb, &recvext);
     // Local copy from root
-    memcpy(&((char*)recvbuf)[displs[root]], sendbuf, sendcount * sendsize * sizeof(char));
+    smpi_datatype_copy(sendbuf, sendcount, sendtype,
+                       (char *)recvbuf + displs[root] * recvext,
+                       recvcounts[root], recvtype);
     // Receive buffers from senders
     requests = xbt_new(MPI_Request, size - 1);
     index = 0;
     for(src = 0; src < size; src++) {
       if(src != root) {
-        requests[index] = smpi_irecv_init(&((char*)recvbuf)[displs[src]], recvcounts[src], recvtype, src, system_tag, comm);
+        requests[index] =
+          smpi_irecv_init((char *)recvbuf + displs[src] * recvext,
+                          recvcounts[src], recvtype, src, system_tag, comm);
         index++;
       }
     }
@@ -386,25 +702,36 @@ void smpi_mpi_gatherv(void* sendbuf, int sendcount, MPI_Datatype sendtype, void*
   }
 }
 
-void smpi_mpi_allgather(void* sendbuf, int sendcount, MPI_Datatype sendtype, void* recvbuf, int recvcount, MPI_Datatype recvtype, MPI_Comm comm) {
+void smpi_mpi_allgather(void *sendbuf, int sendcount,
+                        MPI_Datatype sendtype, void *recvbuf,
+                        int recvcount, MPI_Datatype recvtype,
+                        MPI_Comm comm)
+{
   int system_tag = 666;
-  int rank, size, other, index, sendsize, recvsize;
-  MPI_Request* requests;
+  int rank, size, other, index;
+  MPI_Aint lb = 0, recvext = 0;
+  MPI_Request *requests;
 
   rank = smpi_comm_rank(comm);
   size = smpi_comm_size(comm);
-  sendsize = smpi_datatype_size(sendtype);
-  recvsize = smpi_datatype_size(recvtype);
+  // FIXME: check for errors
+  smpi_datatype_extent(recvtype, &lb, &recvext);
   // Local copy from self
-  memcpy(&((char*)recvbuf)[rank * recvcount * recvsize], sendbuf, sendcount * sendsize * sizeof(char));
+  smpi_datatype_copy(sendbuf, sendcount, sendtype,
+                     (char *)recvbuf + rank * recvcount * recvext, recvcount,
+                     recvtype);
   // Send/Recv buffers to/from others;
   requests = xbt_new(MPI_Request, 2 * (size - 1));
   index = 0;
   for(other = 0; other < size; other++) {
     if(other != rank) {
-      requests[index] = smpi_isend_init(sendbuf, sendcount, sendtype, other, system_tag, comm);
+      requests[index] =
+        smpi_isend_init(sendbuf, sendcount, sendtype, other, system_tag,
+                        comm);
       index++;
-      requests[index] = smpi_irecv_init(&((char*)recvbuf)[other * recvcount * recvsize], recvcount, recvtype, other, system_tag, comm);
+      requests[index] = smpi_irecv_init((char *)recvbuf + other * recvcount * recvext,
+                                        recvcount, recvtype, other,
+                                        system_tag, comm);
       index++;
     }
   }
@@ -414,25 +741,36 @@ void smpi_mpi_allgather(void* sendbuf, int sendcount, MPI_Datatype sendtype, voi
   xbt_free(requests);
 }
 
-void smpi_mpi_allgatherv(void* sendbuf, int sendcount, MPI_Datatype sendtype, void* recvbuf, int* recvcounts, int* displs, MPI_Datatype recvtype, MPI_Comm comm) {
+void smpi_mpi_allgatherv(void *sendbuf, int sendcount,
+                         MPI_Datatype sendtype, void *recvbuf,
+                         int *recvcounts, int *displs,
+                         MPI_Datatype recvtype, MPI_Comm comm)
+{
   int system_tag = 666;
-  int rank, size, other, index, sendsize, recvsize;
-  MPI_Request* requests;
+  int rank, size, other, index;
+  MPI_Aint lb = 0, recvext = 0;
+  MPI_Request *requests;
 
   rank = smpi_comm_rank(comm);
   size = smpi_comm_size(comm);
-  sendsize = smpi_datatype_size(sendtype);
-  recvsize = smpi_datatype_size(recvtype);
+  // FIXME: check for errors
+  smpi_datatype_extent(recvtype, &lb, &recvext);
   // Local copy from self
-  memcpy(&((char*)recvbuf)[displs[rank]], sendbuf, sendcount * sendsize * sizeof(char));
+  smpi_datatype_copy(sendbuf, sendcount, sendtype,
+                     (char *)recvbuf + displs[rank] * recvext,
+                     recvcounts[rank], recvtype);
   // Send buffers to others;
   requests = xbt_new(MPI_Request, 2 * (size - 1));
   index = 0;
   for(other = 0; other < size; other++) {
     if(other != rank) {
-      requests[index] = smpi_isend_init(sendbuf, sendcount, sendtype, other, system_tag, comm);
+      requests[index] =
+        smpi_isend_init(sendbuf, sendcount, sendtype, other, system_tag,
+                        comm);
       index++;
-      requests[index] = smpi_irecv_init(&((char*)recvbuf)[displs[other]], recvcounts[other], recvtype, other, system_tag, comm);
+      requests[index] =
+        smpi_irecv_init((char *)recvbuf + displs[other] * recvext, recvcounts[other],
+                        recvtype, other, system_tag, comm);
       index++;
     }
   }
@@ -442,27 +780,35 @@ void smpi_mpi_allgatherv(void* sendbuf, int sendcount, MPI_Datatype sendtype, vo
   xbt_free(requests);
 }
 
-void smpi_mpi_scatter(void* sendbuf, int sendcount, MPI_Datatype sendtype, void* recvbuf, int recvcount, MPI_Datatype recvtype, int root, MPI_Comm comm) {
+void smpi_mpi_scatter(void *sendbuf, int sendcount, MPI_Datatype sendtype,
+                      void *recvbuf, int recvcount, MPI_Datatype recvtype,
+                      int root, MPI_Comm comm)
+{
   int system_tag = 666;
-  int rank, size, dst, index, sendsize, recvsize;
-  MPI_Request* requests;
+  int rank, size, dst, index;
+  MPI_Aint lb = 0, sendext = 0;
+  MPI_Request *requests;
 
   rank = smpi_comm_rank(comm);
   size = smpi_comm_size(comm);
   if(rank != root) {
     // Recv buffer from root
-    smpi_mpi_recv(recvbuf, recvcount, recvtype, root, system_tag, comm, MPI_STATUS_IGNORE);
+    smpi_mpi_recv(recvbuf, recvcount, recvtype, root, system_tag, comm,
+                  MPI_STATUS_IGNORE);
   } else {
-    sendsize = smpi_datatype_size(sendtype);
-    recvsize = smpi_datatype_size(recvtype);
+    // FIXME: check for errors
+    smpi_datatype_extent(sendtype, &lb, &sendext);
     // Local copy from root
-    memcpy(recvbuf, &((char*)sendbuf)[root * sendcount * sendsize], recvcount * recvsize * sizeof(char));
+    smpi_datatype_copy((char *)sendbuf + root * sendcount * sendext,
+                       sendcount, sendtype, recvbuf, recvcount, recvtype);
     // Send buffers to receivers
     requests = xbt_new(MPI_Request, size - 1);
     index = 0;
     for(dst = 0; dst < size; dst++) {
       if(dst != root) {
-        requests[index] = smpi_isend_init(&((char*)sendbuf)[dst * sendcount * sendsize], sendcount, sendtype, dst, system_tag, comm);
+        requests[index] = smpi_isend_init((char *)sendbuf + dst * sendcount * sendext,
+                                          sendcount, sendtype, dst,
+                                          system_tag, comm);
         index++;
       }
     }
@@ -473,27 +819,35 @@ void smpi_mpi_scatter(void* sendbuf, int sendcount, MPI_Datatype sendtype, void*
   }
 }
 
-void smpi_mpi_scatterv(void* sendbuf, int* sendcounts, int* displs, MPI_Datatype sendtype, void* recvbuf, int recvcount, MPI_Datatype recvtype, int root, MPI_Comm comm) {
+void smpi_mpi_scatterv(void *sendbuf, int *sendcounts, int *displs,
+                       MPI_Datatype sendtype, void *recvbuf, int recvcount,
+                       MPI_Datatype recvtype, int root, MPI_Comm comm)
+{
   int system_tag = 666;
-  int rank, size, dst, index, sendsize, recvsize;
-  MPI_Request* requests;
+  int rank, size, dst, index;
+  MPI_Aint lb = 0, sendext = 0;
+  MPI_Request *requests;
 
   rank = smpi_comm_rank(comm);
   size = smpi_comm_size(comm);
   if(rank != root) {
     // Recv buffer from root
-    smpi_mpi_recv(recvbuf, recvcount, recvtype, root, system_tag, comm, MPI_STATUS_IGNORE);
+    smpi_mpi_recv(recvbuf, recvcount, recvtype, root, system_tag, comm,
+                  MPI_STATUS_IGNORE);
   } else {
-    sendsize = smpi_datatype_size(sendtype);
-    recvsize = smpi_datatype_size(recvtype);
+    // FIXME: check for errors
+    smpi_datatype_extent(sendtype, &lb, &sendext);
     // Local copy from root
-    memcpy(recvbuf, &((char*)sendbuf)[displs[root]], recvcount * recvsize * sizeof(char));
+    smpi_datatype_copy((char *)sendbuf + displs[root] * sendext, sendcounts[root],
+                       sendtype, recvbuf, recvcount, recvtype);
     // Send buffers to receivers
     requests = xbt_new(MPI_Request, size - 1);
     index = 0;
     for(dst = 0; dst < size; dst++) {
       if(dst != root) {
-        requests[index] = smpi_isend_init(&((char*)sendbuf)[displs[dst]], sendcounts[dst], sendtype, dst, system_tag, comm);
+        requests[index] =
+          smpi_isend_init((char *)sendbuf + displs[dst] * sendext, sendcounts[dst],
+                          sendtype, dst, system_tag, comm);
         index++;
       }
     }
@@ -504,11 +858,15 @@ void smpi_mpi_scatterv(void* sendbuf, int* sendcounts, int* displs, MPI_Datatype
   }
 }
 
-void smpi_mpi_reduce(void* sendbuf, void* recvbuf, int count, MPI_Datatype datatype, MPI_Op op, int root, MPI_Comm comm) {
+void smpi_mpi_reduce(void *sendbuf, void *recvbuf, int count,
+                     MPI_Datatype datatype, MPI_Op op, int root,
+                     MPI_Comm comm)
+{
   int system_tag = 666;
-  int rank, size, src, index, datasize;
-  MPI_Request* requests;
-  void** tmpbufs;
+  int rank, size, src, index;
+  MPI_Aint lb = 0, dataext = 0;
+  MPI_Request *requests;
+  void **tmpbufs;
 
   rank = smpi_comm_rank(comm);
   size = smpi_comm_size(comm);
@@ -516,18 +874,24 @@ void smpi_mpi_reduce(void* sendbuf, void* recvbuf, int count, MPI_Datatype datat
     // Send buffer to root
     smpi_mpi_send(sendbuf, count, datatype, root, system_tag, comm);
   } else {
-    datasize = smpi_datatype_size(datatype);
+    // FIXME: check for errors
+    smpi_datatype_extent(datatype, &lb, &dataext);
     // Local copy from root
-    memcpy(recvbuf, sendbuf, count * datasize * sizeof(char));
+    if (sendbuf && recvbuf)
+      smpi_datatype_copy(sendbuf, count, datatype, recvbuf, count, datatype);
     // Receive buffers from senders
     //TODO: make a MPI_barrier here ?
     requests = xbt_new(MPI_Request, size - 1);
-    tmpbufs = xbt_new(void*, size - 1);
+    tmpbufs = xbt_new(void *, size - 1);
     index = 0;
     for(src = 0; src < size; src++) {
       if(src != root) {
-        tmpbufs[index] = xbt_malloc(count * datasize);
-        requests[index] = smpi_irecv_init(tmpbufs[index], count, datatype, src, system_tag, comm);
+        // 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, src,
+                          system_tag, comm);
         index++;
       }
     }
@@ -535,10 +899,12 @@ void smpi_mpi_reduce(void* sendbuf, void* recvbuf, int count, MPI_Datatype datat
     smpi_mpi_startall(size - 1, requests);
     for(src = 0; src < size - 1; src++) {
       index = smpi_mpi_waitany(size - 1, requests, MPI_STATUS_IGNORE);
+      XBT_DEBUG("finished waiting any request with index %d", index);
       if(index == MPI_UNDEFINED) {
         break;
       }
-      smpi_op_apply(op, tmpbufs[index], recvbuf, &count, &datatype);
+      if(op) /* op can be MPI_OP_NULL that does nothing */
+        smpi_op_apply(op, tmpbufs[index], recvbuf, &count, &datatype);
     }
     for(index = 0; index < size - 1; index++) {
       xbt_free(tmpbufs[index]);
@@ -548,84 +914,52 @@ void smpi_mpi_reduce(void* sendbuf, void* recvbuf, int count, MPI_Datatype datat
   }
 }
 
-void smpi_mpi_allreduce(void* sendbuf, void* recvbuf, int count, MPI_Datatype datatype, MPI_Op op, MPI_Comm comm) {
+void smpi_mpi_allreduce(void *sendbuf, void *recvbuf, int count,
+                        MPI_Datatype datatype, MPI_Op op, MPI_Comm comm)
+{
   smpi_mpi_reduce(sendbuf, recvbuf, count, datatype, op, 0, comm);
   smpi_mpi_bcast(recvbuf, count, datatype, 0, comm);
+}
 
-/*
-FIXME: buggy implementation
-
+void smpi_mpi_scan(void *sendbuf, void *recvbuf, int count,
+                   MPI_Datatype datatype, MPI_Op op, MPI_Comm comm)
+{
   int system_tag = 666;
-  int rank, size, other, index, datasize;
-  MPI_Request* requests;
-  void** tmpbufs;
+  int rank, size, other, index;
+  MPI_Aint lb = 0, dataext = 0;
+  MPI_Request *requests;
+  void **tmpbufs;
 
   rank = smpi_comm_rank(comm);
   size = smpi_comm_size(comm);
-  datasize = smpi_datatype_size(datatype);
-  // Local copy from self
-  memcpy(recvbuf, sendbuf, count * datasize * sizeof(char));
-  // Send/Recv buffers to/from others;
-  //TODO: make a MPI_barrier here ?
-  requests = xbt_new(MPI_Request, 2 * (size - 1));
-  tmpbufs = xbt_new(void*, size - 1);
-  index = 0;
-  for(other = 0; other < size; other++) {
-    if(other != rank) {
-      tmpbufs[index / 2] = xbt_malloc(count * datasize);
-      requests[index] = smpi_mpi_isend(sendbuf, count, datatype, other, system_tag, comm);
-      requests[index + 1] = smpi_mpi_irecv(tmpbufs[index / 2], count, datatype, other, system_tag, comm);
-      index += 2;
-    }
-  }
-  // Wait for completion of all comms.
-  for(other = 0; other < 2 * (size - 1); other++) {
-    index = smpi_mpi_waitany(size - 1, requests, MPI_STATUS_IGNORE);
-    if(index == MPI_UNDEFINED) {
-      break;
-    }
-    if((index & 1) == 1) {
-      // Request is odd: it's a irecv
-      smpi_op_apply(op, tmpbufs[index / 2], recvbuf, &count, &datatype);
-    }
-  }
-  for(index = 0; index < size - 1; index++) {
-    xbt_free(tmpbufs[index]);
-  }
-  xbt_free(tmpbufs);
-  xbt_free(requests);
-*/
-}
 
-void smpi_mpi_scan(void* sendbuf, void* recvbuf, int count, MPI_Datatype datatype, MPI_Op op, MPI_Comm comm) {
-  int system_tag = 666;
-  int rank, size, other, index, datasize;
-  int total;
-  MPI_Request* requests;
-  void** tmpbufs;
+  // FIXME: check for errors
+  smpi_datatype_extent(datatype, &lb, &dataext);
 
-  rank = smpi_comm_rank(comm);
-  size = smpi_comm_size(comm);
-  datasize = smpi_datatype_size(datatype);
   // Local copy from self
-  memcpy(recvbuf, sendbuf, count * datasize * sizeof(char));
+  smpi_datatype_copy(sendbuf, count, datatype, recvbuf, count, datatype);
+
   // Send/Recv buffers to/from others;
-  total = rank + (size - (rank + 1));
-  requests = xbt_new(MPI_Request, total);
-  tmpbufs = xbt_new(void*, rank);
+  requests = xbt_new(MPI_Request, size - 1);
+  tmpbufs = xbt_new(void *, rank);
   index = 0;
   for(other = 0; other < rank; other++) {
-    tmpbufs[index] = xbt_malloc(count * datasize);
-    requests[index] = smpi_irecv_init(tmpbufs[index], count, datatype, other, system_tag, comm);
+    // 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);
+    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 < total; other++) {
+  for(other = 0; other < size - 1; other++) {
     index = smpi_mpi_waitany(size - 1, requests, MPI_STATUS_IGNORE);
     if(index == MPI_UNDEFINED) {
       break;
@@ -635,7 +969,7 @@ void smpi_mpi_scan(void* sendbuf, void* recvbuf, int count, MPI_Datatype datatyp
       smpi_op_apply(op, tmpbufs[index], recvbuf, &count, &datatype);
     }
   }
-  for(index = 0; index < size - 1; index++) {
+  for(index = 0; index < rank; index++) {
     xbt_free(tmpbufs[index]);
   }
   xbt_free(tmpbufs);