From: Martin Quinson <martin.quinson@loria.fr>
Date: Wed, 1 Feb 2017 01:10:12 +0000 (+0100)
Subject: don't malloc tons of dynars in mpi_waitany
X-Git-Tag: v3_15~500
X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/commitdiff_plain/e553a03ec20f531e48fab905d2034551c58a683f

don't malloc tons of dynars in mpi_waitany
---

diff --git a/include/xbt/dynar.h b/include/xbt/dynar.h
index ef7a555307..d9796b51f9 100644
--- a/include/xbt/dynar.h
+++ b/include/xbt/dynar.h
@@ -66,6 +66,7 @@ SG_BEGIN_DECL()
 typedef struct xbt_dynar_s *xbt_dynar_t;
 
 XBT_PUBLIC(xbt_dynar_t) xbt_dynar_new(const unsigned long elm_size, void_f_pvoid_t const free_f);
+XBT_PUBLIC(void) xbt_dynar_init(xbt_dynar_t dynar, const unsigned long elmsize, void_f_pvoid_t const free_f);
 XBT_PUBLIC(void) xbt_dynar_free(xbt_dynar_t * dynar);
 XBT_PUBLIC(void) xbt_dynar_free_voidp(void *dynar);
 XBT_PUBLIC(void) xbt_dynar_free_container(xbt_dynar_t * dynar);
diff --git a/src/smpi/smpi_base.cpp b/src/smpi/smpi_base.cpp
index 24f5645c72..9bae432bef 100644
--- a/src/smpi/smpi_base.cpp
+++ b/src/smpi/smpi_base.cpp
@@ -837,7 +837,7 @@ void smpi_mpi_wait(MPI_Request * request, MPI_Status * status)
 
 int smpi_mpi_waitany(int count, MPI_Request requests[], MPI_Status * status)
 {
-  xbt_dynar_t comms;
+  s_xbt_dynar_t comms; // Keep it on stack to save some extra mallocs
   int i;
   int size = 0;
   int index = MPI_UNDEFINED;
@@ -845,14 +845,14 @@ int smpi_mpi_waitany(int count, MPI_Request requests[], MPI_Status * status)
 
   if(count > 0) {
     // Wait for a request to complete
-    comms = xbt_dynar_new(sizeof(smx_activity_t), nullptr);
+    xbt_dynar_init(&comms, sizeof(smx_activity_t), nullptr);
     map = xbt_new(int, count);
     XBT_DEBUG("Wait for one of %d", count);
     for(i = 0; i < count; i++) {
       if (requests[i] != MPI_REQUEST_NULL && !(requests[i]->flags & PREPARED) && !(requests[i]->flags & FINISHED)) {
         if (requests[i]->action != nullptr) {
           XBT_DEBUG("Waiting any %p ", requests[i]);
-          xbt_dynar_push(comms, &requests[i]->action);
+          xbt_dynar_push(&comms, &requests[i]->action);
           map[size] = i;
           size++;
         }else{
@@ -867,7 +867,7 @@ int smpi_mpi_waitany(int count, MPI_Request requests[], MPI_Status * status)
       }
     }
     if(size > 0) {
-      i = simcall_comm_waitany(comms, -1);
+      i = simcall_comm_waitany(&comms, -1);
 
       // not MPI_UNDEFINED, as this is a simix return code
       if (i != -1) {
@@ -878,7 +878,6 @@ int smpi_mpi_waitany(int count, MPI_Request requests[], MPI_Status * status)
       }
     }
     xbt_free(map);
-    xbt_dynar_free(&comms);
   }
 
   if (index==MPI_UNDEFINED)
diff --git a/src/xbt/dynar.cpp b/src/xbt/dynar.cpp
index 44ce025c6e..375b1c5ad6 100644
--- a/src/xbt/dynar.cpp
+++ b/src/xbt/dynar.cpp
@@ -102,6 +102,18 @@ xbt_dynar_t xbt_dynar_new(const unsigned long elmsize, void_f_pvoid_t const free
   return dynar;
 }
 
+/** @brief Initialize a dynar structure that was not malloc'ed
+ * This can be useful to keep temporary dynars on the stack
+ */
+void xbt_dynar_init(xbt_dynar_t dynar, const unsigned long elmsize, void_f_pvoid_t const free_f)
+{
+  dynar->size    = 0;
+  dynar->used    = 0;
+  dynar->elmsize = elmsize;
+  dynar->data    = nullptr;
+  dynar->free_f  = free_f;
+}
+
 /** @brief Destructor of the structure not touching to the content
  *
  * \param dynar poor victim