Fragmented young heap generation and off_heap_message_queue option

* The youngest generation of the heap can now consist of multiple
  blocks. Heap fragments and message fragments are added to the
  youngest generation when needed without triggering a GC. After
  a GC the youngest generation is contained in one single block.
* The off_heap_message_queue process flag has been added. When
  enabled all message data in the queue is kept off heap. When
  a message is selected from the queue, the message fragment (or
  heap fragment) containing the actual message is attached to the
  youngest generation. Messages stored off heap is not part of GC.

1 files changed, 5 insertions, 12 deletions

diff --git a/erts/emulator/beam/utils.c b/erts/emulator/beam/utils.c
index a741e2e2e6..e03113b8cc 100644
--- a/erts/emulator/beam/utils.c
+++ b/erts/emulator/beam/utils.c
@@ -110,7 +110,6 @@ Eterm*
 erts_heap_alloc(Process* p, Uint need, Uint xtra)
 {
     ErlHeapFragment* bp;
-    Eterm* htop;
     Uint n;
 #if defined(DEBUG) || defined(CHECK_FOR_HOLES)
     Uint i;
@@ -156,16 +155,6 @@ erts_heap_alloc(Process* p, Uint need, Uint xtra)
     n--;
 #endif
 
-    /*
-     * When we have created a heap fragment, we are no longer allowed
-     * to store anything more on the heap. 
-     */
-    htop = HEAP_TOP(p);
-    if (htop < HEAP_LIMIT(p)) {
-	*htop = make_pos_bignum_header(HEAP_LIMIT(p)-htop-1);
-	HEAP_TOP(p) = HEAP_LIMIT(p);
-    }
-
     bp->next = MBUF(p);
     MBUF(p) = bp;
     bp->alloc_size = n;
@@ -2285,7 +2274,11 @@ static void do_send_logger_message(Eterm *hp, ErlOffHeap *ohp, ErlHeapFragment *
 	erts_queue_error_logger_message(from, message, bp);
     }
 #else
-    erts_queue_message(p, NULL /* only used for smp build */, bp, message, NIL);
+    {
+	ErtsMessage *mp = erts_alloc_message(0, NULL);
+	mp->data.heap_frag = bp;
+	erts_queue_message(p, NULL /* only used for smp build */, mp, message, NIL);
+    }
 #endif
 }