[Places] improve small message performance

src/racket/gc2/gc2.h

@@ -481,7 +481,7 @@ GC2_EXTERN void *GC_finish_message_allocator();
 
 GC2_EXTERN void GC_adopt_message_allocator(void *msg_memory);
 /*
-   Adopts the message memory captures by the sending place into
+   Adopts the message memory captured by the sending place into
    the current receiving place's gc
 */
 
@@ -491,6 +491,15 @@ GC2_EXTERN intptr_t GC_is_place();
    Otherwise returns 0;
 */
 
+GC2_EXTERN uintptr_t GC_message_allocator_size(void *msg_memory);
+/*
+ Returns the total size of all memory allocated by the message allocator
+ */
+
+GC2_EXTERN void GC_dispose_message_allocator(void *msg_memory);
+/*
+ Disposes of small message allocators that were copied by the receiving place
+ */
 
 
 # ifdef __cplusplus

src/racket/gc2/newgc.c

@@ -1460,6 +1460,46 @@ void GC_adopt_message_allocator(void *param) {
   free(msgm);
 }
 
+uintptr_t GC_message_allocator_size(void *param) {
+  MsgMemory *msgm = (MsgMemory *) param;
+  if (!msgm) { return sizeof(param); }
+  if (msgm->big_pages && msgm->size < 1024) {
+    printf("error message allocators with big pages should be bigger than %u!\n", msgm->size);
+    exit(1);
+  }
+  return msgm->size;
+}
+
+void GC_dispose_message_allocator(void *param) {
+  NewGC *gc = GC_get_GC();
+  mpage *tmp;
+  MsgMemory *msgm = (MsgMemory *) param;
+  
+  if (msgm->big_pages)
+  { 
+    printf("error disposable message allocators should not have big objects!\n");
+    exit(1);
+  }
+
+  if (msgm->pages)
+  {
+    tmp = msgm->pages;
+
+    if (tmp->next)
+    { 
+      printf("error disposable message allocators should not have more than one page!\n");
+      exit(1);
+    }
+    /* free_pages decrements gc->used_pages which is incorrect, since this is an orphaned page
+     * so we use mmu_free_page directly */
+    mmu_free_page(gc->mmu, tmp->addr, round_to_apage_size(tmp->size), MMU_SMALL_GEN0, MMU_NON_PROTECTABLE, &tmp->mmu_src_block);
+    free_mpage(tmp);
+  }
+  free(msgm);
+}
+
+
+
 /* this function resizes generation 0 to the closest it can get (erring high)
    to the size we've computed as ideal */
 inline static void resize_gen0(NewGC *gc, uintptr_t new_size)

src/racket/src/places.c

@@ -1256,6 +1256,20 @@ Scheme_Object *scheme_places_serialize(Scheme_Object *so, void **msg_memory) {
 #if defined(MZ_USE_PLACES) && defined(MZ_PRECISE_GC)
   Scheme_Object *new_so;
   Scheme_Object *tmp;
+
+  if (SCHEME_INTP(so)) { return so; }
+  switch (so->type) {
+    case scheme_true_type:
+    case scheme_false_type:
+    case scheme_null_type:
+    case scheme_void_type:
+      /* place_bi_channels are allocated in the master and can be passed along as is */
+    case scheme_place_bi_channel_type:
+      return so;
+    default:
+      break;
+  }
+
   GC_create_message_allocator();
   new_so = scheme_places_deep_copy(so);
   tmp = GC_finish_message_allocator();
@@ -1269,8 +1283,30 @@ Scheme_Object *scheme_places_serialize(Scheme_Object *so, void **msg_memory) {
 Scheme_Object *scheme_places_deserialize(Scheme_Object *so, void *msg_memory) {
 #if defined(MZ_USE_PLACES) && defined(MZ_PRECISE_GC)
   Scheme_Object *new_so;
+
+  if (SCHEME_INTP(so)) { return so; }
+  switch (so->type) {
+    case scheme_true_type:
+    case scheme_false_type:
+    case scheme_null_type:
+    case scheme_void_type:
+      /* place_bi_channels are allocated in the master and can be passed along as is */
+    case scheme_place_bi_channel_type:
+      return so;
+    default:
+      break;
+  }
+
+  if (GC_message_allocator_size(msg_memory) < 1024) {
+    new_so = scheme_places_deep_copy(so);
+    GC_dispose_message_allocator(msg_memory);
+  }
+  else {
+#if !defined(SHARED_TABLES)
     new_so = scheme_places_deserialize_worker(so);
+#endif
     GC_adopt_message_allocator(msg_memory);
+  }
   return new_so;
 #else
   return so;