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-rw-r--r--erts/emulator/beam/erl_map.h13
1 files changed, 8 insertions, 5 deletions
diff --git a/erts/emulator/beam/erl_map.h b/erts/emulator/beam/erl_map.h
index be6f791a4e..052fa99f03 100644
--- a/erts/emulator/beam/erl_map.h
+++ b/erts/emulator/beam/erl_map.h
@@ -180,14 +180,17 @@ typedef struct hashmap_head_s {
[one cons cell + one list term in parent node] per key
[one header + one boxed term in parent node] per inner node
[one header + one size word] for root node
+ Observed average number of nodes per key is about 0.35.
*/
-#define HASHMAP_HEAP_SIZE(KEYS,NODES) ((KEYS)*3 + (NODES)*2)
+#define HASHMAP_WORDS_PER_KEY 3
+#define HASHMAP_WORDS_PER_NODE 2
#ifdef DEBUG
-# define HASHMAP_ESTIMATED_NODE_COUNT(KEYS) (KEYS)
+# define HASHMAP_ESTIMATED_TOT_NODE_SIZE(KEYS) \
+ (HASHMAP_WORDS_PER_NODE * (KEYS) * 3/10) /* slightly under estimated */
#else
-# define HASHMAP_ESTIMATED_NODE_COUNT(KEYS) (2*(KEYS)/5)
+# define HASHMAP_ESTIMATED_TOT_NODE_SIZE(KEYS) \
+ (HASHMAP_WORDS_PER_NODE * (KEYS) * 4/10) /* slightly over estimated */
#endif
#define HASHMAP_ESTIMATED_HEAP_SIZE(KEYS) \
- HASHMAP_HEAP_SIZE(KEYS,HASHMAP_ESTIMATED_NODE_COUNT(KEYS))
-
+ ((KEYS)*HASHMAP_WORDS_PER_KEY + HASHMAP_ESTIMATED_TOT_NODE_SIZE(KEYS))
#endif