From a2b28094081f1b185a31b33e3c1bcb377d6761bb Mon Sep 17 00:00:00 2001 From: Sverker Eriksson Date: Thu, 3 Dec 2015 18:50:20 +0100 Subject: erts: Tweak hashmap heap size estimation 1. Change order between mul and div to not lose too much in integer divisions. 2. Fix estimation in DEBUG to really be an *under* estimation. --- erts/emulator/beam/erl_map.h | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'erts/emulator') diff --git a/erts/emulator/beam/erl_map.h b/erts/emulator/beam/erl_map.h index c391de3f11..4d9d74bc37 100644 --- a/erts/emulator/beam/erl_map.h +++ b/erts/emulator/beam/erl_map.h @@ -195,14 +195,17 @@ 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 -- cgit v1.2.3