diff options
Diffstat (limited to 'byterun/compact.c')
| -rw-r--r-- | byterun/compact.c | 58 |
1 files changed, 56 insertions, 2 deletions
diff --git a/byterun/compact.c b/byterun/compact.c index d409492877..c310bbebb6 100644 --- a/byterun/compact.c +++ b/byterun/compact.c @@ -144,7 +144,7 @@ static char *compact_allocate (mlsize_t size) return adr; } -void caml_compact_heap (void) +static void do_compaction (void) { char *ch, *chend; Assert (caml_gc_phase == Phase_idle); @@ -395,6 +395,60 @@ void caml_compact_heap (void) uintnat caml_percent_max; /* used in gc_ctrl.c and memory.c */ +void caml_compact_heap (void) +{ + uintnat target_size; + + do_compaction (); + /* Compaction may fail to shrink the heap to a reasonable size + because it deals in complete chunks: if a very large chunk + is at the beginning of the heap, everything gets moved to + it and it is not freed. + + In that case, we allocate a new chunk of the desired heap + size, chain it at the beginning of the heap (thus pretending + its address is smaller), and launch a second compaction. + This will move all data to this new chunk and free the + very large chunk. + + See PR#5389 + */ + /* We compute: + freewords = caml_fl_cur_size (exact) + heapsize = caml_heap_size (exact) + usedwords = heap_size - freewords + target_size = usedwords * (1 + caml_percent_free / 100) + + We recompact if target_size < heap_size / 2 + */ + target_size = (caml_stat_heap_size - Bsize_wsize (caml_fl_cur_size)) + * (100 + caml_percent_free) / 100; + target_size = caml_round_heap_chunk_size (target_size); + if (target_size < caml_stat_heap_size / 2){ + char *chunk; + + caml_gc_message (0x10, "Recompacting...\n", 0); + + /* round it up to a page size */ + chunk = caml_alloc_for_heap (target_size); + if (chunk == NULL) return; + caml_make_free_blocks ((value *) chunk, + Wsize_bsize (Chunk_size (chunk)), 0); + if (caml_page_table_add (In_heap, chunk, chunk + Chunk_size (chunk)) != 0){ + caml_free_for_heap (chunk); + return; + } + Chunk_next (chunk) = caml_heap_start; + caml_heap_start = chunk; + caml_stat_heap_size += Chunk_size (chunk); + if (caml_stat_heap_size > caml_stat_top_heap_size){ + caml_stat_top_heap_size = caml_stat_heap_size; + } + do_compaction (); + Assert (Chunk_next (caml_heap_start) == NULL); + } +} + void caml_compact_heap_maybe (void) { /* Estimated free words in the heap: @@ -408,7 +462,7 @@ void caml_compact_heap_maybe (void) float fw, fp; Assert (caml_gc_phase == Phase_idle); if (caml_percent_max >= 1000000) return; - if (caml_stat_major_collections < 3 || caml_stat_heap_chunks < 3) return; + if (caml_stat_major_collections < 3) return; fw = 3.0 * caml_fl_cur_size - 2.0 * caml_fl_size_at_phase_change; if (fw < 0) fw = caml_fl_cur_size; |