From 6505733012458d8fcd0ae8e1f1acdc9ffe33ff35 Mon Sep 17 00:00:00 2001 From: Mike Hommey Date: Wed, 4 Feb 2015 07:16:55 +0900 Subject: [PATCH] Make opt.lg_dirty_mult work as documented The documentation for opt.lg_dirty_mult says: Per-arena minimum ratio (log base 2) of active to dirty pages. Some dirty unused pages may be allowed to accumulate, within the limit set by the ratio (or one chunk worth of dirty pages, whichever is greater) (...) The restriction in parentheses currently doesn't happen. This makes jemalloc aggressively madvise(), which in turns increases the amount of page faults significantly. For instance, this resulted in several(!) hundred(!) milliseconds startup regression on Firefox for Android. This may require further tweaking, but starting with actually doing what the documentation says is a good start. --- src/arena.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/src/arena.c b/src/arena.c index 984b8ad2..a5033bf8 100644 --- a/src/arena.c +++ b/src/arena.c @@ -850,6 +850,7 @@ arena_maybe_purge(arena_t *arena) if (opt_lg_dirty_mult < 0) return; threshold = (arena->nactive >> opt_lg_dirty_mult); + threshold = threshold < chunk_npages ? chunk_npages : threshold; /* * Don't purge unless the number of purgeable pages exceeds the * threshold. @@ -893,6 +894,7 @@ arena_compute_npurge(arena_t *arena, bool all) */ if (!all) { size_t threshold = (arena->nactive >> opt_lg_dirty_mult); + threshold = threshold < chunk_npages ? chunk_npages : threshold; npurge = arena->ndirty - threshold; } else