From def1a47fc6674fc87b74ba727054c5104694b00c Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn-Egil=20Dahlberg?= Date: Tue, 12 Feb 2013 20:02:26 +0100 Subject: erts: Utilize even more cached sbc segments --- erts/emulator/sys/common/erl_mseg.c | 59 +++++++++++++++++++++++++++++-------- 1 file changed, 47 insertions(+), 12 deletions(-) diff --git a/erts/emulator/sys/common/erl_mseg.c b/erts/emulator/sys/common/erl_mseg.c index 32d753a67b..bd8ba82a5f 100644 --- a/erts/emulator/sys/common/erl_mseg.c +++ b/erts/emulator/sys/common/erl_mseg.c @@ -585,7 +585,10 @@ static ERTS_INLINE int cache_bless_segment(MemKind *mk, void *seg, Uint size, Ui } else if (!MSEG_FLG_IS_2POW(flags)) { /* No free slots and no unpowered (sbc) slots. - * Evict smallest slot from powered cache so we can cache an unpowered (sbc) segment */ + * Evict smallest slot from powered cache so we can cache an unpowered (sbc) segment. + * Note: Though this is the wanted policy I don't think it is used significantly. + * This branch could probably be removed without serious impact. + */ int i; @@ -659,31 +662,63 @@ static ERTS_INLINE void *cache_get_segment(MemKind *mk, Uint *size_p, Uint flags else if (!erts_circleq_is_empty(&(mk->cache_unpowered_node))) { void *seg; cache_t *c; + cache_t *best = NULL; + Uint bdiff = 0; Uint csize; Uint bad_max_abs = mk->ma->abs_max_cache_bad_fit; Uint bad_max_rel = mk->ma->rel_max_cache_bad_fit; erts_circleq_foreach(c, &(mk->cache_unpowered_node)) { csize = c->size; - if (csize >= size && - ((csize - size)*100 < bad_max_rel*size) && - (csize - size) < bad_max_abs ) { + if (csize >= size) { + if (((csize - size)*100 < bad_max_rel*size) && (csize - size) < bad_max_abs ) { - seg = c->seg; + seg = c->seg; - erts_circleq_remove(c); + erts_circleq_remove(c); - mk->cache_size--; - mk->cache_hits++; + mk->cache_size--; + mk->cache_hits++; - mseg_cache_clear_node(c); - erts_circleq_push_head(&(mk->cache_free), c); + mseg_cache_clear_node(c); + erts_circleq_push_head(&(mk->cache_free), c); - *size_p = csize; + *size_p = csize; - return seg; + return seg; + + } else if (!best || (csize - size) < bdiff) { + best = c; + bdiff = csize - size; + } } } + + /* No cached segment met our criteria, use the best one found and trim it */ + + if (best) { + + seg = best->seg; + csize = best->size; + + ASSERT(best->seg); + ASSERT(best->size > 0); + + mk->cache_hits++; + + /* Use current cache placement for remaining segment space */ + + best->seg = seg + size; + best->size = csize - size; + + ASSERT((size % GET_PAGE_SIZE) == 0); + ASSERT((best->size % GET_PAGE_SIZE) == 0); + + *size_p = size; + + return seg; + + } } return NULL; } -- cgit v1.2.3