From 5e229f3d7591b0df7d6d475065e1dc2d5273a148 Mon Sep 17 00:00:00 2001 From: Sverker Eriksson Date: Wed, 16 Sep 2015 15:28:46 +0200 Subject: erts: Fix resurrection of carriers from dc_list Problem #1: Seems the dc_list check did end up as dead code by mistake. Solution: goto check_dc_list Problem #2: crr->cpool.max_size was set to zero for all carriers in dc_list, which meant no carriers were ever resurrected by cpool_fetch. Solution: Do not use callback 'largest_fblk_in_mbc' to set max_size as it will always return 0 (due to problem #3). Problem #3: Resurrected carriers were broken as their one free block was not linked. Solution: Link free block when fetching carrier from dc_list. --- erts/emulator/beam/erl_alloc_util.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/erts/emulator/beam/erl_alloc_util.c b/erts/emulator/beam/erl_alloc_util.c index 236ee35d18..3861196cfc 100644 --- a/erts/emulator/beam/erl_alloc_util.c +++ b/erts/emulator/beam/erl_alloc_util.c @@ -3149,7 +3149,7 @@ cpool_fetch(Allctr_t *allctr, UWord size) cpool_entrance = sentinel; cpdp = cpool_aint2cpd(cpool_read(&cpool_entrance->prev)); if (cpdp == sentinel) - return NULL; + goto check_dc_list; } has_passed_sentinel = 0; @@ -3160,18 +3160,18 @@ cpool_fetch(Allctr_t *allctr, UWord size) if (cpool_entrance == sentinel) { cpdp = cpool_aint2cpd(cpool_read(&cpdp->prev)); if (cpdp == sentinel) - return NULL; + break; } i = 0; /* Last one to inspect */ } else if (cpdp == sentinel) { if (has_passed_sentinel) { /* We been here before. cpool_entrance must have been removed */ - return NULL; + break; } cpdp = cpool_aint2cpd(cpool_read(&cpdp->prev)); if (cpdp == sentinel) - return NULL; + break; has_passed_sentinel = 1; } crr = (Carrier_t *)(((char *)cpdp) - offsetof(Carrier_t, cpool)); @@ -3195,10 +3195,12 @@ cpool_fetch(Allctr_t *allctr, UWord size) return NULL; } +check_dc_list: /* Last; check our own pending dealloc carrier list... */ crr = allctr->cpool.dc_list.last; while (crr) { if (erts_atomic_read_nob(&crr->cpool.max_size) >= size) { + Block_t* blk; unlink_carrier(&allctr->cpool.dc_list, crr); #ifdef ERTS_ALC_CPOOL_DEBUG ERTS_ALC_CPOOL_ASSERT(erts_smp_atomic_xchg_nob(&crr->allctr, @@ -3207,6 +3209,9 @@ cpool_fetch(Allctr_t *allctr, UWord size) #else erts_smp_atomic_set_nob(&crr->allctr, ((erts_aint_t) allctr)); #endif + blk = MBC_TO_FIRST_BLK(allctr, crr); + ASSERT(FBLK_TO_MBC(blk) == crr); + allctr->link_free_block(allctr, blk); return crr; } crr = crr->prev; @@ -3279,7 +3284,6 @@ schedule_dealloc_carrier(Allctr_t *allctr, Carrier_t *crr) orig_allctr = crr->cpool.orig_allctr; if (allctr != orig_allctr) { - Block_t *blk = MBC_TO_FIRST_BLK(allctr, crr); int cinit = orig_allctr->dd.ix - allctr->dd.ix; /* @@ -3296,6 +3300,7 @@ schedule_dealloc_carrier(Allctr_t *allctr, Carrier_t *crr) * since the block is an mbc block that is free and last * in the carrier. */ + blk = MBC_TO_FIRST_BLK(allctr, crr); ERTS_ALC_CPOOL_ASSERT(IS_FREE_LAST_MBC_BLK(blk)); ERTS_ALC_CPOOL_ASSERT(IS_MBC_FIRST_ABLK(allctr, blk)); @@ -3319,7 +3324,9 @@ schedule_dealloc_carrier(Allctr_t *allctr, Carrier_t *crr) return; } - max_size = (erts_aint_t) allctr->largest_fblk_in_mbc(allctr, crr); + blk = MBC_TO_FIRST_BLK(allctr, crr); + ASSERT(IS_FREE_LAST_MBC_BLK(blk)); + max_size = (erts_aint_t) MBC_FBLK_SZ(blk); erts_atomic_set_nob(&crr->cpool.max_size, max_size); crr->next = NULL; -- cgit v1.2.3