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File 6033-erts-Improve-ets-grow-shrink-for-write_concurrency-a.patch of Package erlang
From f733c67f017bb70108b84c1080203fccdab97357 Mon Sep 17 00:00:00 2001 From: Sverker Eriksson <sverker@erlang.org> Date: Mon, 13 Dec 2021 14:13:41 +0100 Subject: [PATCH 3/4] erts: Improve ets grow/shrink for {write_concurrency,auto} and large lock arrays in general by limiting number of item counters, used for grow/shrink decisions, to the first 64 lock structs. --- erts/emulator/beam/erl_db.c | 1 - erts/emulator/beam/erl_db_hash.c | 182 +++++++++++++++---------------- erts/emulator/beam/erl_db_hash.h | 2 +- 3 files changed, 92 insertions(+), 93 deletions(-) diff --git a/erts/emulator/beam/erl_db.c b/erts/emulator/beam/erl_db.c index dc6e356fac..861cc0d917 100644 --- a/erts/emulator/beam/erl_db.c +++ b/erts/emulator/beam/erl_db.c @@ -2338,7 +2338,6 @@ BIF_RETTYPE ets_new_2(BIF_ALIST_2) Sint number_of_locks_param; if (arityval(stp[0]) == 2 && stp[1] == am_debug_hash_fixed_number_of_locks && - is_integer(stp[2]) && term_to_Sint(stp[2], &number_of_locks_param) && number_of_locks_param >= DB_WRITE_CONCURRENCY_MIN_LOCKS && number_of_locks_param <= DB_WRITE_CONCURRENCY_MAX_LOCKS) { diff --git a/erts/emulator/beam/erl_db_hash.c b/erts/emulator/beam/erl_db_hash.c index 1d80db06b5..db8af4a8d3 100644 --- a/erts/emulator/beam/erl_db_hash.c +++ b/erts/emulator/beam/erl_db_hash.c @@ -87,51 +87,63 @@ #define IS_DECENTRALIZED_CTRS(DB) ((DB)->common.counters.is_decentralized) -#define NITEMS_ESTIMATE_FROM_LCK_CTR(LCK_CTR_P) \ - (LCK_CTR_P->nitems <= 0 ? 1: LCK_CTR_P->nitems) - -#define NITEMS_ESTIMATE(DB, LCK_CTR, HASH) \ - (IS_DECENTRALIZED_CTRS(DB) ? \ - (((DB)->nlocks) * \ - (LCK_CTR != NULL ? \ - NITEMS_ESTIMATE_FROM_LCK_CTR(LCK_CTR) : \ - NITEMS_ESTIMATE_FROM_LCK_CTR(GET_LOCK_AND_CTR(DB, HASH)))) : \ - erts_flxctr_read_centralized(&(DB)->common.counters, \ - ERTS_DB_TABLE_NITEMS_COUNTER_ID)) - -#define ADD_NITEMS(DB, LCK_CTR, HASH, TO_ADD) \ - do { \ - if (IS_DECENTRALIZED_CTRS(DB)) { \ - if (LCK_CTR != NULL) { \ - LCK_CTR->nitems += TO_ADD; \ - } else { \ - GET_LOCK_AND_CTR(DB,HASH)->nitems += TO_ADD; \ - } \ - } \ - erts_flxctr_add(&(DB)->common.counters, ERTS_DB_TABLE_NITEMS_COUNTER_ID, TO_ADD); \ - } while(0) -#define INC_NITEMS(DB, LCK_CTR, HASH) \ - do { \ - if (IS_DECENTRALIZED_CTRS(DB)) { \ - if (LCK_CTR != NULL) { \ - LCK_CTR->nitems++; \ - } else { \ - GET_LOCK_AND_CTR(DB,HASH)->nitems++; \ - } \ - } \ - erts_flxctr_inc(&(DB)->common.counters, ERTS_DB_TABLE_NITEMS_COUNTER_ID); \ - } while(0) -#define DEC_NITEMS(DB, LCK_CTR, HASH) \ - do { \ - if (IS_DECENTRALIZED_CTRS(DB)) { \ - if (LCK_CTR != NULL) { \ - LCK_CTR->nitems--; \ - } else { \ - GET_LOCK_AND_CTR(DB,HASH)->nitems--; \ - } \ - } \ - erts_flxctr_dec(&(DB)->common.counters, ERTS_DB_TABLE_NITEMS_COUNTER_ID); \ - } while(0) +/* + * To get reasonable estimate of table load for grow/shrink decisions + * we limit the number of lock structs that hold (used) item counters. + * To simplify, this is also the minimum number of locks. + */ +#define NLOCKS_WITH_ITEM_COUNTERS 64 + +#define LCK_AUTO_MAX_LOCKS 8192 +#define LCK_AUTO_MIN_LOCKS NLOCKS_WITH_ITEM_COUNTERS +#define LCK_AUTO_DEFAULT_NUMBER_OF_LOCKS LCK_AUTO_MIN_LOCKS +#define LCK_AUTO_MAX_LOCKS_FREQ_READ_RW_LOCKS 128 + + +static ERTS_INLINE int +NITEMS_ESTIMATE(DbTableHash* DB, DbTableHashLockAndCounter* LCK_CTR, HashValue HASH) +{ + if (IS_DECENTRALIZED_CTRS(DB)) { + Sint nitems = erts_atomic_read_nob(&DB->locks[HASH % NLOCKS_WITH_ITEM_COUNTERS].u.lck_ctr.nitems); + return nitems * NLOCKS_WITH_ITEM_COUNTERS; + } + else { + return erts_flxctr_read_centralized(&(DB)->common.counters, + ERTS_DB_TABLE_NITEMS_COUNTER_ID); + } +} + +static ERTS_INLINE void +ADD_NITEMS(DbTableHash* DB, DbTableHashLockAndCounter* LCK_CTR, HashValue HASH, + Sint to_add) +{ + if (IS_DECENTRALIZED_CTRS(DB)) { + erts_atomic_add_nob(&DB->locks[HASH % NLOCKS_WITH_ITEM_COUNTERS].u.lck_ctr.nitems, + to_add); + } + erts_flxctr_add(&(DB)->common.counters, ERTS_DB_TABLE_NITEMS_COUNTER_ID, + to_add); +} + + +static ERTS_INLINE void +INC_NITEMS(DbTableHash* DB, DbTableHashLockAndCounter* LCK_CTR, HashValue HASH) +{ + if (IS_DECENTRALIZED_CTRS(DB)) { + erts_atomic_inc_nob(&DB->locks[HASH % NLOCKS_WITH_ITEM_COUNTERS].u.lck_ctr.nitems); + } + erts_flxctr_inc(&(DB)->common.counters, ERTS_DB_TABLE_NITEMS_COUNTER_ID); +} + +static ERTS_INLINE void +DEC_NITEMS(DbTableHash* DB, DbTableHashLockAndCounter* LCK_CTR, HashValue HASH) +{ + if (IS_DECENTRALIZED_CTRS(DB)) { + erts_atomic_dec_nob(&DB->locks[HASH % NLOCKS_WITH_ITEM_COUNTERS].u.lck_ctr.nitems); + } + erts_flxctr_dec(&(DB)->common.counters, ERTS_DB_TABLE_NITEMS_COUNTER_ID); +} + #define RESET_NITEMS(DB) \ erts_flxctr_reset(&(DB)->common.counters, ERTS_DB_TABLE_NITEMS_COUNTER_ID) @@ -276,30 +288,6 @@ static ERTS_INLINE int is_pseudo_deleted(HashDbTerm* p) # define LCK_AUTO_UNCONTENDED_STAT_CONTRIB -1 # define LCK_AUTO_GROW_LIMIT 1000 # define LCK_AUTO_SHRINK_LIMIT -10000000 -# define LCK_AUTO_MAX_LOCKS 8192 -# define LCK_AUTO_MIN_LOCKS 4 -# define LCK_AUTO_DEFAULT_NUMBER_OF_LOCKS 64 -# define LCK_AUTO_MAX_LOCKS_FREQ_READ_RW_LOCKS 128 - -static Sint get_lock_nitems_form_prev_lock_array(int index, - int new_number_of_locks, - int old_number_of_locks, - DbTableHashFineLockSlot* old_locks) { - if (new_number_of_locks > old_number_of_locks) { - Sint nitems = 0; - Sint in_source = old_locks[index % old_number_of_locks].u.lck_ctr.nitems; - nitems += in_source / 2; - if (index >= old_number_of_locks) { - nitems += in_source % 2; - } - return nitems; - } else { - Sint in_source_1 = old_locks[index].u.lck_ctr.nitems; - Sint in_source_2 = old_locks[index + new_number_of_locks].u.lck_ctr.nitems; - return in_source_1 + in_source_2; - } - -} static void calc_shrink_limit(DbTableHash* tb); @@ -375,11 +363,13 @@ void erl_db_hash_adapt_number_of_locks(DbTable* tb) { (DbTable *) tb, sizeof(DbTableHashFineLockSlot) * tbl->nlocks); for (i=0; i < tbl->nlocks; i++) { + erts_aint_t nitems; erts_rwmtx_init_opt(GET_LOCK(tbl, i), &rwmtx_opt, "db_hash_slot", tb->common.the_name, ERTS_LOCK_FLAGS_CATEGORY_DB); ERTS_DB_ALC_MEM_UPDATE_(tb, 0, erts_rwmtx_size(GET_LOCK(tbl,i))); - tbl->locks[i].u.lck_ctr.nitems = - get_lock_nitems_form_prev_lock_array(i, tbl->nlocks, old_number_of_locks, old_locks); + nitems = (i >= NLOCKS_WITH_ITEM_COUNTERS ? 0 : + erts_atomic_read_nob(&old_locks[i].u.lck_ctr.nitems)); + erts_atomic_init_nob(&tbl->locks[i].u.lck_ctr.nitems, nitems); tbl->locks[i].u.lck_ctr.lck_stat = 0; } /* #define HARD_DEBUG_ITEM_CNT_LOCK_CHANGE 1 */ @@ -1004,25 +994,33 @@ int db_create_hash(Process *p, DbTable *tbl) if (!(tb->common.type & DB_FINE_LOCKED)) { /* The number of locks needs to be set even if fine grained - locking is not used as this variable is used when iterating - over the table. + locking is not used as this variable is used as increment + when iterating over the table. */ tb->nlocks = 1; - } else if(tb->nlocks == -1) { - tb->nlocks = DB_HASH_LOCK_CNT; + tb->locks = NULL; } + else { + erts_rwmtx_opt_t rwmtx_opt = ERTS_RWMTX_OPT_DEFAULT_INITER; + int i; - if (tb->common.type & DB_FINE_LOCKED) { - erts_rwmtx_opt_t rwmtx_opt = ERTS_RWMTX_OPT_DEFAULT_INITER; - int i; if (tb->common.type & DB_FINE_LOCKED_AUTO) { tb->nlocks = LCK_AUTO_DEFAULT_NUMBER_OF_LOCKS; } - /* - nlocks needs to be a power of two so we round down to - nearest power of two - */ - tb->nlocks = 1 << (erts_fit_in_bits_int64(tb->nlocks)-1); + else { + if (tb->nlocks < 1) { + tb->nlocks = DB_HASH_LOCK_CNT; + } + /* + * nlocks needs to be a power of two so we round down to + * nearest power of two + */ + tb->nlocks = 1 << (erts_fit_in_bits_int64(tb->nlocks)-1); + if (tb->nlocks < NLOCKS_WITH_ITEM_COUNTERS) { + tb->nlocks = NLOCKS_WITH_ITEM_COUNTERS; + } + } + /* The table needs to be at least as big as the number of locks so we expand until this properly is satisfied. @@ -1043,7 +1041,7 @@ int db_create_hash(Process *p, DbTable *tbl) GET_LOCK(tb,i), &rwmtx_opt, "db_hash_slot", tb->common.the_name, ERTS_LOCK_FLAGS_CATEGORY_DB); ERTS_DB_ALC_MEM_UPDATE_(tb, 0, erts_rwmtx_size(GET_LOCK(tb,i))); - tb->locks[i].u.lck_ctr.nitems = 0; + erts_atomic_init_nob(&tb->locks[i].u.lck_ctr.nitems, 0); tb->locks[i].u.lck_ctr.lck_stat = 0; } /* @@ -1058,9 +1056,6 @@ int db_create_hash(Process *p, DbTable *tbl) ASSERT(IS_POW2(tb->nlocks)); ASSERT(IS_POW2(erts_atomic_read_nob(&tb->szm) + 1)); } - else { /* coarse locking */ - tb->locks = NULL; - } ERTS_THR_MEMORY_BARRIER; return DB_ERROR_NONE; } @@ -2585,9 +2580,14 @@ static Sint get_nitems_from_locks_or_counter(DbTableHash* tb) if (IS_DECENTRALIZED_CTRS(tb)) { int i; Sint total = 0; - for (i=0; i < tb->nlocks; ++i) { - total += tb->locks[i].u.lck_ctr.nitems; + for (i=0; i < NLOCKS_WITH_ITEM_COUNTERS; ++i) { + total += erts_atomic_read_nob(&tb->locks[i].u.lck_ctr.nitems); } +#ifdef DEBUG + for ( ; i < tb->nlocks; ++i) { + ASSERT(erts_atomic_read_nob(&tb->locks[i].u.lck_ctr.nitems) == 0); + } +#endif return total; } else { return erts_flxctr_read_centralized(&tb->common.counters, @@ -3290,7 +3290,7 @@ static void calc_shrink_limit(DbTableHash* tb) /* const double d = n*x / (x + n - 1) + 1; */ /* printf("Cochran_formula=%f size=%d mod_with_size=%f\n", x, n, d); */ /* } */ - const int needed_slots = 100 * tb->nlocks; + const int needed_slots = 100 * NLOCKS_WITH_ITEM_COUNTERS; if (tb->nslots < needed_slots) { sample_size_is_enough = 0; } @@ -4207,7 +4207,7 @@ void erts_lcnt_enable_db_hash_lock_count(DbTableHash *tb, int enable) { return; } - for(i = 0; i < DB_HASH_LOCK_CNT; i++) { + for (i = 0; i < tb->nlocks; i++) { erts_lcnt_ref_t *ref = &tb->locks[i].u.lck_ctr.lck.lcnt; if(enable) { diff --git a/erts/emulator/beam/erl_db_hash.h b/erts/emulator/beam/erl_db_hash.h index 25658af1e8..1590afb931 100644 --- a/erts/emulator/beam/erl_db_hash.h +++ b/erts/emulator/beam/erl_db_hash.h @@ -54,7 +54,7 @@ typedef struct hash_db_term { #endif typedef struct DbTableHashLockAndCounter { - Sint nitems; + erts_atomic_t nitems; Sint lck_stat; erts_rwmtx_t lck; } DbTableHashLockAndCounter; -- 2.34.1
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