From: Honnappa Nagarahalli Date: Sat, 10 Nov 2018 18:55:34 +0000 (-0600) Subject: hash: separate lock-free and r/w lock lookup X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=9eca8bd7a61cc3a0bd29e2ddd493915902bb98a5;p=dpdk.git hash: separate lock-free and r/w lock lookup The lock-free algorithm has caused significant lookup performance regression for certain use cases. The regression is attributed to the use of non-relaxed memory orderings. 2 versions of the lookup functions are created. One that uses the RW lock and the one that is lock-free. This restores the performance regression caused for use cases that used RW lock version of the lookup function. Fixes: e605a1d36 ("hash: add lock-free r/w concurrency") Suggested-by: Jerin Jacob Signed-off-by: Honnappa Nagarahalli Reviewed-by: Ola Liljedahl Reviewed-by: Gavin Hu Acked-by: Jerin Jacob Tested-by: Jerin Jacob --- diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c index 5ddcccd878..e68bf336be 100644 --- a/lib/librte_hash/rte_cuckoo_hash.c +++ b/lib/librte_hash/rte_cuckoo_hash.c @@ -1129,9 +1129,38 @@ rte_hash_add_key_data(const struct rte_hash *h, const void *key, void *data) return ret; } +/* Search one bucket to find the match key - uses rw lock */ +static inline int32_t +search_one_bucket_l(const struct rte_hash *h, const void *key, + uint16_t sig, void **data, + const struct rte_hash_bucket *bkt) +{ + int i; + struct rte_hash_key *k, *keys = h->key_store; + + for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) { + if (bkt->sig_current[i] == sig && + bkt->key_idx[i] != EMPTY_SLOT) { + k = (struct rte_hash_key *) ((char *)keys + + bkt->key_idx[i] * h->key_entry_size); + + if (rte_hash_cmp_eq(key, k->key, h) == 0) { + if (data != NULL) + *data = k->pdata; + /* + * Return index where key is stored, + * subtracting the first dummy index + */ + return bkt->key_idx[i] - 1; + } + } + } + return -1; +} + /* Search one bucket to find the match key */ static inline int32_t -search_one_bucket(const struct rte_hash *h, const void *key, uint16_t sig, +search_one_bucket_lf(const struct rte_hash *h, const void *key, uint16_t sig, void **data, const struct rte_hash_bucket *bkt) { int i; @@ -1163,12 +1192,11 @@ search_one_bucket(const struct rte_hash *h, const void *key, uint16_t sig, } static inline int32_t -__rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key, - hash_sig_t sig, void **data) +__rte_hash_lookup_with_hash_l(const struct rte_hash *h, const void *key, + hash_sig_t sig, void **data) { uint32_t prim_bucket_idx, sec_bucket_idx; struct rte_hash_bucket *bkt, *cur_bkt; - uint32_t cnt_b, cnt_a; int ret; uint16_t short_sig; @@ -1176,8 +1204,48 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key, prim_bucket_idx = get_prim_bucket_index(h, sig); sec_bucket_idx = get_alt_bucket_index(h, prim_bucket_idx, short_sig); + bkt = &h->buckets[prim_bucket_idx]; + __hash_rw_reader_lock(h); + /* Check if key is in primary location */ + ret = search_one_bucket_l(h, key, short_sig, data, bkt); + if (ret != -1) { + __hash_rw_reader_unlock(h); + return ret; + } + /* Calculate secondary hash */ + bkt = &h->buckets[sec_bucket_idx]; + + /* Check if key is in secondary location */ + FOR_EACH_BUCKET(cur_bkt, bkt) { + ret = search_one_bucket_l(h, key, short_sig, + data, cur_bkt); + if (ret != -1) { + __hash_rw_reader_unlock(h); + return ret; + } + } + + __hash_rw_reader_unlock(h); + + return -ENOENT; +} + +static inline int32_t +__rte_hash_lookup_with_hash_lf(const struct rte_hash *h, const void *key, + hash_sig_t sig, void **data) +{ + uint32_t prim_bucket_idx, sec_bucket_idx; + struct rte_hash_bucket *bkt, *cur_bkt; + uint32_t cnt_b, cnt_a; + int ret; + uint16_t short_sig; + + short_sig = get_short_sig(sig); + prim_bucket_idx = get_prim_bucket_index(h, sig); + sec_bucket_idx = get_alt_bucket_index(h, prim_bucket_idx, short_sig); + do { /* Load the table change counter before the lookup * starts. Acquire semantics will make sure that @@ -1188,7 +1256,7 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key, /* Check if key is in primary location */ bkt = &h->buckets[prim_bucket_idx]; - ret = search_one_bucket(h, key, short_sig, data, bkt); + ret = search_one_bucket_lf(h, key, short_sig, data, bkt); if (ret != -1) { __hash_rw_reader_unlock(h); return ret; @@ -1198,7 +1266,7 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key, /* Check if key is in secondary location */ FOR_EACH_BUCKET(cur_bkt, bkt) { - ret = search_one_bucket(h, key, short_sig, + ret = search_one_bucket_lf(h, key, short_sig, data, cur_bkt); if (ret != -1) { __hash_rw_reader_unlock(h); @@ -1222,11 +1290,19 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key, __ATOMIC_ACQUIRE); } while (cnt_b != cnt_a); - __hash_rw_reader_unlock(h); - return -ENOENT; } +static inline int32_t +__rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key, + hash_sig_t sig, void **data) +{ + if (h->readwrite_concur_lf_support) + return __rte_hash_lookup_with_hash_lf(h, key, sig, data); + else + return __rte_hash_lookup_with_hash_l(h, key, sig, data); +} + int32_t rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key, hash_sig_t sig) @@ -1528,7 +1604,197 @@ compare_signatures(uint32_t *prim_hash_matches, uint32_t *sec_hash_matches, #define PREFETCH_OFFSET 4 static inline void -__rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys, +__rte_hash_lookup_bulk_l(const struct rte_hash *h, const void **keys, + int32_t num_keys, int32_t *positions, + uint64_t *hit_mask, void *data[]) +{ + uint64_t hits = 0; + int32_t i; + int32_t ret; + uint32_t prim_hash[RTE_HASH_LOOKUP_BULK_MAX]; + uint32_t prim_index[RTE_HASH_LOOKUP_BULK_MAX]; + uint32_t sec_index[RTE_HASH_LOOKUP_BULK_MAX]; + uint16_t sig[RTE_HASH_LOOKUP_BULK_MAX]; + const struct rte_hash_bucket *primary_bkt[RTE_HASH_LOOKUP_BULK_MAX]; + const struct rte_hash_bucket *secondary_bkt[RTE_HASH_LOOKUP_BULK_MAX]; + uint32_t prim_hitmask[RTE_HASH_LOOKUP_BULK_MAX] = {0}; + uint32_t sec_hitmask[RTE_HASH_LOOKUP_BULK_MAX] = {0}; + struct rte_hash_bucket *cur_bkt, *next_bkt; + + /* Prefetch first keys */ + for (i = 0; i < PREFETCH_OFFSET && i < num_keys; i++) + rte_prefetch0(keys[i]); + + /* + * Prefetch rest of the keys, calculate primary and + * secondary bucket and prefetch them + */ + for (i = 0; i < (num_keys - PREFETCH_OFFSET); i++) { + rte_prefetch0(keys[i + PREFETCH_OFFSET]); + + prim_hash[i] = rte_hash_hash(h, keys[i]); + + sig[i] = get_short_sig(prim_hash[i]); + prim_index[i] = get_prim_bucket_index(h, prim_hash[i]); + sec_index[i] = get_alt_bucket_index(h, prim_index[i], sig[i]); + + primary_bkt[i] = &h->buckets[prim_index[i]]; + secondary_bkt[i] = &h->buckets[sec_index[i]]; + + rte_prefetch0(primary_bkt[i]); + rte_prefetch0(secondary_bkt[i]); + } + + /* Calculate and prefetch rest of the buckets */ + for (; i < num_keys; i++) { + prim_hash[i] = rte_hash_hash(h, keys[i]); + + sig[i] = get_short_sig(prim_hash[i]); + prim_index[i] = get_prim_bucket_index(h, prim_hash[i]); + sec_index[i] = get_alt_bucket_index(h, prim_index[i], sig[i]); + + primary_bkt[i] = &h->buckets[prim_index[i]]; + secondary_bkt[i] = &h->buckets[sec_index[i]]; + + rte_prefetch0(primary_bkt[i]); + rte_prefetch0(secondary_bkt[i]); + } + + __hash_rw_reader_lock(h); + + /* Compare signatures and prefetch key slot of first hit */ + for (i = 0; i < num_keys; i++) { + compare_signatures(&prim_hitmask[i], &sec_hitmask[i], + primary_bkt[i], secondary_bkt[i], + sig[i], h->sig_cmp_fn); + + if (prim_hitmask[i]) { + uint32_t first_hit = + __builtin_ctzl(prim_hitmask[i]) + >> 1; + uint32_t key_idx = + primary_bkt[i]->key_idx[first_hit]; + const struct rte_hash_key *key_slot = + (const struct rte_hash_key *)( + (const char *)h->key_store + + key_idx * h->key_entry_size); + rte_prefetch0(key_slot); + continue; + } + + if (sec_hitmask[i]) { + uint32_t first_hit = + __builtin_ctzl(sec_hitmask[i]) + >> 1; + uint32_t key_idx = + secondary_bkt[i]->key_idx[first_hit]; + const struct rte_hash_key *key_slot = + (const struct rte_hash_key *)( + (const char *)h->key_store + + key_idx * h->key_entry_size); + rte_prefetch0(key_slot); + } + } + + /* Compare keys, first hits in primary first */ + for (i = 0; i < num_keys; i++) { + positions[i] = -ENOENT; + while (prim_hitmask[i]) { + uint32_t hit_index = + __builtin_ctzl(prim_hitmask[i]) + >> 1; + uint32_t key_idx = + primary_bkt[i]->key_idx[hit_index]; + const struct rte_hash_key *key_slot = + (const struct rte_hash_key *)( + (const char *)h->key_store + + key_idx * h->key_entry_size); + + /* + * If key index is 0, do not compare key, + * as it is checking the dummy slot + */ + if (!!key_idx & + !rte_hash_cmp_eq( + key_slot->key, keys[i], h)) { + if (data != NULL) + data[i] = key_slot->pdata; + + hits |= 1ULL << i; + positions[i] = key_idx - 1; + goto next_key; + } + prim_hitmask[i] &= ~(3ULL << (hit_index << 1)); + } + + while (sec_hitmask[i]) { + uint32_t hit_index = + __builtin_ctzl(sec_hitmask[i]) + >> 1; + uint32_t key_idx = + secondary_bkt[i]->key_idx[hit_index]; + const struct rte_hash_key *key_slot = + (const struct rte_hash_key *)( + (const char *)h->key_store + + key_idx * h->key_entry_size); + + /* + * If key index is 0, do not compare key, + * as it is checking the dummy slot + */ + + if (!!key_idx & + !rte_hash_cmp_eq( + key_slot->key, keys[i], h)) { + if (data != NULL) + data[i] = key_slot->pdata; + + hits |= 1ULL << i; + positions[i] = key_idx - 1; + goto next_key; + } + sec_hitmask[i] &= ~(3ULL << (hit_index << 1)); + } +next_key: + continue; + } + + /* all found, do not need to go through ext bkt */ + if ((hits == ((1ULL << num_keys) - 1)) || !h->ext_table_support) { + if (hit_mask != NULL) + *hit_mask = hits; + __hash_rw_reader_unlock(h); + return; + } + + /* need to check ext buckets for match */ + for (i = 0; i < num_keys; i++) { + if ((hits & (1ULL << i)) != 0) + continue; + next_bkt = secondary_bkt[i]->next; + FOR_EACH_BUCKET(cur_bkt, next_bkt) { + if (data != NULL) + ret = search_one_bucket_l(h, keys[i], + sig[i], &data[i], cur_bkt); + else + ret = search_one_bucket_l(h, keys[i], + sig[i], NULL, cur_bkt); + if (ret != -1) { + positions[i] = ret; + hits |= 1ULL << i; + break; + } + } + } + + __hash_rw_reader_unlock(h); + + if (hit_mask != NULL) + *hit_mask = hits; +} + +static inline void +__rte_hash_lookup_bulk_lf(const struct rte_hash *h, const void **keys, int32_t num_keys, int32_t *positions, uint64_t *hit_mask, void *data[]) { @@ -1586,7 +1852,6 @@ __rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys, rte_prefetch0(secondary_bkt[i]); } - __hash_rw_reader_lock(h); do { /* Load the table change counter before the lookup * starts. Acquire semantics will make sure that @@ -1735,10 +2000,10 @@ next_key: next_bkt = secondary_bkt[i]->next; FOR_EACH_BUCKET(cur_bkt, next_bkt) { if (data != NULL) - ret = search_one_bucket(h, keys[i], + ret = search_one_bucket_lf(h, keys[i], sig[i], &data[i], cur_bkt); else - ret = search_one_bucket(h, keys[i], + ret = search_one_bucket_lf(h, keys[i], sig[i], NULL, cur_bkt); if (ret != -1) { positions[i] = ret; @@ -1748,12 +2013,23 @@ next_key: } } - __hash_rw_reader_unlock(h); - if (hit_mask != NULL) *hit_mask = hits; } +static inline void +__rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys, + int32_t num_keys, int32_t *positions, + uint64_t *hit_mask, void *data[]) +{ + if (h->readwrite_concur_lf_support) + return __rte_hash_lookup_bulk_lf(h, keys, num_keys, + positions, hit_mask, data); + else + return __rte_hash_lookup_bulk_l(h, keys, num_keys, + positions, hit_mask, data); +} + int rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys, uint32_t num_keys, int32_t *positions)