From patchwork Thu Oct 11 04:59:30 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Honnappa Nagarahalli X-Patchwork-Id: 46540 X-Patchwork-Delegate: thomas@monjalon.net Return-Path: X-Original-To: patchwork@dpdk.org Delivered-To: patchwork@dpdk.org Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 0AE4D1B439; Thu, 11 Oct 2018 06:59:57 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by dpdk.org (Postfix) with ESMTP id 62D611B3B8 for ; Thu, 11 Oct 2018 06:59:48 +0200 (CEST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D4D567A9; Wed, 10 Oct 2018 21:59:47 -0700 (PDT) Received: from 2p2660v4-1.austin.arm.com (2p2660v4-1.austin.arm.com [10.118.12.190]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7043D3F5B3; Wed, 10 Oct 2018 21:59:47 -0700 (PDT) From: Honnappa Nagarahalli To: bruce.richardson@intel.com, pablo.de.lara.guarch@intel.com Cc: dev@dpdk.org, yipeng1.wang@intel.com, honnappa.nagarahalli@arm.com, Dharmik.Thakkar@arm.com, nd@arm.com Date: Wed, 10 Oct 2018 23:59:30 -0500 Message-Id: <1539233972-49860-6-git-send-email-honnappa.nagarahalli@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1539233972-49860-1-git-send-email-honnappa.nagarahalli@arm.com> References: <1539233972-49860-1-git-send-email-honnappa.nagarahalli@arm.com> Subject: [dpdk-dev] [PATCH v2 5/7] hash: fix rw concurrency while moving keys X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Reader-writer concurrency issue, caused by moving the keys to their alternative locations during key insert, is solved by introducing a global counter(tbl_chng_cnt) indicating a change in table. Signed-off-by: Honnappa Nagarahalli Reviewed-by: Gavin Hu Reviewed-by: Ola Liljedahl Reviewed-by: Steve Capper Reviewed-by: Yipeng Wang --- lib/librte_hash/rte_cuckoo_hash.c | 306 +++++++++++++++++++++++++------------- lib/librte_hash/rte_cuckoo_hash.h | 3 + 2 files changed, 209 insertions(+), 100 deletions(-) diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c index e2b0260..dfd5f2a 100644 --- a/lib/librte_hash/rte_cuckoo_hash.c +++ b/lib/librte_hash/rte_cuckoo_hash.c @@ -96,6 +96,7 @@ rte_hash_create(const struct rte_hash_parameters *params) unsigned int readwrite_concur_support = 0; unsigned int writer_takes_lock = 0; unsigned int recycle_on_del = 1; + uint32_t *tbl_chng_cnt = NULL; rte_hash_function default_hash_func = (rte_hash_function)rte_jhash; @@ -210,6 +211,14 @@ rte_hash_create(const struct rte_hash_parameters *params) goto err_unlock; } + tbl_chng_cnt = rte_zmalloc_socket(NULL, sizeof(uint32_t), + RTE_CACHE_LINE_SIZE, params->socket_id); + + if (tbl_chng_cnt == NULL) { + RTE_LOG(ERR, HASH, "memory allocation failed\n"); + goto err_unlock; + } + /* * If x86 architecture is used, select appropriate compare function, * which may use x86 intrinsics, otherwise use memcmp @@ -276,6 +285,8 @@ rte_hash_create(const struct rte_hash_parameters *params) default_hash_func : params->hash_func; h->key_store = k; h->free_slots = r; + h->tbl_chng_cnt = tbl_chng_cnt; + *h->tbl_chng_cnt = 0; h->hw_trans_mem_support = hw_trans_mem_support; h->multi_writer_support = multi_writer_support; h->readwrite_concur_support = readwrite_concur_support; @@ -321,6 +332,7 @@ rte_hash_create(const struct rte_hash_parameters *params) rte_free(h); rte_free(buckets); rte_free(k); + rte_free(tbl_chng_cnt); return NULL; } @@ -359,6 +371,7 @@ rte_hash_free(struct rte_hash *h) rte_ring_free(h->free_slots); rte_free(h->key_store); rte_free(h->buckets); + rte_free(h->tbl_chng_cnt); rte_free(h); rte_free(te); } @@ -456,6 +469,7 @@ rte_hash_reset(struct rte_hash *h) __hash_rw_writer_lock(h); memset(h->buckets, 0, h->num_buckets * sizeof(struct rte_hash_bucket)); memset(h->key_store, 0, h->key_entry_size * (h->entries + 1)); + *h->tbl_chng_cnt = 0; /* clear the free ring */ while (rte_ring_dequeue(h->free_slots, &ptr) == 0) @@ -650,11 +664,27 @@ rte_hash_cuckoo_move_insert_mw(const struct rte_hash *h, if (unlikely(&h->buckets[prev_alt_bkt_idx] != curr_bkt)) { /* revert it to empty, otherwise duplicated keys */ - curr_bkt->key_idx[curr_slot] = EMPTY_SLOT; + __atomic_store_n(&curr_bkt->key_idx[curr_slot], + EMPTY_SLOT, + __ATOMIC_RELEASE); __hash_rw_writer_unlock(h); return -1; } + /* Inform the previous move. The current move need + * not be informed now as the current bucket entry + * is present in both primary and secondary. + * Since there is one writer, load acquires on + * tbl_chng_cnt are not required. + */ + __atomic_store_n(h->tbl_chng_cnt, + *h->tbl_chng_cnt + 1, + __ATOMIC_RELEASE); + /* The stores to sig_alt and sig_current should not + * move above the store to tbl_chng_cnt. + */ + __atomic_thread_fence(__ATOMIC_RELEASE); + /* Need to swap current/alt sig to allow later * Cuckoo insert to move elements back to its * primary bucket if available @@ -673,6 +703,20 @@ rte_hash_cuckoo_move_insert_mw(const struct rte_hash *h, curr_bkt = curr_node->bkt; } + /* Inform the previous move. The current move need + * not be informed now as the current bucket entry + * is present in both primary and secondary. + * Since there is one writer, load acquires on + * tbl_chng_cnt are not required. + */ + __atomic_store_n(h->tbl_chng_cnt, + *h->tbl_chng_cnt + 1, + __ATOMIC_RELEASE); + /* The stores to sig_alt and sig_current should not + * move above the store to tbl_chng_cnt. + */ + __atomic_thread_fence(__ATOMIC_RELEASE); + curr_bkt->sig_current[curr_slot] = sig; curr_bkt->sig_alt[curr_slot] = alt_hash; /* Release the new bucket entry */ @@ -937,30 +981,56 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key, uint32_t bucket_idx; hash_sig_t alt_hash; struct rte_hash_bucket *bkt; + uint32_t cnt_b, cnt_a; int ret; - bucket_idx = sig & h->bucket_bitmask; - bkt = &h->buckets[bucket_idx]; - __hash_rw_reader_lock(h); - /* Check if key is in primary location */ - ret = search_one_bucket(h, key, sig, data, bkt); - if (ret != -1) { - __hash_rw_reader_unlock(h); - return ret; - } - /* Calculate secondary hash */ - alt_hash = rte_hash_secondary_hash(sig); - bucket_idx = alt_hash & h->bucket_bitmask; - bkt = &h->buckets[bucket_idx]; + do { + /* Load the table change counter before the lookup + * starts. Acquire semantics will make sure that + * loads in search_one_bucket are not hoisted. + */ + cnt_b = __atomic_load_n(h->tbl_chng_cnt, + __ATOMIC_ACQUIRE); + + bucket_idx = sig & h->bucket_bitmask; + bkt = &h->buckets[bucket_idx]; + + /* Check if key is in primary location */ + ret = search_one_bucket(h, key, sig, data, bkt); + if (ret != -1) { + __hash_rw_reader_unlock(h); + return ret; + } + /* Calculate secondary hash */ + alt_hash = rte_hash_secondary_hash(sig); + bucket_idx = alt_hash & h->bucket_bitmask; + bkt = &h->buckets[bucket_idx]; + + /* Check if key is in secondary location */ + ret = search_one_bucket(h, key, alt_hash, data, bkt); + if (ret != -1) { + __hash_rw_reader_unlock(h); + return ret; + } + + /* The loads of sig_current in search_one_bucket + * should not move below the load from tbl_chng_cnt. + */ + __atomic_thread_fence(__ATOMIC_ACQUIRE); + /* Re-read the table change counter to check if the + * table has changed during search. If yes, re-do + * the search. + * This load should not get hoisted. The load + * acquires on cnt_b, key index in primary bucket + * and key index in secondary bucket will make sure + * that it does not get hoisted. + */ + cnt_a = __atomic_load_n(h->tbl_chng_cnt, + __ATOMIC_ACQUIRE); + } while (cnt_b != cnt_a); - /* Check if key is in secondary location */ - ret = search_one_bucket(h, key, alt_hash, data, bkt); - if (ret != -1) { - __hash_rw_reader_unlock(h); - return ret; - } __hash_rw_reader_unlock(h); return -ENOENT; } @@ -1242,6 +1312,7 @@ __rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys, uint32_t prim_hitmask[RTE_HASH_LOOKUP_BULK_MAX] = {0}; uint32_t sec_hitmask[RTE_HASH_LOOKUP_BULK_MAX] = {0}; void *pdata[RTE_HASH_LOOKUP_BULK_MAX]; + uint32_t cnt_b, cnt_a; /* Prefetch first keys */ for (i = 0; i < PREFETCH_OFFSET && i < num_keys; i++) @@ -1277,102 +1348,137 @@ __rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys, } __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], + do { + /* Load the table change counter before the lookup + * starts. Acquire semantics will make sure that + * loads in compare_signatures are not hoisted. + */ + cnt_b = __atomic_load_n(h->tbl_chng_cnt, + __ATOMIC_ACQUIRE); + + /* 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], prim_hash[i], sec_hash[i], h->sig_cmp_fn); - if (prim_hitmask[i]) { - uint32_t first_hit = __builtin_ctzl(prim_hitmask[i]); - 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 (prim_hitmask[i]) { + uint32_t first_hit = + __builtin_ctzl(prim_hitmask[i]); + 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]); - 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); + if (sec_hitmask[i]) { + uint32_t first_hit = + __builtin_ctzl(sec_hitmask[i]); + 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]); + /* 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]); - uint32_t key_idx = - __atomic_load_n( - &primary_bkt[i]->key_idx[hit_index], - __ATOMIC_ACQUIRE); - 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_idx != EMPTY_SLOT) - pdata[i] = __atomic_load_n(&key_slot->pdata, - __ATOMIC_ACQUIRE); - /* - * 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] = pdata[i]; + uint32_t key_idx = + __atomic_load_n( + &primary_bkt[i]->key_idx[hit_index], + __ATOMIC_ACQUIRE); + const struct rte_hash_key *key_slot = + (const struct rte_hash_key *)( + (const char *)h->key_store + + key_idx * h->key_entry_size); - hits |= 1ULL << i; - positions[i] = key_idx - 1; - goto next_key; + if (key_idx != EMPTY_SLOT) + pdata[i] = __atomic_load_n( + &key_slot->pdata, + __ATOMIC_ACQUIRE); + /* + * 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] = pdata[i]; + + hits |= 1ULL << i; + positions[i] = key_idx - 1; + goto next_key; + } + prim_hitmask[i] &= ~(1 << (hit_index)); } - prim_hitmask[i] &= ~(1 << (hit_index)); - } - while (sec_hitmask[i]) { - uint32_t hit_index = __builtin_ctzl(sec_hitmask[i]); + while (sec_hitmask[i]) { + uint32_t hit_index = + __builtin_ctzl(sec_hitmask[i]); - uint32_t key_idx = - __atomic_load_n( - &secondary_bkt[i]->key_idx[hit_index], - __ATOMIC_ACQUIRE); - 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_idx != EMPTY_SLOT) - pdata[i] = __atomic_load_n(&key_slot->pdata, - __ATOMIC_ACQUIRE); - - /* - * If key index is 0, do not compare key, - * as it is checking the dummy slot - */ + uint32_t key_idx = + __atomic_load_n( + &secondary_bkt[i]->key_idx[hit_index], + __ATOMIC_ACQUIRE); + 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_idx & !rte_hash_cmp_eq(key_slot->key, keys[i], h)) { - if (data != NULL) - data[i] = pdata[i]; + if (key_idx != EMPTY_SLOT) + pdata[i] = __atomic_load_n( + &key_slot->pdata, + __ATOMIC_ACQUIRE); + /* + * If key index is 0, do not compare key, + * as it is checking the dummy slot + */ - hits |= 1ULL << i; - positions[i] = key_idx - 1; - goto next_key; + if (!!key_idx & + !rte_hash_cmp_eq( + key_slot->key, keys[i], h)) { + if (data != NULL) + data[i] = pdata[i]; + + hits |= 1ULL << i; + positions[i] = key_idx - 1; + goto next_key; + } + sec_hitmask[i] &= ~(1 << (hit_index)); } - sec_hitmask[i] &= ~(1 << (hit_index)); - } next_key: - continue; - } + continue; + } + + /* The loads of sig_current in compare_signatures + * should not move below the load from tbl_chng_cnt. + */ + __atomic_thread_fence(__ATOMIC_ACQUIRE); + /* Re-read the table change counter to check if the + * table has changed during search. If yes, re-do + * the search. + * This load should not get hoisted. The load + * acquires on cnt_b, primary key index and secondary + * key index will make sure that it does not get + * hoisted. + */ + cnt_a = __atomic_load_n(h->tbl_chng_cnt, + __ATOMIC_ACQUIRE); + } while (cnt_b != cnt_a); __hash_rw_reader_unlock(h); diff --git a/lib/librte_hash/rte_cuckoo_hash.h b/lib/librte_hash/rte_cuckoo_hash.h index a44c6be..cf50ada 100644 --- a/lib/librte_hash/rte_cuckoo_hash.h +++ b/lib/librte_hash/rte_cuckoo_hash.h @@ -1,5 +1,6 @@ /* SPDX-License-Identifier: BSD-3-Clause * Copyright(c) 2016 Intel Corporation + * Copyright(c) 2018 Arm Limited */ /* rte_cuckoo_hash.h @@ -196,6 +197,8 @@ struct rte_hash { * to the key table. */ rte_rwlock_t *readwrite_lock; /**< Read-write lock thread-safety. */ + uint32_t *tbl_chng_cnt; + /**< Indicates if the hash table changed from last read. */ } __rte_cache_aligned; struct queue_node {