[dpdk-dev] [PATCH 0/4] hash: separate lf and rw lock lookup code paths

[dpdk-dev] [PATCH 0/4] hash: separate lf and rw lock lookup code paths

[Honnappa Nagarahalli]

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.

To address the issue, 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.

This series has been split into 4 commits to make the review
process easier. All of these should be squashed into a single
commit after the review process is over.

Honnappa Nagarahalli (4):
  hash: prepare for lock-free and rw-lock separation
  hash: remove rw-lock calls from lock-free functions
  hash: remove memory orderings from rw-lock lookup fns
  hash: separate lf and rw lock lookup code paths

 lib/librte_hash/rte_cuckoo_hash.c | 303 ++++++++++++++++++++++++++++--
 1 file changed, 289 insertions(+), 14 deletions(-)

-- 
2.17.1

[dpdk-dev] [PATCH 1/4] hash: prepare for lock-free and rw-lock separation

[Honnappa Nagarahalli]

Copy and create the lock-free versions of lookup
functions.
This is an intermediate commit meant to ease the
review process.

Fixes: e605a1d36 ("hash: add lock-free r/w concurrency")
Cc: honnappa.nagarahalli@arm.com

Suggested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
---
 lib/librte_hash/rte_cuckoo_hash.c | 325 ++++++++++++++++++++++++++++++
 1 file changed, 325 insertions(+)

diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
index 5ddcccd87..874d77f1c 100644
--- a/lib/librte_hash/rte_cuckoo_hash.c
+++ b/lib/librte_hash/rte_cuckoo_hash.c
@@ -1162,6 +1162,39 @@ search_one_bucket(const struct rte_hash *h, const void *key, uint16_t sig,
 	return -1;
 }
 
+/* Search one bucket to find the match key */
+static inline int32_t
+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;
+	uint32_t key_idx;
+	void *pdata;
+	struct rte_hash_key *k, *keys = h->key_store;
+
+	for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
+		key_idx = __atomic_load_n(&bkt->key_idx[i],
+					  __ATOMIC_ACQUIRE);
+		if (bkt->sig_current[i] == sig && key_idx != EMPTY_SLOT) {
+			k = (struct rte_hash_key *) ((char *)keys +
+					key_idx * h->key_entry_size);
+			pdata = __atomic_load_n(&k->pdata,
+					__ATOMIC_ACQUIRE);
+
+			if (rte_hash_cmp_eq(key, k->key, h) == 0) {
+				if (data != NULL)
+					*data = pdata;
+				/*
+				 * Return index where key is stored,
+				 * subtracting the first dummy index
+				 */
+				return key_idx - 1;
+			}
+		}
+	}
+	return -1;
+}
+
 static inline int32_t
 __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key,
 					hash_sig_t sig, void **data)
@@ -1227,6 +1260,71 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key,
 	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);
+
+	__hash_rw_reader_lock(h);
+
+	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);
+
+		/* Check if key is in primary location */
+		bkt = &h->buckets[prim_bucket_idx];
+		ret = search_one_bucket(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(h, key, short_sig,
+						data, cur_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);
+
+	__hash_rw_reader_unlock(h);
+
+	return -ENOENT;
+}
+
 int32_t
 rte_hash_lookup_with_hash(const struct rte_hash *h,
 			const void *key, hash_sig_t sig)
@@ -1754,6 +1852,233 @@ __rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys,
 		*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[])
+{
+	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;
+	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++)
+		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);
+	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],
+				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 =
+				__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];
+
+					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 =
+				__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
+				 */
+
+				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] &= ~(3ULL << (hit_index << 1));
+			}
+next_key:
+			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);
+
+	/* 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(h, keys[i],
+						sig[i], &data[i], cur_bkt);
+			else
+				ret = search_one_bucket(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;
+}
+
 int
 rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys,
 		      uint32_t num_keys, int32_t *positions)
-- 
2.17.1

[dpdk-dev] [PATCH 2/4] hash: remove rw-lock calls from lock-free functions

[Honnappa Nagarahalli]

Remove the rw-lock calls from lock-free versions of lookup
functions.
This is an intermediate commit meant to ease the
review process.

Fixes: e605a1d36 ("hash: add lock-free r/w concurrency")
Cc: honnappa.nagarahalli@arm.com

Suggested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
---
 lib/librte_hash/rte_cuckoo_hash.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
index 874d77f1c..e6b84c6bc 100644
--- a/lib/librte_hash/rte_cuckoo_hash.c
+++ b/lib/librte_hash/rte_cuckoo_hash.c
@@ -1274,8 +1274,6 @@ __rte_hash_lookup_with_hash_lf(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);
 
-	__hash_rw_reader_lock(h);
-
 	do {
 		/* Load the table change counter before the lookup
 		 * starts. Acquire semantics will make sure that
@@ -1286,7 +1284,7 @@ __rte_hash_lookup_with_hash_lf(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;
@@ -1296,7 +1294,7 @@ __rte_hash_lookup_with_hash_lf(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);
@@ -1320,8 +1318,6 @@ __rte_hash_lookup_with_hash_lf(const struct rte_hash *h, const void *key,
 					__ATOMIC_ACQUIRE);
 	} while (cnt_b != cnt_a);
 
-	__hash_rw_reader_unlock(h);
-
 	return -ENOENT;
 }
 
@@ -1911,7 +1907,6 @@ __rte_hash_lookup_bulk_lf(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
@@ -2060,10 +2055,10 @@ __rte_hash_lookup_bulk_lf(const struct rte_hash *h, const void **keys,
 		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;
@@ -2073,8 +2068,6 @@ __rte_hash_lookup_bulk_lf(const struct rte_hash *h, const void **keys,
 		}
 	}
 
-	__hash_rw_reader_unlock(h);
-
 	if (hit_mask != NULL)
 		*hit_mask = hits;
 }
-- 
2.17.1

[dpdk-dev] [PATCH 3/4] hash: remove memory orderings from rw-lock lookup fns

[Honnappa Nagarahalli]

Remove the memory orderings from lookup functions using
rw-lock.
This is an intermediate commit meant to ease the
review process.

Fixes: e605a1d36 ("hash: add lock-free r/w concurrency")
Cc: honnappa.nagarahalli@arm.com

Suggested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
---
 lib/librte_hash/rte_cuckoo_hash.c | 277 +++++++++++-------------------
 1 file changed, 105 insertions(+), 172 deletions(-)

diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
index e6b84c6bc..9390dc5e4 100644
--- a/lib/librte_hash/rte_cuckoo_hash.c
+++ b/lib/librte_hash/rte_cuckoo_hash.c
@@ -1135,27 +1135,22 @@ search_one_bucket(const struct rte_hash *h, const void *key, uint16_t sig,
 			void **data, const struct rte_hash_bucket *bkt)
 {
 	int i;
-	uint32_t key_idx;
-	void *pdata;
 	struct rte_hash_key *k, *keys = h->key_store;
 
 	for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
-		key_idx = __atomic_load_n(&bkt->key_idx[i],
-					  __ATOMIC_ACQUIRE);
-		if (bkt->sig_current[i] == sig && key_idx != EMPTY_SLOT) {
+		if (bkt->sig_current[i] == sig &&
+				bkt->key_idx[i] != EMPTY_SLOT) {
 			k = (struct rte_hash_key *) ((char *)keys +
-					key_idx * h->key_entry_size);
-			pdata = __atomic_load_n(&k->pdata,
-					__ATOMIC_ACQUIRE);
+					bkt->key_idx[i] * h->key_entry_size);
 
 			if (rte_hash_cmp_eq(key, k->key, h) == 0) {
 				if (data != NULL)
-					*data = pdata;
+					*data = k->pdata;
 				/*
 				 * Return index where key is stored,
 				 * subtracting the first dummy index
 				 */
-				return key_idx - 1;
+				return bkt->key_idx[i] - 1;
 			}
 		}
 	}
@@ -1201,7 +1196,6 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key,
 {
 	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;
 
@@ -1211,49 +1205,25 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key,
 
 	__hash_rw_reader_lock(h);
 
-	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);
+	/* Check if key is in primary location */
+	bkt = &h->buckets[prim_bucket_idx];
+	ret = search_one_bucket(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 primary location */
-		bkt = &h->buckets[prim_bucket_idx];
-		ret = search_one_bucket(h, key, short_sig, data, bkt);
+	/* Check if key is in secondary location */
+	FOR_EACH_BUCKET(cur_bkt, bkt) {
+		ret = search_one_bucket(h, key, short_sig,
+					data, cur_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(h, key, short_sig,
-						data, cur_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);
+	}
 
 	__hash_rw_reader_unlock(h);
 
@@ -1638,8 +1608,6 @@ __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};
 	struct rte_hash_bucket *cur_bkt, *next_bkt;
-	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++)
@@ -1681,138 +1649,103 @@ __rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys,
 	}
 
 	__hash_rw_reader_lock(h);
-	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],
-				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 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;
 		}
 
-		/* 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 =
-				__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 (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);
+		}
+	}
 
-				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];
+	/* 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));
+				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 =
-				__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
-				 */
+		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] = pdata[i];
+			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));
+				hits |= 1ULL << i;
+				positions[i] = key_idx - 1;
+				goto next_key;
 			}
-next_key:
-			continue;
+			sec_hitmask[i] &= ~(3ULL << (hit_index << 1));
 		}
-
-		/* 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);
+next_key:
+		continue;
+	}
 
 	/* all found, do not need to go through ext bkt */
 	if ((hits == ((1ULL << num_keys) - 1)) || !h->ext_table_support) {
-- 
2.17.1

Re: [dpdk-dev] [PATCH 3/4] hash: remove memory orderings from rw-lock lookup fns

[Jerin Jacob]

-----Original Message-----
> Date: Fri, 9 Nov 2018 10:39:16 -0600
> From: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> To: bruce.richardson@intel.com, pablo.de.lara.guarch@intel.com
> CC: dev@dpdk.org, jerin.jacob@caviumnetworks.com, hemant.agrawal@nxp.com,
>  chaozhu@linux.vnet.ibm.com, yipeng1.wang@intel.com,
>  dharmik.thakkar@arm.com, gavin.hu@arm.com, honnappa.nagarahalli@arm.com,
>  nd@arm.com
> Subject: [PATCH 3/4] hash: remove memory orderings from rw-lock lookup fns
> X-Mailer: git-send-email 2.17.1
> 
> 
> Remove the memory orderings from lookup functions using
> rw-lock.
> This is an intermediate commit meant to ease the
> review process.
> 
> Fixes: e605a1d36 ("hash: add lock-free r/w concurrency")
> Cc: honnappa.nagarahalli@arm.com
> 
> Suggested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
> Reviewed-by: Gavin Hu <gavin.hu@arm.com>
> ---
>  lib/librte_hash/rte_cuckoo_hash.c | 277 +++++++++++-------------------
>  1 file changed, 105 insertions(+), 172 deletions(-)
> 
> diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
> index e6b84c6bc..9390dc5e4 100644
> --- a/lib/librte_hash/rte_cuckoo_hash.c
> +++ b/lib/librte_hash/rte_cuckoo_hash.c
> @@ -1135,27 +1135,22 @@ search_one_bucket(const struct rte_hash *h, const void *key, uint16_t sig,
>                         void **data, const struct rte_hash_bucket *bkt)
>  {
>         int i;
> -       uint32_t key_idx;
> -       void *pdata;
>         struct rte_hash_key *k, *keys = h->key_store;
> 
>         for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
> -               key_idx = __atomic_load_n(&bkt->key_idx[i],
> -                                         __ATOMIC_ACQUIRE);
> -               if (bkt->sig_current[i] == sig && key_idx != EMPTY_SLOT) {
> +               if (bkt->sig_current[i] == sig &&
> +                               bkt->key_idx[i] != EMPTY_SLOT) {
>                         k = (struct rte_hash_key *) ((char *)keys +
> -                                       key_idx * h->key_entry_size);
> -                       pdata = __atomic_load_n(&k->pdata,
> -                                       __ATOMIC_ACQUIRE);
> +                                       bkt->key_idx[i] * h->key_entry_size);
> 
>                         if (rte_hash_cmp_eq(key, k->key, h) == 0) {
>                                 if (data != NULL)
> -                                       *data = pdata;
> +                                       *data = k->pdata;
>                                 /*
>                                  * Return index where key is stored,
>                                  * subtracting the first dummy index
>                                  */
> -                               return key_idx - 1;
> +                               return bkt->key_idx[i] - 1;
>                         }
>                 }
>         }
> @@ -1201,7 +1196,6 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key,
>  {
>         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;
> 
> @@ -1211,49 +1205,25 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key,
> 
>         __hash_rw_reader_lock(h);
> 
> -       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);
> +       /* Check if key is in primary location */
> +       bkt = &h->buckets[prim_bucket_idx];


In original version, this bkt assignment is before to __hash_rw_reader_lock().
This causing performance issue in lookup 'hit' case.

Following change is fixing it.i.e bringing back to orginal version.

[master]83xx1.2[dpdk]# git diff
diff --git a/lib/librte_hash/rte_cuckoo_hash.c
b/lib/librte_hash/rte_cuckoo_hash.c
index 7e1a9ac96..bc8a55f0f 100644
--- a/lib/librte_hash/rte_cuckoo_hash.c
+++ b/lib/librte_hash/rte_cuckoo_hash.c
@@ -1204,10 +1204,11 @@ __rte_hash_lookup_with_hash_l(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);
 
-       __hash_rw_reader_lock(h);
-
        /* Check if key is in primary location */
        bkt = &h->buckets[prim_bucket_idx];
+
+       __hash_rw_reader_lock(h);
+
        ret = search_one_bucket_l(h, key, short_sig, data, bkt);
        if (ret != -1) {
                __hash_rw_reader_unlock(h);


Could you send the final version that needs to taken into tree.
i.e remove intermediate commits only for review purpose.
I can test it finally with that.

Re: [dpdk-dev] [PATCH 3/4] hash: remove memory orderings from rw-lock lookup fns

[Honnappa Nagarahalli]

> > @@ -1211,49 +1205,25 @@ __rte_hash_lookup_with_hash(const struct
> > rte_hash *h, const void *key,
> >
> >         __hash_rw_reader_lock(h);
> >
> > -       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);
> > +       /* Check if key is in primary location */
> > +       bkt = &h->buckets[prim_bucket_idx];
> 
> 
> In original version, this bkt assignment is before to __hash_rw_reader_lock().
> This causing performance issue in lookup 'hit' case.
> 
> Following change is fixing it.i.e bringing back to orginal version.
> 
> [master]83xx1.2[dpdk]# git diff
> diff --git a/lib/librte_hash/rte_cuckoo_hash.c
> b/lib/librte_hash/rte_cuckoo_hash.c
> index 7e1a9ac96..bc8a55f0f 100644
> --- a/lib/librte_hash/rte_cuckoo_hash.c
> +++ b/lib/librte_hash/rte_cuckoo_hash.c
> @@ -1204,10 +1204,11 @@ __rte_hash_lookup_with_hash_l(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);
> 
> -       __hash_rw_reader_lock(h);
> -
>         /* Check if key is in primary location */
>         bkt = &h->buckets[prim_bucket_idx];
> +
> +       __hash_rw_reader_lock(h);
> +
>         ret = search_one_bucket_l(h, key, short_sig, data, bkt);
>         if (ret != -1) {
>                 __hash_rw_reader_unlock(h);
> 
> 
> Could you send the final version that needs to taken into tree.
> i.e remove intermediate commits only for review purpose.
> I can test it finally with that.
Thanks Jerin for testing. I have sent out v2.

[dpdk-dev] [PATCH 4/4] hash: separate lf and rw lock lookup code paths

[Honnappa Nagarahalli]

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")
Cc: honnappa.nagarahalli@arm.com

Suggested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
---
 lib/librte_hash/rte_cuckoo_hash.c | 44 ++++++++++++++++++++++++-------
 1 file changed, 34 insertions(+), 10 deletions(-)

diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
index 9390dc5e4..7e1a9ac96 100644
--- a/lib/librte_hash/rte_cuckoo_hash.c
+++ b/lib/librte_hash/rte_cuckoo_hash.c
@@ -1129,10 +1129,11 @@ 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 */
+/* Search one bucket to find the match key - uses rw lock */
 static inline int32_t
-search_one_bucket(const struct rte_hash *h, const void *key, uint16_t sig,
-			void **data, const struct rte_hash_bucket *bkt)
+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;
@@ -1191,8 +1192,8 @@ search_one_bucket_lf(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;
@@ -1207,7 +1208,7 @@ __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_l(h, key, short_sig, data, bkt);
 	if (ret != -1) {
 		__hash_rw_reader_unlock(h);
 		return ret;
@@ -1217,7 +1218,7 @@ __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_l(h, key, short_sig,
 					data, cur_bkt);
 		if (ret != -1) {
 			__hash_rw_reader_unlock(h);
@@ -1291,6 +1292,16 @@ __rte_hash_lookup_with_hash_lf(const struct rte_hash *h, const void *key,
 	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)
@@ -1592,7 +1603,7 @@ 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[])
 {
@@ -1762,10 +1773,10 @@ __rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys,
 		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_l(h, keys[i],
 						sig[i], &data[i], cur_bkt);
 			else
-				ret = search_one_bucket(h, keys[i],
+				ret = search_one_bucket_l(h, keys[i],
 						sig[i], NULL, cur_bkt);
 			if (ret != -1) {
 				positions[i] = ret;
@@ -2005,6 +2016,19 @@ __rte_hash_lookup_bulk_lf(const struct rte_hash *h, const void **keys,
 		*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)
-- 
2.17.1

[dpdk-dev] [PATCH v2 0/1] hash: separate lf and rw lock lookup code paths

[Honnappa Nagarahalli]

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.

To address the issue, 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.

v2:
1) Adjusted the function call to take the lock in
   __rte_hash_lookup_with_hash_l (Jerin)
2) Squash all the intermediate commits into a single one

Honnappa Nagarahalli (1):
  hash: separate lf and rw lock lookup code paths

 lib/librte_hash/rte_cuckoo_hash.c | 304 ++++++++++++++++++++++++++++--
 1 file changed, 290 insertions(+), 14 deletions(-)

-- 
2.17.1

[dpdk-dev] [PATCH v2 1/1] hash: separate lf and rw lock lookup code paths

[Honnappa Nagarahalli]

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")
Cc: honnappa.nagarahalli@arm.com

Suggested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
---
 lib/librte_hash/rte_cuckoo_hash.c | 304 ++++++++++++++++++++++++++++--
 1 file changed, 290 insertions(+), 14 deletions(-)

diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
index 5ddcccd87..e68bf336b 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 @@ __rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys,
 		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 @@ __rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys,
 		}
 	}
 
-	__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)
-- 
2.17.1

Re: [dpdk-dev] [PATCH v2 1/1] hash: separate lf and rw lock lookup code paths

[Jerin Jacob]

-----Original Message-----
> Date: Sat, 10 Nov 2018 12:55:34 -0600
> From: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> To: bruce.richardson@intel.com, pablo.de.lara.guarch@intel.com
> CC: dev@dpdk.org, jerin.jacob@caviumnetworks.com, hemant.agrawal@nxp.com,
>  chaozhu@linux.vnet.ibm.com, yipeng1.wang@intel.com,
>  dharmik.thakkar@arm.com, gavin.hu@arm.com, honnappa.nagarahalli@arm.com,
>  nd@arm.com
> Subject: [PATCH v2 1/1] hash: separate lf and rw lock lookup code paths
> X-Mailer: git-send-email 2.17.1
> 
> 
> 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")
> Cc: honnappa.nagarahalli@arm.com
> 
> Suggested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
> Reviewed-by: Gavin Hu <gavin.hu@arm.com>
> ---

Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Tested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>

- Reported l3fwd hash regression for ARMv8 platform fixed
  with this patch by introducing two different code path(obviously!!)
- Verified lock version of lookup() is same as e605a1d36~1 changeset

+ Thomas,

If there is no objection, please consider this patch into -RC3

Re: [dpdk-dev] [PATCH v2 1/1] hash: separate lf and rw lock lookup code paths

[Thomas Monjalon]

11/11/2018 08:48, Jerin Jacob:
> > 
> > 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")
> > Cc: honnappa.nagarahalli@arm.com
> > 
> > Suggested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> > Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> > Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
> > Reviewed-by: Gavin Hu <gavin.hu@arm.com>
> > ---
> 
> Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> Tested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>

Applied, thanks

Re: [dpdk-dev] [PATCH v2 1/1] hash: separate lf and rw lock lookup code paths

[Wang, Yipeng1]

> -----Original Message-----
> From: Honnappa Nagarahalli [mailto:honnappa.nagarahalli@arm.com]
> Sent: Saturday, November 10, 2018 10:56 AM
> To: Richardson, Bruce <bruce.richardson@intel.com>; De Lara Guarch, Pablo
> <pablo.de.lara.guarch@intel.com>
> Cc: dev@dpdk.org; jerin.jacob@caviumnetworks.com;
> hemant.agrawal@nxp.com; chaozhu@linux.vnet.ibm.com; Wang, Yipeng1
> <yipeng1.wang@intel.com>; dharmik.thakkar@arm.com; gavin.hu@arm.com;
> honnappa.nagarahalli@arm.com; nd@arm.com
> Subject: [PATCH v2 1/1] hash: separate lf and rw lock lookup code paths
> 
> 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")
> Cc: honnappa.nagarahalli@arm.com
> 
> Suggested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
> Reviewed-by: Gavin Hu <gavin.hu@arm.com>
> ---
[Wang, Yipeng] 
I tested my modified l3fwd with this new patch applied on x86 platform and it does
not cause any performance drop anymore.

There are extra code duplication though but I believe in future version together
with fined-grained lock, the duplication could be fixed later.

Re: [dpdk-dev] [PATCH v2 1/1] hash: separate lf and rw lock lookup code paths

[Honnappa Nagarahalli]

> > Subject: [PATCH v2 1/1] hash: separate lf and rw lock lookup code
> > paths
> >
> > 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")
> > Cc: honnappa.nagarahalli@arm.com
> >
> > Suggested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> > Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> > Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
> > Reviewed-by: Gavin Hu <gavin.hu@arm.com>
> > ---
> [Wang, Yipeng]
> I tested my modified l3fwd with this new patch applied on x86 platform and it
> does not cause any performance drop anymore.
> 
> There are extra code duplication though but I believe in future version
> together with fined-grained lock, the duplication could be fixed later.
> 
Thank you Yipeng for testing this. Agree, the code duplication is worrying. I will try to get the optimization patch out soon. Once we have that we can do the testing and take a decision to address the duplication.