[dpdk-dev] [PATCH v5 2/4] hash: reorganize bucket structure

[Pablo de Lara]

From: Byron Marohn <byron.marohn at intel.com>

Move current signatures of all entries together in the bucket
and same with all alternative signatures, instead of having
current and alternative signatures together per entry in the bucket.
This will be benefitial in the next commits, where a vectorized
comparison will be performed, achieving better performance.

The alternative signatures have been moved away from
the current signatures, to make the key indices be consecutive
to the current signatures, as these two fields are used by lookup,
so they are in the same cache line.

Signed-off-by: Byron Marohn <byron.marohn at intel.com>
Signed-off-by: Saikrishna Edupuganti <saikrishna.edupuganti at intel.com>
Acked-by: Bruce Richardson <bruce.richardson at intel.com>
Acked-by: Sameh Gobriel <sameh.gobriel at intel.com>
---
 lib/librte_hash/rte_cuckoo_hash.c     | 43 ++++++++++++++++++-----------------
 lib/librte_hash/rte_cuckoo_hash.h     | 17 ++++----------
 lib/librte_hash/rte_cuckoo_hash_x86.h | 20 ++++++++--------
 3 files changed, 37 insertions(+), 43 deletions(-)

diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
index 4de4422..a7ee2b9 100644
--- a/lib/librte_hash/rte_cuckoo_hash.c
+++ b/lib/librte_hash/rte_cuckoo_hash.c
@@ -421,7 +421,7 @@ make_space_bucket(const struct rte_hash *h, struct rte_hash_bucket *bkt)
 	 */
 	for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
 		/* Search for space in alternative locations */
-		next_bucket_idx = bkt->signatures[i].alt & h->bucket_bitmask;
+		next_bucket_idx = bkt->sig_alt[i] & h->bucket_bitmask;
 		next_bkt[i] = &h->buckets[next_bucket_idx];
 		for (j = 0; j < RTE_HASH_BUCKET_ENTRIES; j++) {
 			if (next_bkt[i]->key_idx[j] == EMPTY_SLOT)
@@ -434,8 +434,8 @@ make_space_bucket(const struct rte_hash *h, struct rte_hash_bucket *bkt)
 
 	/* Alternative location has spare room (end of recursive function) */
 	if (i != RTE_HASH_BUCKET_ENTRIES) {
-		next_bkt[i]->signatures[j].alt = bkt->signatures[i].current;
-		next_bkt[i]->signatures[j].current = bkt->signatures[i].alt;
+		next_bkt[i]->sig_alt[j] = bkt->sig_current[i];
+		next_bkt[i]->sig_current[j] = bkt->sig_alt[i];
 		next_bkt[i]->key_idx[j] = bkt->key_idx[i];
 		return i;
 	}
@@ -461,8 +461,8 @@ make_space_bucket(const struct rte_hash *h, struct rte_hash_bucket *bkt)
 	 */
 	bkt->flag[i] = 0;
 	if (ret >= 0) {
-		next_bkt[i]->signatures[ret].alt = bkt->signatures[i].current;
-		next_bkt[i]->signatures[ret].current = bkt->signatures[i].alt;
+		next_bkt[i]->sig_alt[ret] = bkt->sig_current[i];
+		next_bkt[i]->sig_current[ret] = bkt->sig_alt[i];
 		next_bkt[i]->key_idx[ret] = bkt->key_idx[i];
 		return i;
 	} else
@@ -544,8 +544,8 @@ __rte_hash_add_key_with_hash(const struct rte_hash *h, const void *key,
 
 	/* Check if key is already inserted in primary location */
 	for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
-		if (prim_bkt->signatures[i].current == sig &&
-				prim_bkt->signatures[i].alt == alt_hash) {
+		if (prim_bkt->sig_current[i] == sig &&
+				prim_bkt->sig_alt[i] == alt_hash) {
 			k = (struct rte_hash_key *) ((char *)keys +
 					prim_bkt->key_idx[i] * h->key_entry_size);
 			if (rte_hash_cmp_eq(key, k->key, h) == 0) {
@@ -564,8 +564,8 @@ __rte_hash_add_key_with_hash(const struct rte_hash *h, const void *key,
 
 	/* Check if key is already inserted in secondary location */
 	for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
-		if (sec_bkt->signatures[i].alt == sig &&
-				sec_bkt->signatures[i].current == alt_hash) {
+		if (sec_bkt->sig_alt[i] == sig &&
+				sec_bkt->sig_current[i] == alt_hash) {
 			k = (struct rte_hash_key *) ((char *)keys +
 					sec_bkt->key_idx[i] * h->key_entry_size);
 			if (rte_hash_cmp_eq(key, k->key, h) == 0) {
@@ -611,8 +611,8 @@ __rte_hash_add_key_with_hash(const struct rte_hash *h, const void *key,
 		for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
 			/* Check if slot is available */
 			if (likely(prim_bkt->key_idx[i] == EMPTY_SLOT)) {
-				prim_bkt->signatures[i].current = sig;
-				prim_bkt->signatures[i].alt = alt_hash;
+				prim_bkt->sig_current[i] = sig;
+				prim_bkt->sig_alt[i] = alt_hash;
 				prim_bkt->key_idx[i] = new_idx;
 				break;
 			}
@@ -632,8 +632,8 @@ __rte_hash_add_key_with_hash(const struct rte_hash *h, const void *key,
 		 */
 		ret = make_space_bucket(h, prim_bkt);
 		if (ret >= 0) {
-			prim_bkt->signatures[ret].current = sig;
-			prim_bkt->signatures[ret].alt = alt_hash;
+			prim_bkt->sig_current[ret] = sig;
+			prim_bkt->sig_alt[ret] = alt_hash;
 			prim_bkt->key_idx[ret] = new_idx;
 			if (h->add_key == ADD_KEY_MULTIWRITER)
 				rte_spinlock_unlock(h->multiwriter_lock);
@@ -707,7 +707,7 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key,
 
 	/* Check if key is in primary location */
 	for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
-		if (bkt->signatures[i].current == sig &&
+		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);
@@ -730,8 +730,8 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key,
 
 	/* Check if key is in secondary location */
 	for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
-		if (bkt->signatures[i].current == alt_hash &&
-				bkt->signatures[i].alt == sig) {
+		if (bkt->sig_current[i] == alt_hash &&
+				bkt->sig_alt[i] == sig) {
 			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) {
@@ -785,7 +785,8 @@ remove_entry(const struct rte_hash *h, struct rte_hash_bucket *bkt, unsigned i)
 	unsigned lcore_id, n_slots;
 	struct lcore_cache *cached_free_slots;
 
-	bkt->signatures[i].sig = NULL_SIGNATURE;
+	bkt->sig_current[i] = NULL_SIGNATURE;
+	bkt->sig_alt[i] = NULL_SIGNATURE;
 	if (h->hw_trans_mem_support) {
 		lcore_id = rte_lcore_id();
 		cached_free_slots = &h->local_free_slots[lcore_id];
@@ -823,7 +824,7 @@ __rte_hash_del_key_with_hash(const struct rte_hash *h, const void *key,
 
 	/* Check if key is in primary location */
 	for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
-		if (bkt->signatures[i].current == sig &&
+		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);
@@ -848,7 +849,7 @@ __rte_hash_del_key_with_hash(const struct rte_hash *h, const void *key,
 
 	/* Check if key is in secondary location */
 	for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
-		if (bkt->signatures[i].current == alt_hash &&
+		if (bkt->sig_current[i] == alt_hash &&
 				bkt->key_idx[i] != EMPTY_SLOT) {
 			k = (struct rte_hash_key *) ((char *)keys +
 					bkt->key_idx[i] * h->key_entry_size);
@@ -957,8 +958,8 @@ lookup_stage2(unsigned idx, hash_sig_t prim_hash, hash_sig_t sec_hash,
 	prim_hash_matches = 1 << RTE_HASH_BUCKET_ENTRIES;
 	sec_hash_matches = 1 << RTE_HASH_BUCKET_ENTRIES;
 	for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
-		prim_hash_matches |= ((prim_hash == prim_bkt->signatures[i].current) << i);
-		sec_hash_matches |= ((sec_hash == sec_bkt->signatures[i].current) << i);
+		prim_hash_matches |= ((prim_hash == prim_bkt->sig_current[i]) << i);
+		sec_hash_matches |= ((sec_hash == sec_bkt->sig_current[i]) << i);
 	}
 
 	key_idx = prim_bkt->key_idx[__builtin_ctzl(prim_hash_matches)];
diff --git a/lib/librte_hash/rte_cuckoo_hash.h b/lib/librte_hash/rte_cuckoo_hash.h
index 27a47e5..6549731 100644
--- a/lib/librte_hash/rte_cuckoo_hash.h
+++ b/lib/librte_hash/rte_cuckoo_hash.h
@@ -151,17 +151,6 @@ struct lcore_cache {
 	void *objs[LCORE_CACHE_SIZE]; /**< Cache objects */
 } __rte_cache_aligned;
 
-/* Structure storing both primary and secondary hashes */
-struct rte_hash_signatures {
-	union {
-		struct {
-			hash_sig_t current;
-			hash_sig_t alt;
-		};
-		uint64_t sig;
-	};
-};
-
 /* Structure that stores key-value pair */
 struct rte_hash_key {
 	union {
@@ -174,9 +163,13 @@ struct rte_hash_key {
 
 /** Bucket structure */
 struct rte_hash_bucket {
-	struct rte_hash_signatures signatures[RTE_HASH_BUCKET_ENTRIES];
+	hash_sig_t sig_current[RTE_HASH_BUCKET_ENTRIES];
+
 	/* Includes dummy key index that always contains index 0 */
 	uint32_t key_idx[RTE_HASH_BUCKET_ENTRIES + 1];
+
+	hash_sig_t sig_alt[RTE_HASH_BUCKET_ENTRIES];
+
 	uint8_t flag[RTE_HASH_BUCKET_ENTRIES];
 } __rte_cache_aligned;
 
diff --git a/lib/librte_hash/rte_cuckoo_hash_x86.h b/lib/librte_hash/rte_cuckoo_hash_x86.h
index 7ffa56f..47aec6d 100644
--- a/lib/librte_hash/rte_cuckoo_hash_x86.h
+++ b/lib/librte_hash/rte_cuckoo_hash_x86.h
@@ -54,8 +54,8 @@ rte_hash_cuckoo_insert_mw_tm(struct rte_hash_bucket *prim_bkt,
 			for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
 				/* Check if slot is available */
 				if (likely(prim_bkt->key_idx[i] == EMPTY_SLOT)) {
-					prim_bkt->signatures[i].current = sig;
-					prim_bkt->signatures[i].alt = alt_hash;
+					prim_bkt->sig_current[i] = sig;
+					prim_bkt->sig_alt[i] = alt_hash;
 					prim_bkt->key_idx[i] = new_idx;
 					break;
 				}
@@ -101,7 +101,7 @@ rte_hash_cuckoo_move_insert_mw_tm(const struct rte_hash *h,
 				prev_slot = curr_node->prev_slot;
 
 				prev_alt_bkt_idx
-					= prev_bkt->signatures[prev_slot].alt
+					= prev_bkt->sig_alt[prev_slot]
 					    & h->bucket_bitmask;
 
 				if (unlikely(&h->buckets[prev_alt_bkt_idx]
@@ -113,10 +113,10 @@ rte_hash_cuckoo_move_insert_mw_tm(const struct rte_hash *h,
 				 * Cuckoo insert to move elements back to its
 				 * primary bucket if available
 				 */
-				curr_bkt->signatures[curr_slot].alt =
-				    prev_bkt->signatures[prev_slot].current;
-				curr_bkt->signatures[curr_slot].current =
-				    prev_bkt->signatures[prev_slot].alt;
+				curr_bkt->sig_alt[curr_slot] =
+				    prev_bkt->sig_current[prev_slot];
+				curr_bkt->sig_current[curr_slot] =
+				    prev_bkt->sig_alt[prev_slot];
 				curr_bkt->key_idx[curr_slot]
 				    = prev_bkt->key_idx[prev_slot];
 
@@ -125,8 +125,8 @@ rte_hash_cuckoo_move_insert_mw_tm(const struct rte_hash *h,
 				curr_bkt = curr_node->bkt;
 			}
 
-			curr_bkt->signatures[curr_slot].current = sig;
-			curr_bkt->signatures[curr_slot].alt = alt_hash;
+			curr_bkt->sig_current[curr_slot] = sig;
+			curr_bkt->sig_alt[curr_slot] = alt_hash;
 			curr_bkt->key_idx[curr_slot] = new_idx;
 
 			rte_xend();
@@ -178,7 +178,7 @@ rte_hash_cuckoo_make_space_mw_tm(const struct rte_hash *h,
 			}
 
 			/* Enqueue new node and keep prev node info */
-			alt_bkt = &(h->buckets[curr_bkt->signatures[i].alt
+			alt_bkt = &(h->buckets[curr_bkt->sig_alt[i]
 						    & h->bucket_bitmask]);
 			head->bkt = alt_bkt;
 			head->prev = tail;
-- 
2.7.4