[dpdk-dev] [PATCH v2 1/4] hash: reorder hash structure

[Pablo de Lara]

In order to optimize lookup performance, hash structure
is reordered, so all fields used for lookup will be
in the first cache line.

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch at intel.com>
---
 lib/librte_hash/rte_cuckoo_hash.h | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/lib/librte_hash/rte_cuckoo_hash.h b/lib/librte_hash/rte_cuckoo_hash.h
index e290dab..701531a 100644
--- a/lib/librte_hash/rte_cuckoo_hash.h
+++ b/lib/librte_hash/rte_cuckoo_hash.h
@@ -182,9 +182,7 @@ struct rte_hash_bucket {
 
 /** A hash table structure. */
 struct rte_hash {
-	char name[RTE_HASH_NAMESIZE];   /**< Name of the hash. */
-	uint32_t entries;               /**< Total table entries. */
-	uint32_t num_buckets;           /**< Number of buckets in table. */
+	/* first cache line - fields used in lookup */
 	uint32_t key_len;               /**< Length of hash key. */
 	rte_hash_function hash_func;    /**< Function used to calculate hash. */
 	uint32_t hash_func_init_val;    /**< Init value used by hash_func. */
@@ -196,12 +194,13 @@ struct rte_hash {
 						from hash signature. */
 	uint32_t key_entry_size;         /**< Size of each key entry. */
 
-	struct rte_ring *free_slots;    /**< Ring that stores all indexes
-						of the free slots in the key table */
 	void *key_store;                /**< Table storing all keys and data */
 	struct rte_hash_bucket *buckets;	/**< Table with buckets storing all the
 							hash values and key indexes
 							to the key table*/
+
+	struct rte_ring *free_slots;    /**< Ring that stores all indexes
+						of the free slots in the key table */
 	uint8_t hw_trans_mem_support;	/**< Hardware transactional
 							memory support */
 	struct lcore_cache *local_free_slots;
@@ -209,6 +208,9 @@ struct rte_hash {
 	enum add_key_case add_key; /**< Multi-writer hash add behavior */
 
 	rte_spinlock_t *multiwriter_lock; /**< Multi-writer spinlock for w/o TM */
+	char name[RTE_HASH_NAMESIZE];   /**< Name of the hash. */
+	uint32_t entries;               /**< Total table entries. */
+	uint32_t num_buckets;           /**< Number of buckets in table. */
 } __rte_cache_aligned;
 
 struct queue_node {
-- 
2.7.4