[dpdk-dev] [PATCH 2/3] hash: run-time function selection

[Elza Mathew]

Compile-time function selection can potentially lead to
lower performance on generic builds done by distros.
Replaced compile time flag checks with run-time function
selection.

Signed-off-by: Elza Mathew <elza.mathew at intel.com>
---
 lib/librte_hash/rte_fbk_hash.c | 11 ++++++++++-
 lib/librte_hash/rte_fbk_hash.h |  8 --------
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/lib/librte_hash/rte_fbk_hash.c b/lib/librte_hash/rte_fbk_hash.c
index 55c9f35..7c4e194 100644
--- a/lib/librte_hash/rte_fbk_hash.c
+++ b/lib/librte_hash/rte_fbk_hash.c
@@ -114,6 +114,7 @@ struct rte_fbk_hash_table *
 			sizeof(*ht) + (sizeof(ht->t[0]) * params->entries);
 	uint32_t i;
 	struct rte_fbk_hash_list *fbk_hash_list;
+	rte_fbk_hash_fn default_hash_func = (rte_fbk_hash_fn)rte_jhash_1word;
 
 	fbk_hash_list = RTE_TAILQ_CAST(rte_fbk_hash_tailq.head,
 				       rte_fbk_hash_list);
@@ -161,6 +162,14 @@ struct rte_fbk_hash_table *
 		goto exit;
 	}
 
+	/* Default hash function */
+#if defined(RTE_ARCH_X86)
+	default_hash_func = (rte_fbk_hash_fn)rte_hash_crc_4byte;
+#elif defined(RTE_ARCH_ARM64)
+	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_CRC32))
+		default_hash_func = (rte_fbk_hash_fn)rte_hash_crc_4byte;
+#endif
+
 	/* Set up hash table context. */
 	snprintf(ht->name, sizeof(ht->name), "%s", params->name);
 	ht->entries = params->entries;
@@ -177,7 +186,7 @@ struct rte_fbk_hash_table *
 		ht->init_val = params->init_val;
 	}
 	else {
-		ht->hash_func = RTE_FBK_HASH_FUNC_DEFAULT;
+		ht->hash_func = default_hash_func;
 		ht->init_val = RTE_FBK_HASH_INIT_VAL_DEFAULT;
 	}
 
diff --git a/lib/librte_hash/rte_fbk_hash.h b/lib/librte_hash/rte_fbk_hash.h
index c39c097..1b1b7df 100644
--- a/lib/librte_hash/rte_fbk_hash.h
+++ b/lib/librte_hash/rte_fbk_hash.h
@@ -54,16 +54,8 @@
 
 #include <string.h>
 
-#ifndef RTE_FBK_HASH_FUNC_DEFAULT
-#if defined(RTE_ARCH_X86) || defined(RTE_MACHINE_CPUFLAG_CRC32)
 #include <rte_hash_crc.h>
-/** Default four-byte key hash function if none is specified. */
-#define RTE_FBK_HASH_FUNC_DEFAULT		rte_hash_crc_4byte
-#else
 #include <rte_jhash.h>
-#define RTE_FBK_HASH_FUNC_DEFAULT		rte_jhash_1word
-#endif
-#endif
 
 #ifndef RTE_FBK_HASH_INIT_VAL_DEFAULT
 /** Initialising value used when calculating hash. */
-- 
1.9.1