[dpdk-dev] [PATCH v1] hash: optimize signature compare by using neon intrinsic

[Ruifeng Wang]

Implemented signature compare function based on neon intrinsic.
Hash bulk lookup had 3% - 6% performance gain after optimization.

Signed-off-by: Ruifeng Wang <ruifeng.wang at arm.com>
---
 lib/librte_hash/rte_cuckoo_hash.c | 32 ++++++++++++++++++++++++++++++-
 lib/librte_hash/rte_cuckoo_hash.h |  1 +
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
index c01489ba5..5745a254f 100644
--- a/lib/librte_hash/rte_cuckoo_hash.c
+++ b/lib/librte_hash/rte_cuckoo_hash.c
@@ -26,6 +26,9 @@
 #include <rte_spinlock.h>
 #include <rte_ring.h>
 #include <rte_compat.h>
+#if defined(RTE_ARCH_ARM64)
+#include <arm_neon.h>
+#endif
 
 #include "rte_hash.h"
 #include "rte_cuckoo_hash.h"
@@ -407,6 +410,10 @@ rte_hash_create(const struct rte_hash_parameters *params)
 	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_SSE2))
 		h->sig_cmp_fn = RTE_HASH_COMPARE_SSE;
 	else
+#elif defined(RTE_ARCH_ARM64)
+	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_NEON))
+		h->sig_cmp_fn = RTE_HASH_COMPARE_NEON;
+	else
 #endif
 		h->sig_cmp_fn = RTE_HASH_COMPARE_SCALAR;
 
@@ -1578,10 +1585,15 @@ compare_signatures(uint32_t *prim_hash_matches, uint32_t *sec_hash_matches,
 			enum rte_hash_sig_compare_function sig_cmp_fn)
 {
 	unsigned int i;
+#ifdef RTE_MACHINE_CPUFLAG_NEON
+	uint16x8_t vmat, vsig, x;
+	uint64x2_t x64;
+	int16x8_t shift = {-15, -13, -11, -9, -7, -5, -3, -1};
+#endif
 
 	/* For match mask the first bit of every two bits indicates the match */
 	switch (sig_cmp_fn) {
-#ifdef RTE_MACHINE_CPUFLAG_SSE2
+#if defined(RTE_MACHINE_CPUFLAG_SSE2)
 	case RTE_HASH_COMPARE_SSE:
 		/* Compare all signatures in the bucket */
 		*prim_hash_matches = _mm_movemask_epi8(_mm_cmpeq_epi16(
@@ -1594,6 +1606,24 @@ compare_signatures(uint32_t *prim_hash_matches, uint32_t *sec_hash_matches,
 					(__m128i const *)sec_bkt->sig_current),
 				_mm_set1_epi16(sig)));
 		break;
+#elif defined(RTE_MACHINE_CPUFLAG_NEON)
+	case RTE_HASH_COMPARE_NEON:
+		vsig = vld1q_dup_u16((uint16_t const *)&sig);
+		/* Compare all signatures in the primary bucket */
+		vmat = vceqq_u16(vsig,
+			vld1q_u16((uint16_t const *)prim_bkt->sig_current));
+		x = vshlq_u16(vandq_u16(vmat, vdupq_n_u16(0x8000)), shift);
+		x64 = vpaddlq_u32(vpaddlq_u16(x));
+		*prim_hash_matches = (uint32_t)(vgetq_lane_u64(x64, 0) +
+			vgetq_lane_u64(x64, 1));
+		/* Compare all signatures in the secondary bucket */
+		vmat = vceqq_u16(vsig,
+			vld1q_u16((uint16_t const *)sec_bkt->sig_current));
+		x = vshlq_u16(vandq_u16(vmat, vdupq_n_u16(0x8000)), shift);
+		x64 = vpaddlq_u32(vpaddlq_u16(x));
+		*sec_hash_matches = (uint32_t)(vgetq_lane_u64(x64, 0) +
+			vgetq_lane_u64(x64, 1));
+		break;
 #endif
 	default:
 		for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
diff --git a/lib/librte_hash/rte_cuckoo_hash.h b/lib/librte_hash/rte_cuckoo_hash.h
index eacdaa8d4..0548c97f0 100644
--- a/lib/librte_hash/rte_cuckoo_hash.h
+++ b/lib/librte_hash/rte_cuckoo_hash.h
@@ -141,6 +141,7 @@ struct rte_hash_key {
 enum rte_hash_sig_compare_function {
 	RTE_HASH_COMPARE_SCALAR = 0,
 	RTE_HASH_COMPARE_SSE,
+	RTE_HASH_COMPARE_NEON,
 	RTE_HASH_COMPARE_NUM
 };
 
-- 
2.17.1