[dpdk-dev] [PATCH v2] 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.w...@arm.com>
Reviewed-by: Gavin Hu <gavin...@arm.com>
---
v2:
* Use 'rte_vect.h' instead of 'arm_neon.h'.
* Moved down variable declaration to avoid extra #ifdef.

 lib/librte_hash/rte_cuckoo_hash.c | 29 ++++++++++++++++++++++++++++-
 lib/librte_hash/rte_cuckoo_hash.h |  1 +
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/lib/librte_hash/rte_cuckoo_hash.c 
b/lib/librte_hash/rte_cuckoo_hash.c
index c01489ba5..0dddce226 100644
--- a/lib/librte_hash/rte_cuckoo_hash.c
+++ b/lib/librte_hash/rte_cuckoo_hash.c
@@ -26,6 +26,7 @@
 #include <rte_spinlock.h>
 #include <rte_ring.h>
 #include <rte_compat.h>
+#include <rte_vect.h>
 
 #include "rte_hash.h"
 #include "rte_cuckoo_hash.h"
@@ -407,6 +408,10 @@ 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;
 
@@ -1581,7 +1586,7 @@ compare_signatures(uint32_t *prim_hash_matches, uint32_t 
*sec_hash_matches,
 
        /* 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 +1599,28 @@ 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: {
+               uint16x8_t vmat, vsig, x;
+               uint64x2_t x64;
+               int16x8_t shift = {-15, -13, -11, -9, -7, -5, -3, -1};
+
+               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