[PATCH v2] efd: lookup with RISC-V vector extension

[P1erreCashon]

Implement EFD lookup internal function for RISC-V architecture
using RISC-V Vector Extension instruction set

Performance results (EFD perf autotest)
These performance results are the average of five test runs.
Results (in CPU cycles/operation):

Before optimization:
Keysize           Add               Lookup            Lookup_bulk       Delete
4                 136.0            5.6               5.0               25.6
8                 149.4            6.0               6.0               31.4
16                156.8           8.0               7.0               36.8
32                179.2           13.0             14.0              45.4
48                205.8           13.0             15.0              45.6
64                214.4           16.0            18.4               46.6
9                 152.8             6.2              6.0               30.0
13                160.6            7.2               7.0               35.0
37                191.2            12.0             13.0              44.2
40                195.0            12.0             13.6              43.2

After optimization:
Keysize           Add               Lookup            Lookup_bulk       Delete
4                 131.6             5.0               5.0               26.6
8                 143.6             6.0               6.2               33.0
16                153.2            7.0               7.0               35.8
32                173.6            14.0             14.0             45.0
48                201.6            12.6             14.0             46.2
64                211.4            15.0             16.0             46.8
9                 146.6             6.0               6.0              30.6
13                154.8            7.0               7.0               35.0
37                189.2            11.0             12.2             45.4
40                191.8            11.0             12.4             43.8

This patch is co-developed with Gong Xiaofei.

Signed-off-by: gong-flying <gongxiaofei24 at iscas.ac.cn>
Signed-off-by: P1erreCashon <2022302111412 at whu.edu.cn>
---
 lib/efd/rte_efd.c     | 20 +++++++++++++-
 lib/efd/rte_efd_rvv.h | 64 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 83 insertions(+), 1 deletion(-)
 create mode 100644 lib/efd/rte_efd_rvv.h

diff --git a/lib/efd/rte_efd.c b/lib/efd/rte_efd.c
index 4dfc0ec9a4..053ee4f232 100644
--- a/lib/efd/rte_efd.c
+++ b/lib/efd/rte_efd.c
@@ -29,6 +29,9 @@
 #include "rte_efd_x86.h"
 #elif defined(RTE_ARCH_ARM64)
 #include "rte_efd_arm64.h"
+#elif defined(RTE_ARCH_RISCV) && defined(RTE_RISCV_FEATURE_V)
+#include <riscv_vector.h>
+#include "rte_efd_rvv.h"
 #endif
 
 RTE_LOG_REGISTER_DEFAULT(efd_logtype, INFO);
@@ -85,7 +88,8 @@ enum efd_lookup_internal_function {
 	EFD_LOOKUP_SCALAR = 0,
 	EFD_LOOKUP_AVX2,
 	EFD_LOOKUP_NEON,
-	EFD_LOOKUP_NUM
+	EFD_LOOKUP_NUM,
+	EFD_LOOKUP_RVV
 };
 
 TAILQ_HEAD(rte_efd_list, rte_tailq_entry);
@@ -675,6 +679,12 @@ rte_efd_create(const char *name, uint32_t max_num_rules, uint32_t key_len,
 			rte_vect_get_max_simd_bitwidth() >= RTE_VECT_SIMD_128)
 		table->lookup_fn = EFD_LOOKUP_NEON;
 	else
+#endif
+#if defined(RTE_ARCH_RISCV) && defined(RTE_RISCV_FEATURE_V)
+	if (RTE_EFD_VALUE_NUM_BITS > 16 &&
+		__riscv_vsetvl_e32m1(4) == 4)
+		table->lookup_fn = EFD_LOOKUP_RVV;
+	else
 #endif
 		table->lookup_fn = EFD_LOOKUP_SCALAR;
 
@@ -1305,6 +1315,14 @@ efd_lookup_internal(const struct efd_online_group_entry * const group,
 					hash_val_a,
 					hash_val_b);
 		break;
+#endif
+#if defined(RTE_ARCH_RISCV) && defined(RTE_RISCV_FEATURE_V)
+	case EFD_LOOKUP_RVV:
+		return efd_lookup_internal_rvv(group->hash_idx,
+				group->lookup_table,
+				hash_val_a,
+				hash_val_b);
+		break;
 #endif
 	case EFD_LOOKUP_SCALAR:
 	/* Fall-through */
diff --git a/lib/efd/rte_efd_rvv.h b/lib/efd/rte_efd_rvv.h
new file mode 100644
index 0000000000..7facefd4ae
--- /dev/null
+++ b/lib/efd/rte_efd_rvv.h
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2026 Institute of Software Chinese Academy of Sciences (ISCAS).
+ */
+
+#ifndef __RTE_EFD_RISCV_H__
+#define __RTE_EFD_RISCV_H__
+
+#include <riscv_vector.h>
+
+static inline efd_value_t
+efd_lookup_internal_rvv(const efd_hashfunc_t *group_hash_idx,
+				const efd_lookuptbl_t *group_lookup_table,
+				const uint32_t hash_val_a, const uint32_t hash_val_b)
+{
+		efd_value_t value = 0;
+		const uint32_t N = RTE_EFD_VALUE_NUM_BITS;
+		size_t vl = 4;
+		vuint32m1_t vhash_val_a = __riscv_vmv_v_x_u32m1(hash_val_a, vl);
+		vuint32m1_t vhash_val_b = __riscv_vmv_v_x_u32m1(hash_val_b, vl);
+		vuint32m1_t vshift = __riscv_vid_v_u32m1(vl);
+		vuint32m1_t vmask = __riscv_vmv_v_x_u32m1(0x1, vl);
+		vuint32m1_t vincr = __riscv_vmv_v_x_u32m1(4, vl);
+		for (unsigned int i = 0; i < N; i += vl) {
+			vuint16mf2_t vhash_idx16 =
+				__riscv_vle16_v_u16mf2(
+					(const uint16_t *)&group_hash_idx[i], vl);
+
+			vuint32m1_t vhash_idx =
+				__riscv_vwcvtu_x_x_v_u32m1(vhash_idx16, vl);
+
+			vuint16mf2_t vlookup16 =
+				__riscv_vle16_v_u16mf2(
+					(const uint16_t *)&group_lookup_table[i], vl);
+
+			vuint32m1_t vlookup =
+				__riscv_vwcvtu_x_x_v_u32m1(vlookup16, vl);
+
+			vuint32m1_t vhash =
+				__riscv_vmadd_vv_u32m1(vhash_idx, vhash_val_b, vhash_val_a, vl);
+
+			vuint32m1_t vbucket =
+				__riscv_vsrl_vx_u32m1(vhash, EFD_LOOKUPTBL_SHIFT, vl);
+
+			vuint32m1_t vresult =
+				__riscv_vsrl_vv_u32m1(vlookup, vbucket, vl);
+
+			vresult = __riscv_vand_vv_u32m1(vresult, vmask, vl);
+
+			vresult = __riscv_vsll_vv_u32m1(vresult, vshift, vl);
+
+			vuint32m1_t vzero = __riscv_vmv_v_x_u32m1(0, vl);
+
+			vuint32m1_t vsum =
+				__riscv_vredsum_vs_u32m1_u32m1(vresult, vzero, vl);
+
+			value |= __riscv_vmv_x_s_u32m1_u32(vsum);
+
+			vshift = __riscv_vadd_vv_u32m1(vshift, vincr, vl);
+		}
+
+		return value;
+}
+
+#endif /* __RTE_EFD_RISCV_H__ */
-- 
2.43.0