Initially, SSE4.2 support is detected via CPUID instruction.
Added rte_hash_crc_set_alg() function to detect and set CRC32
implementation if necessary. SSE4.2 is allowed by default. If it's
not available, fall back to sw implementation.
Signed-off-by: Yerden Zhumabekov <e_zhumabekov at sts.kz>
---
lib/librte_hash/rte_hash_crc.h | 60 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 58 insertions(+), 2 deletions(-)
diff --git a/lib/librte_hash/rte_hash_crc.h b/lib/librte_hash/rte_hash_crc.h
index 74e2d92..178b162 100644
--- a/lib/librte_hash/rte_hash_crc.h
+++ b/lib/librte_hash/rte_hash_crc.h
@@ -45,7 +45,11 @@ extern "C" {
#endif
#include <stdint.h>
+#ifdef RTE_MACHINE_CPUFLAG_SSE4_2
#include <nmmintrin.h>
+#endif
+#include <rte_cpuflags.h>
+#include <rte_branch_prediction.h>
/* Lookup table for software implementation of CRC32C */
static const uint32_t crc32c_table[256] = {
@@ -152,8 +156,42 @@ crc32c_2words(uint64_t data, uint32_t init_val)
return init_val;
}
+enum crc32_alg_t {
+ CRC32_SW = 0,
+ CRC32_SSE42,
+ CRC32_AUTODETECT
+};
+
+/* Default algorithm is left for autodetection,
+ * it is detected on first run of hash function
+ */
+static enum crc32_alg_t crc32_alg = CRC32_AUTODETECT;
+
+/**
+ * Allow or disallow use of SSE4.2 instrinsics for CRC32 hash
+ * hash calculation.
+ *
+ * @param flag
+ * unsigned integer flag
+ * - (CRC32_SW) Don't use SSE4.2 intrinsics
+ * - (CRC32_SSE42) Use SSE4.2 intrinsics if available, set by default
+ */
+static inline void
+rte_hash_crc_set_alg(enum crc32_alg_t alg)
+{
+ int sse42_supp = rte_cpu_get_flag_enabled(RTE_CPUFLAG_SSE4_2);
+ enum crc32_alg_t alg_supp = sse42_supp ? CRC32_SSE42 : CRC32_SW;
+
+ if (alg == CRC32_SSE42)
+ crc32_alg = alg_supp;
+ else
+ crc32_alg = CRC32_SW;
+}
+
/**
* Use single crc32 instruction to perform a hash on a 4 byte value.
+ * Fall back to software crc32 implementation in case SSE4.2 is
+ * not supported
*
* @param data
* Data to perform hash on.
@@ -165,11 +203,21 @@ crc32c_2words(uint64_t data, uint32_t init_val)
static inline uint32_t
rte_hash_crc_4byte(uint32_t data, uint32_t init_val)
{
- return _mm_crc32_u32(init_val, data);
+ if (unlikely(crc32_alg == CRC32_AUTODETECT))
+ rte_hash_crc_set_alg(CRC32_SSE42);
+
+#ifdef RTE_MACHINE_CPUFLAG_SSE4_2
+ if (likely(crc32_alg == CRC32_SSE42))
+ return _mm_crc32_u32(init_val, data);
+#endif
+
+ return crc32c_1word(data, init_val);
}
/**
* Use single crc32 instruction to perform a hash on a 8 byte value.
+ * Fall back to software crc32 implementation in case SSE4.2 is
+ * not supported
*
* @param data
* Data to perform hash on.
@@ -181,7 +229,15 @@ rte_hash_crc_4byte(uint32_t data, uint32_t init_val)
static inline uint32_t
rte_hash_crc_8byte(uint64_t data, uint32_t init_val)
{
- return _mm_crc32_u64(init_val, data);
+ if (unlikely(crc32_alg == CRC32_AUTODETECT))
+ rte_hash_crc_set_alg(CRC32_SSE42);
+
+#ifdef RTE_MACHINE_CPUFLAG_SSE4_2
+ if (likely(crc32_alg == CRC32_SSE42))
+ return _mm_crc32_u64(init_val, data);
+#endif
+
+ return crc32c_2words(data, init_val);
}
/**
--
1.7.9.5
