From 3fb1ea032bd6ff8317af5dac9af901f1f324cab4 Mon Sep 17 00:00:00 2001 From: Yangchao Zhou Date: Tue, 22 Aug 2017 20:02:35 +0800 Subject: [PATCH] hash: optimize Toeplitz RSS computation Use rte_bsf32 and fast bit unset operation to optimize the softrss computation. The following measurements shows improvement over the default softrss computation function. tuple lens old(cycles) new(cycles) 3 1225 337 9 3743 992 Signed-off-by: Yangchao Zhou Reviewed-by: Vladimir Medvedkin --- lib/librte_hash/rte_thash.h | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-) diff --git a/lib/librte_hash/rte_thash.h b/lib/librte_hash/rte_thash.h index 2fffd61dc1..4fa5e07a5e 100644 --- a/lib/librte_hash/rte_thash.h +++ b/lib/librte_hash/rte_thash.h @@ -207,15 +207,14 @@ static inline uint32_t rte_softrss(uint32_t *input_tuple, uint32_t input_len, const uint8_t *rss_key) { - uint32_t i, j, ret = 0; + uint32_t i, j, map, ret = 0; for (j = 0; j < input_len; j++) { - for (i = 0; i < 32; i++) { - if (input_tuple[j] & (1 << (31 - i))) { - ret ^= rte_cpu_to_be_32(((const uint32_t *)rss_key)[j]) << i | + for (map = input_tuple[j]; map; map &= (map - 1)) { + i = rte_bsf32(map); + ret ^= rte_cpu_to_be_32(((const uint32_t *)rss_key)[j]) << (31 - i) | (uint32_t)((uint64_t)(rte_cpu_to_be_32(((const uint32_t *)rss_key)[j + 1])) >> - (32 - i)); - } + (i + 1)); } } return ret; @@ -238,14 +237,13 @@ static inline uint32_t rte_softrss_be(uint32_t *input_tuple, uint32_t input_len, const uint8_t *rss_key) { - uint32_t i, j, ret = 0; + uint32_t i, j, map, ret = 0; for (j = 0; j < input_len; j++) { - for (i = 0; i < 32; i++) { - if (input_tuple[j] & (1 << (31 - i))) { - ret ^= ((const uint32_t *)rss_key)[j] << i | - (uint32_t)((uint64_t)(((const uint32_t *)rss_key)[j + 1]) >> (32 - i)); - } + for (map = input_tuple[j]; map; map &= (map - 1)) { + i = rte_bsf32(map); + ret ^= ((const uint32_t *)rss_key)[j] << (31 - i) | + (uint32_t)((uint64_t)(((const uint32_t *)rss_key)[j + 1]) >> (i + 1)); } } return ret;