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hash: optimize Toeplitz RSS computation

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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 <zhouyates@gmail.com>
Reviewed-by: Vladimir Medvedkin <medvedkinv@gmail.com>
This commit is contained in:
Yangchao Zhou 2017-08-22 20:02:35 +08:00 committed by Thomas Monjalon
parent 98b8ec7060
commit 3fb1ea032b
1 changed files with 10 additions and 12 deletions
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22
lib/librte_hash/rte_thash.h
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@ -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;