Read the four tbl24 entries before resolving any of them, as the SSE and NEON versions do. On an in-order core the cache misses then overlap instead of being served one after another.
Signed-off-by: Sun Yuechi <[email protected]> --- lib/lpm/rte_lpm_scalar.h | 40 +++++++++++++++++++++++++++++----------- 1 file changed, 29 insertions(+), 11 deletions(-) diff --git a/lib/lpm/rte_lpm_scalar.h b/lib/lpm/rte_lpm_scalar.h index df4f83fa48..9ad25838fd 100644 --- a/lib/lpm/rte_lpm_scalar.h +++ b/lib/lpm/rte_lpm_scalar.h @@ -13,22 +13,40 @@ extern "C" { #endif +static inline uint32_t +__rte_lpm_lookupx4_hop(const struct rte_lpm *lpm, uint32_t tbl_entry, + uint32_t ip, uint32_t defv) +{ + if (unlikely((tbl_entry & RTE_LPM_VALID_EXT_ENTRY_BITMASK) == + RTE_LPM_VALID_EXT_ENTRY_BITMASK)) { + const uint32_t *tbl8 = (const uint32_t *)lpm->tbl8; + + tbl_entry = tbl8[(uint8_t)ip + (tbl_entry & 0x00FFFFFF) * + RTE_LPM_TBL8_GROUP_NUM_ENTRIES]; + } + + return (tbl_entry & RTE_LPM_LOOKUP_SUCCESS) ? + (tbl_entry & 0x00FFFFFF) : defv; +} + static inline void rte_lpm_lookupx4(const struct rte_lpm *lpm, xmm_t ip, uint32_t hop[4], uint32_t defv) { rte_xmm_t xip = { .x = ip }; - uint32_t nh; - int ret; - - ret = rte_lpm_lookup(lpm, xip.u32[0], &nh); - hop[0] = (ret == 0) ? nh : defv; - ret = rte_lpm_lookup(lpm, xip.u32[1], &nh); - hop[1] = (ret == 0) ? nh : defv; - ret = rte_lpm_lookup(lpm, xip.u32[2], &nh); - hop[2] = (ret == 0) ? nh : defv; - ret = rte_lpm_lookup(lpm, xip.u32[3], &nh); - hop[3] = (ret == 0) ? nh : defv; + const uint32_t *tbl24 = (const uint32_t *)lpm->tbl24; + uint32_t tbl0, tbl1, tbl2, tbl3; + + /* Issue the four tbl24 loads before any entry is examined. */ + tbl0 = tbl24[xip.u32[0] >> 8]; + tbl1 = tbl24[xip.u32[1] >> 8]; + tbl2 = tbl24[xip.u32[2] >> 8]; + tbl3 = tbl24[xip.u32[3] >> 8]; + + hop[0] = __rte_lpm_lookupx4_hop(lpm, tbl0, xip.u32[0], defv); + hop[1] = __rte_lpm_lookupx4_hop(lpm, tbl1, xip.u32[1], defv); + hop[2] = __rte_lpm_lookupx4_hop(lpm, tbl2, xip.u32[2], defv); + hop[3] = __rte_lpm_lookupx4_hop(lpm, tbl3, xip.u32[3], defv); } #ifdef __cplusplus -- 2.56.0
