[dpdk-dev] [PATCH v3 1/7] mlx5: prefetch next TX mbuf header and data
Adrien Mazarguil
adrien.mazarguil at 6wind.com
Thu Mar 3 15:27:11 CET 2016
From: Nelio Laranjeiro <nelio.laranjeiro at 6wind.com>
This change improves performance noticeably.
Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro at 6wind.com>
---
drivers/net/mlx5/mlx5_rxtx.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
index 7585570..bee5ce2 100644
--- a/drivers/net/mlx5/mlx5_rxtx.c
+++ b/drivers/net/mlx5/mlx5_rxtx.c
@@ -443,8 +443,11 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
unsigned int i;
unsigned int max;
int err;
+ struct rte_mbuf *buf = pkts[0];
assert(elts_comp_cd != 0);
+ /* Prefetch first packet cacheline. */
+ rte_prefetch0(buf);
txq_complete(txq);
max = (elts_n - (elts_head - txq->elts_tail));
if (max > elts_n)
@@ -458,7 +461,7 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
if (max > pkts_n)
max = pkts_n;
for (i = 0; (i != max); ++i) {
- struct rte_mbuf *buf = pkts[i];
+ struct rte_mbuf *buf_next = pkts[i + 1];
unsigned int elts_head_next =
(((elts_head + 1) == elts_n) ? 0 : elts_head + 1);
struct txq_elt *elt_next = &(*txq->elts)[elts_head_next];
@@ -481,6 +484,8 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
tmp = next;
} while (tmp != NULL);
}
+ if (i + 1 < max)
+ rte_prefetch0(buf_next);
/* Request TX completion. */
if (unlikely(--elts_comp_cd == 0)) {
elts_comp_cd = txq->elts_comp_cd_init;
@@ -502,6 +507,7 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
uintptr_t addr;
uint32_t length;
uint32_t lkey;
+ uintptr_t buf_next_addr;
/* Retrieve buffer information. */
addr = rte_pktmbuf_mtod(buf, uintptr_t);
@@ -522,6 +528,13 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
rte_prefetch0((volatile void *)
(uintptr_t)addr);
RTE_MBUF_PREFETCH_TO_FREE(elt_next->buf);
+ /* Prefetch next buffer data. */
+ if (i + 1 < max) {
+ buf_next_addr =
+ rte_pktmbuf_mtod(buf_next, uintptr_t);
+ rte_prefetch0((volatile void *)
+ (uintptr_t)buf_next_addr);
+ }
/* Put packet into send queue. */
#if MLX5_PMD_MAX_INLINE > 0
if (length <= txq->max_inline)
@@ -571,6 +584,7 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
#endif /* MLX5_PMD_SGE_WR_N > 1 */
}
elts_head = elts_head_next;
+ buf = buf_next;
#ifdef MLX5_PMD_SOFT_COUNTERS
/* Increment sent bytes counter. */
txq->stats.obytes += sent_size;
--
2.1.4
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