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net/mlx5: remove inefficient prefetching

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Prefetching completion queue entries is inefficient because too few CPU
cycles are spent before their use, which results into cache misses anyway.

Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
This commit is contained in:
Nélio Laranjeiro 2016-11-24 17:03:36 +01:00 committed by Ferruh Yigit
parent eef822dd73
commit 0f3f22298e
1 changed files with 0 additions and 21 deletions
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21
drivers/net/mlx5/mlx5_rxtx.c
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@ -345,23 +345,6 @@ mlx5_tx_dbrec(struct txq *txq)
txq->bf_offset ^= (1 << txq->bf_buf_size);
}
/**
* Prefetch a CQE.
*
* @param txq
* Pointer to TX queue structure.
* @param cqe_ci
* CQE consumer index.
*/
static inline void
tx_prefetch_cqe(struct txq *txq, uint16_t ci)
{
volatile struct mlx5_cqe *cqe;
cqe = &(*txq->cqes)[ci & ((1 << txq->cqe_n) - 1)];
rte_prefetch0(cqe);
}
/**
* DPDK callback for TX.
*
@ -393,8 +376,6 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
if (unlikely(!pkts_n))
return 0;
/* Prefetch first packet cacheline. */
tx_prefetch_cqe(txq, txq->cq_ci);
tx_prefetch_cqe(txq, txq->cq_ci + 1);
rte_prefetch0(*pkts);
/* Start processing. */
txq_complete(txq);
@ -732,7 +713,6 @@ mlx5_tx_burst_mpw(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
if (unlikely(!pkts_n))
return 0;
/* Prefetch first packet cacheline. */
tx_prefetch_cqe(txq, txq->cq_ci);
rte_prefetch0(tx_mlx5_wqe(txq, txq->wqe_ci));
rte_prefetch0(tx_mlx5_wqe(txq, txq->wqe_ci + 1));
/* Start processing. */
@ -937,7 +917,6 @@ mlx5_tx_burst_mpw_inline(void *dpdk_txq, struct rte_mbuf **pkts,
if (unlikely(!pkts_n))
return 0;
/* Prefetch first packet cacheline. */
tx_prefetch_cqe(txq, txq->cq_ci);
rte_prefetch0(tx_mlx5_wqe(txq, txq->wqe_ci));
rte_prefetch0(tx_mlx5_wqe(txq, txq->wqe_ci + 1));
/* Start processing. */