[dpdk-dev] [PATCH] net/i40e: add additional prefetch instructions for bulk rx

[Ferruh Yigit]

On 7/14/2016 6:27 PM, Vladyslav Buslov wrote:
> Added prefetch of first packet payload cacheline in i40e_rx_scan_hw_ring
> Added prefetch of second mbuf cacheline in i40e_rx_alloc_bufs
> 
> Signed-off-by: Vladyslav Buslov <vladyslav.buslov at harmonicinc.com>
> ---
>  drivers/net/i40e/i40e_rxtx.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c
> index d3cfb98..e493fb4 100644
> --- a/drivers/net/i40e/i40e_rxtx.c
> +++ b/drivers/net/i40e/i40e_rxtx.c
> @@ -1003,6 +1003,7 @@ i40e_rx_scan_hw_ring(struct i40e_rx_queue *rxq)
>                 /* Translate descriptor info to mbuf parameters */
>                 for (j = 0; j < nb_dd; j++) {
>                         mb = rxep[j].mbuf;
> +                       rte_prefetch0(RTE_PTR_ADD(mb->buf_addr, RTE_PKTMBUF_HEADROOM));
>                         qword1 = rte_le_to_cpu_64(\
>                                 rxdp[j].wb.qword1.status_error_len);
>                         pkt_len = ((qword1 & I40E_RXD_QW1_LENGTH_PBUF_MASK) >>
> @@ -1086,9 +1087,11 @@ i40e_rx_alloc_bufs(struct i40e_rx_queue *rxq)
> 
>         rxdp = &rxq->rx_ring[alloc_idx];
>         for (i = 0; i < rxq->rx_free_thresh; i++) {
> -               if (likely(i < (rxq->rx_free_thresh - 1)))
> +               if (likely(i < (rxq->rx_free_thresh - 1))) {
>                         /* Prefetch next mbuf */
> -                       rte_prefetch0(rxep[i + 1].mbuf);
> +                       rte_prefetch0(&rxep[i + 1].mbuf->cacheline0);
> +                       rte_prefetch0(&rxep[i + 1].mbuf->cacheline1);
> +               }
> 
>                 mb = rxep[i].mbuf;
>                 rte_mbuf_refcnt_set(mb, 1);
> --
> 2.8.3
> 

i40e maintainers, can you please review the patch?

Thanks,
ferruh