From mboxrd@z Thu Jan  1 00:00:00 1970
From: Zoltan Kiss <zoltan.kiss@linaro.org>
Subject: Re: [PATCH] ixgbe: prefetch packet headers in vector PMD
 receive function
Date: Mon, 7 Sep 2015 13:25:54 +0100
Message-ID: <55ED8252.1020900@linaro.org>
References: <1441135036-7491-1-git-send-email-zoltan.kiss@linaro.org>
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Hi,

I just realized I've missed the "[PATCH]" tag from the subject. Did 
anyone had time to review this?

Regards,

Zoltan

On 01/09/15 20:17, Zoltan Kiss wrote:
> The lack of this prefetch causes a significant performance drop in
> OVS-DPDK: 13.3 Mpps instead of 14 when forwarding 64 byte packets. Even
> though OVS prefetches the next packet's header before it starts processing
> the current one, it doesn't get there fast enough. This aligns with the
> behaviour of other receive functions.
>
> Signed-off-by: Zoltan Kiss <zoltan.kiss@linaro.org>
> ---
> diff --git a/drivers/net/ixgbe/ixgbe_rxtx_vec.c b/drivers/net/ixgbe/ixgbe_rxtx_vec.c
> index cf25a53..51299fa 100644
> --- a/drivers/net/ixgbe/ixgbe_rxtx_vec.c
> +++ b/drivers/net/ixgbe/ixgbe_rxtx_vec.c
> @@ -502,6 +502,15 @@ _recv_raw_pkts_vec(struct ixgbe_rx_queue *rxq, struct rte_mbuf **rx_pkts,
>                  _mm_storeu_si128((void *)&rx_pkts[pos]->rx_descriptor_fields1,
>                                  pkt_mb1);
>
> +               rte_packet_prefetch((char*)(rx_pkts[pos]->buf_addr) +
> +                                   RTE_PKTMBUF_HEADROOM);
> +               rte_packet_prefetch((char*)(rx_pkts[pos + 1]->buf_addr) +
> +                                   RTE_PKTMBUF_HEADROOM);
> +               rte_packet_prefetch((char*)(rx_pkts[pos + 2]->buf_addr) +
> +                                   RTE_PKTMBUF_HEADROOM);
> +               rte_packet_prefetch((char*)(rx_pkts[pos + 3]->buf_addr) +
> +                                   RTE_PKTMBUF_HEADROOM);
> +
>                  /* C.4 calc avaialbe number of desc */
>                  var = __builtin_popcountll(_mm_cvtsi128_si64(staterr));
>                  nb_pkts_recd += var;
>