Regards
_Sugesh


> -----Original Message-----
> From: Kavanagh, Mark B
> Sent: Friday, December 8, 2017 12:02 PM
> To: [email protected]; [email protected]
> Cc: Stokes, Ian <[email protected]>; Loftus, Ciara 
> <[email protected]>;
> [email protected]; Chandran, Sugesh
> <[email protected]>; Kavanagh, Mark B
> <[email protected]>
> Subject: [ovs-dev][RFC PATCH V4 8/9] netdev-dpdk: copy large packet to multi-
> seg. mbufs
> 
> From: Michael Qiu <[email protected]>
> 
> Currently, packets are only copied to a single segment in the function
> dpdk_do_tx_copy(). This could be an issue in the case of jumbo frames,
> particularly when multi-segment mbufs are involved.
> 
> This patch calculates the number of segments needed by a packet and copies the
> data to each segment.
> 
> Co-authored-by: Mark Kavanagh <[email protected]>
> 
> Signed-off-by: Michael Qiu <[email protected]>
> Signed-off-by: Mark Kavanagh <[email protected]>
> ---
>  lib/netdev-dpdk.c | 56
> +++++++++++++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 52 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c index 8a81690..f83bb9e
> 100644
> --- a/lib/netdev-dpdk.c
> +++ b/lib/netdev-dpdk.c
> @@ -1830,8 +1830,10 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid,
> struct dp_packet_batch *batch)  #endif
>      struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
>      struct rte_mbuf *pkts[PKT_ARRAY_SIZE];
> +    struct rte_mbuf *temp, *head = NULL;
>      uint32_t cnt = batch_cnt;
>      uint32_t dropped = 0;
> +    uint32_t i, j, nb_segs;
[Sugesh] This function become bit longer, can we split it ?
> 
>      if (dev->type != DPDK_DEV_VHOST) {
>          /* Check if QoS has been configured for this netdev. */ @@ -1844,9
> +1846,10 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, struct
> dp_packet_batch *batch)
> 
>      uint32_t txcnt = 0;
> 
> -    for (uint32_t i = 0; i < cnt; i++) {
> +    for (i = 0; i < cnt; i++) {
>          struct dp_packet *packet = batch->packets[i];
>          uint32_t size = dp_packet_size(packet);
> +        uint16_t max_data_len, data_len;
> 
>          if (OVS_UNLIKELY(size > dev->max_packet_len)) {
>              VLOG_WARN_RL(&rl, "Too big size %u max_packet_len %d", @@ -
> 1856,15 +1859,60 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, struct
> dp_packet_batch *batch)
>              continue;
>          }
> 
> -        pkts[txcnt] = rte_pktmbuf_alloc(dev->mp);
> +        temp = pkts[txcnt] = rte_pktmbuf_alloc(dev->mp);
>          if (OVS_UNLIKELY(!pkts[txcnt])) {
>              dropped += cnt - i;
>              break;
>          }
> 
> +        /* All new allocated mbuf's max data len is the same */
> +        max_data_len = temp->buf_len - temp->data_off;
> +
> +        /* Calculate # of output mbufs. */
> +        nb_segs = size / max_data_len;
> +        if (size % max_data_len) {
> +            nb_segs = nb_segs + 1;
> +        }
> +
> +        /* Allocate additional mbufs when multiple output mbufs required. */
> +        for (j = 1; j < nb_segs; j++) {
> +            temp->next = rte_pktmbuf_alloc(dev->mp);
[Sugesh] Does alloc_bulk would be better to use than multiple single allocation 
from the pool?

> +            if (!temp->next) {
> +                rte_pktmbuf_free(pkts[txcnt]);

> +                pkts[txcnt] = NULL;
> +                break;
> +            }
> +            temp = temp->next;
> +        }
>          /* We have to do a copy for now */
> -        memcpy(rte_pktmbuf_mtod(pkts[txcnt], void *),
> -               dp_packet_data(packet), size);
> +        rte_pktmbuf_pkt_len(pkts[txcnt]) = size;
> +        temp = pkts[txcnt];
> +
> +        data_len = size < max_data_len ? size: max_data_len;
> +        if (packet->source == DPBUF_DPDK) {
> +            head = &(packet->mbuf);
> +            while (temp && head && size > 0) {
> +                rte_memcpy(rte_pktmbuf_mtod(temp, void *),
> +                        dp_packet_data((struct dp_packet *)head), data_len);
> +                rte_pktmbuf_data_len(temp) = data_len;
> +                head = head->next;
> +                size = size - data_len;
> +                data_len =  size < max_data_len ? size: max_data_len;
> +                temp = temp->next;
> +            }
> +        } else {
> +            int offset = 0;
> +            while (temp && size > 0) {
> +                memcpy(rte_pktmbuf_mtod(temp, void *),
> +                    dp_packet_at(packet, offset, data_len), data_len);
> +                rte_pktmbuf_data_len(temp) = data_len;
> +                temp = temp->next;
> +                size = size - data_len;
> +                offset += data_len;
> +                data_len = size < max_data_len ? size: max_data_len;
> +            }
> +        }
> +
>          dp_packet_set_size((struct dp_packet *)pkts[txcnt], size);
>          pkts[txcnt]->nb_segs = packet->mbuf.nb_segs;
>          pkts[txcnt]->ol_flags = packet->mbuf.ol_flags;
> --
> 1.9.3

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