Re: [dpdk-dev] [PATCH v2] net/bnxt: fix cp ring size calculation

[Ajit Khaparde <ajit.khaparde@broadcom.com>]

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On Fri, Jan 29, 2021 at 10:07 AM Lance Richardson
<lance.richardson@broadcom.com> wrote:
>
> The size of the receive completion ring should be recalculated
> when MTU is increased to a size that requires scattered receive
> or when LRO is enabled. Move logic for this calculation from
> the ring configuration path to the device start path.
>    - Made size calculation dependent only on scattered_rx
>      status.
>    - Moved calculation of scattered_rx up in the initialization
>      sequence.
>    - Made LRO offload status part of scattered_rx calculation.
>
> When the completion ring size is too small, completion overflows
> can occur causing the ring to be disabled in hardware.
>
> Fixes: 04067844a3e9 ("net/bnxt: reduce CQ queue size without aggregation ring")
> Cc: stable@dpdk.org
> Signed-off-by: Lance Richardson <lance.richardson@broadcom.com>
> Reviewed-by: Ajit Kumar Khaparde <ajit.khaparde@broadcom.com>
Patch applied to dpdk-next-net-brcm/for-next-net. Thanks

> ---
> v2: Fixed conflict resolution mistake (two missing hunks).
>
>  drivers/net/bnxt/bnxt_ethdev.c |  6 +++++-
>  drivers/net/bnxt/bnxt_ring.c   | 22 ++++++++++++++++++++++
>  drivers/net/bnxt/bnxt_rxr.c    | 15 +--------------
>  3 files changed, 28 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/net/bnxt/bnxt_ethdev.c b/drivers/net/bnxt/bnxt_ethdev.c
> index ec88cb0046..ca779726ec 100644
> --- a/drivers/net/bnxt/bnxt_ethdev.c
> +++ b/drivers/net/bnxt/bnxt_ethdev.c
> @@ -1143,6 +1143,9 @@ static int bnxt_scattered_rx(struct rte_eth_dev *eth_dev)
>         if (eth_dev->data->dev_conf.rxmode.offloads & DEV_RX_OFFLOAD_SCATTER)
>                 return 1;
>
> +       if (eth_dev->data->dev_conf.rxmode.offloads & DEV_RX_OFFLOAD_TCP_LRO)
> +               return 1;
> +
>         for (i = 0; i < eth_dev->data->nb_rx_queues; i++) {
>                 struct bnxt_rx_queue *rxq = eth_dev->data->rx_queues[i];
>
> @@ -1418,11 +1421,12 @@ static int bnxt_dev_start_op(struct rte_eth_dev *eth_dev)
>
>         bnxt_enable_int(bp);
>
> +       eth_dev->data->scattered_rx = bnxt_scattered_rx(eth_dev);
> +
>         rc = bnxt_start_nic(bp);
>         if (rc)
>                 goto error;
>
> -       eth_dev->data->scattered_rx = bnxt_scattered_rx(eth_dev);
>         eth_dev->data->dev_started = 1;
>
>         bnxt_link_update_op(eth_dev, 1);
> diff --git a/drivers/net/bnxt/bnxt_ring.c b/drivers/net/bnxt/bnxt_ring.c
> index 4e513244a6..ba23c1fa03 100644
> --- a/drivers/net/bnxt/bnxt_ring.c
> +++ b/drivers/net/bnxt/bnxt_ring.c
> @@ -583,6 +583,17 @@ int bnxt_alloc_hwrm_rx_ring(struct bnxt *bp, int queue_index)
>         struct bnxt_rx_ring_info *rxr = rxq->rx_ring;
>         int rc;
>
> +       /*
> +        * Storage for the cp ring is allocated based on worst-case
> +        * usage, the actual size to be used by hw is computed here.
> +        */
> +       cp_ring->ring_size = rxr->rx_ring_struct->ring_size * 2;
> +
> +       if (bp->eth_dev->data->scattered_rx)
> +               cp_ring->ring_size *= AGG_RING_SIZE_FACTOR;
> +
> +       cp_ring->ring_mask = cp_ring->ring_size - 1;
> +
>         rc = bnxt_alloc_cmpl_ring(bp, queue_index, cpr);
>         if (rc)
>                 goto err_out;
> @@ -693,6 +704,17 @@ int bnxt_alloc_hwrm_rings(struct bnxt *bp)
>                 struct bnxt_ring *cp_ring = cpr->cp_ring_struct;
>                 struct bnxt_rx_ring_info *rxr = rxq->rx_ring;
>
> +               /*
> +                * Storage for the cp ring is allocated based on worst-case
> +                * usage, the actual size to be used by hw is computed here.
> +                */
> +               cp_ring->ring_size = rxr->rx_ring_struct->ring_size * 2;
> +
> +               if (bp->eth_dev->data->scattered_rx)
> +                       cp_ring->ring_size *= AGG_RING_SIZE_FACTOR;
> +
> +               cp_ring->ring_mask = cp_ring->ring_size - 1;
> +
>                 if (bnxt_alloc_cmpl_ring(bp, i, cpr))
>                         goto err_out;
>
> diff --git a/drivers/net/bnxt/bnxt_rxr.c b/drivers/net/bnxt/bnxt_rxr.c
> index 8c2781c968..4674f7cea2 100644
> --- a/drivers/net/bnxt/bnxt_rxr.c
> +++ b/drivers/net/bnxt/bnxt_rxr.c
> @@ -1116,12 +1116,9 @@ void bnxt_free_rx_rings(struct bnxt *bp)
>
>  int bnxt_init_rx_ring_struct(struct bnxt_rx_queue *rxq, unsigned int socket_id)
>  {
> -       struct rte_eth_dev *eth_dev = rxq->bp->eth_dev;
> -       struct rte_eth_rxmode *rxmode;
>         struct bnxt_cp_ring_info *cpr;
>         struct bnxt_rx_ring_info *rxr;
>         struct bnxt_ring *ring;
> -       bool use_agg_ring;
>
>         rxq->rx_buf_size = BNXT_MAX_PKT_LEN + sizeof(struct rte_mbuf);
>
> @@ -1164,19 +1161,9 @@ int bnxt_init_rx_ring_struct(struct bnxt_rx_queue *rxq, unsigned int socket_id)
>                 return -ENOMEM;
>         cpr->cp_ring_struct = ring;
>
> -       rxmode = &eth_dev->data->dev_conf.rxmode;
> -       use_agg_ring = (rxmode->offloads & DEV_RX_OFFLOAD_SCATTER) ||
> -                      (rxmode->offloads & DEV_RX_OFFLOAD_TCP_LRO) ||
> -                      (rxmode->max_rx_pkt_len >
> -                        (uint32_t)(rte_pktmbuf_data_room_size(rxq->mb_pool) -
> -                                   RTE_PKTMBUF_HEADROOM));
> -
>         /* Allocate two completion slots per entry in desc ring. */
>         ring->ring_size = rxr->rx_ring_struct->ring_size * 2;
> -
> -       /* Allocate additional slots if aggregation ring is in use. */
> -       if (use_agg_ring)
> -               ring->ring_size *= AGG_RING_SIZE_FACTOR;
> +       ring->ring_size *= AGG_RING_SIZE_FACTOR;
>
>         ring->ring_size = rte_align32pow2(ring->ring_size);
>         ring->ring_mask = ring->ring_size - 1;
> --
> 2.25.1
>