>
> Previously, there is instability during vector Rx if descriptor
> number is not power of 2, e.g. process hang and some Rx packets
> are unexpectedly empty. That's because vector Rx mode assumes Rx
> descriptor number is power of 2 when doing bit mask.
> This patch allows vector mode only when the number of Rx descriptor
> is power of 2.
>
> Fixes: 8e109464c022 ("i40e: allow vector Rx and Tx usage")
> Fixes: a3c83a2527e1 ("net/i40e: enable runtime queue setup")
> Cc: sta...@dpdk.org
>
> Signed-off-by: Beilei Xing <beilei.x...@intel.com>
> ---
> v4 changes:
> - Configure rx_vec_allowed in i40e_rx_vec_dev_conf_condition_check function.
> v3 changes:
> - Add branch for non-first queue during runtime queue setup.
> - Use function rte_is_power_of_2().
> - Configure rx_vec_allowed during setting Rx function.
> v2 changes:
> - rx_vec_allowed is global configuration, avoid overwrite.
>
> doc/guides/nics/i40e.rst | 7 ++++++
> drivers/net/i40e/i40e_rxtx.c | 5 +++++
> drivers/net/i40e/i40e_rxtx_vec_common.h | 38
> +++++++++++++++++++++++++++++++++
> 3 files changed, 50 insertions(+)
>
> diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst
> index ab3928a..bfacbd1 100644
> --- a/doc/guides/nics/i40e.rst
> +++ b/doc/guides/nics/i40e.rst
> @@ -172,6 +172,13 @@ Runtime Config Options
>
> -w 84:00.0,use-latest-supported-vec=1
>
> +Vector RX Pre-conditions
> +~~~~~~~~~~~~~~~~~~~~~~~~
> +For Vector RX it is assumed that the number of descriptor rings will be a
> power
> +of 2. With this pre-condition, the ring pointer can easily scroll back to the
> +head after hitting the tail without a conditional check. In addition Vector
> RX
> +can use this assumption to do a bit mask using ``ring_size - 1``.
> +
> Driver compilation and testing
> ------------------------------
>
> diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c
> index a827456..5bb1a3c 100644
> --- a/drivers/net/i40e/i40e_rxtx.c
> +++ b/drivers/net/i40e/i40e_rxtx.c
> @@ -1741,6 +1741,11 @@ i40e_dev_rx_queue_setup_runtime(struct rte_eth_dev
> *dev,
> ad->rx_bulk_alloc_allowed = false;
> i40e_set_rx_function(dev);
> return 0;
> + } else if (ad->rx_vec_allowed && !rte_is_power_of_2(rxq->nb_rx_desc)) {
> + PMD_DRV_LOG(ERR, "Vector mode is allowed, but descriptor"
> + " number %d of queue %d isn't power of 2",
> + rxq->nb_rx_desc, rxq->queue_id);
> + return -EINVAL;
> }
>
> /* check bulk alloc conflict */
> diff --git a/drivers/net/i40e/i40e_rxtx_vec_common.h
> b/drivers/net/i40e/i40e_rxtx_vec_common.h
> index f00f6d6..0e6ffa0 100644
> --- a/drivers/net/i40e/i40e_rxtx_vec_common.h
> +++ b/drivers/net/i40e/i40e_rxtx_vec_common.h
> @@ -192,8 +192,13 @@ static inline int
> i40e_rx_vec_dev_conf_condition_check_default(struct rte_eth_dev *dev)
> {
> #ifndef RTE_LIBRTE_IEEE1588
> + struct i40e_adapter *ad =
> + I40E_DEV_PRIVATE_TO_ADAPTER(dev->data->dev_private);
> struct rte_eth_rxmode *rxmode = &dev->data->dev_conf.rxmode;
> struct rte_fdir_conf *fconf = &dev->data->dev_conf.fdir_conf;
> + struct i40e_rx_queue *rxq;
> + uint16_t desc, i;
> + bool first_queue;
>
> /* no fdir support */
> if (fconf->mode != RTE_FDIR_MODE_NONE)
> @@ -207,6 +212,39 @@ i40e_rx_vec_dev_conf_condition_check_default(struct
> rte_eth_dev *dev)
> if (rxmode->offloads & DEV_RX_OFFLOAD_VLAN_EXTEND)
> return -1;
>
> + /**
> + * Vector mode is allowed only when number of Rx queue
> + * descriptor is power of 2.
> + */
> + if (!dev->data->dev_started) {
> + first_queue = true;
> + for (i = 0; i < dev->data->nb_rx_queues; i++) {
> + rxq = dev->data->rx_queues[i];
> + if (!rxq)
> + continue;
> + desc = rxq->nb_rx_desc;
> + if (first_queue)
> + ad->rx_vec_allowed =
> + rte_is_power_of_2(desc);
> + else
> + ad->rx_vec_allowed =
> + ad->rx_vec_allowed ?
> + rte_is_power_of_2(desc) :
> + ad->rx_vec_allowed;
> + first_queue = false;
> + }
> + } else {
> + /* Only check the first queue's descriptor number */
> + for (i = 0; i < dev->data->nb_rx_queues; i++) {
> + rxq = dev->data->rx_queues[i];
> + if (!rxq)
> + continue;
> + desc = rxq->nb_rx_desc;
> + ad->rx_vec_allowed = rte_is_power_of_2(desc);
> + break;
> + }
> + }
> +
> return 0;
> #else
> RTE_SET_USED(dev);
> --
Acked-by: Konstantin Ananyev <konstantin.anan...@intel.com>
> 2.5.5
