Hi
>
> 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>
> ---
> 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 | 30 +++++++++++++++++++++++++++---
> 2 files changed, 34 insertions(+), 3 deletions(-)
>
> 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..771193a 100644
> --- a/drivers/net/i40e/i40e_rxtx.c
> +++ b/drivers/net/i40e/i40e_rxtx.c
> @@ -1735,12 +1735,21 @@ i40e_dev_rx_queue_setup_runtime(struct rte_eth_dev
> *dev,
> * i40e_set_rx_function.
> */
> ad->rx_bulk_alloc_allowed = true;
> - ad->rx_vec_allowed = true;
> dev->data->scattered_rx = use_scattered_rx;
> if (use_def_burst_func)
> ad->rx_bulk_alloc_allowed = false;
> + /**
> + * Vector mode is allowed only when number of Rx queue
> + * descriptor is a power of 2.
> + */
> + ad->rx_vec_allowed = rte_is_power_of_2(rxq->nb_rx_desc);
Actually do we need to do it here?
We call set_rx_function() anyway, it would do that check for us, wouldn't it?
> 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 */
> @@ -2948,11 +2957,26 @@ i40e_set_rx_function(struct rte_eth_dev *dev)
> {
> struct i40e_adapter *ad =
> I40E_DEV_PRIVATE_TO_ADAPTER(dev->data->dev_private);
> + struct i40e_rx_queue *rxq;
> uint16_t rx_using_sse, i;
> + uint16_t desc;
Please add empty line between var definitions and start of code.
Helps readability.
> /* In order to allow Vector Rx there are a few configuration
> * conditions to be met and Rx Bulk Allocation should be allowed.
> */
> if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
> + if (!dev->data->dev_started) {
> + for (i = 0; i < dev->data->nb_rx_queues; i++) {
> + rxq = dev->data->rx_queues[i];
> + desc = rxq->nb_rx_desc;
> + if (!i)
> + ad->rx_vec_allowed =
> + rte_is_power_of_2(desc);
> + else if (ad->rx_vec_allowed &&
> + !rte_is_power_of_2(desc))
> + ad->rx_vec_allowed = false;
Wouldn't be a bit cleaner:
ad->rx_vec_allowed = (ad->rx_vec_allowed == true) ? rte_is_power_of_2(desc)) :
ad->rx_vec_allowed;
> + }
> + }
> +
Probably better to move that code into i40e_rx_vec_dev_conf_condition_check()
that will be called on next line?
> if (i40e_rx_vec_dev_conf_condition_check(dev) ||
> !ad->rx_bulk_alloc_allowed) {
> PMD_INIT_LOG(DEBUG, "Port[%d] doesn't meet"
> @@ -2961,10 +2985,10 @@ i40e_set_rx_function(struct rte_eth_dev *dev)
>
> ad->rx_vec_allowed = false;
> }
> +
> if (ad->rx_vec_allowed) {
> for (i = 0; i < dev->data->nb_rx_queues; i++) {
> - struct i40e_rx_queue *rxq =
> - dev->data->rx_queues[i];
> + rxq = dev->data->rx_queues[i];
>
> if (rxq && i40e_rxq_vec_setup(rxq)) {
> ad->rx_vec_allowed = false;
> --
> 2.5.5
