Re: [RFC PATCH] ethdev: support Rx data discard

Stephen Hemminger
2026-01-04T18:04:39Z

On Sun, 4 Jan 2026 15:13:01 +0200
Gregory Etelson <getelson@nvidia.com> wrote:

> In some cases application does not need to receive entire packet
> from port hardware.
> If application could fetch required data only and safely discard the
> rest of Rx packet data, that could improve port performance by
> reducing PCI bandwidth.
>
> The RTE_ETH_DEV_DISCARD_RX_DATA device capability flag notifies that
> a port hardware supports Rx data discard.
>
> Signed-off-by: Gregory Etelson <getelson@nvidia.com>
> ---
> lib/ethdev/rte_ethdev.h | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
> index a66c2abbdb..10938ddad3 100644
> --- a/lib/ethdev/rte_ethdev.h
> +++ b/lib/ethdev/rte_ethdev.h
> @@ -2170,6 +2170,8 @@ struct rte_eth_dev_owner {
> * PMDs filling the queue xstats themselves should not set this flag
> */
> #define RTE_ETH_DEV_AUTOFILL_QUEUE_XSTATS RTE_BIT32(6)
> +/** Device supports Rx data discard */
> +#define RTE_ETH_DEV_DISCARD_RX_DATA RTE_BIT32(7)
> /**@}*/
>
> /**

Just because HW can do a feature doesn't mean that DPDK has to support it.
There needs to be more justification.

Why not use a flow rule?