On Tue, Feb 25, 2025 at 09:12:36AM +0000, Mingjin Ye wrote:
> The minimum free packet threshold (tx_free_thresh) and the minimum RS bit
> threshold (tx_rs_thresh) both have a default value of 32. Therefore, the
> default minimum number of ring descriptors value is 64.
>
> For reference, see "Configuration of Transmit Queues" in
> doc/guides/prog_guide/ethdev/ethdev.rst
>
> Fixes: dee5f1fd5fc7 ("ixgbe: get queue info and descriptor limits")
> Cc: sta...@dpdk.org
>
> Signed-off-by: Mingjin Ye <mingjinx...@intel.com>
> ---
> v2: Change doc.
> ---
> doc/guides/nics/ixgbe.rst | 5 +++--
> drivers/net/intel/ixgbe/ixgbe_rxtx.h | 2 +-
> 2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/doc/guides/nics/ixgbe.rst b/doc/guides/nics/ixgbe.rst
> index c5c6a6c34b..aaed324e15 100644
> --- a/doc/guides/nics/ixgbe.rst
> +++ b/doc/guides/nics/ixgbe.rst
> @@ -68,11 +68,12 @@ Ensure that the following pre-conditions are satisfied:
>
> * (rxq->nb_rx_desc % rxq->rx_free_thresh) == 0
>
> -* rxq->nb_rx_desc < (IXGBE_MAX_RING_DESC - RTE_PMD_IXGBE_RX_MAX_BURST)
> +* rxq->nb_rx_desc >= IXGBE_MIN_RING_DESC
> +
> +* rxq->nb_rx_desc <= IXGBE_MAX_RING_DESC
>
> These conditions are checked in the code.
>
> -Scattered packets are not supported in this mode.
> If an incoming packet is greater than the maximum acceptable length of one
> "mbuf" data size (by default, the size is 2 KB),
> vPMD for RX would be disabled.
>
These two lines in the doc should be removed as well, since they also imply
the unavailability of scattered Rx.
Fixing this by dropping them on apply.
> diff --git a/drivers/net/intel/ixgbe/ixgbe_rxtx.h
> b/drivers/net/intel/ixgbe/ixgbe_rxtx.h
> index 278f665108..54569c7ade 100644
> --- a/drivers/net/intel/ixgbe/ixgbe_rxtx.h
> +++ b/drivers/net/intel/ixgbe/ixgbe_rxtx.h
> @@ -26,7 +26,7 @@
> * descriptors should meet the following condition:
> * (num_ring_desc * sizeof(rx/tx descriptor)) % 128 == 0
> */
> -#define IXGBE_MIN_RING_DESC 32
> +#define IXGBE_MIN_RING_DESC 64
> #define IXGBE_MAX_RING_DESC 8192
>
> #define RTE_PMD_IXGBE_TX_MAX_BURST 32
> --
> 2.25.1
>
Acked-by: Bruce Richardson <bruce.richard...@intel.com>
Applied to dpdk-next-net-intel.
Thanks,
/Bruce
