[PATCH] net/ixgbe: fix min Rx/Tx descriptors

[Bruce Richardson]

On Fri, Feb 21, 2025 at 08:23:18AM +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.
> 
> Fixes: dee5f1fd5fc7 ("ixgbe: get queue info and descriptor limits")
> Cc: stable at dpdk.org
> 
> Signed-off-by: Mingjin Ye <mingjinx.ye at intel.com>
> ---
>  doc/guides/nics/ixgbe.rst            | 2 +-
>  drivers/net/intel/ixgbe/ixgbe_rxtx.h | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/doc/guides/nics/ixgbe.rst b/doc/guides/nics/ixgbe.rst
> index c5c6a6c34b..10a0cdd270 100644
> --- a/doc/guides/nics/ixgbe.rst
> +++ b/doc/guides/nics/ixgbe.rst
> @@ -76,7 +76,7 @@ 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.
>  
> -By default, IXGBE_MAX_RING_DESC is set to 8192 and RTE_PMD_IXGBE_RX_MAX_BURST is set to 32.
> +By default, IXGBE_MAX_RING_DESC is set to 8192 and RTE_PMD_IXGBE_RX_MAX_BURST is set to 64.
>  
>  Windows Prerequisites and Pre-conditions
>  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 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

Ack for this part of the change. Just ran a quick test using ixgbe and
things stopped working pretty quickly with an Rx ring size of 32.

With the doc update above dropped:

Acked-by: Bruce Richardson <bruce.richardson at intel.com>