[PATCH] net/i40e: increase descriptor queue length to 8160

[Igor Gutorov]

On Mon, May 27, 2024 at 7:20 PM Igor Gutorov <igootorov at gmail.com> wrote:
>
> According to the Intel X710/XXV710/XL710 Datasheet, the maximum receive
> queue descriptor length is 0x1FE0 (8160 in base 10). This is specified
> as QLEN in table 8-12, page 1083.
>
> I've tested this change with an XXV710 NIC and it has positive effect on
> performance under high load scenarios. Where previously I'd get
> ~2000 packets/sec miss rate, now I get only ~40 packets/sec miss rate.
>
> Signed-off-by: Igor Gutorov <igootorov at gmail.com>
> ---
>  drivers/net/i40e/i40e_rxtx.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/i40e/i40e_rxtx.h b/drivers/net/i40e/i40e_rxtx.h
> index 2f2f890855..33fc9770d9 100644
> --- a/drivers/net/i40e/i40e_rxtx.h
> +++ b/drivers/net/i40e/i40e_rxtx.h
> @@ -25,7 +25,7 @@
>  #define I40E_RX_MAX_DATA_BUF_SIZE      (16 * 1024 - 128)
>
>  #define        I40E_MIN_RING_DESC      64
> -#define        I40E_MAX_RING_DESC      4096
> +#define        I40E_MAX_RING_DESC      8160
>
>  #define I40E_FDIR_NUM_TX_DESC   (I40E_FDIR_PRG_PKT_CNT << 1)
>  #define I40E_FDIR_NUM_RX_DESC   (I40E_FDIR_PRG_PKT_CNT << 1)
> --
> 2.45.1
>

CC'ing to a different email (got an address rejected error, the
MAINTAINERS file might need an update).

Also, I've noticed that an X722 NIC is also supported by the i40e
driver, but it seems the datasheet isn't on Intel's website for that
NIC. Does anybody know if X722 has 4096 or 8160 usable descriptors? If
someone could test this patch against X722, that would be great.