Re: [PATCH net-next 08/15] net/mlx5e: set the tx_queue_len for pfifo_fast

Michal Swiatkowski
2025-02-10T09:54:44Z

On Sun, Feb 09, 2025 at 12:17:09PM +0200, Tariq Toukan wrote:
> From: William Tu <witu@nvidia.com>
>
> By default, the mq netdev creates a pfifo_fast qdisc. On a
> system with 16 core, the pfifo_fast with 3 bands consumes
> 16 * 3 * 8 (size of pointer) * 1024 (default tx queue len)
> = 393KB. The patch sets the tx qlen to representor default
> value, 128 (1<<MLX5E_REP_PARAMS_DEF_LOG_SQ_SIZE), which
> consumes 16 * 3 * 8 * 128 = 49KB, saving 344KB for each
> representor at ECPF.
>
> Signed-off-by: William Tu <witu@nvidia.com>
> Reviewed-by: Daniel Jurgens <danielj@nvidia.com>
> Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
> ---
> drivers/net/ethernet/mellanox/mlx5/core/en_rep.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
> index da399adc8854..07f38f472a27 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
> @@ -889,6 +889,8 @@ static void mlx5e_build_rep_netdev(struct net_device *netdev,
> netdev->ethtool_ops = &mlx5e_rep_ethtool_ops;
>
> netdev->watchdog_timeo = 15 * HZ;
> + if (mlx5_core_is_ecpf(mdev))
> + netdev->tx_queue_len = 1 << MLX5E_REP_PARAMS_DEF_LOG_SQ_SIZE;
>
> #if IS_ENABLED(CONFIG_MLX5_CLS_ACT)
> netdev->hw_features |= NETIF_F_HW_TC;

Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>

> --
> 2.45.0