linux-kernel - Re: [PATCH net-next 4/6] net/mlx5e: SHAMPO, Cleanup reservation size formula

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Message-ID: <aHX/LMSuUBG3X5Ph@mev-dev.igk.intel.com>
Date: Tue, 15 Jul 2025 09:11:40 +0200
From: Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>
To: Tariq Toukan <tariqt@...dia.com>
Cc: Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Saeed Mahameed <saeed@...nel.org>, Gal Pressman <gal@...dia.com>,
	Leon Romanovsky <leon@...nel.org>,
	Saeed Mahameed <saeedm@...dia.com>, Mark Bloch <mbloch@...dia.com>,
	netdev@...r.kernel.org, linux-rdma@...r.kernel.org,
	linux-kernel@...r.kernel.org, Lama Kayal <lkayal@...dia.com>
Subject: Re: [PATCH net-next 4/6] net/mlx5e: SHAMPO, Cleanup reservation size
 formula

On Mon, Jul 14, 2025 at 08:39:43AM +0300, Tariq Toukan wrote:
> From: Lama Kayal <lkayal@...dia.com>
> 
> The reservation size formula can be reduced to a simple evaluation of
> MLX5E_SHAMPO_WQ_RESRV_SIZE. This leaves mlx5e_shampo_get_log_rsrv_size()
> with one single use, which can be replaced with a macro for simplicity.
> 
> Also, function mlx5e_shampo_get_log_rsrv_size() is used only throughout
> params.c, make it static.
> 
> Signed-off-by: Lama Kayal <lkayal@...dia.com>
> Reviewed-by: Dragos Tatulea <dtatulea@...dia.com>
> Signed-off-by: Tariq Toukan <tariqt@...dia.com>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/en.h  |  5 +--
>  .../ethernet/mellanox/mlx5/core/en/params.c   | 34 +++++++------------
>  .../ethernet/mellanox/mlx5/core/en/params.h   |  4 ---
>  3 files changed, 15 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
> index 64e69e616b1f..019bc6ca4455 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
> @@ -85,8 +85,9 @@ struct page_pool;
>  #define MLX5E_SHAMPO_WQ_HEADER_PER_PAGE (PAGE_SIZE >> MLX5E_SHAMPO_LOG_MAX_HEADER_ENTRY_SIZE)
>  #define MLX5E_SHAMPO_LOG_WQ_HEADER_PER_PAGE (PAGE_SHIFT - MLX5E_SHAMPO_LOG_MAX_HEADER_ENTRY_SIZE)
>  #define MLX5E_SHAMPO_WQ_BASE_HEAD_ENTRY_SIZE (64)
> -#define MLX5E_SHAMPO_WQ_RESRV_SIZE (64 * 1024)
> -#define MLX5E_SHAMPO_WQ_BASE_RESRV_SIZE (4096)
> +#define MLX5E_SHAMPO_WQ_RESRV_SIZE_BASE_SHIFT (12)
> +#define MLX5E_SHAMPO_WQ_LOG_RESRV_SIZE (16)
> +#define MLX5E_SHAMPO_WQ_RESRV_SIZE BIT(MLX5E_SHAMPO_WQ_LOG_RESRV_SIZE)
>  
>  #define MLX5_MPWRQ_MIN_LOG_STRIDE_SZ(mdev) \
>  	(6 + MLX5_CAP_GEN(mdev, cache_line_128byte)) /* HW restriction */
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/params.c b/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
> index fc945bce933a..616251ec6d69 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/params.c

[...]

>  
>  u8 mlx5e_mpwqe_get_log_stride_size(struct mlx5_core_dev *mdev,
> @@ -834,10 +825,9 @@ static u32 mlx5e_shampo_get_log_cq_size(struct mlx5_core_dev *mdev,
>  					struct mlx5e_params *params,
>  					struct mlx5e_xsk_param *xsk)
>  {
> -	int rsrv_size = BIT(mlx5e_shampo_get_log_rsrv_size(mdev, params)) *
> -		MLX5E_SHAMPO_WQ_BASE_RESRV_SIZE;
> +	int rsrv_size = MLX5E_SHAMPO_WQ_RESRV_SIZE;

Broken RCT, you can use MLX5E_SHAMPO_WQ_RESRV_SIZE directly in
order_base_2() call.

>  	u16 num_strides = BIT(mlx5e_mpwqe_get_log_num_strides(mdev, params, xsk));
> -	int pkt_per_rsrv = BIT(mlx5e_shampo_get_log_pkt_per_rsrv(mdev, params));
> +	int pkt_per_rsrv = BIT(mlx5e_shampo_get_log_pkt_per_rsrv(params));
>  	u8 log_stride_sz = mlx5e_mpwqe_get_log_stride_size(mdev, params, xsk);
>  	int wq_size = BIT(mlx5e_mpwqe_get_log_rq_size(mdev, params, xsk));
>  	int wqe_size = BIT(log_stride_sz) * num_strides;
> @@ -932,10 +922,11 @@ int mlx5e_build_rq_param(struct mlx5_core_dev *mdev,
>  
>  		MLX5_SET(wq, wq, shampo_enable, true);
>  		MLX5_SET(wq, wq, log_reservation_size,
> -			 mlx5e_shampo_get_log_rsrv_size(mdev, params));
> +			 MLX5E_SHAMPO_WQ_LOG_RESRV_SIZE -
> +			 MLX5E_SHAMPO_WQ_RESRV_SIZE_BASE_SHIFT);
>  		MLX5_SET(wq, wq,
>  			 log_max_num_of_packets_per_reservation,
> -			 mlx5e_shampo_get_log_pkt_per_rsrv(mdev, params));
> +			 mlx5e_shampo_get_log_pkt_per_rsrv(params));
>  		MLX5_SET(wq, wq, log_headers_entry_size,
>  			 mlx5e_shampo_get_log_hd_entry_size(mdev, params));
>  		lro_timeout =
> @@ -1048,18 +1039,17 @@ u32 mlx5e_shampo_hd_per_wqe(struct mlx5_core_dev *mdev,
>  			    struct mlx5e_params *params,
>  			    struct mlx5e_rq_param *rq_param)
>  {
> -	int resv_size = BIT(mlx5e_shampo_get_log_rsrv_size(mdev, params)) *
> -		MLX5E_SHAMPO_WQ_BASE_RESRV_SIZE;
> +	int rsrv_size = MLX5E_SHAMPO_WQ_RESRV_SIZE;

Can be moved down to have RCT.

>  	u16 num_strides = BIT(mlx5e_mpwqe_get_log_num_strides(mdev, params, NULL));
> -	int pkt_per_resv = BIT(mlx5e_shampo_get_log_pkt_per_rsrv(mdev, params));
> +	int pkt_per_resv = BIT(mlx5e_shampo_get_log_pkt_per_rsrv(params));
>  	u8 log_stride_sz = mlx5e_mpwqe_get_log_stride_size(mdev, params, NULL);
>  	int wqe_size = BIT(log_stride_sz) * num_strides;
>  	u32 hd_per_wqe;
>  
>  	/* Assumption: hd_per_wqe % 8 == 0. */
> -	hd_per_wqe = (wqe_size / resv_size) * pkt_per_resv;
> +	hd_per_wqe = (wqe_size / rsrv_size) * pkt_per_resv;
>  	mlx5_core_dbg(mdev, "%s hd_per_wqe = %d rsrv_size = %d wqe_size = %d pkt_per_resv = %d\n",
> -		      __func__, hd_per_wqe, resv_size, wqe_size, pkt_per_resv);
> +		      __func__, hd_per_wqe, rsrv_size, wqe_size, pkt_per_resv);
>  	return hd_per_wqe;
>  }
>  
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/params.h b/drivers/net/ethernet/mellanox/mlx5/core/en/params.h
> index bd5877acc5b1..919895f64dcd 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en/params.h
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/params.h
> @@ -97,10 +97,6 @@ u8 mlx5e_mpwqe_get_log_rq_size(struct mlx5_core_dev *mdev,
>  			       struct mlx5e_xsk_param *xsk);
>  u8 mlx5e_shampo_get_log_hd_entry_size(struct mlx5_core_dev *mdev,
>  				      struct mlx5e_params *params);
> -u8 mlx5e_shampo_get_log_rsrv_size(struct mlx5_core_dev *mdev,
> -				  struct mlx5e_params *params);
> -u8 mlx5e_shampo_get_log_pkt_per_rsrv(struct mlx5_core_dev *mdev,
> -				     struct mlx5e_params *params);
>  u32 mlx5e_shampo_hd_per_wqe(struct mlx5_core_dev *mdev,
>  			    struct mlx5e_params *params,
>  			    struct mlx5e_rq_param *rq_param);

Just small nits, otherwise:
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>

> -- 
> 2.40.1