netdev - Re: [PATCH net-next 3/3] net/mlx5e: use indirect calls wrapper for the rx packet handler

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Message-ID: <1b740c86d3917640657934961b40fe4b288c2a40.camel@mellanox.com>
Date:   Fri, 31 May 2019 18:41:04 +0000
From:   Saeed Mahameed <saeedm@...lanox.com>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "leon@...nel.org" <leon@...nel.org>
Subject: Re: [PATCH net-next 3/3] net/mlx5e: use indirect calls wrapper for
 the rx packet handler

On Fri, 2019-05-31 at 14:53 +0200, Paolo Abeni wrote:
> We can avoid another indirect call per packet wrapping the rx
> handler call with the proper helper.
> 
> To ensure that even the last listed direct call experience
> measurable gain, despite the additional conditionals we must
> traverse before reaching it, I tested reversing the order of the
> listed options, with performance differences below noise level.
> 
> Together with the previous indirect call patch, this gives
> ~6% performance improvement in raw UDP tput.
> 

Nice ! I like it.

> Signed-off-by: Paolo Abeni <pabeni@...hat.com>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> index 0fe5f13d07cc..c3752dbe00c8 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> @@ -1333,7 +1333,9 @@ int mlx5e_poll_rx_cq(struct mlx5e_cq *cq, int
> budget)
>  
>  		mlx5_cqwq_pop(cqwq);
>  
> -		rq->handle_rx_cqe(rq, cqe);
> +		INDIRECT_CALL_4(rq->handle_rx_cqe,
> mlx5e_handle_rx_cqe_mpwrq,
> +				mlx5e_handle_rx_cqe,
> mlx5e_handle_rx_cqe_rep,
> +				mlx5e_ipsec_handle_rx_cqe, rq, cqe);

you missed mlx5i_handle_rx_cqe, anyway don't add INDIRECT_CALL_5 :D

just replace mlx5e_handle_rx_cqe_rep with mlx5i_handle_rx_cqe, 
mlx5e_handle_rx_cqe_rep is actually a slow path of switchdev mode.

Maybe define the list somewhere in en.h where it is visible for every
one:

#define MLX5_RX_INDIRECT_CALL_LIST \
mlx5e_handle_rx_cqe_mpwrq, mlx5e_handle_rx_cqe, mlx5i_handle_rx_cqe,
mlx5e_ipsec_handle_rx_cqe

and here:
INDIRECT_CALL_4(rq->handle_rx_cqe, MLX5_RX_INDIRECT_CALL_LIST, rq,
cqe);

>  	} while ((++work_done < budget) && (cqe =
> mlx5_cqwq_get_cqe(cqwq)));
>  
>  out: