netdev - Re: [PATCH bpf] samples/bpf: consider frame size in tx

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Date:   Thu, 6 May 2021 15:09:07 +0200
From:   Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To:     Magnus Karlsson <magnus.karlsson@...il.com>
Cc:     magnus.karlsson@...el.com, bjorn@...nel.org, ast@...nel.org,
        daniel@...earbox.net, netdev@...r.kernel.org,
        jonathan.lemon@...il.com, bpf@...r.kernel.org
Subject: Re: [PATCH bpf] samples/bpf: consider frame size in tx_only of
 xdpsock sample

On Thu, May 06, 2021 at 02:43:49PM +0200, Magnus Karlsson wrote:
> From: Magnus Karlsson <magnus.karlsson@...el.com>
> 
> Fix the tx_only micro-benchmark in xdpsock to take frame size into
> consideration. It was hardcoded to the default value of frame_size
> which is 4K. Changing this on the command line to 2K made half of the
> packets illegal as they were outside the umem and were therefore
> discarded by the kernel.
> 
> Fixes: 46738f73ea4f ("samples/bpf: add use of need_wakeup flag in xdpsock")
> Signed-off-by: Magnus Karlsson <magnus.karlsson@...el.com>

Acked-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com>

> ---
>  samples/bpf/xdpsock_user.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
> index aa696854be78..53e300f860bb 100644
> --- a/samples/bpf/xdpsock_user.c
> +++ b/samples/bpf/xdpsock_user.c
> @@ -1255,7 +1255,7 @@ static void tx_only(struct xsk_socket_info *xsk, u32 *frame_nb, int batch_size)
>  	for (i = 0; i < batch_size; i++) {
>  		struct xdp_desc *tx_desc = xsk_ring_prod__tx_desc(&xsk->tx,
>  								  idx + i);
> -		tx_desc->addr = (*frame_nb + i) << XSK_UMEM__DEFAULT_FRAME_SHIFT;
> +		tx_desc->addr = (*frame_nb + i) * opt_xsk_frame_size;
>  		tx_desc->len = PKT_SIZE;
>  	}
>  
> 
> base-commit: 9683e5775c75097c46bd24e65411b16ac6c6cbb3
> -- 
> 2.29.0
>