netdev - Re: [PATCH net-next v3] lan966x: Don't use xdp_frame when action is XDP

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Date:   Mon, 24 Apr 2023 15:36:22 +0200
From:   Alexander Lobakin <aleksander.lobakin@...el.com>
To:     Horatiu Vultur <horatiu.vultur@...rochip.com>
CC:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <bpf@...r.kernel.org>, <davem@...emloft.net>,
        <edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
        <ast@...nel.org>, <daniel@...earbox.net>, <hawk@...nel.org>,
        <john.fastabend@...il.com>, <maciej.fijalkowski@...el.com>,
        <UNGLinuxDriver@...rochip.com>
Subject: Re: [PATCH net-next v3] lan966x: Don't use xdp_frame when action is
 XDP_TX

From: Horatiu Vultur <horatiu.vultur@...rochip.com>
Date: Sat, 22 Apr 2023 16:23:44 +0200

> When the action of an xdp program was XDP_TX, lan966x was creating
> a xdp_frame and use this one to send the frame back. But it is also
> possible to send back the frame without needing a xdp_frame, because
> it is possible to send it back using the page.
> And then once the frame is transmitted is possible to use directly
> page_pool_recycle_direct as lan966x is using page pools.
> This would save some CPU usage on this path, which results in higher
> number of transmitted frames. Bellow are the statistics:
> Frame size:    Improvement:
> 64                ~8%
> 256              ~11%
> 512               ~8%
> 1000              ~0%
> 1500              ~0%
> 
> Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>

Reviewed-by: Alexander Lobakin <aleksander.lobakin@...el.com>

> ---
> v2->v3:
> - fix length issue when the XDP action is XDP_REDIRECT, this issue was
>   introduced in v2 of this patch series.
> - reduce the number of changes by moving back all the assignments to
>   next_dcb_buf
> 
> v1->v2:
> - reduce number of arguments for the function lan966x_fdma_xmit_xdpf,
>   as some of them are mutual exclusive, and other can be replaced with
>   deduced from the other ones
> - update commit message and add statistics for the improvement
[...]

Thanks,
Olek