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Message-ID: <f79e2dde-6d45-cc97-0cde-05454bdb5077@intel.com>
Date: Thu, 20 Apr 2023 16:49:06 +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>,
<daniel@...earbox.net>, <hawk@...nel.org>,
<john.fastabend@...il.com>, <richardcochran@...il.com>,
<UNGLinuxDriver@...rochip.com>, <maciej.fijalkowski@...el.com>,
<alexandr.lobakin@...el.com>
Subject: Re: [PATCH net-next] net: lan966x: Don't use xdp_frame when action is
XDP_TX
From: Horatiu Vultur <horatiu.vultur@...rochip.com>
Date: Thu, 20 Apr 2023 14:11:52 +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 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.
>
> Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>
[...]
> @@ -702,6 +704,7 @@ static void lan966x_fdma_tx_start(struct lan966x_tx *tx, int next_to_use)
> int lan966x_fdma_xmit_xdpf(struct lan966x_port *port,
> struct xdp_frame *xdpf,
> struct page *page,
> + u32 len,
> bool dma_map)
I think you can cut the number of arguments by almost a half:
int lan966x_fdma_xmit_xdpf(struct lan966x_port *port,
void *ptr, u32 len)
{
if (len) {
/* XDP_TX, ptr is page */
page = ptr;
dma_sync_here(page, len);
} else {
/* XDP_REDIR, ptr is xdp_frame */
xdpf = ptr;
dma_map_here(xdpf->data, xdpf->len);
}
@page and @xdpf are mutually exclusive. When @xdpf is non-null, @len is
excessive (xdpf->len is here), so you can use @len as logical
`len * !dma_map`, i.e. zero for REDIR and the actual frame length for TX.
I generally enjoy seeing how you constantly improve stuff in your driver :)
> {
> struct lan966x *lan966x = port->lan966x;
> @@ -722,6 +725,15 @@ int lan966x_fdma_xmit_xdpf(struct lan966x_port *port,
> goto out;
> }
[...]
Thanks,
Olek
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