Re: [PATCH v3 bpf-next 2/2] net: xdp: introduce xdp_prepare_buff utility routine

On Thu, 2020-12-17 at 19:28 +0100, Maciej Fijalkowski wrote:

On Thu, Dec 17, 2020 at 10:16:06AM -0800, Saeed Mahameed wrote:

quoted

On Wed, 2020-12-16 at 16:01 +0100, Lorenzo Bianconi wrote:

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On Tue, 15 Dec 2020 14:47:10 +0100
Lorenzo Bianconi [off-list ref] wrote:

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[...]

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 	xdp_act = bpf_prog_run_xdp(xdp_prog, &xdp);

diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c

b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 4dbbbd49c389..fcd1ca3343fb 100644

--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c

@@ -2393,12 +2393,12 @@ static int

i40e_clean_rx_irq(struct
i40e_ring *rx_ring, int budget)
 
 		/* retrieve a buffer from the ring */
 		if (!skb) {
-			xdp.data = page_address(rx_buffer-

quoted

page) +

-				   rx_buffer->page_offset;
-			xdp.data_meta = xdp.data;
-			xdp.data_hard_start = xdp.data -
-					      i40e_rx_offset(rx
_ring);
-			xdp.data_end = xdp.data + size;
+			unsigned int offset =
i40e_rx_offset(rx_ring);  

I now see that we could call the i40e_rx_offset() once per
napi, so can
you pull this variable out and have it initialized a single
time? Applies
to other intel drivers as well.  

How is this related to this series? i suggest to keep this series
clean
of vendor specific unrelated optimizations, this must be done in a
separate patchset.

Well, Lorenzo explicitly is touching the thing that I referred to, so
I
just ask if he can optimize it while he's at it.

Of course I'm fine with addressing this by myself once -next opens :)

Oh, don't get me wrong I am ok with doing this now, and i can do it my
self if you want :), but it shouldn't be part of the this series, so we
won't confuse others who want to implement XDP in the future, that's
all.