On 2021/01/27 3:41, Lorenzo Bianconi wrote:

quoted

Introduce bulking support for XDP_PASS verdict forwarding skbs to
the networking stack

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
  drivers/net/veth.c | 43 ++++++++++++++++++++++++++-----------------
  1 file changed, 26 insertions(+), 17 deletions(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 6e03b619c93c..23137d9966da 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c

@@ -35,6 +35,7 @@
  #define VETH_XDP_HEADROOM	(XDP_PACKET_HEADROOM + NET_IP_ALIGN)
  #define VETH_XDP_TX_BULK_SIZE	16
+#define VETH_XDP_BATCH		8
  struct veth_stats {
  	u64	rx_drops;

@@ -787,27 +788,35 @@ static int veth_xdp_rcv(struct veth_rq *rq, int budget,
  	int i, done = 0;
  	for (i = 0; i < budget; i++) {
-		void *ptr = __ptr_ring_consume(&rq->xdp_ring);
-		struct sk_buff *skb;
+		void *frames[VETH_XDP_BATCH];
+		void *skbs[VETH_XDP_BATCH];
+		int i, n_frame, n_skb = 0;

'i' is a shadowed variable. I think this may be confusing.

ack, I will fix it in v2

quoted

-		if (!ptr)
+		n_frame = __ptr_ring_consume_batched(&rq->xdp_ring, frames,
+						     VETH_XDP_BATCH);

This apparently exceeds the budget.
This will process budget*VETH_XDP_BATCH packets at most.
(You are probably aware of this because you return 'i' instead of 'done'?)

right, I will fix it in v2

Also I'm not sure if we need to introduce __ptr_ring_consume_batched() here.
The function just does __ptr_ring_consume() n times.

IIUC Your final code looks like this:

for (budget) {
	n_frame = __ptr_ring_consume_batched(VETH_XDP_BATCH);
	for (n_frame) {
		if (frame is XDP)
			xdpf[n_xdpf++] = to_xdp(frame);
		else
			skbs[n_skb++] = frame;
	}

	if (n_xdpf)
		veth_xdp_rcv_batch(xdpf);

	for (n_skb) {
		skb = veth_xdp_rcv_skb(skbs[i]);
		napi_gro_receive(skb);
	}
}

Your code processes VETH_XDP_BATCH packets at a time no matter whether each
of them is xdp_frame or skb, but I think you actually want to process
VETH_XDP_BATCH xdp_frames at a time?
Then, why not doing like this?

for (budget) {
	ptr = __ptr_ring_consume();
	if (ptr is XDP) {
		if (n_xdpf >= VETH_XDP_BATCH) {
			veth_xdp_rcv_batch(xdpf);
			n_xdpf = 0;
		}
		xdpf[n_xdpf++] = to_xdp(ptr);
	} else {
		skb = veth_xdp_rcv_skb(ptr);
		napi_gro_receive(skb);
	}
}
if (n_xdpf)
	veth_xdp_rcv_batch(xdpf);

I agree, the code is more readable. I will fix it in v2.
I guess we can drop patch 2/3 and squash patch 1/3 and 3/3.

Regards,
Lorenzo

Toshiaki Makita