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Commit 7379f97a authored by John Fastabend's avatar John Fastabend Committed by Jeff Kirsher
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ixgbe: delay tail write to every 'n' packets 



Current XDP implementation hits the tail on every XDP_TX return
code. This patch changes driver behavior to only hit the tail after
packet processing is complete.

With this patch I can run XDP drop programs @ 14+Mpps and XDP_TX
programs are at ~13.5Mpps.

Signed-off-by: default avatarJohn Fastabend <john.r.fastabend@intel.com>
Tested-by: default avatarAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
parent 33fdc82f

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

+17 −11
Original line number Diff line number Diff line
@@ -2283,6 +2283,7 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector, 
	unsigned int mss = 0;

#endif /* IXGBE_FCOE */

	u16 cleaned_count = ixgbe_desc_unused(rx_ring);

	bool xdp_xmit = false;



	while (likely(total_rx_packets < budget)) {

		union ixgbe_adv_rx_desc *rx_desc;
@@ -2322,10 +2323,12 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector, 
		}



		if (IS_ERR(skb)) {

			if (PTR_ERR(skb) == -IXGBE_XDP_TX)

			if (PTR_ERR(skb) == -IXGBE_XDP_TX) {

				xdp_xmit = true;

				ixgbe_rx_buffer_flip(rx_ring, rx_buffer, size);

			else

			} else {

				rx_buffer->pagecnt_bias++;

			}

			total_rx_packets++;

			total_rx_bytes += size;

		} else if (skb) {
@@ -2393,6 +2396,16 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector, 
		total_rx_packets++;

	}



	if (xdp_xmit) {

		struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];



		/* Force memory writes to complete before letting h/w

		 * know there are new descriptors to fetch.

		 */

		wmb();

		writel(ring->next_to_use, ring->tail);

	}



	u64_stats_update_begin(&rx_ring->syncp);

	rx_ring->stats.packets += total_rx_packets;

	rx_ring->stats.bytes += total_rx_bytes;
@@ -8238,14 +8251,8 @@ static int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter, 
	tx_desc->read.olinfo_status =

		cpu_to_le32(len << IXGBE_ADVTXD_PAYLEN_SHIFT);



	/* Force memory writes to complete before letting h/w know there

	 * are new descriptors to fetch.  (Only applicable for weak-ordered

	 * memory model archs, such as IA-64).

	 *

	 * We also need this memory barrier to make certain all of the

	 * status bits have been updated before next_to_watch is written.

	 */

	wmb();

	/* Avoid any potential race with xdp_xmit and cleanup */

	smp_wmb();



	/* set next_to_watch value indicating a packet is present */

	i++;
@@ -8255,7 +8262,6 @@ static int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter, 
	tx_buffer->next_to_watch = tx_desc;

	ring->next_to_use = i;



	writel(i, ring->tail);

	return IXGBE_XDP_TX;

}