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Commit 4b95fe3d authored by Emil Tantilov's avatar Emil Tantilov Committed by Jeff Kirsher
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ixgbevf: Update Rx next to clean in real time 



Since the next_to_clean value is only accessed by the Rx interrupt handler
we can save on stack space by just storing our updated values back in
next_to_clean instead of using the stack variable i.  This should help to
reduce stack space and we can further collapse the size of the function.

Also removed  non_eop_descs counter as it was never shown in the stats.

CC: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: default avatarEmil Tantilov <emil.s.tantilov@intel.com>
Tested-by: default avatarPhil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
parent 0579eefc

drivers/net/ethernet/intel/ixgbevf/ixgbevf.h

+0 −2
Original line number Diff line number Diff line
@@ -79,7 +79,6 @@ struct ixgbevf_tx_queue_stats { 
};



struct ixgbevf_rx_queue_stats {

	u64 non_eop_descs;

	u64 alloc_rx_page_failed;

	u64 alloc_rx_buff_failed;

	u64 csum_err;
@@ -372,7 +371,6 @@ struct ixgbevf_adapter { 
	struct ixgbevf_ring *rx_ring[MAX_TX_QUEUES]; /* One per active queue */

	u64 hw_csum_rx_error;

	u64 hw_rx_no_dma_resources;

	u64 non_eop_descs;

	int num_msix_vectors;

	u32 alloc_rx_page_failed;

	u32 alloc_rx_buff_failed;

drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c

+36 −19
Original line number Diff line number Diff line
@@ -410,6 +410,35 @@ static void ixgbevf_process_skb_fields(struct ixgbevf_ring *rx_ring, 
	skb->protocol = eth_type_trans(skb, rx_ring->netdev);

}



/**

 * ixgbevf_is_non_eop - process handling of non-EOP buffers

 * @rx_ring: Rx ring being processed

 * @rx_desc: Rx descriptor for current buffer

 * @skb: current socket buffer containing buffer in progress

 *

 * This function updates next to clean.  If the buffer is an EOP buffer

 * this function exits returning false, otherwise it will place the

 * sk_buff in the next buffer to be chained and return true indicating

 * that this is in fact a non-EOP buffer.

 **/

static bool ixgbevf_is_non_eop(struct ixgbevf_ring *rx_ring,

			       union ixgbe_adv_rx_desc *rx_desc,

			       struct sk_buff *skb)

{

	u32 ntc = rx_ring->next_to_clean + 1;



	/* fetch, update, and store next to clean */

	ntc = (ntc < rx_ring->count) ? ntc : 0;

	rx_ring->next_to_clean = ntc;



	prefetch(IXGBEVF_RX_DESC(rx_ring, ntc));



	if (likely(ixgbevf_test_staterr(rx_desc, IXGBE_RXD_STAT_EOP)))

		return false;



	return true;

}



static bool ixgbevf_alloc_mapped_skb(struct ixgbevf_ring *rx_ring,

				     struct ixgbevf_rx_buffer *bi)

{
@@ -517,16 +546,14 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector *q_vector, 
				struct ixgbevf_ring *rx_ring,

				int budget)

{

	unsigned int i;

	unsigned int total_rx_bytes = 0, total_rx_packets = 0;

	u16 cleaned_count = ixgbevf_desc_unused(rx_ring);



	i = rx_ring->next_to_clean;



	do {

		union ixgbe_adv_rx_desc *rx_desc, *next_rxd;

		union ixgbe_adv_rx_desc *rx_desc;

		struct ixgbevf_rx_buffer *rx_buffer;

		struct sk_buff *skb;

		u16 ntc;



		/* return some buffers to hardware, one at a time is too slow */

		if (cleaned_count >= IXGBEVF_RX_BUFFER_WRITE) {
@@ -534,8 +561,9 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector *q_vector, 
			cleaned_count = 0;

		}



		rx_desc = IXGBEVF_RX_DESC(rx_ring, i);

		rx_buffer = &rx_ring->rx_buffer_info[i];

		ntc = rx_ring->next_to_clean;

		rx_desc = IXGBEVF_RX_DESC(rx_ring, ntc);

		rx_buffer = &rx_ring->rx_buffer_info[ntc];



		if (!ixgbevf_test_staterr(rx_desc, IXGBE_RXD_STAT_DD))

			break;
@@ -562,19 +590,9 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector *q_vector, 


		cleaned_count++;



		i++;

		if (i == rx_ring->count)

			i = 0;



		next_rxd = IXGBEVF_RX_DESC(rx_ring, i);

		prefetch(next_rxd);



		if (!(ixgbevf_test_staterr(rx_desc, IXGBE_RXD_STAT_EOP))) {

			skb->next = rx_ring->rx_buffer_info[i].skb;

			IXGBE_CB(skb->next)->prev = skb;

			rx_ring->rx_stats.non_eop_descs++;

		/* place incomplete frames back on ring for completion */

		if (ixgbevf_is_non_eop(rx_ring, rx_desc, skb))

			continue;

		}



		/* we should not be chaining buffers, if we did drop the skb */

		if (IXGBE_CB(skb)->prev) {
@@ -617,7 +635,6 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector *q_vector, 
		budget--;

	} while (likely(budget));



	rx_ring->next_to_clean = i;

	u64_stats_update_begin(&rx_ring->syncp);

	rx_ring->stats.packets += total_rx_packets;

	rx_ring->stats.bytes += total_rx_bytes;