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Commit 7ec0116c authored by Alexander Duyck's avatar Alexander Duyck Committed by Jeff Kirsher
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igb: Use length to determine if descriptor is done 



This change makes it so that we use the length of the packet instead of the
DD status bit to determine if a new descriptor is ready to be processed.
The obvious advantage is that it cuts down on reads as we don't really even
need the DD bit if going from a 0 to a non-zero value on size is enough to
inform us that the packet has been completed.

In addition I have updated the code so that we only reset the Rx descriptor
length for descriptor zero when resetting a ring instead of having to do a
memset with 0 over the entire ring.  By doing this we can save some time on
initialization.

Signed-off-by: default avatarAlexander Duyck <alexander.h.duyck@intel.com>
Tested-by: default avatarAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
parent 7bd17592

drivers/net/ethernet/intel/igb/igb_ethtool.c

+1 −1
Original line number Diff line number Diff line
@@ -1811,7 +1811,7 @@ static int igb_clean_test_rings(struct igb_ring *rx_ring, 
	tx_ntc = tx_ring->next_to_clean;

	rx_desc = IGB_RX_DESC(rx_ring, rx_ntc);



	while (igb_test_staterr(rx_desc, E1000_RXD_STAT_DD)) {

	while (rx_desc->wb.upper.length) {

		/* check Rx buffer */

		rx_buffer_info = &rx_ring->rx_buffer_info[rx_ntc];

drivers/net/ethernet/intel/igb/igb_main.c

+8 −6
Original line number Diff line number Diff line
@@ -3720,6 +3720,7 @@ void igb_configure_rx_ring(struct igb_adapter *adapter, 
			   struct igb_ring *ring)

{

	struct e1000_hw *hw = &adapter->hw;

	union e1000_adv_rx_desc *rx_desc;

	u64 rdba = ring->dma;

	int reg_idx = ring->reg_idx;

	u32 srrctl = 0, rxdctl = 0;
@@ -3758,6 +3759,10 @@ void igb_configure_rx_ring(struct igb_adapter *adapter, 
	rxdctl |= IGB_RX_HTHRESH << 8;

	rxdctl |= IGB_RX_WTHRESH << 16;



	/* initialize Rx descriptor 0 */

	rx_desc = IGB_RX_DESC(ring, 0);

	rx_desc->wb.upper.length = 0;



	/* enable receive descriptor fetching */

	rxdctl |= E1000_RXDCTL_QUEUE_ENABLE;

	wr32(E1000_RXDCTL(reg_idx), rxdctl);
@@ -3973,9 +3978,6 @@ static void igb_clean_rx_ring(struct igb_ring *rx_ring) 
	size = sizeof(struct igb_rx_buffer) * rx_ring->count;

	memset(rx_ring->rx_buffer_info, 0, size);



	/* Zero out the descriptor ring */

	memset(rx_ring->desc, 0, rx_ring->size);



	rx_ring->next_to_alloc = 0;

	rx_ring->next_to_clean = 0;

	rx_ring->next_to_use = 0;
@@ -7172,7 +7174,7 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget) 


		rx_desc = IGB_RX_DESC(rx_ring, rx_ring->next_to_clean);



		if (!rx_desc->wb.upper.status_error)

		if (!rx_desc->wb.upper.length)

			break;



		/* This memory barrier is needed to keep us from reading
@@ -7312,8 +7314,8 @@ void igb_alloc_rx_buffers(struct igb_ring *rx_ring, u16 cleaned_count) 
			i -= rx_ring->count;

		}



		/* clear the status bits for the next_to_use descriptor */

		rx_desc->wb.upper.status_error = 0;

		/* clear the length for the next_to_use descriptor */

		rx_desc->wb.upper.length = 0;



		cleaned_count--;

	} while (cleaned_count);