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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: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
Alexander Duyck 2017-02-06 18:25:41 -08:00 committed by Jeff Kirsher
parent 7bd1759282
commit 7ec0116c91
2 changed files with 9 additions and 7 deletions
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2
drivers/net/ethernet/intel/igb/igb_ethtool.c
View File

@ -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];

14
drivers/net/ethernet/intel/igb/igb_main.c
View File

@ -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);