Commit f0064bfd authored by Björn Töpel's avatar Björn Töpel Committed by Tony Nguyen
Browse files

i40e: use 16B HW descriptors instead of 32B 



The i40e NIC supports two flavors of HW descriptors, 16 and 32
byte. The latter has, obviously, room for more offloading
information. However, the only fields of the 32B HW descriptor that is
being used by the driver, is also available in the 16B descriptor.

In other words; Reading and writing 32 bytes instead of 16 byte is a
waste of bus bandwidth.

This commit starts using 16 byte descriptors instead of 32 byte
descriptors.

For AF_XDP the rx_drop benchmark was improved by 2%.

Signed-off-by: default avatarBjörn Töpel <bjorn.topel@intel.com>
Tested-by: default avatarAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: default avatarTony Nguyen <anthony.l.nguyen@intel.com>
parent f78bd130

drivers/net/ethernet/intel/i40e/i40e.h

+1 −1
Original line number Diff line number Diff line
@@ -90,7 +90,7 @@ 
#define I40E_OEM_RELEASE_MASK		0x0000ffff



#define I40E_RX_DESC(R, i)	\

	(&(((union i40e_32byte_rx_desc *)((R)->desc))[i]))

	(&(((union i40e_rx_desc *)((R)->desc))[i]))

#define I40E_TX_DESC(R, i)	\

	(&(((struct i40e_tx_desc *)((R)->desc))[i]))

#define I40E_TX_CTXTDESC(R, i)	\

drivers/net/ethernet/intel/i40e/i40e_debugfs.c

+4 −6
Original line number Diff line number Diff line
@@ -604,10 +604,9 @@ static void i40e_dbg_dump_desc(int cnt, int vsi_seid, int ring_id, int desc_n, 
			} else {

				rxd = I40E_RX_DESC(ring, i);

				dev_info(&pf->pdev->dev,

					 "   d[%03x] = 0x%016llx 0x%016llx 0x%016llx 0x%016llx\n",

					 "   d[%03x] = 0x%016llx 0x%016llx\n",

					 i, rxd->read.pkt_addr,

					 rxd->read.hdr_addr,

					 rxd->read.rsvd1, rxd->read.rsvd2);

					 rxd->read.hdr_addr);

			}

		}

	} else if (cnt == 3) {
@@ -625,10 +624,9 @@ static void i40e_dbg_dump_desc(int cnt, int vsi_seid, int ring_id, int desc_n, 
		} else {

			rxd = I40E_RX_DESC(ring, desc_n);

			dev_info(&pf->pdev->dev,

				 "vsi = %02i rx ring = %02i d[%03x] = 0x%016llx 0x%016llx 0x%016llx 0x%016llx\n",

				 "vsi = %02i rx ring = %02i d[%03x] = 0x%016llx 0x%016llx\n",

				 vsi_seid, ring_id, desc_n,

				 rxd->read.pkt_addr, rxd->read.hdr_addr,

				 rxd->read.rsvd1, rxd->read.rsvd2);

				 rxd->read.pkt_addr, rxd->read.hdr_addr);

		}

	} else {

		dev_info(&pf->pdev->dev, "dump desc rx/tx/xdp <vsi_seid> <ring_id> [<desc_n>]\n");

drivers/net/ethernet/intel/i40e/i40e_main.c

+2 −2
Original line number Diff line number Diff line
@@ -3321,8 +3321,8 @@ static int i40e_configure_rx_ring(struct i40e_ring *ring) 
	rx_ctx.base = (ring->dma / 128);

	rx_ctx.qlen = ring->count;



	/* use 32 byte descriptors */

	rx_ctx.dsize = 1;

	/* use 16 byte descriptors */

	rx_ctx.dsize = 0;



	/* descriptor type is always zero

	 * rx_ctx.dtype = 0;

drivers/net/ethernet/intel/i40e/i40e_trace.h

+3 −3
Original line number Diff line number Diff line
@@ -112,7 +112,7 @@ DECLARE_EVENT_CLASS( 
	i40e_rx_template,



	TP_PROTO(struct i40e_ring *ring,

		 union i40e_32byte_rx_desc *desc,

		 union i40e_16byte_rx_desc *desc,

		 struct sk_buff *skb),



	TP_ARGS(ring, desc, skb),
@@ -140,7 +140,7 @@ DECLARE_EVENT_CLASS( 
DEFINE_EVENT(

	i40e_rx_template, i40e_clean_rx_irq,

	TP_PROTO(struct i40e_ring *ring,

		 union i40e_32byte_rx_desc *desc,

		 union i40e_16byte_rx_desc *desc,

		 struct sk_buff *skb),



	TP_ARGS(ring, desc, skb));
@@ -148,7 +148,7 @@ DEFINE_EVENT( 
DEFINE_EVENT(

	i40e_rx_template, i40e_clean_rx_irq_rx,

	TP_PROTO(struct i40e_ring *ring,

		 union i40e_32byte_rx_desc *desc,

		 union i40e_16byte_rx_desc *desc,

		 struct sk_buff *skb),



	TP_ARGS(ring, desc, skb));

drivers/net/ethernet/intel/i40e/i40e_txrx.c

+3 −3
Original line number Diff line number Diff line
@@ -533,11 +533,11 @@ static void i40e_fd_handle_status(struct i40e_ring *rx_ring, u64 qword0_raw, 
{

	struct i40e_pf *pf = rx_ring->vsi->back;

	struct pci_dev *pdev = pf->pdev;

	struct i40e_32b_rx_wb_qw0 *qw0;

	struct i40e_16b_rx_wb_qw0 *qw0;

	u32 fcnt_prog, fcnt_avail;

	u32 error;



	qw0 = (struct i40e_32b_rx_wb_qw0 *)&qword0_raw;

	qw0 = (struct i40e_16b_rx_wb_qw0 *)&qword0_raw;

	error = (qword1 & I40E_RX_PROG_STATUS_DESC_QW1_ERROR_MASK) >>

		I40E_RX_PROG_STATUS_DESC_QW1_ERROR_SHIFT;
@@ -1418,7 +1418,7 @@ int i40e_setup_rx_descriptors(struct i40e_ring *rx_ring) 
	u64_stats_init(&rx_ring->syncp);



	/* Round up to nearest 4K */

	rx_ring->size = rx_ring->count * sizeof(union i40e_32byte_rx_desc);

	rx_ring->size = rx_ring->count * sizeof(union i40e_rx_desc);

	rx_ring->size = ALIGN(rx_ring->size, 4096);

	rx_ring->desc = dma_alloc_coherent(dev, rx_ring->size,

					   &rx_ring->dma, GFP_KERNEL);