[NET-NEXT PATCH 1/2] igb: defeature tx head writeback

[NET-NEXT PATCH 1/2] igb: defeature tx head writeback

[Jeff Kirsher]

From: Alexander Duyck <alexander.h.duyck@intel.com>

This patch removes tx head writeback as it was found to not provide a
significant improvement in tx performance and on some systems has been seen
to cause a performance degredation due to partial cache line writes.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
---

 drivers/net/igb/e1000_defines.h |    1 
 drivers/net/igb/igb.h           |    5 +-
 drivers/net/igb/igb_main.c      |   85 +++++++++++++++++----------------------
 3 files changed, 39 insertions(+), 52 deletions(-)

diff --git a/drivers/net/igb/e1000_defines.h b/drivers/net/igb/e1000_defines.h
index c5fe784..40d0342 100644
--- a/drivers/net/igb/e1000_defines.h
+++ b/drivers/net/igb/e1000_defines.h
@@ -323,6 +323,7 @@
 #define E1000_TXD_CMD_IFCS   0x02000000 /* Insert FCS (Ethernet CRC) */
 #define E1000_TXD_CMD_RS     0x08000000 /* Report Status */
 #define E1000_TXD_CMD_DEXT   0x20000000 /* Descriptor extension (0 = legacy) */
+#define E1000_TXD_STAT_DD    0x00000001 /* Descriptor Done */
 /* Extended desc bits for Linksec and timesync */
 
 /* Transmit Control */
diff --git a/drivers/net/igb/igb.h b/drivers/net/igb/igb.h
index 2121b8b..c906325 100644
--- a/drivers/net/igb/igb.h
+++ b/drivers/net/igb/igb.h
@@ -43,8 +43,6 @@ struct igb_adapter;
 #endif
 
 /* Interrupt defines */
-#define IGB_MAX_TX_CLEAN 72
-
 #define IGB_MIN_DYN_ITR 3000
 #define IGB_MAX_DYN_ITR 96000
 
@@ -127,7 +125,8 @@ struct igb_buffer {
 		/* TX */
 		struct {
 			unsigned long time_stamp;
-			u32 length;
+			u16 length;
+			u16 next_to_watch;
 		};
 		/* RX */
 		struct {
diff --git a/drivers/net/igb/igb_main.c b/drivers/net/igb/igb_main.c
index 6a40d94..4962cdf 100644
--- a/drivers/net/igb/igb_main.c
+++ b/drivers/net/igb/igb_main.c
@@ -1575,8 +1575,7 @@ int igb_setup_tx_resources(struct igb_adapter *adapter,
 	memset(tx_ring->buffer_info, 0, size);
 
 	/* round up to nearest 4K */
-	tx_ring->size = tx_ring->count * sizeof(struct e1000_tx_desc)
-			+ sizeof(u32);
+	tx_ring->size = tx_ring->count * sizeof(struct e1000_tx_desc);
 	tx_ring->size = ALIGN(tx_ring->size, 4096);
 
 	tx_ring->desc = pci_alloc_consistent(pdev, tx_ring->size,
@@ -1635,7 +1634,7 @@ static int igb_setup_all_tx_resources(struct igb_adapter *adapter)
  **/
 static void igb_configure_tx(struct igb_adapter *adapter)
 {
-	u64 tdba, tdwba;
+	u64 tdba;
 	struct e1000_hw *hw = &adapter->hw;
 	u32 tctl;
 	u32 txdctl, txctrl;
@@ -1651,12 +1650,6 @@ static void igb_configure_tx(struct igb_adapter *adapter)
 				tdba & 0x00000000ffffffffULL);
 		wr32(E1000_TDBAH(i), tdba >> 32);
 
-		tdwba = ring->dma + ring->count * sizeof(struct e1000_tx_desc);
-		tdwba |= 1; /* enable head wb */
-		wr32(E1000_TDWBAL(i),
-				tdwba & 0x00000000ffffffffULL);
-		wr32(E1000_TDWBAH(i), tdwba >> 32);
-
 		ring->head = E1000_TDH(i);
 		ring->tail = E1000_TDT(i);
 		writel(0, hw->hw_addr + ring->tail);
@@ -2710,6 +2703,7 @@ static inline int igb_tso_adv(struct igb_adapter *adapter,
 	context_desc->seqnum_seed = 0;
 
 	buffer_info->time_stamp = jiffies;
+	buffer_info->next_to_watch = i;
 	buffer_info->dma = 0;
 	i++;
 	if (i == tx_ring->count)
@@ -2773,6 +2767,7 @@ static inline bool igb_tx_csum_adv(struct igb_adapter *adapter,
 				cpu_to_le32(tx_ring->queue_index << 4);
 
 		buffer_info->time_stamp = jiffies;
+		buffer_info->next_to_watch = i;
 		buffer_info->dma = 0;
 
 		i++;
@@ -2791,8 +2786,8 @@ static inline bool igb_tx_csum_adv(struct igb_adapter *adapter,
 #define IGB_MAX_DATA_PER_TXD	(1<<IGB_MAX_TXD_PWR)
 
 static inline int igb_tx_map_adv(struct igb_adapter *adapter,
-				 struct igb_ring *tx_ring,
-				 struct sk_buff *skb)
+				 struct igb_ring *tx_ring, struct sk_buff *skb,
+				 unsigned int first)
 {
 	struct igb_buffer *buffer_info;
 	unsigned int len = skb_headlen(skb);
@@ -2806,6 +2801,7 @@ static inline int igb_tx_map_adv(struct igb_adapter *adapter,
 	buffer_info->length = len;
 	/* set time_stamp *before* dma to help avoid a possible race */
 	buffer_info->time_stamp = jiffies;
+	buffer_info->next_to_watch = i;
 	buffer_info->dma = pci_map_single(adapter->pdev, skb->data, len,
 					  PCI_DMA_TODEVICE);
 	count++;
@@ -2823,6 +2819,7 @@ static inline int igb_tx_map_adv(struct igb_adapter *adapter,
 		BUG_ON(len >= IGB_MAX_DATA_PER_TXD);
 		buffer_info->length = len;
 		buffer_info->time_stamp = jiffies;
+		buffer_info->next_to_watch = i;
 		buffer_info->dma = pci_map_page(adapter->pdev,
 						frag->page,
 						frag->page_offset,
@@ -2835,8 +2832,9 @@ static inline int igb_tx_map_adv(struct igb_adapter *adapter,
 			i = 0;
 	}
 
-	i = (i == 0) ? tx_ring->count - 1 : i - 1;
+	i = ((i == 0) ? tx_ring->count - 1 : i - 1);
 	tx_ring->buffer_info[i].skb = skb;
+	tx_ring->buffer_info[first].next_to_watch = i;
 
 	return count;
 }
@@ -2943,6 +2941,7 @@ static int igb_xmit_frame_ring_adv(struct sk_buff *skb,
 				   struct igb_ring *tx_ring)
 {
 	struct igb_adapter *adapter = netdev_priv(netdev);
+	unsigned int first;
 	unsigned int tx_flags = 0;
 	unsigned int len;
 	u8 hdr_len = 0;
@@ -2979,6 +2978,8 @@ static int igb_xmit_frame_ring_adv(struct sk_buff *skb,
 	if (skb->protocol == htons(ETH_P_IP))
 		tx_flags |= IGB_TX_FLAGS_IPV4;
 
+	first = tx_ring->next_to_use;
+
 	tso = skb_is_gso(skb) ? igb_tso_adv(adapter, tx_ring, skb, tx_flags,
 					      &hdr_len) : 0;
 
@@ -2994,7 +2995,7 @@ static int igb_xmit_frame_ring_adv(struct sk_buff *skb,
 				tx_flags |= IGB_TX_FLAGS_CSUM;
 
 	igb_tx_queue_adv(adapter, tx_ring, tx_flags,
-			 igb_tx_map_adv(adapter, tx_ring, skb),
+			 igb_tx_map_adv(adapter, tx_ring, skb, first),
 			 skb->len, hdr_len);
 
 	netdev->trans_start = jiffies;
@@ -3617,12 +3618,6 @@ static int igb_clean_rx_ring_msix(struct napi_struct *napi, int budget)
 	return 1;
 }
 
-static inline u32 get_head(struct igb_ring *tx_ring)
-{
-	void *end = (struct e1000_tx_desc *)tx_ring->desc + tx_ring->count;
-	return le32_to_cpu(*(volatile __le32 *)end);
-}
-
 /**
  * igb_clean_tx_irq - Reclaim resources after transmit completes
  * @adapter: board private structure
@@ -3631,24 +3626,25 @@ static inline u32 get_head(struct igb_ring *tx_ring)
 static bool igb_clean_tx_irq(struct igb_ring *tx_ring)
 {
 	struct igb_adapter *adapter = tx_ring->adapter;
-	struct e1000_hw *hw = &adapter->hw;
 	struct net_device *netdev = adapter->netdev;
-	struct e1000_tx_desc *tx_desc;
+	struct e1000_hw *hw = &adapter->hw;
 	struct igb_buffer *buffer_info;
 	struct sk_buff *skb;
-	unsigned int i;
-	u32 head, oldhead;
-	unsigned int count = 0;
+	union e1000_adv_tx_desc *tx_desc, *eop_desc;
 	unsigned int total_bytes = 0, total_packets = 0;
-	bool retval = true;
+	unsigned int i, eop, count = 0;
+	bool cleaned = false;
 
-	rmb();
-	head = get_head(tx_ring);
 	i = tx_ring->next_to_clean;
-	while (1) {
-		while (i != head) {
-			tx_desc = E1000_TX_DESC(*tx_ring, i);
+	eop = tx_ring->buffer_info[i].next_to_watch;
+	eop_desc = E1000_TX_DESC_ADV(*tx_ring, eop);
+
+	while ((eop_desc->wb.status & cpu_to_le32(E1000_TXD_STAT_DD)) &&
+	       (count < tx_ring->count)) {
+		for (cleaned = false; !cleaned; count++) {
+			tx_desc = E1000_TX_DESC_ADV(*tx_ring, i);
 			buffer_info = &tx_ring->buffer_info[i];
+			cleaned = (i == eop);
 			skb = buffer_info->skb;
 
 			if (skb) {
@@ -3663,25 +3659,17 @@ static bool igb_clean_tx_irq(struct igb_ring *tx_ring)
 			}
 
 			igb_unmap_and_free_tx_resource(adapter, buffer_info);
+			tx_desc->wb.status = 0;
 
 			i++;
 			if (i == tx_ring->count)
 				i = 0;
-
-			count++;
-			if (count == IGB_MAX_TX_CLEAN) {
-				retval = false;
-				goto done_cleaning;
-			}
 		}
-		oldhead = head;
-		rmb();
-		head = get_head(tx_ring);
-		if (head == oldhead)
-			goto done_cleaning;
-	}  /* while (1) */
-
-done_cleaning:
+
+		eop = tx_ring->buffer_info[i].next_to_watch;
+		eop_desc = E1000_TX_DESC_ADV(*tx_ring, eop);
+	}
+
 	tx_ring->next_to_clean = i;
 
 	if (unlikely(count &&
@@ -3708,7 +3696,6 @@ done_cleaning:
 		    && !(rd32(E1000_STATUS) &
 			 E1000_STATUS_TXOFF)) {
 
-			tx_desc = E1000_TX_DESC(*tx_ring, i);
 			/* detected Tx unit hang */
 			dev_err(&adapter->pdev->dev,
 				"Detected Tx Unit Hang\n"
@@ -3717,9 +3704,9 @@ done_cleaning:
 				"  TDT                  <%x>\n"
 				"  next_to_use          <%x>\n"
 				"  next_to_clean        <%x>\n"
-				"  head (WB)            <%x>\n"
 				"buffer_info[next_to_clean]\n"
 				"  time_stamp           <%lx>\n"
+				"  next_to_watch        <%x>\n"
 				"  jiffies              <%lx>\n"
 				"  desc.status          <%x>\n",
 				tx_ring->queue_index,
@@ -3727,10 +3714,10 @@ done_cleaning:
 				readl(adapter->hw.hw_addr + tx_ring->tail),
 				tx_ring->next_to_use,
 				tx_ring->next_to_clean,
-				head,
 				tx_ring->buffer_info[i].time_stamp,
+				eop,
 				jiffies,
-				tx_desc->upper.fields.status);
+				eop_desc->wb.status);
 			netif_stop_subqueue(netdev, tx_ring->queue_index);
 		}
 	}
@@ -3740,7 +3727,7 @@ done_cleaning:
 	tx_ring->tx_stats.packets += total_packets;
 	adapter->net_stats.tx_bytes += total_bytes;
 	adapter->net_stats.tx_packets += total_packets;
-	return retval;
+	return (count < tx_ring->count);
 }
 
 #ifdef CONFIG_IGB_LRO

[NET-NEXT PATCH 2/2] igb: re-order queues to support cleaner use of ivar on 82576

[Jeff Kirsher]

From: Alexander Duyck <alexander.h.duyck@intel.com>

The 82576 adapter orders the queues in pairs when virtualization is in use.
The queue ordering previously conflicted with the ordering when sr-iov was
enabled.  This new ordering allows a PF to allocate 2 queues without using
any VF resources.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
---

 drivers/net/igb/igb.h      |    3 +
 drivers/net/igb/igb_main.c |  115 +++++++++++++++++++++++++++++---------------
 2 files changed, 79 insertions(+), 39 deletions(-)

diff --git a/drivers/net/igb/igb.h b/drivers/net/igb/igb.h
index c906325..5a27825 100644
--- a/drivers/net/igb/igb.h
+++ b/drivers/net/igb/igb.h
@@ -159,7 +159,8 @@ struct igb_ring {
 	u16 itr_register;
 	u16 cpu;
 
-	int queue_index;
+	u16 queue_index;
+	u16 reg_idx;
 	unsigned int total_bytes;
 	unsigned int total_packets;
 
diff --git a/drivers/net/igb/igb_main.c b/drivers/net/igb/igb_main.c
index 4962cdf..9331e52 100644
--- a/drivers/net/igb/igb_main.c
+++ b/drivers/net/igb/igb_main.c
@@ -231,6 +231,40 @@ static void __exit igb_exit_module(void)
 
 module_exit(igb_exit_module);
 
+#define Q_IDX_82576(i) (((i & 0x1) << 3) + (i >> 1))
+/**
+ * igb_cache_ring_register - Descriptor ring to register mapping
+ * @adapter: board private structure to initialize
+ *
+ * Once we know the feature-set enabled for the device, we'll cache
+ * the register offset the descriptor ring is assigned to.
+ **/
+static void igb_cache_ring_register(struct igb_adapter *adapter)
+{
+	int i;
+
+	switch (adapter->hw.mac.type) {
+	case e1000_82576:
+		/* The queues are allocated for virtualization such that VF 0
+		 * is allocated queues 0 and 8, VF 1 queues 1 and 9, etc.
+		 * In order to avoid collision we start at the first free queue
+		 * and continue consuming queues in the same sequence
+		 */
+		for (i = 0; i < adapter->num_rx_queues; i++)
+			adapter->rx_ring[i].reg_idx = Q_IDX_82576(i);
+		for (i = 0; i < adapter->num_tx_queues; i++)
+			adapter->tx_ring[i].reg_idx = Q_IDX_82576(i);
+		break;
+	case e1000_82575:
+	default:
+		for (i = 0; i < adapter->num_rx_queues; i++)
+			adapter->rx_ring[i].reg_idx = i;
+		for (i = 0; i < adapter->num_tx_queues; i++)
+			adapter->tx_ring[i].reg_idx = i;
+		break;
+	}
+}
+
 /**
  * igb_alloc_queues - Allocate memory for all rings
  * @adapter: board private structure to initialize
@@ -272,6 +306,8 @@ static int igb_alloc_queues(struct igb_adapter *adapter)
 		/* set a default napi handler for each rx_ring */
 		netif_napi_add(adapter->netdev, &ring->napi, igb_poll, 64);
 	}
+
+	igb_cache_ring_register(adapter);
 	return 0;
 }
 
@@ -312,36 +348,36 @@ static void igb_assign_vector(struct igb_adapter *adapter, int rx_queue,
 		array_wr32(E1000_MSIXBM(0), msix_vector, msixbm);
 		break;
 	case e1000_82576:
-		/* The 82576 uses a table-based method for assigning vectors.
+		/* 82576 uses a table-based method for assigning vectors.
 		   Each queue has a single entry in the table to which we write
 		   a vector number along with a "valid" bit.  Sadly, the layout
 		   of the table is somewhat counterintuitive. */
 		if (rx_queue > IGB_N0_QUEUE) {
-			index = (rx_queue & 0x7);
+			index = (rx_queue >> 1);
 			ivar = array_rd32(E1000_IVAR0, index);
-			if (rx_queue < 8) {
-				/* vector goes into low byte of register */
-				ivar = ivar & 0xFFFFFF00;
-				ivar |= msix_vector | E1000_IVAR_VALID;
-			} else {
+			if (rx_queue & 0x1) {
 				/* vector goes into third byte of register */
 				ivar = ivar & 0xFF00FFFF;
 				ivar |= (msix_vector | E1000_IVAR_VALID) << 16;
+			} else {
+				/* vector goes into low byte of register */
+				ivar = ivar & 0xFFFFFF00;
+				ivar |= msix_vector | E1000_IVAR_VALID;
 			}
 			adapter->rx_ring[rx_queue].eims_value= 1 << msix_vector;
 			array_wr32(E1000_IVAR0, index, ivar);
 		}
 		if (tx_queue > IGB_N0_QUEUE) {
-			index = (tx_queue & 0x7);
+			index = (tx_queue >> 1);
 			ivar = array_rd32(E1000_IVAR0, index);
-			if (tx_queue < 8) {
-				/* vector goes into second byte of register */
-				ivar = ivar & 0xFFFF00FF;
-				ivar |= (msix_vector | E1000_IVAR_VALID) << 8;
-			} else {
+			if (tx_queue & 0x1) {
 				/* vector goes into high byte of register */
 				ivar = ivar & 0x00FFFFFF;
 				ivar |= (msix_vector | E1000_IVAR_VALID) << 24;
+			} else {
+				/* vector goes into second byte of register */
+				ivar = ivar & 0xFFFF00FF;
+				ivar |= (msix_vector | E1000_IVAR_VALID) << 8;
 			}
 			adapter->tx_ring[tx_queue].eims_value= 1 << msix_vector;
 			array_wr32(E1000_IVAR0, index, ivar);
@@ -1638,33 +1674,33 @@ static void igb_configure_tx(struct igb_adapter *adapter)
 	struct e1000_hw *hw = &adapter->hw;
 	u32 tctl;
 	u32 txdctl, txctrl;
-	int i;
+	int i, j;
 
 	for (i = 0; i < adapter->num_tx_queues; i++) {
 		struct igb_ring *ring = &(adapter->tx_ring[i]);
-
-		wr32(E1000_TDLEN(i),
+		j = ring->reg_idx;
+		wr32(E1000_TDLEN(j),
 				ring->count * sizeof(struct e1000_tx_desc));
 		tdba = ring->dma;
-		wr32(E1000_TDBAL(i),
+		wr32(E1000_TDBAL(j),
 				tdba & 0x00000000ffffffffULL);
-		wr32(E1000_TDBAH(i), tdba >> 32);
+		wr32(E1000_TDBAH(j), tdba >> 32);
 
-		ring->head = E1000_TDH(i);
-		ring->tail = E1000_TDT(i);
+		ring->head = E1000_TDH(j);
+		ring->tail = E1000_TDT(j);
 		writel(0, hw->hw_addr + ring->tail);
 		writel(0, hw->hw_addr + ring->head);
-		txdctl = rd32(E1000_TXDCTL(i));
+		txdctl = rd32(E1000_TXDCTL(j));
 		txdctl |= E1000_TXDCTL_QUEUE_ENABLE;
-		wr32(E1000_TXDCTL(i), txdctl);
+		wr32(E1000_TXDCTL(j), txdctl);
 
 		/* Turn off Relaxed Ordering on head write-backs.  The
 		 * writebacks MUST be delivered in order or it will
 		 * completely screw up our bookeeping.
 		 */
-		txctrl = rd32(E1000_DCA_TXCTRL(i));
+		txctrl = rd32(E1000_DCA_TXCTRL(j));
 		txctrl &= ~E1000_DCA_TXCTRL_TX_WB_RO_EN;
-		wr32(E1000_DCA_TXCTRL(i), txctrl);
+		wr32(E1000_DCA_TXCTRL(j), txctrl);
 	}
 
 
@@ -1781,7 +1817,7 @@ static void igb_setup_rctl(struct igb_adapter *adapter)
 	struct e1000_hw *hw = &adapter->hw;
 	u32 rctl;
 	u32 srrctl = 0;
-	int i;
+	int i, j;
 
 	rctl = rd32(E1000_RCTL);
 
@@ -1839,8 +1875,10 @@ static void igb_setup_rctl(struct igb_adapter *adapter)
 		srrctl |= E1000_SRRCTL_DESCTYPE_ADV_ONEBUF;
 	}
 
-	for (i = 0; i < adapter->num_rx_queues; i++)
-		wr32(E1000_SRRCTL(i), srrctl);
+	for (i = 0; i < adapter->num_rx_queues; i++) {
+		j = adapter->rx_ring[i].reg_idx;
+		wr32(E1000_SRRCTL(j), srrctl);
+	}
 
 	wr32(E1000_RCTL, rctl);
 }
@@ -1857,7 +1895,7 @@ static void igb_configure_rx(struct igb_adapter *adapter)
 	struct e1000_hw *hw = &adapter->hw;
 	u32 rctl, rxcsum;
 	u32 rxdctl;
-	int i;
+	int i, j;
 
 	/* disable receives while setting up the descriptors */
 	rctl = rd32(E1000_RCTL);
@@ -1872,25 +1910,26 @@ static void igb_configure_rx(struct igb_adapter *adapter)
 	 * the Base and Length of the Rx Descriptor Ring */
 	for (i = 0; i < adapter->num_rx_queues; i++) {
 		struct igb_ring *ring = &(adapter->rx_ring[i]);
+		j = ring->reg_idx;
 		rdba = ring->dma;
-		wr32(E1000_RDBAL(i),
+		wr32(E1000_RDBAL(j),
 				rdba & 0x00000000ffffffffULL);
-		wr32(E1000_RDBAH(i), rdba >> 32);
-		wr32(E1000_RDLEN(i),
+		wr32(E1000_RDBAH(j), rdba >> 32);
+		wr32(E1000_RDLEN(j),
 			       ring->count * sizeof(union e1000_adv_rx_desc));
 
-		ring->head = E1000_RDH(i);
-		ring->tail = E1000_RDT(i);
+		ring->head = E1000_RDH(j);
+		ring->tail = E1000_RDT(j);
 		writel(0, hw->hw_addr + ring->tail);
 		writel(0, hw->hw_addr + ring->head);
 
-		rxdctl = rd32(E1000_RXDCTL(i));
+		rxdctl = rd32(E1000_RXDCTL(j));
 		rxdctl |= E1000_RXDCTL_QUEUE_ENABLE;
 		rxdctl &= 0xFFF00000;
 		rxdctl |= IGB_RX_PTHRESH;
 		rxdctl |= IGB_RX_HTHRESH << 8;
 		rxdctl |= IGB_RX_WTHRESH << 16;
-		wr32(E1000_RXDCTL(i), rxdctl);
+		wr32(E1000_RXDCTL(j), rxdctl);
 #ifdef CONFIG_IGB_LRO
 		/* Intitial LRO Settings */
 		ring->lro_mgr.max_aggr = MAX_LRO_AGGR;
@@ -1920,7 +1959,7 @@ static void igb_configure_rx(struct igb_adapter *adapter)
 			shift = 6;
 		for (j = 0; j < (32 * 4); j++) {
 			reta.bytes[j & 3] =
-				(j % adapter->num_rx_queues) << shift;
+				adapter->rx_ring[(j % adapter->num_rx_queues)].reg_idx << shift;
 			if ((j & 3) == 3)
 				writel(reta.dword,
 				       hw->hw_addr + E1000_RETA(0) + (j & ~3));
@@ -3365,7 +3404,7 @@ static void igb_update_rx_dca(struct igb_ring *rx_ring)
 	struct igb_adapter *adapter = rx_ring->adapter;
 	struct e1000_hw *hw = &adapter->hw;
 	int cpu = get_cpu();
-	int q = rx_ring - adapter->rx_ring;
+	int q = rx_ring->reg_idx;
 
 	if (rx_ring->cpu != cpu) {
 		dca_rxctrl = rd32(E1000_DCA_RXCTRL(q));
@@ -3392,7 +3431,7 @@ static void igb_update_tx_dca(struct igb_ring *tx_ring)
 	struct igb_adapter *adapter = tx_ring->adapter;
 	struct e1000_hw *hw = &adapter->hw;
 	int cpu = get_cpu();
-	int q = tx_ring - adapter->tx_ring;
+	int q = tx_ring->reg_idx;
 
 	if (tx_ring->cpu != cpu) {
 		dca_txctrl = rd32(E1000_DCA_TXCTRL(q));

Re: [NET-NEXT PATCH 1/2] igb: defeature tx head writeback

[Joe Perches]

On Wed, 2008-12-24 at 14:31 -0800, Jeff Kirsher wrote:
> diff --git a/drivers/net/igb/igb.h b/drivers/net/igb/igb.h
> index 2121b8b..c906325 100644
> --- a/drivers/net/igb/igb.h
> +++ b/drivers/net/igb/igb.h
[]
> @@ -127,7 +125,8 @@ struct igb_buffer {
>  		/* TX */
>  		struct {
>  			unsigned long time_stamp;
> -			u32 length;
> +			u16 length;
> +			u16 next_to_watch;
>  		};
>  		/* RX */
>  		struct {

struct igb_buffer {
	struct sk_buff *skb;
	dma_addr_t dma;
	union {
		/* TX */
		struct {
			unsigned long time_stamp;
			u32 length;
		};
		/* RX */
		struct {
			struct page *page;
			u64 page_dma;
			unsigned int page_offset;
		};
	};
};

anonymous unions with anonymous structs?
That's not used very often in kernel source.
Should it be used here?

Re: [NET-NEXT PATCH 1/2] igb: defeature tx head writeback

[David Miller]

From: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Date: Wed, 24 Dec 2008 14:31:42 -0800

> This patch removes tx head writeback as it was found to not provide a
> significant improvement in tx performance and on some systems has been seen
> to cause a performance degredation due to partial cache line writes.
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Applied.

Re: [NET-NEXT PATCH 2/2] igb: re-order queues to support cleaner use of ivar on 82576

[David Miller]

From: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Date: Wed, 24 Dec 2008 14:32:01 -0800

> The 82576 adapter orders the queues in pairs when virtualization is in use.
> The queue ordering previously conflicted with the ordering when sr-iov was
> enabled.  This new ordering allows a PF to allocate 2 queues without using
> any VF resources.
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Applied.