ixgbe: Cleanup q_vector interrupt throttle rate logic

This patch is meant to help cleanup the interrupt throttle rate logic by
storing the interrupt throttle rate as a value in microseconds instead of
interrupts per second.  The advantage to this approach is that the value
can now be stored in an 16 bit field and doesn't require as much math to
flip the value back and forth since the hardware already used microseconds
when setting the rate.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 35 insertions, 42 deletions

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index c26ea9437fed..3594b09f4993 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -1500,12 +1500,19 @@ static void ixgbe_configure_msix(struct ixgbe_adapter *adapter)
 		for (ring = q_vector->tx.ring; ring != NULL; ring = ring->next)
 			ixgbe_set_ivar(adapter, 1, ring->reg_idx, v_idx);
 
-		if (q_vector->tx.ring && !q_vector->rx.ring)
-			/* tx only */
-			q_vector->eitr = adapter->tx_eitr_param;
-		else if (q_vector->rx.ring)
-			/* rx or mixed */
-			q_vector->eitr = adapter->rx_eitr_param;
+		if (q_vector->tx.ring && !q_vector->rx.ring) {
+			/* tx only vector */
+			if (adapter->tx_itr_setting == 1)
+				q_vector->itr = IXGBE_10K_ITR;
+			else
+				q_vector->itr = adapter->tx_itr_setting;
+		} else {
+			/* rx or rx/tx vector */
+			if (adapter->rx_itr_setting == 1)
+				q_vector->itr = IXGBE_20K_ITR;
+			else
+				q_vector->itr = adapter->rx_itr_setting;
+		}
 
 		ixgbe_write_eitr(q_vector);
 	}
@@ -1519,7 +1526,6 @@ static void ixgbe_configure_msix(struct ixgbe_adapter *adapter)
 	case ixgbe_mac_X540:
 		ixgbe_set_ivar(adapter, -1, 1, v_idx);
 		break;
-
 	default:
 		break;
 	}
@@ -1527,12 +1533,10 @@ static void ixgbe_configure_msix(struct ixgbe_adapter *adapter)
 
 	/* set up to autoclear timer, and the vectors */
 	mask = IXGBE_EIMS_ENABLE_MASK;
-	if (adapter->num_vfs)
-		mask &= ~(IXGBE_EIMS_OTHER |
-			  IXGBE_EIMS_MAILBOX |
-			  IXGBE_EIMS_LSC);
-	else
-		mask &= ~(IXGBE_EIMS_OTHER | IXGBE_EIMS_LSC);
+	mask &= ~(IXGBE_EIMS_OTHER |
+		  IXGBE_EIMS_MAILBOX |
+		  IXGBE_EIMS_LSC);
+
 	IXGBE_WRITE_REG(&adapter->hw, IXGBE_EIAC, mask);
 }
 
@@ -1577,7 +1581,7 @@ static void ixgbe_update_itr(struct ixgbe_q_vector *q_vector,
 	 *  100-1249MB/s bulk (8000 ints/s)
 	 */
 	/* what was last interrupt timeslice? */
-	timepassed_us = 1000000/q_vector->eitr;
+	timepassed_us = q_vector->itr >> 2;
 	bytes_perint = bytes / timepassed_us; /* bytes/usec */
 
 	switch (itr_setting) {
@@ -1618,7 +1622,7 @@ void ixgbe_write_eitr(struct ixgbe_q_vector *q_vector)
 	struct ixgbe_adapter *adapter = q_vector->adapter;
 	struct ixgbe_hw *hw = &adapter->hw;
 	int v_idx = q_vector->v_idx;
-	u32 itr_reg = EITR_INTS_PER_SEC_TO_REG(q_vector->eitr);
+	u32 itr_reg = q_vector->itr;
 
 	switch (adapter->hw.mac.type) {
 	case ixgbe_mac_82598EB:
@@ -1628,15 +1632,6 @@ void ixgbe_write_eitr(struct ixgbe_q_vector *q_vector)
 	case ixgbe_mac_82599EB:
 	case ixgbe_mac_X540:
 		/*
-		 * 82599 and X540 can support a value of zero, so allow it for
-		 * max interrupt rate, but there is an errata where it can
-		 * not be zero with RSC
-		 */
-		if (itr_reg == 8 &&
-		    !(adapter->flags2 & IXGBE_FLAG2_RSC_ENABLED))
-			itr_reg = 0;
-
-		/*
 		 * set the WDIS bit to not clear the timer bits and cause an
 		 * immediate assertion of the interrupt
 		 */
@@ -1650,7 +1645,7 @@ void ixgbe_write_eitr(struct ixgbe_q_vector *q_vector)
 
 static void ixgbe_set_itr(struct ixgbe_q_vector *q_vector)
 {
-	u32 new_itr = q_vector->eitr;
+	u32 new_itr = q_vector->itr;
 	u8 current_itr;
 
 	ixgbe_update_itr(q_vector, &q_vector->tx);
@@ -1661,24 +1656,25 @@ static void ixgbe_set_itr(struct ixgbe_q_vector *q_vector)
 	switch (current_itr) {
 	/* counts and packets in update_itr are dependent on these numbers */
 	case lowest_latency:
-		new_itr = 100000;
+		new_itr = IXGBE_100K_ITR;
 		break;
 	case low_latency:
-		new_itr = 20000; /* aka hwitr = ~200 */
+		new_itr = IXGBE_20K_ITR;
 		break;
 	case bulk_latency:
-		new_itr = 8000;
+		new_itr = IXGBE_8K_ITR;
 		break;
 	default:
 		break;
 	}
 
-	if (new_itr != q_vector->eitr) {
+	if (new_itr != q_vector->itr) {
 		/* do an exponential smoothing */
-		new_itr = ((q_vector->eitr * 9) + new_itr)/10;
+		new_itr = (10 * new_itr * q_vector->itr) /
+			  ((9 * new_itr) + q_vector->itr);
 
 		/* save the algorithm value here */
-		q_vector->eitr = new_itr;
+		q_vector->itr = new_itr & IXGBE_MAX_EITR;
 
 		ixgbe_write_eitr(q_vector);
 	}
@@ -2301,10 +2297,15 @@ static inline void ixgbe_irq_disable(struct ixgbe_adapter *adapter)
  **/
 static void ixgbe_configure_msi_and_legacy(struct ixgbe_adapter *adapter)
 {
-	struct ixgbe_hw *hw = &adapter->hw;
+	struct ixgbe_q_vector *q_vector = adapter->q_vector[0];
 
-	IXGBE_WRITE_REG(hw, IXGBE_EITR(0),
-			EITR_INTS_PER_SEC_TO_REG(adapter->rx_eitr_param));
+	/* rx/tx vector */
+	if (adapter->rx_itr_setting == 1)
+		q_vector->itr = IXGBE_20K_ITR;
+	else
+		q_vector->itr = adapter->rx_itr_setting;
+
+	ixgbe_write_eitr(q_vector);
 
 	ixgbe_set_ivar(adapter, 0, 0, 0);
 	ixgbe_set_ivar(adapter, 1, 0, 0);
@@ -4613,12 +4614,6 @@ static int ixgbe_alloc_q_vectors(struct ixgbe_adapter *adapter)
 		if (!alloc_cpumask_var(&q_vector->affinity_mask, GFP_KERNEL))
 			goto err_out;
 		cpumask_set_cpu(v_idx, q_vector->affinity_mask);
-
-		if (q_vector->tx.count && !q_vector->rx.count)
-			q_vector->eitr = adapter->tx_eitr_param;
-		else
-			q_vector->eitr = adapter->rx_eitr_param;
-
 		netif_napi_add(adapter->netdev, &q_vector->napi,
 			       ixgbe_poll, 64);
 		adapter->q_vector[v_idx] = q_vector;
@@ -4864,9 +4859,7 @@ static int __devinit ixgbe_sw_init(struct ixgbe_adapter *adapter)
 
 	/* enable itr by default in dynamic mode */
 	adapter->rx_itr_setting = 1;
-	adapter->rx_eitr_param = 20000;
 	adapter->tx_itr_setting = 1;
-	adapter->tx_eitr_param = 10000;
 
 	/* set defaults for eitr in MegaBytes */
 	adapter->eitr_low = 10;