igb: Improve multiqueue AIM support

Improve multiqueue performance
Change itr_val to reflect ITR timer value instead of ints/sec
Cleaned up AIM algorithms in general

Based on work by Mitch Williams

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 97 insertions, 72 deletions

diff --git a/drivers/net/igb/igb_main.c b/drivers/net/igb/igb_main.c
index 2a5303c311bc..aaed129f4ca0 100644
--- a/drivers/net/igb/igb_main.c
+++ b/drivers/net/igb/igb_main.c
@@ -255,6 +255,8 @@ static int igb_alloc_queues(struct igb_adapter *adapter)
                 return -ENOMEM;
         }
 
+        adapter->rx_ring->buddy = adapter->tx_ring;
+
         for (i = 0; i < adapter->num_tx_queues; i++) {
                 struct igb_ring *ring = &(adapter->tx_ring[i]);
                 ring->adapter = adapter;
@@ -375,7 +377,7 @@ static void igb_configure_msix(struct igb_adapter *adapter)
                 igb_assign_vector(adapter, IGB_N0_QUEUE, i, vector++);
                 adapter->eims_enable_mask |= tx_ring->eims_value;
                 if (tx_ring->itr_val)
-                        writel(1000000000 / (tx_ring->itr_val * 256),
+                        writel(tx_ring->itr_val,
                                hw->hw_addr + tx_ring->itr_register);
                 else
                         writel(1, hw->hw_addr + tx_ring->itr_register);
@@ -383,10 +385,11 @@ static void igb_configure_msix(struct igb_adapter *adapter)
 
         for (i = 0; i < adapter->num_rx_queues; i++) {
                 struct igb_ring *rx_ring = &adapter->rx_ring[i];
+                rx_ring->buddy = 0;
                 igb_assign_vector(adapter, i, IGB_N0_QUEUE, vector++);
                 adapter->eims_enable_mask |= rx_ring->eims_value;
                 if (rx_ring->itr_val)
-                        writel(1000000000 / (rx_ring->itr_val * 256),
+                        writel(rx_ring->itr_val,
                                hw->hw_addr + rx_ring->itr_register);
                 else
                         writel(1, hw->hw_addr + rx_ring->itr_register);
@@ -449,7 +452,7 @@ static int igb_request_msix(struct igb_adapter *adapter)
                 if (err)
                         goto out;
                 ring->itr_register = E1000_EITR(0) + (vector << 2);
-                ring->itr_val = adapter->itr;
+                ring->itr_val = 976; /* ~4000 ints/sec */
                 vector++;
         }
         for (i = 0; i < adapter->num_rx_queues; i++) {
@@ -1898,8 +1901,7 @@ static void igb_configure_rx(struct igb_adapter *adapter)
         mdelay(10);
 
         if (adapter->itr_setting > 3)
-                wr32(E1000_ITR,
-                                1000000000 / (adapter->itr * 256));
+                wr32(E1000_ITR, adapter->itr);
 
         /* Setup the HW Rx Head and Tail Descriptor Pointers and
          * the Base and Length of the Rx Descriptor Ring */
@@ -2463,38 +2465,60 @@ enum latency_range {
 };
 
 
-static void igb_lower_rx_eitr(struct igb_adapter *adapter,
-                              struct igb_ring *rx_ring)
+/**
+ * igb_update_ring_itr - update the dynamic ITR value based on packet size
+ *
+ *      Stores a new ITR value based on strictly on packet size.  This
+ *      algorithm is less sophisticated than that used in igb_update_itr,
+ *      due to the difficulty of synchronizing statistics across multiple
+ *      receive rings.  The divisors and thresholds used by this fuction
+ *      were determined based on theoretical maximum wire speed and testing
+ *      data, in order to minimize response time while increasing bulk
+ *      throughput.
+ *      This functionality is controlled by the InterruptThrottleRate module
+ *      parameter (see igb_param.c)
+ *      NOTE:  This function is called only when operating in a multiqueue
+ *             receive environment.
+ * @rx_ring: pointer to ring
+ **/
+static void igb_update_ring_itr(struct igb_ring *rx_ring)
 {
-        struct e1000_hw *hw = &adapter->hw;
-        int new_val;
+        int new_val = rx_ring->itr_val;
+        int avg_wire_size = 0;
+        struct igb_adapter *adapter = rx_ring->adapter;
 
-        new_val = rx_ring->itr_val / 2;
-        if (new_val < IGB_MIN_DYN_ITR)
-                new_val = IGB_MIN_DYN_ITR;
+        if (!rx_ring->total_packets)
+                goto clear_counts; /* no packets, so don't do anything */
 
-        if (new_val != rx_ring->itr_val) {
-                rx_ring->itr_val = new_val;
-                wr32(rx_ring->itr_register,
-                                1000000000 / (new_val * 256));
+        /* For non-gigabit speeds, just fix the interrupt rate at 4000
+         * ints/sec - ITR timer value of 120 ticks.
+         */
+        if (adapter->link_speed != SPEED_1000) {
+                new_val = 120;
+                goto set_itr_val;
         }
-}
+        avg_wire_size = rx_ring->total_bytes / rx_ring->total_packets;
 
-static void igb_raise_rx_eitr(struct igb_adapter *adapter,
-                              struct igb_ring *rx_ring)
-{
-        struct e1000_hw *hw = &adapter->hw;
-        int new_val;
+        /* Add 24 bytes to size to account for CRC, preamble, and gap */
+        avg_wire_size += 24;
+
+        /* Don't starve jumbo frames */
+        avg_wire_size = min(avg_wire_size, 3000);
 
-        new_val = rx_ring->itr_val * 2;
-        if (new_val > IGB_MAX_DYN_ITR)
-                new_val = IGB_MAX_DYN_ITR;
+        /* Give a little boost to mid-size frames */
+        if ((avg_wire_size > 300) && (avg_wire_size < 1200))
+                new_val = avg_wire_size / 3;
+        else
+                new_val = avg_wire_size / 2;
 
+set_itr_val:
         if (new_val != rx_ring->itr_val) {
                 rx_ring->itr_val = new_val;
-                wr32(rx_ring->itr_register,
-                                1000000000 / (new_val * 256));
+                rx_ring->set_itr = 1;
         }
+clear_counts:
+        rx_ring->total_bytes = 0;
+        rx_ring->total_packets = 0;
 }
 
 /**
@@ -2561,8 +2585,7 @@ update_itr_done:
         return retval;
 }
 
-static void igb_set_itr(struct igb_adapter *adapter, u16 itr_register,
-                        int rx_only)
+static void igb_set_itr(struct igb_adapter *adapter)
 {
         u16 current_itr;
         u32 new_itr = adapter->itr;
@@ -2578,26 +2601,23 @@ static void igb_set_itr(struct igb_adapter *adapter, u16 itr_register,
                                     adapter->rx_itr,
                                     adapter->rx_ring->total_packets,
                                     adapter->rx_ring->total_bytes);
-        /* conservative mode (itr 3) eliminates the lowest_latency setting */
-        if (adapter->itr_setting == 3 && adapter->rx_itr == lowest_latency)
-                adapter->rx_itr = low_latency;
 
-        if (!rx_only) {
+        if (adapter->rx_ring->buddy) {
                 adapter->tx_itr = igb_update_itr(adapter,
                                             adapter->tx_itr,
                                             adapter->tx_ring->total_packets,
                                             adapter->tx_ring->total_bytes);
-                /* conservative mode (itr 3) eliminates the
-                 * lowest_latency setting */
-                if (adapter->itr_setting == 3 &&
-                    adapter->tx_itr == lowest_latency)
-                        adapter->tx_itr = low_latency;
 
                 current_itr = max(adapter->rx_itr, adapter->tx_itr);
         } else {
                 current_itr = adapter->rx_itr;
         }
 
+        /* conservative mode (itr 3) eliminates the lowest_latency setting */
+        if (adapter->itr_setting == 3 &&
+            current_itr == lowest_latency)
+                current_itr = low_latency;
+
         switch (current_itr) {
         /* counts and packets in update_itr are dependent on these numbers */
         case lowest_latency:
@@ -2614,6 +2634,13 @@ static void igb_set_itr(struct igb_adapter *adapter, u16 itr_register,
         }
 
 set_itr_now:
+        adapter->rx_ring->total_bytes = 0;
+        adapter->rx_ring->total_packets = 0;
+        if (adapter->rx_ring->buddy) {
+                adapter->rx_ring->buddy->total_bytes = 0;
+                adapter->rx_ring->buddy->total_packets = 0;
+        }
+
         if (new_itr != adapter->itr) {
                 /* this attempts to bias the interrupt rate towards Bulk
                  * by adding intermediate steps when interrupt rate is
@@ -2628,7 +2655,8 @@ set_itr_now:
                  * ends up being correct.
                  */
                 adapter->itr = new_itr;
-                adapter->set_itr = 1;
+                adapter->rx_ring->itr_val = 1000000000 / (new_itr * 256);
+                adapter->rx_ring->set_itr = 1;
         }
 
         return;
@@ -2979,6 +3007,7 @@ static int igb_xmit_frame_ring_adv(struct sk_buff *skb,
                 /* this is a hard error */
                 return NETDEV_TX_BUSY;
         }
+        skb_orphan(skb);
 
         if (adapter->vlgrp && vlan_tx_tag_present(skb)) {
                 tx_flags |= IGB_TX_FLAGS_VLAN;
@@ -3312,8 +3341,6 @@ static irqreturn_t igb_msix_tx(int irq, void *data)
         struct igb_adapter *adapter = tx_ring->adapter;
         struct e1000_hw *hw = &adapter->hw;
 
-        if (!tx_ring->itr_val)
-                wr32(E1000_EIMC, tx_ring->eims_value);
 #ifdef CONFIG_DCA
         if (adapter->flags & IGB_FLAG_DCA_ENABLED)
                 igb_update_tx_dca(tx_ring);
@@ -3332,21 +3359,36 @@ static irqreturn_t igb_msix_tx(int irq, void *data)
         return IRQ_HANDLED;
 }
 
+static void igb_write_itr(struct igb_ring *ring)
+{
+        struct e1000_hw *hw = &ring->adapter->hw;
+        if ((ring->adapter->itr_setting & 3) && ring->set_itr) {
+                switch (hw->mac.type) {
+                case e1000_82576:
+                        wr32(ring->itr_register,
+                             ring->itr_val |
+                             0x80000000);
+                        break;
+                default:
+                        wr32(ring->itr_register,
+                             ring->itr_val |
+                             (ring->itr_val << 16));
+                        break;
+                }
+                ring->set_itr = 0;
+        }
+}
+
 static irqreturn_t igb_msix_rx(int irq, void *data)
 {
         struct igb_ring *rx_ring = data;
         struct igb_adapter *adapter = rx_ring->adapter;
-        struct e1000_hw *hw = &adapter->hw;
 
         /* Write the ITR value calculated at the end of the
          * previous interrupt.
          */
 
-        if (adapter->set_itr) {
-                wr32(rx_ring->itr_register,
-                     1000000000 / (rx_ring->itr_val * 256));
-                adapter->set_itr = 0;
-        }
+        igb_write_itr(rx_ring);
 
         if (netif_rx_schedule_prep(adapter->netdev, &rx_ring->napi))
                 __netif_rx_schedule(adapter->netdev, &rx_ring->napi);
@@ -3493,13 +3535,7 @@ static irqreturn_t igb_intr_msi(int irq, void *data)
         /* read ICR disables interrupts using IAM */
         u32 icr = rd32(E1000_ICR);
 
-        /* Write the ITR value calculated at the end of the
-         * previous interrupt.
-         */
-        if (adapter->set_itr) {
-                wr32(E1000_ITR, 1000000000 / (adapter->itr * 256));
-                adapter->set_itr = 0;
-        }
+        igb_write_itr(adapter->rx_ring);
 
         if (icr & (E1000_ICR_RXSEQ | E1000_ICR_LSC)) {
                 hw->mac.get_link_status = 1;
@@ -3529,13 +3565,7 @@ static irqreturn_t igb_intr(int irq, void *data)
         if (!icr)
                 return IRQ_NONE;  /* Not our interrupt */
 
-        /* Write the ITR value calculated at the end of the
-         * previous interrupt.
-         */
-        if (adapter->set_itr) {
-                wr32(E1000_ITR, 1000000000 / (adapter->itr * 256));
-                adapter->set_itr = 0;
-        }
+        igb_write_itr(adapter->rx_ring);
 
         /* IMS will not auto-mask if INT_ASSERTED is not set, and if it is
          * not set, then the adapter didn't send an interrupt */
@@ -3585,7 +3615,7 @@ static int igb_poll(struct napi_struct *napi, int budget)
         if ((tx_clean_complete && (work_done < budget)) ||
             !netif_running(netdev)) {
                 if (adapter->itr_setting & 3)
-                        igb_set_itr(adapter, E1000_ITR, false);
+                        igb_set_itr(adapter);
                 netif_rx_complete(netdev, napi);
                 if (!test_bit(__IGB_DOWN, &adapter->state))
                         igb_irq_enable(adapter);
@@ -3619,15 +3649,11 @@ static int igb_clean_rx_ring_msix(struct napi_struct *napi, int budget)
 quit_polling:
                 netif_rx_complete(netdev, napi);
 
-                wr32(E1000_EIMS, rx_ring->eims_value);
-                if ((adapter->itr_setting & 3) && !rx_ring->no_itr_adjust &&
-                    (rx_ring->total_packets > IGB_DYN_ITR_PACKET_THRESHOLD)) {
-                        int mean_size = rx_ring->total_bytes /
-                                        rx_ring->total_packets;
-                        if (mean_size < IGB_DYN_ITR_LENGTH_LOW)
-                                igb_raise_rx_eitr(adapter, rx_ring);
-                        else if (mean_size > IGB_DYN_ITR_LENGTH_HIGH)
-                                igb_lower_rx_eitr(adapter, rx_ring);
+                if (adapter->itr_setting & 3) {
+                        if (adapter->num_rx_queues == 1)
+                                igb_set_itr(adapter);
+                        else
+                                igb_update_ring_itr(rx_ring);
                 }
 
                 if (!test_bit(__IGB_DOWN, &adapter->state))
@@ -3972,7 +3998,6 @@ send_up:
                         dev_kfree_skb_irq(skb);
                         goto next_desc;
                 }
-                rx_ring->no_itr_adjust |= (staterr & E1000_RXD_STAT_DYNINT);
 
                 total_bytes += skb->len;
                 total_packets++;