ixgbe: Disable RSC when ITR setting is too high to allow RSC
authorAlexander Duyck <alexander.h.duyck@intel.com>
Wed, 17 Nov 2010 03:26:57 +0000 (19:26 -0800)
committerJeff Kirsher <jeffrey.t.kirsher@intel.com>
Wed, 17 Nov 2010 03:26:57 +0000 (19:26 -0800)
RSC will flush its descriptors every time the interrupt throttle timer
expires.  In addition there are known issues with RSC when the rx-usecs
value is set too low.  As such we are forced to clear the RSC_ENABLED bit
and reset the adapter when the rx-usecs value is set too low.

However we do not need to clear the NETIF_F_LRO flag because it is used to
indicate that the user wants to leave the LRO feature enabled, and in fact
with this change we will now re-enable RSC as soon as the rx-usecs value is
increased and the flag is still set.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
drivers/net/ixgbe/ixgbe_ethtool.c

index c19594a4e8f8c6054fba141d3c4d70529d197beb..561d47895d828e1f9f54bb54c793dacc3dc66b56 100644 (file)
@@ -1975,6 +1975,41 @@ static int ixgbe_get_coalesce(struct net_device *netdev,
        return 0;
 }
 
+/*
+ * this function must be called before setting the new value of
+ * rx_itr_setting
+ */
+static bool ixgbe_update_rsc(struct ixgbe_adapter *adapter,
+                            struct ethtool_coalesce *ec)
+{
+       struct net_device *netdev = adapter->netdev;
+
+       if (!(adapter->flags2 & IXGBE_FLAG2_RSC_CAPABLE))
+               return false;
+
+       /* if interrupt rate is too high then disable RSC */
+       if (ec->rx_coalesce_usecs != 1 &&
+           ec->rx_coalesce_usecs <= 1000000/IXGBE_MAX_RSC_INT_RATE) {
+               if (adapter->flags2 & IXGBE_FLAG2_RSC_ENABLED) {
+                       e_info(probe, "rx-usecs set too low, "
+                                     "disabling RSC\n");
+                       adapter->flags2 &= ~IXGBE_FLAG2_RSC_ENABLED;
+                       return true;
+               }
+       } else {
+               /* check the feature flag value and enable RSC if necessary */
+               if ((netdev->features & NETIF_F_LRO) &&
+                   !(adapter->flags2 & IXGBE_FLAG2_RSC_ENABLED)) {
+                       e_info(probe, "rx-usecs set to %d, "
+                                     "re-enabling RSC\n",
+                              ec->rx_coalesce_usecs);
+                       adapter->flags2 |= IXGBE_FLAG2_RSC_ENABLED;
+                       return true;
+               }
+       }
+       return false;
+}
+
 static int ixgbe_set_coalesce(struct net_device *netdev,
                               struct ethtool_coalesce *ec)
 {
@@ -1992,17 +2027,14 @@ static int ixgbe_set_coalesce(struct net_device *netdev,
                adapter->tx_ring[0]->work_limit = ec->tx_max_coalesced_frames_irq;
 
        if (ec->rx_coalesce_usecs > 1) {
-               u32 max_int;
-               if (adapter->flags2 & IXGBE_FLAG2_RSC_ENABLED)
-                       max_int = IXGBE_MAX_RSC_INT_RATE;
-               else
-                       max_int = IXGBE_MAX_INT_RATE;
-
                /* check the limits */
-               if ((1000000/ec->rx_coalesce_usecs > max_int) ||
+               if ((1000000/ec->rx_coalesce_usecs > IXGBE_MAX_INT_RATE) ||
                    (1000000/ec->rx_coalesce_usecs < IXGBE_MIN_INT_RATE))
                        return -EINVAL;
 
+               /* check the old value and enable RSC if necessary */
+               need_reset = ixgbe_update_rsc(adapter, ec);
+
                /* store the value in ints/second */
                adapter->rx_eitr_param = 1000000/ec->rx_coalesce_usecs;
 
@@ -2011,32 +2043,21 @@ static int ixgbe_set_coalesce(struct net_device *netdev,
                /* clear the lower bit as its used for dynamic state */
                adapter->rx_itr_setting &= ~1;
        } else if (ec->rx_coalesce_usecs == 1) {
+               /* check the old value and enable RSC if necessary */
+               need_reset = ixgbe_update_rsc(adapter, ec);
+
                /* 1 means dynamic mode */
                adapter->rx_eitr_param = 20000;
                adapter->rx_itr_setting = 1;
        } else {
+               /* check the old value and enable RSC if necessary */
+               need_reset = ixgbe_update_rsc(adapter, ec);
                /*
                 * any other value means disable eitr, which is best
                 * served by setting the interrupt rate very high
                 */
                adapter->rx_eitr_param = IXGBE_MAX_INT_RATE;
                adapter->rx_itr_setting = 0;
-
-               /*
-                * if hardware RSC is enabled, disable it when
-                * setting low latency mode, to avoid errata, assuming
-                * that when the user set low latency mode they want
-                * it at the cost of anything else
-                */
-               if (adapter->flags2 & IXGBE_FLAG2_RSC_ENABLED) {
-                       adapter->flags2 &= ~IXGBE_FLAG2_RSC_ENABLED;
-                       if (netdev->features & NETIF_F_LRO) {
-                               netdev->features &= ~NETIF_F_LRO;
-                               e_info(probe, "rx-usecs set to 0, "
-                                      "disabling RSC\n");
-                       }
-                       need_reset = true;
-               }
        }
 
        if (ec->tx_coalesce_usecs > 1) {
@@ -2123,15 +2144,15 @@ static int ixgbe_set_flags(struct net_device *netdev, u32 data)
                return rc;
 
        /* if state changes we need to update adapter->flags and reset */
-       if (adapter->flags2 & IXGBE_FLAG2_RSC_CAPABLE) {
-               /*
-                * cast both to bool and verify if they are set the same
-                * but only enable RSC if itr is non-zero, as
-                * itr=0 and RSC are mutually exclusive
-                */
-               if (((!!(data & ETH_FLAG_LRO)) !=
-                    (!!(adapter->flags2 & IXGBE_FLAG2_RSC_ENABLED))) &&
-                   adapter->rx_itr_setting) {
+       if ((adapter->flags2 & IXGBE_FLAG2_RSC_CAPABLE) &&
+           (!!(data & ETH_FLAG_LRO) !=
+            !!(adapter->flags2 & IXGBE_FLAG2_RSC_ENABLED))) {
+               if ((data & ETH_FLAG_LRO) &&
+                   (!adapter->rx_itr_setting ||
+                    (adapter->rx_itr_setting > IXGBE_MAX_RSC_INT_RATE))) {
+                       e_info(probe, "rx-usecs set too low, "
+                                     "not enabling RSC.\n");
+               } else {
                        adapter->flags2 ^= IXGBE_FLAG2_RSC_ENABLED;
                        switch (adapter->hw.mac.type) {
                        case ixgbe_mac_82599EB:
@@ -2140,11 +2161,6 @@ static int ixgbe_set_flags(struct net_device *netdev, u32 data)
                        default:
                                break;
                        }
-               } else if (!adapter->rx_itr_setting) {
-                       netdev->features &= ~NETIF_F_LRO;
-                       if (data & ETH_FLAG_LRO)
-                               e_info(probe, "rx-usecs set to 0, "
-                                      "LRO/RSC cannot be enabled.\n");
                }
        }