sfc: Implement adaptive IRQ moderation

Calculate a score for each 1000 IRQs:
- TX completions are worth 1 point
- RX completions are worth 4 if merged using LRO or 2 otherwise

Reduce moderation if the score is less than 10000, down to a minimum
of 5 us.  Increase moderation if the score is more than 20000, up to
the specified maximum.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 13 deletions

diff --git a/drivers/net/sfc/ethtool.c b/drivers/net/sfc/ethtool.c
index 589d1329296..64309f4e8b1 100644
--- a/drivers/net/sfc/ethtool.c
+++ b/drivers/net/sfc/ethtool.c
@@ -604,7 +604,6 @@ static int efx_ethtool_get_coalesce(struct net_device *net_dev,
 {
         struct efx_nic *efx = netdev_priv(net_dev);
         struct efx_tx_queue *tx_queue;
-        struct efx_rx_queue *rx_queue;
         struct efx_channel *channel;
 
         memset(coalesce, 0, sizeof(*coalesce));
@@ -622,14 +621,8 @@ static int efx_ethtool_get_coalesce(struct net_device *net_dev,
                 }
         }
 
-        /* Find lowest IRQ moderation across all used RX queues */
-        coalesce->rx_coalesce_usecs_irq = ~((u32) 0);
-        efx_for_each_rx_queue(rx_queue, efx) {
-                channel = rx_queue->channel;
-                if (channel->irq_moderation < coalesce->rx_coalesce_usecs_irq)
-                        coalesce->rx_coalesce_usecs_irq =
-                                channel->irq_moderation;
-        }
+        coalesce->use_adaptive_rx_coalesce = efx->irq_rx_adaptive;
+        coalesce->rx_coalesce_usecs_irq = efx->irq_rx_moderation;
 
         return 0;
 }
@@ -643,10 +636,9 @@ static int efx_ethtool_set_coalesce(struct net_device *net_dev,
         struct efx_nic *efx = netdev_priv(net_dev);
         struct efx_channel *channel;
         struct efx_tx_queue *tx_queue;
-        unsigned tx_usecs, rx_usecs;
+        unsigned tx_usecs, rx_usecs, adaptive;
 
-        if (coalesce->use_adaptive_rx_coalesce ||
-            coalesce->use_adaptive_tx_coalesce)
+        if (coalesce->use_adaptive_tx_coalesce)
                 return -EOPNOTSUPP;
 
         if (coalesce->rx_coalesce_usecs || coalesce->tx_coalesce_usecs) {
@@ -657,6 +649,7 @@ static int efx_ethtool_set_coalesce(struct net_device *net_dev,
 
         rx_usecs = coalesce->rx_coalesce_usecs_irq;
         tx_usecs = coalesce->tx_coalesce_usecs_irq;
+        adaptive = coalesce->use_adaptive_rx_coalesce;
 
         /* If the channel is shared only allow RX parameters to be set */
         efx_for_each_tx_queue(tx_queue, efx) {
@@ -668,7 +661,7 @@ static int efx_ethtool_set_coalesce(struct net_device *net_dev,
                 }
         }
 
-        efx_init_irq_moderation(efx, tx_usecs, rx_usecs);
+        efx_init_irq_moderation(efx, tx_usecs, rx_usecs, adaptive);
 
         /* Reset channel to pick up new moderation value.  Note that
          * this may change the value of the irq_moderation field