mlx4_en: Adaptive moderation policy change

If the net device is identified as "sender" (number of sent packets
is higher then the number of received packets and the incoming packets are
small), set the moderation time to its low limit.
We do it because the incoming packets are acks, and we don't want to delay them

Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/mlx4/en_netdev.c b/drivers/net/mlx4/en_netdev.c
index 93f4abd990a923c715e98daa19b99662afbf71cb..c8a24dcca7621112c460d019f67c5c90de7c6d00 100644 (file)
--- a/drivers/net/mlx4/en_netdev.c
+++ b/drivers/net/mlx4/en_netdev.c
@@ -414,6 +414,7 @@ static void mlx4_en_auto_moderation(struct mlx4_en_priv *priv)
        unsigned long avg_pkt_size;
        unsigned long rx_packets;
        unsigned long rx_bytes;
+       unsigned long rx_byte_diff;
        unsigned long tx_packets;
        unsigned long tx_pkt_diff;
        unsigned long rx_pkt_diff;
@@ -437,6 +438,8 @@ static void mlx4_en_auto_moderation(struct mlx4_en_priv *priv)
        rx_pkt_diff = ((unsigned long) (rx_packets -
                                        priv->last_moder_packets));
        packets = max(tx_pkt_diff, rx_pkt_diff);
+       rx_byte_diff = rx_bytes - priv->last_moder_bytes;
+       rx_byte_diff = rx_byte_diff ? rx_byte_diff : 1;
        rate = packets * HZ / period;
        avg_pkt_size = packets ? ((unsigned long) (rx_bytes -
                                 priv->last_moder_bytes)) / packets : 0;
@@ -447,10 +450,13 @@ static void mlx4_en_auto_moderation(struct mlx4_en_priv *priv)
                /* If tx and rx packet rates are not balanced, assume that
                 * traffic is mainly BW bound and apply maximum moderation.
                 * Otherwise, moderate according to packet rate */
-               if (2 * tx_pkt_diff > 3 * rx_pkt_diff ||
-                   2 * rx_pkt_diff > 3 * tx_pkt_diff) {
+               if (2 * tx_pkt_diff > 3 * rx_pkt_diff &&
+                   rx_pkt_diff / rx_byte_diff <
+                   MLX4_EN_SMALL_PKT_SIZE)
+                       moder_time = priv->rx_usecs_low;
+               else if (2 * rx_pkt_diff > 3 * tx_pkt_diff)
                        moder_time = priv->rx_usecs_high;
-               } else {
+               else {
                        if (rate < priv->pkt_rate_low)
                                moder_time = priv->rx_usecs_low;
                        else if (rate > priv->pkt_rate_high)