igb: Record host memory receive overflow in net_stats

Based on previous patch from Jesper Dangaard Brouer.

The RNBC (Receive No Buffers Count) register for the 82576, indicate
that frames were received when there were no available buffers in host
memory to store those frames (receive descriptor head and tail
pointers were equal).  The packet is still received by the NIC if
there is space in the FIFO on the NIC.

As the RNBC value is not a packet drop, the driver stores this value
in net_stats.rx_fifo_errors to indicate that there were no system
buffers available for the incoming packet.  Actual dropped packets
are counted in the MPC value.

Saving the stats in dev->net_stats makes it visible via
/proc/net/dev as "fifo", and thus viewable to ifconfig
as "overruns" and 'netstat -i' as "RX-OVR".

The Receive No Buffers Count (RNBC) can already be queried by
ethtool -S as "rx_no_buffer_count".

Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
CC: Jesper Dangaard Brouer <hawk@comx.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/igb/igb_ethtool.c b/drivers/net/igb/igb_ethtool.c
index 2ae98f91372e8c3d46d8ef5dfe76aeca0f018047..9598ac09f4b87942da669029352e502e263aa968 100644 (file)
--- a/drivers/net/igb/igb_ethtool.c
+++ b/drivers/net/igb/igb_ethtool.c
@@ -64,6 +64,7 @@ static const struct igb_stats igb_gstrings_stats[] = {
        { "rx_crc_errors", IGB_STAT(stats.crcerrs) },
        { "rx_frame_errors", IGB_STAT(net_stats.rx_frame_errors) },
        { "rx_no_buffer_count", IGB_STAT(stats.rnbc) },
+       { "rx_queue_drop_packet_count", IGB_STAT(net_stats.rx_fifo_errors) },
        { "rx_missed_errors", IGB_STAT(stats.mpc) },
        { "tx_aborted_errors", IGB_STAT(stats.ecol) },
        { "tx_carrier_errors", IGB_STAT(stats.tncrs) },

diff --git a/drivers/net/igb/igb_main.c b/drivers/net/igb/igb_main.c
index 4ae81331dca5db7a11046a9c990b6109ee115874..8e93750d5120790276c066b9dda5b7c6b7c4984f 100644 (file)
--- a/drivers/net/igb/igb_main.c
+++ b/drivers/net/igb/igb_main.c
@@ -3590,6 +3590,7 @@ void igb_update_stats(struct igb_adapter *adapter)
 
        if (hw->mac.type != e1000_82575) {
                u32 rqdpc_tmp;
+               u64 rqdpc_total = 0;
                int i;
                /* Read out drops stats per RX queue.  Notice RQDPC (Receive
                 * Queue Drop Packet Count) stats only gets incremented, if
@@ -3602,9 +3603,18 @@ void igb_update_stats(struct igb_adapter *adapter)
                for (i = 0; i < adapter->num_rx_queues; i++) {
                        rqdpc_tmp = rd32(E1000_RQDPC(i)) & 0xFFF;
                        adapter->rx_ring[i].rx_stats.drops += rqdpc_tmp;
+                       rqdpc_total += adapter->rx_ring[i].rx_stats.drops;
                }
+               adapter->net_stats.rx_fifo_errors = rqdpc_total;
        }
 
+       /* Note RNBC (Receive No Buffers Count) is an not an exact
+        * drop count as the hardware FIFO might save the day.  Thats
+        * one of the reason for saving it in rx_fifo_errors, as its
+        * potentially not a true drop.
+        */
+       adapter->net_stats.rx_fifo_errors += adapter->stats.rnbc;
+
        /* RLEC on some newer hardware can be incorrect so build
         * our own version based on RUC and ROC */
        adapter->net_stats.rx_errors = adapter->stats.rxerrc +