e1000: add queue restart counter

Add a netif_wake/start_queue counter to the ethtool statistics to indicated
to the user that their transmit ring could be too small for their workload.
Signed-off-by: NJesse brandeburg <jesse.brandeburg@intel.com>
Cc: Jamal Hadi <hadi@cyberus.ca>
Signed-off-by: NAuke Kok <auke-jan.h.kok@intel.com>

drivers/net/e1000/e1000.h

@@ -265,6 +265,7 @@ struct e1000_adapter {
 
 	/* TX */
 	struct e1000_tx_ring *tx_ring;      /* One per active queue */
+	unsigned int restart_queue;
 	unsigned long tx_queue_len;
 	uint32_t txd_cmd;
 	uint32_t tx_int_delay;

drivers/net/e1000/e1000_ethtool.c

@@ -85,6 +85,7 @@ static const struct e1000_stats e1000_gstrings_stats[] = {
 	{ "tx_single_coll_ok", E1000_STAT(stats.scc) },
 	{ "tx_multi_coll_ok", E1000_STAT(stats.mcc) },
 	{ "tx_timeout_count", E1000_STAT(tx_timeout_count) },
+	{ "tx_restart_queue", E1000_STAT(restart_queue) },
 	{ "rx_long_length_errors", E1000_STAT(stats.roc) },
 	{ "rx_short_length_errors", E1000_STAT(stats.ruc) },
 	{ "rx_align_errors", E1000_STAT(stats.algnerrc) },

drivers/net/e1000/e1000_main.c

@@ -2974,6 +2974,7 @@ static int __e1000_maybe_stop_tx(struct net_device *netdev, int size)
 
 	/* A reprieve! */
 	netif_start_queue(netdev);
+	++adapter->restart_queue;
 	return 0;
 }
 
@@ -3654,8 +3655,10 @@ e1000_clean_tx_irq(struct e1000_adapter *adapter,
 		 * sees the new next_to_clean.
 		 */
 		smp_mb();
-		if (netif_queue_stopped(netdev))
+		if (netif_queue_stopped(netdev)) {
 			netif_wake_queue(netdev);
+			++adapter->restart_queue;
+		}
 	}
 
 	if (adapter->detect_tx_hung) {