Staging: Octeon: Free transmit SKBs in a timely manner

If we wait for the once-per-second cleanup to free transmit SKBs,
sockets with small transmit buffer sizes might spend most of their
time blocked waiting for the cleanup.

Normally we do a cleanup for each transmitted packet.  We add a
watchdog type timer so that we also schedule a timeout for 150uS after
a packet is transmitted.  The watchdog is reset for each transmitted
packet, so for high packet rates, it never expires.  At these high
rates, the cleanups are done for each packet so the extra watchdog
initiated cleanups are neither needed nor triggered.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
To: netdev@vger.kernel.org
To: gregkh@suse.de
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Patchwork: http://patchwork.linux-mips.org/patch/968/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

This version has spelling and comment changes based on feedback from
Eric Dumazet.

1 files changed, 23 insertions, 24 deletions

diff --git a/drivers/staging/octeon/ethernet.c b/drivers/staging/octeon/ethernet.c
index 1771c10..5ee60ab 100644
--- a/drivers/staging/octeon/ethernet.c
+++ b/drivers/staging/octeon/ethernet.c
@@ -140,6 +140,8 @@ atomic_t cvm_oct_poll_queue_stopping = ATOMIC_INIT(0);
  */
 struct net_device *cvm_oct_device[TOTAL_NUMBER_OF_PORTS];
 
+u64 cvm_oct_tx_poll_interval;
+
 static void cvm_oct_rx_refill_worker(struct work_struct *work);
 static DECLARE_DELAYED_WORK(cvm_oct_rx_refill_work, cvm_oct_rx_refill_worker);
 
@@ -159,18 +161,19 @@ static void cvm_oct_rx_refill_worker(struct work_struct *work)
 				   &cvm_oct_rx_refill_work, HZ);
 }
 
-static void cvm_oct_tx_clean_worker(struct work_struct *work)
+static void cvm_oct_periodic_worker(struct work_struct *work)
 {
 	struct octeon_ethernet *priv = container_of(work,
 						    struct octeon_ethernet,
-						    tx_clean_work.work);
+						    port_periodic_work.work);
 
 	if (priv->poll)
 		priv->poll(cvm_oct_device[priv->port]);
-	cvm_oct_free_tx_skbs(priv);
+
 	cvm_oct_device[priv->port]->netdev_ops->ndo_get_stats(cvm_oct_device[priv->port]);
+
 	if (!atomic_read(&cvm_oct_poll_queue_stopping))
-		queue_delayed_work(cvm_oct_poll_queue, &priv->tx_clean_work, HZ);
+		queue_delayed_work(cvm_oct_poll_queue, &priv->port_periodic_work, HZ);
  }
 
 /**
@@ -662,6 +665,9 @@ static int __init cvm_oct_init_module(void)
 	 */
 	cvmx_fau_atomic_write32(FAU_NUM_PACKET_BUFFERS_TO_FREE, 0);
 
+	/* Initialize the FAU used for counting tx SKBs that need to be freed */
+	cvmx_fau_atomic_write32(FAU_TOTAL_TX_TO_CLEAN, 0);
+
 	if ((pow_send_group != -1)) {
 		struct net_device *dev;
 		pr_info("\tConfiguring device for POW only access\n");
@@ -670,18 +676,6 @@ static int __init cvm_oct_init_module(void)
 			/* Initialize the device private structure. */
 			struct octeon_ethernet *priv = netdev_priv(dev);
 
-			hrtimer_init(&priv->tx_restart_timer,
-				     CLOCK_MONOTONIC,
-				     HRTIMER_MODE_REL);
-			priv->tx_restart_timer.function = cvm_oct_restart_tx;
-
-			/*
-			 * Default for 10GE 5000nS enough time to
-			 * transmit about 100 64byte packtes.  1GE
-			 * interfaces will get 50000nS below.
-			 */
-			priv->tx_restart_interval = ktime_set(0, 5000);
-
 			dev->netdev_ops = &cvm_oct_pow_netdev_ops;
 			priv->imode = CVMX_HELPER_INTERFACE_MODE_DISABLED;
 			priv->port = CVMX_PIP_NUM_INPUT_PORTS;
@@ -725,9 +719,8 @@ static int __init cvm_oct_init_module(void)
 			/* Initialize the device private structure. */
 			priv = netdev_priv(dev);
 
-			INIT_DELAYED_WORK(&priv->tx_clean_work,
-					  cvm_oct_tx_clean_worker);
-
+			INIT_DELAYED_WORK(&priv->port_periodic_work,
+					  cvm_oct_periodic_worker);
 			priv->imode = imode;
 			priv->port = port;
 			priv->queue = cvmx_pko_get_base_queue(priv->port);
@@ -763,7 +756,6 @@ static int __init cvm_oct_init_module(void)
 
 			case CVMX_HELPER_INTERFACE_MODE_SGMII:
 				dev->netdev_ops = &cvm_oct_sgmii_netdev_ops;
-				priv->tx_restart_interval = ktime_set(0, 50000);
 				strcpy(dev->name, "eth%d");
 				break;
 
@@ -775,7 +767,6 @@ static int __init cvm_oct_init_module(void)
 			case CVMX_HELPER_INTERFACE_MODE_RGMII:
 			case CVMX_HELPER_INTERFACE_MODE_GMII:
 				dev->netdev_ops = &cvm_oct_rgmii_netdev_ops;
-				priv->tx_restart_interval = ktime_set(0, 50000);
 				strcpy(dev->name, "eth%d");
 				break;
 			}
@@ -793,13 +784,19 @@ static int __init cvm_oct_init_module(void)
 				    cvmx_pko_get_num_queues(priv->port) *
 				    sizeof(uint32_t);
 				queue_delayed_work(cvm_oct_poll_queue,
-						   &priv->tx_clean_work, HZ);
+						   &priv->port_periodic_work, HZ);
 			}
 		}
 	}
 
+	cvm_oct_tx_initialize();
 	cvm_oct_rx_initialize();
 
+	/*
+	 * 150 uS: about 10 1500-byte packtes at 1GE.
+	 */
+	cvm_oct_tx_poll_interval = 150 * (octeon_get_clock_rate() / 1000000);
+
 	queue_delayed_work(cvm_oct_poll_queue, &cvm_oct_rx_refill_work, HZ);
 
 	return 0;
@@ -826,6 +823,8 @@ static void __exit cvm_oct_cleanup_module(void)
 	cancel_delayed_work_sync(&cvm_oct_rx_refill_work);
 
 	cvm_oct_rx_shutdown();
+	cvm_oct_tx_shutdown();
+
 	cvmx_pko_disable();
 
 	/* Free the ethernet devices */
@@ -833,9 +832,9 @@ static void __exit cvm_oct_cleanup_module(void)
 		if (cvm_oct_device[port]) {
 			struct net_device *dev = cvm_oct_device[port];
 			struct octeon_ethernet *priv = netdev_priv(dev);
-			cancel_delayed_work_sync(&priv->tx_clean_work);
+			cancel_delayed_work_sync(&priv->port_periodic_work);
 
-			cvm_oct_tx_shutdown(dev);
+			cvm_oct_tx_shutdown_dev(dev);
 			unregister_netdev(dev);
 			kfree(dev);
 			cvm_oct_device[port] = NULL;