Commit d3dfe8d6 authored by Gerhard Engleder's avatar Gerhard Engleder Committed by David S. Miller
Browse files

tsnep: Throttle interrupts 



Without interrupt throttling, iperf server mode generates a CPU load of
100% (A53 1.2GHz). Also the throughput suffers with less than 900Mbit/s
on a 1Gbit/s link. The reason is a high interrupt load with interrupts
every ~20us.

Reduce interrupt load by throttling of interrupts. Interrupt delay
default is 64us. For iperf server mode the CPU load is significantly
reduced to ~20% and the throughput reaches the maximum of 941MBit/s.
Interrupts are generated every ~140us.

RX and TX coalesce can be configured with ethtool. RX coalesce has
priority over TX coalesce if the same interrupt is used.

Signed-off-by: default avatarGerhard Engleder <gerhard@engleder-embedded.com>
Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4f661ccf

drivers/net/ethernet/engleder/tsnep.h

+4 −0
Original line number Diff line number Diff line
@@ -132,6 +132,8 @@ struct tsnep_queue { 


	int irq;

	u32 irq_mask;

	void __iomem *irq_delay_addr;

	u8 irq_delay;

};



struct tsnep_adapter {
@@ -223,5 +225,7 @@ static inline void tsnep_ethtool_self_test(struct net_device *dev, 
#endif /* CONFIG_TSNEP_SELFTESTS */



void tsnep_get_system_time(struct tsnep_adapter *adapter, u64 *time);

int tsnep_set_irq_coalesce(struct tsnep_queue *queue, u32 usecs);

u32 tsnep_get_irq_coalesce(struct tsnep_queue *queue);



#endif /* _TSNEP_H */

drivers/net/ethernet/engleder/tsnep_ethtool.c

+134 −0
Original line number Diff line number Diff line
@@ -324,7 +324,137 @@ static int tsnep_ethtool_get_ts_info(struct net_device *netdev, 
	return 0;

}



static struct tsnep_queue *tsnep_get_queue_with_tx(struct tsnep_adapter *adapter,

						   int index)

{

	int i;



	for (i = 0; i < adapter->num_queues; i++) {

		if (adapter->queue[i].tx) {

			if (index == 0)

				return &adapter->queue[i];



			index--;

		}

	}



	return NULL;

}



static struct tsnep_queue *tsnep_get_queue_with_rx(struct tsnep_adapter *adapter,

						   int index)

{

	int i;



	for (i = 0; i < adapter->num_queues; i++) {

		if (adapter->queue[i].rx) {

			if (index == 0)

				return &adapter->queue[i];



			index--;

		}

	}



	return NULL;

}



static int tsnep_ethtool_get_coalesce(struct net_device *netdev,

				      struct ethtool_coalesce *ec,

				      struct kernel_ethtool_coalesce *kernel_coal,

				      struct netlink_ext_ack *extack)

{

	struct tsnep_adapter *adapter = netdev_priv(netdev);

	struct tsnep_queue *queue;



	queue = tsnep_get_queue_with_rx(adapter, 0);

	if (queue)

		ec->rx_coalesce_usecs = tsnep_get_irq_coalesce(queue);



	queue = tsnep_get_queue_with_tx(adapter, 0);

	if (queue)

		ec->tx_coalesce_usecs = tsnep_get_irq_coalesce(queue);



	return 0;

}



static int tsnep_ethtool_set_coalesce(struct net_device *netdev,

				      struct ethtool_coalesce *ec,

				      struct kernel_ethtool_coalesce *kernel_coal,

				      struct netlink_ext_ack *extack)

{

	struct tsnep_adapter *adapter = netdev_priv(netdev);

	int i;

	int retval;



	for (i = 0; i < adapter->num_queues; i++) {

		/* RX coalesce has priority for queues with TX and RX */

		if (adapter->queue[i].rx)

			retval = tsnep_set_irq_coalesce(&adapter->queue[i],

							ec->rx_coalesce_usecs);

		else

			retval = tsnep_set_irq_coalesce(&adapter->queue[i],

							ec->tx_coalesce_usecs);

		if (retval != 0)

			return retval;

	}



	return 0;

}



static int tsnep_ethtool_get_per_queue_coalesce(struct net_device *netdev,

						u32 queue,

						struct ethtool_coalesce *ec)

{

	struct tsnep_adapter *adapter = netdev_priv(netdev);

	struct tsnep_queue *queue_with_rx;

	struct tsnep_queue *queue_with_tx;



	if (queue >= max(adapter->num_tx_queues, adapter->num_rx_queues))

		return -EINVAL;



	queue_with_rx = tsnep_get_queue_with_rx(adapter, queue);

	if (queue_with_rx)

		ec->rx_coalesce_usecs = tsnep_get_irq_coalesce(queue_with_rx);



	queue_with_tx = tsnep_get_queue_with_tx(adapter, queue);

	if (queue_with_tx)

		ec->tx_coalesce_usecs = tsnep_get_irq_coalesce(queue_with_tx);



	return 0;

}



static int tsnep_ethtool_set_per_queue_coalesce(struct net_device *netdev,

						u32 queue,

						struct ethtool_coalesce *ec)

{

	struct tsnep_adapter *adapter = netdev_priv(netdev);

	struct tsnep_queue *queue_with_rx;

	struct tsnep_queue *queue_with_tx;

	int retval;



	if (queue >= max(adapter->num_tx_queues, adapter->num_rx_queues))

		return -EINVAL;



	queue_with_rx = tsnep_get_queue_with_rx(adapter, queue);

	if (queue_with_rx) {

		retval = tsnep_set_irq_coalesce(queue_with_rx, ec->rx_coalesce_usecs);

		if (retval != 0)

			return retval;

	}



	/* RX coalesce has priority for queues with TX and RX */

	queue_with_tx = tsnep_get_queue_with_tx(adapter, queue);

	if (queue_with_tx && !queue_with_tx->rx) {

		retval = tsnep_set_irq_coalesce(queue_with_tx, ec->tx_coalesce_usecs);

		if (retval != 0)

			return retval;

	}



	return 0;

}



const struct ethtool_ops tsnep_ethtool_ops = {

	.supported_coalesce_params = ETHTOOL_COALESCE_USECS,

	.get_drvinfo = tsnep_ethtool_get_drvinfo,

	.get_regs_len = tsnep_ethtool_get_regs_len,

	.get_regs = tsnep_ethtool_get_regs,
@@ -340,6 +470,10 @@ const struct ethtool_ops tsnep_ethtool_ops = { 
	.set_rxnfc = tsnep_ethtool_set_rxnfc,

	.get_channels = tsnep_ethtool_get_channels,

	.get_ts_info = tsnep_ethtool_get_ts_info,

	.get_coalesce = tsnep_ethtool_get_coalesce,

	.set_coalesce = tsnep_ethtool_set_coalesce,

	.get_per_queue_coalesce = tsnep_ethtool_get_per_queue_coalesce,

	.set_per_queue_coalesce = tsnep_ethtool_set_per_queue_coalesce,

	.get_link_ksettings = phy_ethtool_get_link_ksettings,

	.set_link_ksettings = phy_ethtool_set_link_ksettings,

};

drivers/net/ethernet/engleder/tsnep_hw.h

+7 −0
Original line number Diff line number Diff line
@@ -48,6 +48,13 @@ 
#define ECM_COUNTER_LOW 0x0028

#define ECM_COUNTER_HIGH 0x002C



/* interrupt delay */

#define ECM_INT_DELAY 0x0030

#define ECM_INT_DELAY_MASK 0xF0

#define ECM_INT_DELAY_SHIFT 4

#define ECM_INT_DELAY_BASE_US 16

#define ECM_INT_DELAY_OFFSET 1



/* control and status */

#define ECM_STATUS 0x0080

#define ECM_LINK_MODE_OFF 0x01000000

drivers/net/ethernet/engleder/tsnep_main.c

+42 −0
Original line number Diff line number Diff line
@@ -39,6 +39,10 @@ 
#endif

#define DMA_ADDR_LOW(dma_addr) ((u32)((dma_addr) & 0xFFFFFFFF))



#define TSNEP_COALESCE_USECS_DEFAULT 64

#define TSNEP_COALESCE_USECS_MAX     ((ECM_INT_DELAY_MASK >> ECM_INT_DELAY_SHIFT) * \

				      ECM_INT_DELAY_BASE_US + ECM_INT_DELAY_BASE_US - 1)



static void tsnep_enable_irq(struct tsnep_adapter *adapter, u32 mask)

{

	iowrite32(mask, adapter->addr + ECM_INT_ENABLE);
@@ -83,6 +87,33 @@ static irqreturn_t tsnep_irq_txrx(int irq, void *arg) 
	return IRQ_HANDLED;

}



int tsnep_set_irq_coalesce(struct tsnep_queue *queue, u32 usecs)

{

	if (usecs > TSNEP_COALESCE_USECS_MAX)

		return -ERANGE;



	usecs /= ECM_INT_DELAY_BASE_US;

	usecs <<= ECM_INT_DELAY_SHIFT;

	usecs &= ECM_INT_DELAY_MASK;



	queue->irq_delay &= ~ECM_INT_DELAY_MASK;

	queue->irq_delay |= usecs;

	iowrite8(queue->irq_delay, queue->irq_delay_addr);



	return 0;

}



u32 tsnep_get_irq_coalesce(struct tsnep_queue *queue)

{

	u32 usecs;



	usecs = (queue->irq_delay & ECM_INT_DELAY_MASK);

	usecs >>= ECM_INT_DELAY_SHIFT;

	usecs *= ECM_INT_DELAY_BASE_US;



	return usecs;

}



static int tsnep_mdiobus_read(struct mii_bus *bus, int addr, int regnum)

{

	struct tsnep_adapter *adapter = bus->priv;
@@ -1371,6 +1402,11 @@ static int tsnep_queue_init(struct tsnep_adapter *adapter, int queue_count) 
	adapter->queue[0].tx = &adapter->tx[0];

	adapter->queue[0].rx = &adapter->rx[0];

	adapter->queue[0].irq_mask = irq_mask;

	adapter->queue[0].irq_delay_addr = adapter->addr + ECM_INT_DELAY;

	retval = tsnep_set_irq_coalesce(&adapter->queue[0],

					TSNEP_COALESCE_USECS_DEFAULT);

	if (retval < 0)

		return retval;



	adapter->netdev->irq = adapter->queue[0].irq;
@@ -1391,6 +1427,12 @@ static int tsnep_queue_init(struct tsnep_adapter *adapter, int queue_count) 
		adapter->queue[i].rx = &adapter->rx[i];

		adapter->queue[i].irq_mask =

			irq_mask << (ECM_INT_TXRX_SHIFT * i);

		adapter->queue[i].irq_delay_addr =

			adapter->addr + ECM_INT_DELAY + ECM_INT_DELAY_OFFSET * i;

		retval = tsnep_set_irq_coalesce(&adapter->queue[i],

						TSNEP_COALESCE_USECS_DEFAULT);

		if (retval < 0)

			return retval;

	}



	return 0;