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tsnep: Throttle interrupts

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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: Gerhard Engleder <gerhard@engleder-embedded.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Gerhard Engleder 2022-11-30 20:37:07 +01:00 committed by David S. Miller
parent 4f661ccfca
commit d3dfe8d6c0
4 changed files with 187 additions and 0 deletions
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4
drivers/net/ethernet/engleder/tsnep.h
View File

@ -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 */

134
drivers/net/ethernet/engleder/tsnep_ethtool.c
View File

@ -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,
};

7
drivers/net/ethernet/engleder/tsnep_hw.h
View File

@ -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

42
drivers/net/ethernet/engleder/tsnep_main.c
View File

@ -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;