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Date: Wed, 30 Nov 2022 20:37:07 +0100
From: Gerhard Engleder <gerhard@...leder-embedded.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, kuba@...nel.org, edumazet@...gle.com,
pabeni@...hat.com, Gerhard Engleder <gerhard@...leder-embedded.com>
Subject: [PATCH net-next v2 3/4] 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: Gerhard Engleder <gerhard@...leder-embedded.com>
---
drivers/net/ethernet/engleder/tsnep.h | 4 +
drivers/net/ethernet/engleder/tsnep_ethtool.c | 134 ++++++++++++++++++
drivers/net/ethernet/engleder/tsnep_hw.h | 7 +
drivers/net/ethernet/engleder/tsnep_main.c | 42 ++++++
4 files changed, 187 insertions(+)
diff --git a/drivers/net/ethernet/engleder/tsnep.h b/drivers/net/ethernet/engleder/tsnep.h
index 09a723b827c7..6bb74dd36544 100644
--- a/drivers/net/ethernet/engleder/tsnep.h
+++ b/drivers/net/ethernet/engleder/tsnep.h
@@ -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 */
diff --git a/drivers/net/ethernet/engleder/tsnep_ethtool.c b/drivers/net/ethernet/engleder/tsnep_ethtool.c
index 517ac8de32bb..b97ba3544708 100644
--- a/drivers/net/ethernet/engleder/tsnep_ethtool.c
+++ b/drivers/net/ethernet/engleder/tsnep_ethtool.c
@@ -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,
};
diff --git a/drivers/net/ethernet/engleder/tsnep_hw.h b/drivers/net/ethernet/engleder/tsnep_hw.h
index 315dada75323..55e1caf193a6 100644
--- a/drivers/net/ethernet/engleder/tsnep_hw.h
+++ b/drivers/net/ethernet/engleder/tsnep_hw.h
@@ -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
diff --git a/drivers/net/ethernet/engleder/tsnep_main.c b/drivers/net/ethernet/engleder/tsnep_main.c
index 13d5ff4e0e02..5e0d23dd2d42 100644
--- a/drivers/net/ethernet/engleder/tsnep_main.c
+++ b/drivers/net/ethernet/engleder/tsnep_main.c
@@ -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;
--
2.30.2
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