[RFC v1 3/7] ethdev: introduce Rx queue based limit watermark

[Spike Du <spiked@nvidia.com>]

LWM(limit watermark) is a per Rx queue attribute that notifies dpdk
application event of RTE_ETH_EVENT_RXQ_LIMIT_REACHED when the Rx
queue's usable descriptor is under the watermark.
To simplify its configuration, LWM is a percentage of Rx queue
descriptor size with valid value of [0,99].
Setting LWM to 0 means disable it.
Add LWM's configuration handle in eth_dev_ops.

Signed-off-by: Spike Du <spiked@nvidia.com>
---
 lib/ethdev/ethdev_driver.h |  7 +++++++
 lib/ethdev/rte_ethdev.c    | 28 ++++++++++++++++++++++++++++
 lib/ethdev/rte_ethdev.h    | 30 +++++++++++++++++++++++++++++-
 lib/ethdev/version.map     |  3 +++
 4 files changed, 67 insertions(+), 1 deletion(-)

diff --git a/lib/ethdev/ethdev_driver.h b/lib/ethdev/ethdev_driver.h
index 69d9dc2..1e9cdbf 100644
--- a/lib/ethdev/ethdev_driver.h
+++ b/lib/ethdev/ethdev_driver.h
@@ -470,6 +470,10 @@ typedef int (*eth_rx_queue_setup_t)(struct rte_eth_dev *dev,
 				    const struct rte_eth_rxconf *rx_conf,
 				    struct rte_mempool *mb_pool);
 
+typedef int (*eth_rx_queue_set_lwm_t)(struct rte_eth_dev *dev,
+				      uint16_t rx_queue_id,
+				      uint8_t lwm);
+
 /** @internal Setup a transmit queue of an Ethernet device. */
 typedef int (*eth_tx_queue_setup_t)(struct rte_eth_dev *dev,
 				    uint16_t tx_queue_id,
@@ -1283,6 +1287,9 @@ struct eth_dev_ops {
 
 	/** Dump private info from device */
 	eth_dev_priv_dump_t eth_dev_priv_dump;
+
+	/** Set Rx queue limit watermark */
+	eth_rx_queue_set_lwm_t rx_queue_set_lwm;
 };
 
 /**
diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
index 29a3d80..1e4fc6a 100644
--- a/lib/ethdev/rte_ethdev.c
+++ b/lib/ethdev/rte_ethdev.c
@@ -4414,6 +4414,34 @@ int rte_eth_set_queue_rate_limit(uint16_t port_id, uint16_t queue_idx,
 							queue_idx, tx_rate));
 }
 
+int rte_eth_rx_queue_set_lwm(uint16_t port_id, uint16_t queue_idx,
+			     uint8_t lwm)
+{
+	struct rte_eth_dev *dev;
+	struct rte_eth_dev_info dev_info;
+	int ret;
+
+	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
+	dev = &rte_eth_devices[port_id];
+
+	ret = rte_eth_dev_info_get(port_id, &dev_info);
+	if (ret != 0)
+		return ret;
+
+	if (queue_idx > dev_info.max_rx_queues) {
+		RTE_ETHDEV_LOG(ERR,
+			"Set queue rate limit:port %u: invalid queue ID=%u\n",
+			port_id, queue_idx);
+		return -EINVAL;
+	}
+
+	if (lwm > 99)
+		return -EINVAL;
+	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->rx_queue_set_lwm, -ENOTSUP);
+	return eth_err(port_id, (*dev->dev_ops->rx_queue_set_lwm)(dev,
+							     queue_idx, lwm));
+}
+
 RTE_INIT(eth_dev_init_fp_ops)
 {
 	uint32_t i;
diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
index 04cff8e..f29e53b 100644
--- a/lib/ethdev/rte_ethdev.h
+++ b/lib/ethdev/rte_ethdev.h
@@ -1249,8 +1249,12 @@ struct rte_eth_rxconf {
 	 */
 	union rte_eth_rxseg *rx_seg;
 
-	uint64_t reserved_64s[2]; /**< Reserved for future fields */
+	uint64_t reserved_64s;
+	uint32_t reserved_32s;
+	uint32_t lwm:8;
+	uint32_t reserved_bits:24;
 	void *reserved_ptrs[2];   /**< Reserved for future fields */
+
 };
 
 /**
@@ -3668,6 +3672,29 @@ int rte_eth_dev_set_vlan_ether_type(uint16_t port_id,
  */
 int rte_eth_dev_set_vlan_pvid(uint16_t port_id, uint16_t pvid, int on);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Set Rx queue based limit watermark.
+ *
+ * @param port_id
+ *  The port identifier of the Ethernet device.
+ * @param queue_idx
+ *  The index of the receive queue
+ * @param lwm
+ *  The limit watermark percentage of Rx queue descriptor size.
+ *  The valid range is [0,99].
+ *  Setting 0 means disable limit watermark.
+ *
+ * @return
+ *   - (0) if successful.
+ *   - negative if failed.
+ */
+__rte_experimental
+int rte_eth_rx_queue_set_lwm(uint16_t port_id, uint16_t queue_idx,
+				uint8_t lwm);
+
 typedef void (*buffer_tx_error_fn)(struct rte_mbuf **unsent, uint16_t count,
 		void *userdata);
 
@@ -3873,6 +3900,7 @@ enum rte_eth_event_type {
 	RTE_ETH_EVENT_DESTROY,  /**< port is released */
 	RTE_ETH_EVENT_IPSEC,    /**< IPsec offload related event */
 	RTE_ETH_EVENT_FLOW_AGED,/**< New aged-out flows is detected */
+	RTE_ETH_EVENT_RXQ_LIMIT_REACHED,/**< RX queue limit reached */
 	RTE_ETH_EVENT_MAX       /**< max value of this enum */
 };
 
diff --git a/lib/ethdev/version.map b/lib/ethdev/version.map
index 20391ab..8b85ad8 100644
--- a/lib/ethdev/version.map
+++ b/lib/ethdev/version.map
@@ -279,6 +279,9 @@ EXPERIMENTAL {
 	rte_flow_async_action_handle_create;
 	rte_flow_async_action_handle_destroy;
 	rte_flow_async_action_handle_update;
+
+	# added in 22.07
+	rte_eth_rx_queue_set_lwm;
 };
 
 INTERNAL {
-- 
1.8.3.1