Re: [RFC] eventdev: add event adapter for ethernet Rx queues

Hi Jerin,

Comments inline.

Also, another function needed is
bool rte_event_eth_rx_adapter_multithread_capable(void). 

This would be used to set the "multithread_capable" service core 
configuration parameter. 

Thanks,
Nikhil

On 5/11/2017 10:08 PM, Jerin Jacob wrote:

-----Original Message-----

quoted

Date: Tue, 9 May 2017 15:38:46 -0500
From: Gage Eads <redacted>
To: dev@dpdk.org
CC: nikhil.rao@intel.com, jerin.jacob@caviumnetworks.com,
 thomas@monjalon.net, bruce.richardson@intel.com,
 harry.van.haaren@intel.com, hemant.agrawal@nxp.com, nipun.gupta@nxp.com,
 narender.vangati@intel.com
Subject: [RFC] eventdev: add event adapter for ethernet Rx queues
X-Mailer: git-send-email 2.7.4

From: Nikhil Rao <redacted>

Hi Nikhil and Gage,

Thanks for the RFC. A few questions and comments below.
Looks like SW has more constraints on event producer side, after we
finalize on this RFC(I guess only a few minor changes are only required).
I will align other[1] RFC based on _your_ RFC as we need to
converge on name space and we can't duplicate configs like struct
rte_event_dev_producer_conf etc

[1]
http://dpdk.org/ml/archives/dev/2017-May/065341.html

quoted

+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+#include <rte_mbuf.h>
+#include <rte_eventdev.h>
+
+/* struct rte_eth_rx_event_adapter_queue_config flags definitions */
+#define RTE_ETH_RX_EVENT_ADAPTER_QUEUE_FLOW_ID_VALID	0x1
+/*< This flag indicates the flow identifier is valid */
+
+struct rte_eth_rx_event_adapter_config {

Since this code is going to be at lib/librte_eventdev, We must start all
public symbols and file name with rte_event_*.

example:
May be this structure can be changed as rte_event_eth_rx_adapter_config

OK.

quoted

+	uint8_t event_dev_id;
+	/**< Event device identifier */
+	uint8_t rx_event_port_id;
+	/**< Event port identifier, the adapter enqueues mbuf events to this
+	 * port
+	 */
+};
+
+struct rte_eth_rx_event_adapter_queue_config {
+	uint32_t rx_queue_flags;
+	 /**< Flags for handling received packets */

Better to add references with @see
example:
	@see RTE_ETH_RX_EVENT_ADAPTER_QUEUE_FLOW_ID_VALID

OK.

quoted

+	uint16_t servicing_weight;
+	/**< Relative polling frequency of ethernet receive queue, if this
+	 * is set to zero, the Rx queue is interrupt driven
+	 */
+	struct rte_event ev;
+	/**<
+	 *  The values from the following event fields will be used when
+	 *  enqueuing mbuf events:
+	 *   - event_queue_id: Targeted event queue ID for received packets.
+	 *   - event_priority: Event priority of packets from this Rx queue in
+	 *                     the event queue relative to other events.
+	 *   - sched_type: Scheduling type for packets from this Rx queue.
+	 *   - flow_id: If the RTE_ETH_RX_EVENT_ADAPTER_QUEUE_FLOW_ID_VALID bit
+	 *		is set in rx_queue_flags, this flow_id is used for all
+	 *		packets received from this queue. Otherwise the flow ID
+	 *		is set to the RSS hash.

This scheme is good. I was duplicating the elements in "struct
rte_event_dev_producer_conf"

IMO, We need to set ev.event_type == RTE_EVENT_TYPE_ETHDEV implicitly in
library.
You can mention that here as a info.

OK.

quoted

+	 */
+};
+
+struct rte_eth_rx_event_adapter_run_args {
+	uint8_t id;
+	/**< Adapter identifier */
+	unsigned int max_nb_rx;
+	/**< The adapter can return early if it has processed at least
+	 * max_nb_rx mbufs. This isn't treated as a requirement; batching may
+	 * cause the adapter to process more than max_nb_rx mbufs.
+	 */
+};
+
+struct rte_eth_rx_event_adapter_stats {
+	uint64_t rx_poll_count;
+	/**< Receive queue poll count across both polled and interrupt mode
+	 * queues
+	 */
+	uint64_t rx_packets;
+	/**< Received packet count */
+	uint64_t rx_enq_fail;
+	/**< Eventdev enqueue failed count */
+	uint64_t rx_enq_retry;
+	/**< Eventdev enqueue retry count */
+};
+
+/**
+ * Create a new ethernet Rx event adapter with the specified identifier.
+ *
+ * @param adapter_id
+ *   Event adapter identifier.
+ * @param config
+ *   Event adapter config parameters.
+ * @return
+ *   - 0: Success
+ *   - <0: Error code on failure
+ */
+int rte_eth_rx_event_adapter_create(
+	uint8_t id,
+	const struct rte_eth_rx_event_adapter_config *config);
+

One adapter creates one service function. right?
It is good to mention the mapping.It is missing in the doc.

Yes, in this case, the application creates a service per adapter, it may create multiple
Rx event adapters with each adapter handling a subset of Rx queues. As per Harry's
patch, only DPDK internal components are expected to request service cores, once Harry posts
an updated patch, I will make any necesssary changes and post the next version of this
patch.

quoted

+/**
+ * Free an event adapter
+ *
+ * @param id
+ *   Adapter identifier.
+ * @return
+ *   - 0: Success
+ *   - <0: Error code on failure
+ */
+int rte_eth_rx_event_adapter_free(uint8_t id);
+
+/**
+ * Add eth device to the event adapter
+ *
+ * @param id
+ *   Adapter identifier.
+ * @param eth_dev_id
+ *  Port identifier of the Ethernet device.
+ * @return
+ *   - 0: Success
+ *   - <0: Error code on failure
+ */
+int rte_eth_rx_event_adapter_dev_add(uint8_t id, uint8_t eth_dev_id);

rte_eth_event_rx_queue_add() also have eth_dev_id.What is the
significance of eth_dev_id here. Looks like eth_dev_id is a duplicate info.

if it is duplicate or it can be avoided then I propose to reduce the number
of APIs for easiness of application programming(i.e removing rte_eth_rx_event_adapter_dev_add,
rte_eth_rx_event_adapter_dev_del)

OK.

You can also mention the following for better clarify. If following is
true.If not, What do you think about, co-existence of poll and event mode?

Yes, its true.

The rte_eth_rx_burst() result is undefined if application invokes on
bounded ethdev_port and rx_queue_id.

quoted

+
+/**
+ * Delete eth device from an event adapter
+ *
+ * @param id
+ *   Adapter identifier.
+ * @param eth_dev_id
+ *  Port identifier of the Ethernet device.
+ * @return
+ *   - 0: Success
+ *   - <0: Error code on failure
+ */
+int rte_eth_rx_event_adapter_dev_del(uint8_t id, uint8_t eth_dev_id);
+
+/**
+ * Add receive queue to event adapter
+ *
+ * @param id
+ *   Adapter identifier.
+ * @param eth_dev_id
+ *  Port identifier of Ethernet device.
+ * @param rx_queue_id
+ *  Ethernet device receive queue index.
+ * @param config
+ *  Additonal configuration structure.
+ * @return
+ *  - 0: Success, Receive queue added correctly.
+ *  - <0: Error code on failure.
+ */
+int rte_eth_event_rx_queue_add(
+	uint8_t id,
+	uint8_t eth_dev_id,
+	uint16_t rx_queue_id,

How about changing it as int32_t rx_queue_id and -1 to denote all Rx
queues configured for given eth_dev_id are added. This will avoid the
case where application needs to call this API one by one when application
interested in all the queues.

Sounds good.
 

quoted

+	const struct rte_eth_rx_event_adapter_queue_config *config);
+

Don't we need rte_eth_event_rx_queue_del() for tear down?

Yes.