[dpdk-dev] [RFC v2 1/3] eventdev: allow for event devices requiring maintenance

["Mattias Rönnblom" <mattias.ronnblom@ericsson.com>]

Extend Eventdev API to allow for event devices which require various
forms of internal processing to happen, even when events are not
enqueued to or dequeued from a port.

RFC v2:
  - Change rte_event_maintain() return type to be consistent
    with the documentation.
  - Remove unused typedef from eventdev_pmd.h.

Signed-off-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>
Tested-by: Richard Eklycke <richard.eklycke@ericsson.com>
Tested-by: Liron Himi <lironh@marvell.com>
---
 lib/eventdev/rte_eventdev.h | 62 +++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/lib/eventdev/rte_eventdev.h b/lib/eventdev/rte_eventdev.h
index a9c496fb62..2c17d9272e 100644
--- a/lib/eventdev/rte_eventdev.h
+++ b/lib/eventdev/rte_eventdev.h
@@ -299,6 +299,15 @@ struct rte_event;
  * the content of this field is implementation dependent.
  */
 
+#define RTE_EVENT_DEV_CAP_REQUIRES_MAINT (1ULL << 10)
+/**< Event device requires calls to rte_event_maintain() during
+ * periods when neither rte_event_dequeue_burst() nor
+ * rte_event_enqueue_burst() are called on a port. This will allow the
+ * event device to perform internal processing, such as flushing
+ * buffered events, return credits to a global pool, or process
+ * signaling related to load balancing.
+ */
+
 /* Event device priority levels */
 #define RTE_EVENT_DEV_PRIORITY_HIGHEST   0
 /**< Highest priority expressed across eventdev subsystem
@@ -1342,6 +1351,9 @@ typedef uint16_t (*event_dequeue_burst_t)(void *port, struct rte_event ev[],
 		uint16_t nb_events, uint64_t timeout_ticks);
 /**< @internal Dequeue burst of events from port of a device */
 
+typedef void (*event_maintain_t)(void *port);
+/**< @internal Maintains a port */
+
 typedef uint16_t (*event_tx_adapter_enqueue)(void *port,
 				struct rte_event ev[], uint16_t nb_events);
 /**< @internal Enqueue burst of events on port of a device */
@@ -1421,6 +1433,8 @@ struct rte_eventdev {
 	/**< Pointer to PMD dequeue function. */
 	event_dequeue_burst_t dequeue_burst;
 	/**< Pointer to PMD dequeue burst function. */
+	event_maintain_t maintain;
+	/**< Maintains an event port. */
 	event_tx_adapter_enqueue_same_dest txa_enqueue_same_dest;
 	/**< Pointer to PMD eth Tx adapter burst enqueue function with
 	 * events destined to same Eth port & Tx queue.
@@ -1758,6 +1772,54 @@ rte_event_dequeue_burst(uint8_t dev_id, uint8_t port_id, struct rte_event ev[],
 				timeout_ticks);
 }
 
+/**
+ * Maintain an event device.
+ *
+ * This function is only relevant for event devices which has the
+ * RTE_EVENT_DEV_CAP_REQUIRES_MAINT flag set. Such devices requires
+ * the application to call rte_event_maintain() on a port during periods
+ * which it is neither enqueuing nor dequeuing events from this
+ * port. No port may be left unattended.
+ *
+ * An event device's rte_event_maintain() is a low overhead function. In
+ * situations when rte_event_maintain() must be called, the application
+ * should do so often.
+ *
+ * rte_event_maintain() may be called on event devices which hasn't
+ * set RTE_EVENT_DEV_CAP_REQUIRES_MAINT flag, in which case it is a
+ * successful no-operation.
+ *
+ * @param dev_id
+ *   The identifier of the device.
+ * @param port_id
+ *   The identifier of the event port.
+ * @return
+ *  - 0 on success.
+ *  - -EINVAL if *dev_id* or *port_id* is invalid
+ *
+ * @see RTE_EVENT_DEV_CAP_REQUIRES_MAINT
+ */
+static inline int
+rte_event_maintain(uint8_t dev_id, uint8_t port_id)
+{
+	struct rte_eventdev *dev = &rte_eventdevs[dev_id];
+	event_maintain_t fn;
+
+#ifdef RTE_LIBRTE_EVENTDEV_DEBUG
+	if (dev_id >= RTE_EVENT_MAX_DEVS || !rte_eventdevs[dev_id].attached)
+		return -EINVAL;
+
+	if (port_id >= dev->data->nb_ports)
+		return -EINVAL;
+#endif
+	fn = *dev->maintain;
+
+	if (fn != NULL)
+		fn(dev->data->ports[port_id]);
+
+	return 0;
+}
+
 /**
  * Link multiple source event queues supplied in *queues* to the destination
  * event port designated by its *port_id* with associated service priority
-- 
2.25.1