[dpdk-dev] [PATCH v6 1/8] eventdev: introduce event vector capability

[pbhagavatula at marvell.com]

From: Pavan Nikhilesh <pbhagavatula at marvell.com>

Introduce rte_event_vector datastructure which is capable of holding
multiple uintptr_t of the same flow thereby allowing applications
to vectorize their pipeline and reducing the complexity of pipelining
the events across multiple stages.
This approach also reduces the scheduling overhead on a event device.

Add a event vector mempool create handler to create mempools based on
the best mempool ops available on a given platform.

Signed-off-by: Pavan Nikhilesh <pbhagavatula at marvell.com>
Acked-by: Jerin Jacob <jerinj at marvell.com>
Acked-by: Ray Kinsella <mdr at ashroe.eu>
---
 doc/guides/prog_guide/eventdev.rst     | 36 ++++++++++-
 doc/guides/rel_notes/release_21_05.rst |  8 +++
 lib/librte_eventdev/rte_eventdev.c     | 42 +++++++++++++
 lib/librte_eventdev/rte_eventdev.h     | 82 +++++++++++++++++++++++++-
 lib/librte_eventdev/version.map        |  3 +
 5 files changed, 168 insertions(+), 3 deletions(-)

diff --git a/doc/guides/prog_guide/eventdev.rst b/doc/guides/prog_guide/eventdev.rst
index ccde086f6..fda9c3743 100644
--- a/doc/guides/prog_guide/eventdev.rst
+++ b/doc/guides/prog_guide/eventdev.rst
@@ -63,13 +63,45 @@ the actual event being scheduled is. The payload is a union of the following:
 * ``uint64_t u64``
 * ``void *event_ptr``
 * ``struct rte_mbuf *mbuf``
+* ``struct rte_event_vector *vec``
 
-These three items in a union occupy the same 64 bits at the end of the rte_event
+These four items in a union occupy the same 64 bits at the end of the rte_event
 structure. The application can utilize the 64 bits directly by accessing the
-u64 variable, while the event_ptr and mbuf are provided as convenience
+u64 variable, while the event_ptr, mbuf, vec are provided as a convenience
 variables.  For example the mbuf pointer in the union can used to schedule a
 DPDK packet.
 
+Event Vector
+~~~~~~~~~~~~
+
+The rte_event_vector struct contains a vector of elements defined by the event
+type specified in the ``rte_event``. The event_vector structure contains the
+following data:
+
+* ``nb_elem`` - The number of elements held within the vector.
+
+Similar to ``rte_event`` the payload of event vector is also a union, allowing
+flexibility in what the actual vector is.
+
+* ``struct rte_mbuf *mbufs[0]`` - An array of mbufs.
+* ``void *ptrs[0]`` - An array of pointers.
+* ``uint64_t *u64s[0]`` - An array of uint64_t elements.
+
+The size of the event vector is related to the total number of elements it is
+configured to hold, this is achieved by making `rte_event_vector` a variable
+length structure.
+A helper function is provided to create a mempool that holds event vector, which
+takes name of the pool, total number of required ``rte_event_vector``,
+cache size, number of elements in each ``rte_event_vector`` and socket id.
+
+.. code-block:: c
+
+        rte_event_vector_pool_create("vector_pool", nb_event_vectors, cache_sz,
+                                     nb_elements_per_vector, socket_id);
+
+The function ``rte_event_vector_pool_create`` creates mempool with the best
+platform mempool ops.
+
 Queues
 ~~~~~~
 
diff --git a/doc/guides/rel_notes/release_21_05.rst b/doc/guides/rel_notes/release_21_05.rst
index 8a601e0a7..aeb56533a 100644
--- a/doc/guides/rel_notes/release_21_05.rst
+++ b/doc/guides/rel_notes/release_21_05.rst
@@ -106,6 +106,14 @@ New Features
   * Added support for periodic timer mode in eventdev timer adapter.
   * Added support for periodic timer mode in octeontx2 event device driver.
 
+* **Add Event device vector capability.**
+
+  * Added ``rte_event_vector`` data structure which is capable of holding
+    multiple ``uintptr_t`` of the same flow thereby allowing applications
+    to vectorize their pipelines and also reduce the complexity of pipelining
+    the events across multiple stages.
+  * This also reduces the scheduling overhead on a event device.
+
 
 Removed Items
 -------------
diff --git a/lib/librte_eventdev/rte_eventdev.c b/lib/librte_eventdev/rte_eventdev.c
index b57363f80..be0499c52 100644
--- a/lib/librte_eventdev/rte_eventdev.c
+++ b/lib/librte_eventdev/rte_eventdev.c
@@ -1266,6 +1266,48 @@ int rte_event_dev_selftest(uint8_t dev_id)
 	return -ENOTSUP;
 }
 
+struct rte_mempool *
+rte_event_vector_pool_create(const char *name, unsigned int n,
+			     unsigned int cache_size, uint16_t nb_elem,
+			     int socket_id)
+{
+	const char *mp_ops_name;
+	struct rte_mempool *mp;
+	unsigned int elt_sz;
+	int ret;
+
+	if (!nb_elem) {
+		RTE_LOG(ERR, EVENTDEV,
+			"Invalid number of elements=%d requested\n", nb_elem);
+		rte_errno = EINVAL;
+		return NULL;
+	}
+
+	elt_sz =
+		sizeof(struct rte_event_vector) + (nb_elem * sizeof(uintptr_t));
+	mp = rte_mempool_create_empty(name, n, elt_sz, cache_size, 0, socket_id,
+				      0);
+	if (mp == NULL)
+		return NULL;
+
+	mp_ops_name = rte_mbuf_best_mempool_ops();
+	ret = rte_mempool_set_ops_byname(mp, mp_ops_name, NULL);
+	if (ret != 0) {
+		RTE_LOG(ERR, EVENTDEV, "error setting mempool handler\n");
+		goto err;
+	}
+
+	ret = rte_mempool_populate_default(mp);
+	if (ret < 0)
+		goto err;
+
+	return mp;
+err:
+	rte_mempool_free(mp);
+	rte_errno = -ret;
+	return NULL;
+}
+
 int
 rte_event_dev_start(uint8_t dev_id)
 {
diff --git a/lib/librte_eventdev/rte_eventdev.h b/lib/librte_eventdev/rte_eventdev.h
index 9fc39e9ca..dee468ed0 100644
--- a/lib/librte_eventdev/rte_eventdev.h
+++ b/lib/librte_eventdev/rte_eventdev.h
@@ -212,8 +212,10 @@ extern "C" {
 
 #include <rte_common.h>
 #include <rte_config.h>
-#include <rte_memory.h>
 #include <rte_errno.h>
+#include <rte_mbuf_pool_ops.h>
+#include <rte_memory.h>
+#include <rte_mempool.h>
 
 #include "rte_eventdev_trace_fp.h"
 
@@ -913,6 +915,31 @@ rte_event_dev_stop_flush_callback_register(uint8_t dev_id,
 int
 rte_event_dev_close(uint8_t dev_id);
 
+/**
+ * Event vector structure.
+ */
+struct rte_event_vector {
+	uint64_t nb_elem : 16;
+	/**< Number of elements in this event vector. */
+	uint64_t rsvd : 48;
+	/**< Reserved for future use */
+	uint64_t impl_opaque;
+	/**< Implementation specific opaque value.
+	 * An implementation may use this field to hold implementation specific
+	 * value to share between dequeue and enqueue operation.
+	 * The application should not modify this field.
+	 */
+	union {
+		struct rte_mbuf *mbufs[0];
+		void *ptrs[0];
+		uint64_t *u64s[0];
+	} __rte_aligned(16);
+	/**< Start of the vector array union. Depending upon the event type the
+	 * vector array can be an array of mbufs or pointers or opaque u64
+	 * values.
+	 */
+};
+
 /* Scheduler type definitions */
 #define RTE_SCHED_TYPE_ORDERED          0
 /**< Ordered scheduling
@@ -986,6 +1013,21 @@ rte_event_dev_close(uint8_t dev_id);
  */
 #define RTE_EVENT_TYPE_ETH_RX_ADAPTER   0x4
 /**< The event generated from event eth Rx adapter */
+#define RTE_EVENT_TYPE_VECTOR           0x8
+/**< Indicates that event is a vector.
+ * All vector event types should be a logical OR of EVENT_TYPE_VECTOR.
+ * This simplifies the pipeline design as one can split processing the events
+ * between vector events and normal event across event types.
+ * Example:
+ *	if (ev.event_type & RTE_EVENT_TYPE_VECTOR) {
+ *		// Classify and handle vector event.
+ *	} else {
+ *		// Classify and handle event.
+ *	}
+ */
+#define RTE_EVENT_TYPE_CPU_VECTOR (RTE_EVENT_TYPE_VECTOR | RTE_EVENT_TYPE_CPU)
+/**< The event vector generated from cpu for pipelining. */
+
 #define RTE_EVENT_TYPE_MAX              0x10
 /**< Maximum number of event types */
 
@@ -1108,6 +1150,8 @@ struct rte_event {
 		/**< Opaque event pointer */
 		struct rte_mbuf *mbuf;
 		/**< mbuf pointer if dequeued event is associated with mbuf */
+		struct rte_event_vector *vec;
+		/**< Event vector pointer. */
 	};
 };
 
@@ -2026,6 +2070,42 @@ rte_event_dev_xstats_reset(uint8_t dev_id,
  */
 int rte_event_dev_selftest(uint8_t dev_id);
 
+/**
+ * Get the memory required per event vector based on the number of elements per
+ * vector.
+ * This should be used to create the mempool that holds the event vectors.
+ *
+ * @param name
+ *   The name of the vector pool.
+ * @param n
+ *   The number of elements in the mbuf pool.
+ * @param cache_size
+ *   Size of the per-core object cache. See rte_mempool_create() for
+ *   details.
+ * @param nb_elem
+ *   The number of elements that a single event vector should be able to hold.
+ * @param socket_id
+ *   The socket identifier where the memory should be allocated. The
+ *   value can be *SOCKET_ID_ANY* if there is no NUMA constraint for the
+ *   reserved zone
+ *
+ * @return
+ *   The pointer to the newly allocated mempool, on success. NULL on error
+ *   with rte_errno set appropriately. Possible rte_errno values include:
+ *    - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
+ *    - E_RTE_SECONDARY - function was called from a secondary process instance
+ *    - EINVAL - cache size provided is too large, or priv_size is not aligned.
+ *    - ENOSPC - the maximum number of memzones has already been allocated
+ *    - EEXIST - a memzone with the same name already exists
+ *    - ENOMEM - no appropriate memory area found in which to create memzone
+ *    - ENAMETOOLONG - mempool name requested is too long.
+ */
+__rte_experimental
+struct rte_mempool *
+rte_event_vector_pool_create(const char *name, unsigned int n,
+			     unsigned int cache_size, uint16_t nb_elem,
+			     int socket_id);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/librte_eventdev/version.map b/lib/librte_eventdev/version.map
index 3e5c09cfd..a070ef56e 100644
--- a/lib/librte_eventdev/version.map
+++ b/lib/librte_eventdev/version.map
@@ -138,6 +138,9 @@ EXPERIMENTAL {
 	__rte_eventdev_trace_port_setup;
 	# added in 20.11
 	rte_event_pmd_pci_probe_named;
+
+	#added in 21.05
+	rte_event_vector_pool_create;
 };
 
 INTERNAL {
-- 
2.17.1