Clarify the meaning of the NEW, FORWARD and RELEASE event types.
For the fields in "rte_event" struct, enhance the comments on each to
clarify the field's use, and whether it is preserved between enqueue and
dequeue, and it's role, if any, in scheduling.
Signed-off-by: Bruce Richardson <bruce.richard...@intel.com>
---
V3: updates following review
---
lib/eventdev/rte_eventdev.h | 161 +++++++++++++++++++++++++-----------
1 file changed, 111 insertions(+), 50 deletions(-)
diff --git a/lib/eventdev/rte_eventdev.h b/lib/eventdev/rte_eventdev.h
index 8d72765ae7..58219e027e 100644
--- a/lib/eventdev/rte_eventdev.h
+++ b/lib/eventdev/rte_eventdev.h
@@ -1463,47 +1463,54 @@ struct rte_event_vector {
/* Event enqueue operations */
#define RTE_EVENT_OP_NEW 0
-/**< The event producers use this operation to inject a new event to the
- * event device.
+/**< The @ref rte_event.op field must be set to this operation type to inject
a new event,
+ * i.e. one not previously dequeued, into the event device, to be scheduled
+ * for processing.
*/
#define RTE_EVENT_OP_FORWARD 1
-/**< The CPU use this operation to forward the event to different event queue
or
- * change to new application specific flow or schedule type to enable
- * pipelining.
+/**< The application must set the @ref rte_event.op field to this operation
type to return a
+ * previously dequeued event to the event device to be scheduled for further
processing.
*
- * This operation must only be enqueued to the same port that the
+ * This event *must* be enqueued to the same port that the
* event to be forwarded was dequeued from.
+ *
+ * The event's fields, including (but not limited to) flow_id, scheduling type,
+ * destination queue, and event payload e.g. mbuf pointer, may all be updated
as
+ * desired by the application, but the @ref rte_event.impl_opaque field must
+ * be kept to the same value as was present when the event was dequeued.
*/
#define RTE_EVENT_OP_RELEASE 2
/**< Release the flow context associated with the schedule type.
*
- * If current flow's scheduler type method is *RTE_SCHED_TYPE_ATOMIC*
- * then this function hints the scheduler that the user has completed critical
- * section processing in the current atomic context.
- * The scheduler is now allowed to schedule events from the same flow from
- * an event queue to another port. However, the context may be still held
- * until the next rte_event_dequeue_burst() call, this call allows but does not
- * force the scheduler to release the context early.
- *
- * Early atomic context release may increase parallelism and thus system
+ * If current flow's scheduler type method is @ref RTE_SCHED_TYPE_ATOMIC
+ * then this operation type hints the scheduler that the user has completed
critical
+ * section processing for this event in the current atomic context, and that
the
+ * scheduler may unlock any atomic locks held for this event.
+ * If this is the last event from an atomic flow, i.e. all flow locks are
released,
+ * the scheduler is now allowed to schedule events from that flow from to
another port.
+ * However, the atomic locks may be still held until the next
rte_event_dequeue_burst()
+ * call; enqueuing an event with opt type @ref RTE_EVENT_OP_RELEASE allows,
+ * but does not force, the scheduler to release the atomic locks early.
+ *
+ * Early atomic lock release may increase parallelism and thus system
* performance, but the user needs to design carefully the split into critical
* vs non-critical sections.
*
- * If current flow's scheduler type method is *RTE_SCHED_TYPE_ORDERED*
- * then this function hints the scheduler that the user has done all that need
- * to maintain event order in the current ordered context.
- * The scheduler is allowed to release the ordered context of this port and
- * avoid reordering any following enqueues.
- *
- * Early ordered context release may increase parallelism and thus system
- * performance.
+ * If current flow's scheduler type method is @ref RTE_SCHED_TYPE_ORDERED
+ * then this operation type informs the scheduler that the current event has
+ * completed processing and will not be returned to the scheduler, i.e.
+ * it has been dropped, and so the reordering context for that event
+ * should be considered filled.
*
- * If current flow's scheduler type method is *RTE_SCHED_TYPE_PARALLEL*
- * or no scheduling context is held then this function may be an NOOP,
- * depending on the implementation.
+ * Events with this operation type must only be enqueued to the same port that
the
+ * event to be released was dequeued from. The @ref rte_event.impl_opaque
+ * field in the release event must have the same value as that in the original
dequeued event.
*
- * This operation must only be enqueued to the same port that the
- * event to be released was dequeued from.
+ * If a dequeued event is re-enqueued with operation type of @ref
RTE_EVENT_OP_RELEASE,
+ * then any subsequent enqueue of that event - or a copy of it - must be done
as event of type
+ * @ref RTE_EVENT_OP_NEW, not @ref RTE_EVENT_OP_FORWARD. This is because any
context for
+ * the originally dequeued event, i.e. atomic locks, or reorder buffer
entries, will have
+ * been removed or invalidated by the release operation.
*/
/**
@@ -1517,56 +1524,110 @@ struct rte_event {
/** Event attributes for dequeue or enqueue operation */
struct {
uint32_t flow_id:20;
- /**< Targeted flow identifier for the enqueue and
- * dequeue operation.
- * The value must be in the range of
- * [0, nb_event_queue_flows - 1] which
- * previously supplied to rte_event_dev_configure().
+ /**< Target flow identifier for the enqueue and dequeue
operation.
+ *
+ * For @ref RTE_SCHED_TYPE_ATOMIC, this field is used
to identify a
+ * flow for atomicity within a queue & priority level,
such that events
+ * from each individual flow will only be scheduled to
one port at a time.
+ *
+ * This field is preserved between enqueue and dequeue
when
+ * a device reports the @ref
RTE_EVENT_DEV_CAP_CARRY_FLOW_ID
+ * capability. Otherwise the value is implementation
dependent
+ * on dequeue.
*/
uint32_t sub_event_type:8;
/**< Sub-event types based on the event source.
+ *
+ * This field is preserved between enqueue and dequeue.
+ * This field is for application or event adapter use,
+ * and is not considered in scheduling decisions.
+ *
* @see RTE_EVENT_TYPE_CPU
*/
uint32_t event_type:4;
- /**< Event type to classify the event source.
- * @see RTE_EVENT_TYPE_ETHDEV, (RTE_EVENT_TYPE_*)
+ /**< Event type to classify the event source.
(RTE_EVENT_TYPE_*)
+ *
+ * This field is preserved between enqueue and dequeue
+ * This field is for application or event adapter use,
+ * and is not considered in scheduling decisions.
*/
uint8_t op:2;
- /**< The type of event enqueue operation - new/forward/
- * etc.This field is not preserved across an instance
- * and is undefined on dequeue.
- * @see RTE_EVENT_OP_NEW, (RTE_EVENT_OP_*)
+ /**< The type of event enqueue operation - new/forward/
etc.
+ *
+ * This field is *not* preserved across an instance
+ * and is implementation dependent on dequeue.
+ *
+ * @see RTE_EVENT_OP_NEW
+ * @see RTE_EVENT_OP_FORWARD
+ * @see RTE_EVENT_OP_RELEASE
*/
uint8_t rsvd:4;
- /**< Reserved for future use */
+ /**< Reserved for future use.
+ *
+ * Should be set to zero on enqueue.
+ */
uint8_t sched_type:2;
/**< Scheduler synchronization type (RTE_SCHED_TYPE_*)
* associated with flow id on a given event queue
* for the enqueue and dequeue operation.
+ *
+ * This field is used to determine the scheduling type
+ * for events sent to queues where @ref
RTE_EVENT_QUEUE_CFG_ALL_TYPES
+ * is configured.
+ * For queues where only a single scheduling type is
available,
+ * this field must be set to match the configured
scheduling type.
+ *
+ * This field is preserved between enqueue and dequeue.
+ *
+ * @see RTE_SCHED_TYPE_ORDERED
+ * @see RTE_SCHED_TYPE_ATOMIC
+ * @see RTE_SCHED_TYPE_PARALLEL
*/
uint8_t queue_id;
/**< Targeted event queue identifier for the enqueue or
* dequeue operation.
- * The value must be in the range of
- * [0, nb_event_queues - 1] which previously supplied to
- * rte_event_dev_configure().
+ * The value must be less than @ref
rte_event_dev_config.nb_event_queues
+ * which was previously supplied to
rte_event_dev_configure().
+ *
+ * This field is preserved between enqueue on dequeue.
*/
uint8_t priority;
/**< Event priority relative to other events in the
* event queue. The requested priority should in the
- * range of [RTE_EVENT_DEV_PRIORITY_HIGHEST,
- * RTE_EVENT_DEV_PRIORITY_LOWEST].
+ * range of [@ref RTE_EVENT_DEV_PRIORITY_HIGHEST,
+ * @ref RTE_EVENT_DEV_PRIORITY_LOWEST].
+ *
* The implementation shall normalize the requested
* priority to supported priority value.
- * Valid when the device has
- * RTE_EVENT_DEV_CAP_EVENT_QOS capability.
+ * [For devices with where the supported priority range
is a power-of-2, the
+ * normalization will be done via bit-shifting, so only
the highest
+ * log2(num_priorities) bits will be used by the event
device]
+ *
+ * Valid when the device has @ref
RTE_EVENT_DEV_CAP_EVENT_QOS capability
+ * and this field is preserved between enqueue and
dequeue,
+ * though with possible loss of precision due to
normalization and
+ * subsequent de-normalization. (For example, if a
device only supports 8
+ * priority levels, only the high 3 bits of this field
will be
+ * used by that device, and hence only the value of
those 3 bits are
+ * guaranteed to be preserved between enqueue and
dequeue.)
+ *
+ * Ignored when device does not support @ref
RTE_EVENT_DEV_CAP_EVENT_QOS
+ * capability, and it is implementation dependent if
this field is preserved
+ * between enqueue and dequeue.
*/
uint8_t impl_opaque;
- /**< Implementation specific opaque value.
- * An implementation may use this field to hold
+ /**< Opaque field for event device use.
+ *
+ * An event driver implementation may use this field to
hold an
* implementation specific value to share between
* dequeue and enqueue operation.
- * The application should not modify this field.
+ *
+ * The application most not modify this field.
+ * Its value is implementation dependent on dequeue,
+ * and must be returned unmodified on enqueue when
+ * op type is @ref RTE_EVENT_OP_FORWARD or @ref
RTE_EVENT_OP_RELEASE.
+ * This field is ignored on events with op type
+ * @ref RTE_EVENT_OP_NEW.
*/
};
};
--
2.40.1
