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From: Bruce Richardson <bruce.richardson@intel.com>
To: dev@dpdk.org, jerinj@marvell.com, mattias.ronnblom@ericsson.com
Cc: Bruce Richardson <bruce.richardson@intel.com>
Subject: [PATCH v4 09/12] eventdev: improve comments on scheduling types
Date: Wed, 21 Feb 2024 10:32:18 +0000	[thread overview]
Message-ID: <20240221103221.933238-10-bruce.richardson@intel.com> (raw)
In-Reply-To: <20240221103221.933238-1-bruce.richardson@intel.com>

The description of ordered and atomic scheduling given in the eventdev
doxygen documentation was not always clear. Try and simplify this so
that it is clearer for the end-user of the application

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>

---
V4: reworked following review by Jerin
V3: extensive rework following feedback. Please re-review!
---
 lib/eventdev/rte_eventdev.h | 77 +++++++++++++++++++++++--------------
 1 file changed, 48 insertions(+), 29 deletions(-)

diff --git a/lib/eventdev/rte_eventdev.h b/lib/eventdev/rte_eventdev.h
index 72814719b2..6d881bd665 100644
--- a/lib/eventdev/rte_eventdev.h
+++ b/lib/eventdev/rte_eventdev.h
@@ -1397,25 +1397,36 @@ struct rte_event_vector {
 /**< Ordered scheduling
  *
  * Events from an ordered flow of an event queue can be scheduled to multiple
- * ports for concurrent processing while maintaining the original event order.
- * This scheme enables the user to achieve high single flow throughput by
- * avoiding SW synchronization for ordering between ports which bound to cores.
- *
- * The source flow ordering from an event queue is maintained when events are
- * enqueued to their destination queue within the same ordered flow context.
- * An event port holds the context until application call
- * rte_event_dequeue_burst() from the same port, which implicitly releases
- * the context.
- * User may allow the scheduler to release the context earlier than that
- * by invoking rte_event_enqueue_burst() with RTE_EVENT_OP_RELEASE operation.
- *
- * Events from the source queue appear in their original order when dequeued
- * from a destination queue.
- * Event ordering is based on the received event(s), but also other
- * (newly allocated or stored) events are ordered when enqueued within the same
- * ordered context. Events not enqueued (e.g. released or stored) within the
- * context are  considered missing from reordering and are skipped at this time
- * (but can be ordered again within another context).
+ * ports for concurrent processing while maintaining the original event order,
+ * i.e. the order in which they were first enqueued to that queue.
+ * This scheme allows events pertaining to the same, potentially large, flow to
+ * be processed in parallel on multiple cores without incurring any
+ * application-level order restoration logic overhead.
+ *
+ * After events are dequeued from a set of ports, as those events are re-enqueued
+ * to another queue (with the op field set to @ref RTE_EVENT_OP_FORWARD), the event
+ * device restores the original event order - including events returned from all
+ * ports in the set - before the events are placed on the destination queue,
+ * for subsequent scheduling to ports.
+ *
+ * Any events not forwarded i.e. dropped explicitly via RELEASE or implicitly
+ * released by the next dequeue operation on a port, are skipped by the reordering
+ * stage and do not affect the reordering of other returned events.
+ *
+ * Any NEW events sent on a port are not ordered with respect to FORWARD events sent
+ * on the same port, since they have no original event order. They also are not
+ * ordered with respect to NEW events enqueued on other ports.
+ * However, NEW events to the same destination queue from the same port are guaranteed
+ * to be enqueued in the order they were submitted via rte_event_enqueue_burst().
+ *
+ * NOTE:
+ *   In restoring event order of forwarded events, the eventdev API guarantees that
+ *   all events from the same flow (i.e. same @ref rte_event.flow_id,
+ *   @ref rte_event.priority and @ref rte_event.queue_id) will be put in the original
+ *   order before being forwarded to the destination queue.
+ *   Some eventdevs may implement stricter ordering to achieve this aim,
+ *   for example, restoring the order across *all* flows dequeued from the same ORDERED
+ *   queue.
  *
  * @see rte_event_queue_setup(), rte_event_dequeue_burst(), RTE_EVENT_OP_RELEASE
  */
@@ -1423,18 +1434,26 @@ struct rte_event_vector {
 #define RTE_SCHED_TYPE_ATOMIC           1
 /**< Atomic scheduling
  *
- * Events from an atomic flow of an event queue can be scheduled only to a
+ * Events from an atomic flow, identified by a combination of @ref rte_event.flow_id,
+ * @ref rte_event.queue_id and @ref rte_event.priority, can be scheduled only to a
  * single port at a time. The port is guaranteed to have exclusive (atomic)
  * access to the associated flow context, which enables the user to avoid SW
- * synchronization. Atomic flows also help to maintain event ordering
- * since only one port at a time can process events from a flow of an
- * event queue.
- *
- * The atomic queue synchronization context is dedicated to the port until
- * application call rte_event_dequeue_burst() from the same port,
- * which implicitly releases the context. User may allow the scheduler to
- * release the context earlier than that by invoking rte_event_enqueue_burst()
- * with RTE_EVENT_OP_RELEASE operation.
+ * synchronization. Atomic flows also maintain event ordering
+ * since only one port at a time can process events from each flow of an
+ * event queue, and events within a flow are not reordered within the scheduler.
+ *
+ * An atomic flow is locked to a port when events from that flow are first
+ * scheduled to that port. That lock remains in place until the
+ * application calls rte_event_dequeue_burst() from the same port,
+ * which implicitly releases the lock (if @ref RTE_EVENT_PORT_CFG_DISABLE_IMPL_REL flag is not set).
+ * User may allow the scheduler to release the lock earlier than that by invoking
+ * rte_event_enqueue_burst() with RTE_EVENT_OP_RELEASE operation for each event from that flow.
+ *
+ * NOTE: Where multiple events from the same queue and atomic flow are scheduled to a port,
+ * the lock for that flow is only released once the last event from the flow is released,
+ * or forwarded to another queue. So long as there is at least one event from an atomic
+ * flow scheduled to a port/core (including any events in the port's dequeue queue, not yet read
+ * by the application), that port will hold the synchronization lock for that flow.
  *
  * @see rte_event_queue_setup(), rte_event_dequeue_burst(), RTE_EVENT_OP_RELEASE
  */
-- 
2.40.1


  parent reply	other threads:[~2024-02-21 10:33 UTC|newest]

Thread overview: 123+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-18 13:45 [PATCH v1 0/7] improve eventdev API specification/documentation Bruce Richardson
2024-01-18 13:45 ` [PATCH v1 1/7] eventdev: improve doxygen introduction text Bruce Richardson
2024-01-18 13:45 ` [PATCH v1 2/7] eventdev: move text on driver internals to proper section Bruce Richardson
2024-01-18 13:45 ` [PATCH v1 3/7] eventdev: update documentation on device capability flags Bruce Richardson
2024-01-18 13:45 ` [PATCH v1 4/7] eventdev: cleanup doxygen comments on info structure Bruce Richardson
2024-01-18 13:49   ` Bruce Richardson
2024-01-18 13:45 ` [PATCH v1 5/7] eventdev: improve function documentation for query fns Bruce Richardson
2024-01-18 13:45 ` [PATCH v1 6/7] eventdev: improve doxygen comments on configure struct Bruce Richardson
2024-01-18 13:45 ` [PATCH v1 7/7] eventdev: fix documentation for counting single-link ports Bruce Richardson
2024-01-19 17:43 ` [PATCH v2 00/11] improve eventdev API specification/documentation Bruce Richardson
2024-01-19 17:43   ` [PATCH v2 01/11] eventdev: improve doxygen introduction text Bruce Richardson
2024-01-23  8:57     ` Mattias Rönnblom
2024-01-23  9:06       ` Bruce Richardson
2024-01-24 11:37         ` Mattias Rönnblom
2024-01-31 13:45       ` Bruce Richardson
2024-01-19 17:43   ` [PATCH v2 02/11] eventdev: move text on driver internals to proper section Bruce Richardson
2024-01-19 17:43   ` [PATCH v2 03/11] eventdev: update documentation on device capability flags Bruce Richardson
2024-01-23  9:18     ` Mattias Rönnblom
2024-01-23  9:34       ` Bruce Richardson
2024-01-31 14:09       ` Bruce Richardson
2024-02-02  8:58         ` Mattias Rönnblom
2024-02-02 11:20           ` Bruce Richardson
2024-01-19 17:43   ` [PATCH v2 04/11] eventdev: cleanup doxygen comments on info structure Bruce Richardson
2024-01-23  9:35     ` Mattias Rönnblom
2024-01-23  9:43       ` Bruce Richardson
2024-01-24 11:51         ` Mattias Rönnblom
2024-01-31 14:37           ` Bruce Richardson
2024-02-02  9:24             ` Mattias Rönnblom
2024-02-02 10:30               ` Bruce Richardson
2024-01-19 17:43   ` [PATCH v2 05/11] eventdev: improve function documentation for query fns Bruce Richardson
2024-01-23  9:40     ` Mattias Rönnblom
2024-01-19 17:43   ` [PATCH v2 06/11] eventdev: improve doxygen comments on configure struct Bruce Richardson
2024-01-23  9:46     ` Mattias Rönnblom
2024-01-31 16:15       ` Bruce Richardson
2024-01-19 17:43   ` [PATCH v2 07/11] eventdev: fix documentation for counting single-link ports Bruce Richardson
2024-01-23  9:48     ` Mattias Rönnblom
2024-01-23  9:56       ` Bruce Richardson
2024-01-31 16:18         ` Bruce Richardson
2024-01-19 17:43   ` [PATCH v2 08/11] eventdev: improve doxygen comments on config fns Bruce Richardson
2024-01-23 10:00     ` Mattias Rönnblom
2024-01-23 10:07       ` Bruce Richardson
2024-01-19 17:43   ` [PATCH v2 09/11] eventdev: improve doxygen comments for control APIs Bruce Richardson
2024-01-23 10:10     ` Mattias Rönnblom
2024-01-19 17:43   ` [PATCH v2 10/11] eventdev: RFC clarify comments on scheduling types Bruce Richardson
2024-01-23 16:19     ` Mattias Rönnblom
2024-01-24 11:21       ` Bruce Richardson
2024-01-31 17:54       ` Bruce Richardson
2024-01-19 17:43   ` [PATCH v2 11/11] eventdev: RFC clarify docs on event object fields Bruce Richardson
2024-01-24 11:34     ` Mattias Rönnblom
2024-02-01 16:59       ` Bruce Richardson
2024-02-02  9:38         ` Mattias Rönnblom
2024-02-02 11:33           ` Bruce Richardson
2024-02-02 12:02             ` Bruce Richardson
2024-02-01 17:02       ` Bruce Richardson
2024-02-02  9:14         ` Bruce Richardson
2024-02-02  9:22         ` Jerin Jacob
2024-02-02  9:36           ` Bruce Richardson
2024-02-02  9:45         ` Mattias Rönnblom
2024-02-02 10:32           ` Bruce Richardson
2024-02-01  9:35     ` Bruce Richardson
2024-02-01 15:00       ` Jerin Jacob
2024-02-01 15:24         ` Bruce Richardson
2024-02-01 16:20           ` Jerin Jacob
2024-02-02 12:39   ` [PATCH v3 00/11] improve eventdev API specification/documentation Bruce Richardson
2024-02-02 12:39     ` [PATCH v3 01/11] eventdev: improve doxygen introduction text Bruce Richardson
2024-02-07 10:14       ` Jerin Jacob
2024-02-08  9:50         ` Mattias Rönnblom
2024-02-09  8:43           ` Jerin Jacob
2024-02-10  7:24             ` Mattias Rönnblom
2024-02-20 16:28               ` Bruce Richardson
2024-02-20 16:33         ` Bruce Richardson
2024-02-02 12:39     ` [PATCH v3 02/11] eventdev: move text on driver internals to proper section Bruce Richardson
2024-02-02 12:39     ` [PATCH v3 03/11] eventdev: update documentation on device capability flags Bruce Richardson
2024-02-07 10:30       ` Jerin Jacob
2024-02-20 16:42         ` Bruce Richardson
2024-02-02 12:39     ` [PATCH v3 04/11] eventdev: cleanup doxygen comments on info structure Bruce Richardson
2024-02-02 12:39     ` [PATCH v3 05/11] eventdev: improve function documentation for query fns Bruce Richardson
2024-02-02 12:39     ` [PATCH v3 06/11] eventdev: improve doxygen comments on configure struct Bruce Richardson
2024-02-02 12:39     ` [PATCH v3 07/11] eventdev: improve doxygen comments on config fns Bruce Richardson
2024-02-02 12:39     ` [PATCH v3 08/11] eventdev: improve doxygen comments for control APIs Bruce Richardson
2024-02-02 12:39     ` [PATCH v3 09/11] eventdev: improve comments on scheduling types Bruce Richardson
2024-02-08  9:18       ` Jerin Jacob
2024-02-08 10:04         ` Mattias Rönnblom
2024-02-20 17:23           ` Bruce Richardson
2024-02-02 12:39     ` [PATCH v3 10/11] eventdev: clarify docs on event object fields and op types Bruce Richardson
2024-02-09  9:14       ` Jerin Jacob
2024-02-20 17:39         ` Bruce Richardson
2024-02-21  9:31           ` Jerin Jacob
2024-02-21 10:28             ` Bruce Richardson
2024-02-20 17:50         ` Bruce Richardson
2024-02-20 18:03         ` Bruce Richardson
2024-02-02 12:39     ` [PATCH v3 11/11] eventdev: drop comment for anon union from doxygen Bruce Richardson
2024-02-21 10:32   ` [PATCH v4 00/12] improve eventdev API specification/documentation Bruce Richardson
2024-02-21 10:32     ` [PATCH v4 01/12] eventdev: improve doxygen introduction text Bruce Richardson
2024-02-26  4:51       ` [EXT] " Pavan Nikhilesh Bhagavatula
2024-02-26  9:59         ` Bruce Richardson
2024-02-29 16:13           ` Jerin Jacob
2024-02-21 10:32     ` [PATCH v4 02/12] eventdev: move text on driver internals to proper section Bruce Richardson
2024-02-26  5:01       ` [EXT] " Pavan Nikhilesh Bhagavatula
2024-02-21 10:32     ` [PATCH v4 03/12] eventdev: update documentation on device capability flags Bruce Richardson
2024-02-26  5:07       ` [EXT] " Pavan Nikhilesh Bhagavatula
2024-02-21 10:32     ` [PATCH v4 04/12] eventdev: cleanup doxygen comments on info structure Bruce Richardson
2024-02-26  5:18       ` [EXT] " Pavan Nikhilesh Bhagavatula
2024-02-21 10:32     ` [PATCH v4 05/12] eventdev: improve function documentation for query fns Bruce Richardson
2024-02-26  5:18       ` [EXT] " Pavan Nikhilesh Bhagavatula
2024-02-21 10:32     ` [PATCH v4 06/12] eventdev: improve doxygen comments on configure struct Bruce Richardson
2024-02-26  6:36       ` [EXT] " Pavan Nikhilesh Bhagavatula
2024-02-21 10:32     ` [PATCH v4 07/12] eventdev: improve doxygen comments on config fns Bruce Richardson
2024-02-26  6:43       ` [EXT] " Pavan Nikhilesh Bhagavatula
2024-02-26  6:44         ` Pavan Nikhilesh Bhagavatula
2024-02-21 10:32     ` [PATCH v4 08/12] eventdev: improve doxygen comments for control APIs Bruce Richardson
2024-02-26  6:44       ` [EXT] " Pavan Nikhilesh Bhagavatula
2024-02-21 10:32     ` Bruce Richardson [this message]
2024-02-26  6:49       ` [EXT] [PATCH v4 09/12] eventdev: improve comments on scheduling types Pavan Nikhilesh Bhagavatula
2024-02-21 10:32     ` [PATCH v4 10/12] eventdev: clarify docs on event object fields and op types Bruce Richardson
2024-02-26  6:52       ` [EXT] " Pavan Nikhilesh Bhagavatula
2024-02-21 10:32     ` [PATCH v4 11/12] eventdev: drop comment for anon union from doxygen Bruce Richardson
2024-02-26  6:52       ` [EXT] " Pavan Nikhilesh Bhagavatula
2024-02-21 10:32     ` [PATCH v4 12/12] eventdev: fix doxygen processing of event vector struct Bruce Richardson
2024-02-26  6:53       ` [EXT] " Pavan Nikhilesh Bhagavatula
2024-03-04 15:35       ` Thomas Monjalon
2024-03-04 15:49         ` Bruce Richardson
2024-02-23 12:36     ` [PATCH v4 00/12] improve eventdev API specification/documentation Jerin Jacob

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