[v4,0/6] Introduce event pre-scheduling

From: Pavan Nikhilesh <pbhagavatula@marvell.com>

Event pre-scheduling improves scheduling performance by assigning events
to event ports in advance when dequeues are issued.
This series introduces various types and levels of pre-scheduling to the
eventdev library.

pre-scheduling Types:
 * RTE_EVENT_DEV_PRESCHEDULE_NONE: No pre-scheduling.
 * RTE_EVENT_DEV_PRESCHEDULE: Always issue a pre-schedule when dequeue is issued.
 * RTE_EVENT_DEV_PRESCHEDULE_ADAPTIVE: Delay issuing pre-schedule until there
   are no forward progress constraints with the held flow contexts.

pre-scheduling Levels:
 * Event Device Level Pre-scheduling: Pre-scheduling can be enabled or disabled at the
   event device during configuration. Event devices can indicate pre-scheduling
   capabilities using `RTE_EVENT_DEV_CAP_EVENT_PRESCHEDULE` and
  `RTE_EVENT_DEV_CAP_EVENT_PRESCHEDULE_ADAPTIVE` via the event device info
  function `info.event_dev_cap`.
 * Event Port Level Prefetch: Pre-scheduling can be selectively enabled or disabled
   at the event port during runtime. Event devices can indicate this capability
   using `RTE_EVENT_PORT_CAP_EVENT_PER_PORT_PRESCHEDULE` via the event device info
   function `info.event_port_cap`.
 * Application Controlled Prefetch Hint: Applications can provide hints to the
   event device to start pre-scheduling events using the new API
   `rte_event_port_pre-schedule`. Event devices can indicate this capabilities using
   `RTE_EVENT_DEV_CAP_SW_PRESCHEDULE` via the event device info function
   `info.event_dev_cap`.

The rte_event_dequeue_burst operation initiates the pre-schedule operation, which
completes in parallel without affecting the flow context of the dequeued events and
dequeue latency. On the next dequeue operation, the pre-scheduleed events are
dequeued, and pre-schedule operation is initiated again.

In the case of application-controlled pre-schedule hints, the currently held flow
contexts, if any, are not affected by the pre-schedule operation. On the next
dequeue operation, the pre-scheduleed events are returned, but pre-schedule is not
initiated again until the application provides the hint again. If pre-scheduling
is already enabled at the event device level or event port level, the hint is ignored.

v2 Changes:
- s/prefetch/pre-schedule (Mattias).
v3 Changes:
- Add CNXK preschedule implementation.
- Update test-eventdev to use prescheduling.
- Update examples to use prescheduling.
v4 Changes:
- Fix compilation.

Pavan Nikhilesh (6):
  eventdev: introduce event pre-scheduling
  eventdev: add event port pre-schedule modify
  eventdev: add SW event preschedule hint
  event/cnkx: add pre-schedule support
  app/test-eventdev: add pre-scheduling support
  examples: use eventdev pre-scheduling

 app/test-eventdev/evt_common.h                |  45 ++++--
 app/test-eventdev/evt_options.c               |  17 ++
 app/test-eventdev/evt_options.h               |   1 +
 app/test/test_eventdev.c                      | 143 ++++++++++++++++
 doc/guides/eventdevs/cnxk.rst                 |  10 --
 doc/guides/eventdevs/features/cnxk.ini        |   1 +
 doc/guides/eventdevs/features/default.ini     |   1 +
 doc/guides/prog_guide/eventdev/eventdev.rst   |  42 +++++
 doc/guides/rel_notes/release_24_11.rst        |  11 ++
 doc/guides/tools/testeventdev.rst             |   6 +
 drivers/event/cnxk/cn10k_eventdev.c           |  19 ++-
 drivers/event/cnxk/cn10k_worker.c             |  21 +++
 drivers/event/cnxk/cn10k_worker.h             |   1 +
 drivers/event/cnxk/cnxk_eventdev.c            |   2 -
 drivers/event/cnxk/cnxk_eventdev.h            |   1 -
 .../pipeline_worker_generic.c                 |   6 +
 .../eventdev_pipeline/pipeline_worker_tx.c    |   6 +
 examples/ipsec-secgw/event_helper.c           |   6 +
 examples/l2fwd-event/l2fwd_event_generic.c    |   6 +
 .../l2fwd-event/l2fwd_event_internal_port.c   |   6 +
 examples/l3fwd/l3fwd_event_generic.c          |   6 +
 examples/l3fwd/l3fwd_event_internal_port.c    |   6 +
 lib/eventdev/eventdev_pmd.h                   |   4 +
 lib/eventdev/eventdev_private.c               |  41 ++++-
 lib/eventdev/eventdev_trace_points.c          |   6 +
 lib/eventdev/rte_eventdev.h                   | 152 ++++++++++++++++++
 lib/eventdev/rte_eventdev_core.h              |  11 ++
 lib/eventdev/rte_eventdev_trace_fp.h          |  19 ++-
 lib/eventdev/version.map                      |   6 +
 29 files changed, 574 insertions(+), 28 deletions(-)

--
2.25.1
  

On Tue, 1 Oct 2024 18:48:55 +0530
<pbhagavatula@marvell.com> wrote:

> From: Pavan Nikhilesh <pbhagavatula@marvell.com>
> 
> Event pre-scheduling improves scheduling performance by assigning events
> to event ports in advance when dequeues are issued.
> This series introduces various types and levels of pre-scheduling to the
> eventdev library.

Any numbers on how much this improves the overhead?
  

> > From: Pavan Nikhilesh <pbhagavatula@marvell.com>
> >
> > Event pre-scheduling improves scheduling performance by assigning events
> > to event ports in advance when dequeues are issued.
> > This series introduces various types and levels of pre-scheduling to the
> > eventdev library.
> 
> Any numbers on how much this improves the overhead?

In case of CNXK pmd, it preschedule doubles the scheduler performance.