Re: [PATCH v4 3/6] eventdev: add SW event preschedule hint

[Jerin Jacob <jerinjacobk@gmail.com>]

On Wed, Oct 2, 2024 at 2:19 AM <pbhagavatula@marvell.com> wrote:
>
> From: Pavan Nikhilesh <pbhagavatula@marvell.com>
>
> Add a new eventdev API to provide a hint to the eventdev PMD to
> pre-schedule the next event into the event port, without releasing
> the current flow context.
> Event device that support this feature advertises the capability
> using the RTE_EVENT_DEV_CAP_SW_PRESCHEDULE capability flag.

Change to RTE_EVENT_DEV_CAP_PRESCHEDULE_* prefix like other capas.



>
> Application can invoke `rte_event_port_preschedule` to hint the PMD.
>
> Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
> ---
>  doc/guides/prog_guide/eventdev/eventdev.rst |  8 ++++
>  doc/guides/rel_notes/release_24_11.rst      |  3 +-
>  lib/eventdev/eventdev_pmd.h                 |  2 +
>  lib/eventdev/eventdev_private.c             | 21 ++++++++-
>  lib/eventdev/eventdev_trace_points.c        |  3 ++
>  lib/eventdev/rte_eventdev.h                 | 49 +++++++++++++++++++++
>  lib/eventdev/rte_eventdev_core.h            |  5 +++
>  lib/eventdev/rte_eventdev_trace_fp.h        |  8 ++++
>  lib/eventdev/version.map                    |  2 +
>  9 files changed, 98 insertions(+), 3 deletions(-)
>
> diff --git a/doc/guides/prog_guide/eventdev/eventdev.rst b/doc/guides/prog_guide/eventdev/eventdev.rst
> index 2deab0333e..1d8b86ab66 100644
> --- a/doc/guides/prog_guide/eventdev/eventdev.rst
> +++ b/doc/guides/prog_guide/eventdev/eventdev.rst
> @@ -390,6 +390,14 @@ To enable or disable event pre-scheduling at a given event port, the application
>     // Disable pre-scheduling if thread is about to be scheduled out and issue dequeue() to drain
>     // pending events.
>
> +Event Pre-schedule Hint can be used to provide a hint to the eventdev PMD to pre-schedule the next

pre-schedule
Hint -> hint

Application may provide pre-schedule hint to eventdev PMD to pre-schedule ....

> +event without releasing the current flow context. Event device that support this feature advertises
> +the capability using the ``RTE_EVENT_DEV_CAP_SW_PRESCHEDULE`` capability flag.

SW is a very overloaded term, How about RTE_EVENT_DEV_CAP_PRESCHEDULE_EXPLICT?


Tell it is HINT. No need to check the capability in fast path.

> +If pre-scheduling is already enabled at a event device or event port level then the hint is ignored.
> +
> +.. code-block:: c
> +
> +   rte_event_port_preschedule(dev_id, port_id, RTE_EVENT_DEV_PRESCHEDULE);

Since it is used at port level. Remove _DEV_.

>
>  Starting the EventDev
>  ~~~~~~~~~~~~~~~~~~~~~
> diff --git a/doc/guides/rel_notes/release_24_11.rst b/doc/guides/rel_notes/release_24_11.rst
> index 6e36ac7b7e..3ada21c084 100644
> --- a/doc/guides/rel_notes/release_24_11.rst
> +++ b/doc/guides/rel_notes/release_24_11.rst
> @@ -64,7 +64,8 @@ New Features
>      level pre-scheduling type.
>    * Added ``rte_event_port_preschedule_modify`` to modify pre-scheduling type
>      on a given event port.
> -
> +  * Added ``rte_event_port_preschedule`` to allow applications to decide when
> +    to pre-schedule events on an event port.

As an explicit request or so.

>
>  Removed Items
>  -------------
> diff --git a/lib/eventdev/eventdev_pmd.h b/lib/eventdev/eventdev_pmd.h
> index 9ea23aa6cd..0bee2347ef 100644
> --- a/lib/eventdev/eventdev_pmd.h
> +++ b/lib/eventdev/eventdev_pmd.h
> @@ -186,6 +186,8 @@ struct __rte_cache_aligned rte_eventdev {
>         /**< Pointer to PMD Event switch profile function. */
>         event_preschedule_modify_t preschedule_modify;
>         /**< Pointer to PMD Event port pre-schedule type modify function.  */
> +       event_preschedule_t preschedule;
> +       /**< Pointer to PMD Event port pre-schedule function. */
>
>         uint64_t reserved_64s[3]; /**< Reserved for future fields */
>         void *reserved_ptrs[3];   /**< Reserved for future fields */
> diff --git a/lib/eventdev/eventdev_private.c b/lib/eventdev/eventdev_private.c
> index dc37f736f8..6aed1cba9a 100644
> --- a/lib/eventdev/eventdev_private.c
> +++ b/lib/eventdev/eventdev_private.c
> @@ -111,6 +111,19 @@ dummy_event_port_preschedule_modify_hint(__rte_unused void *port,
>         return -ENOTSUP;
>  }
>
> +static void
> +dummy_event_port_preschedule(__rte_unused void *port,
> +                            __rte_unused rte_event_dev_preschedule_type_t preschedule)
> +{
> +       RTE_EDEV_LOG_ERR("pre-schedule requested for unconfigured event device");
> +}
> +
> +static void
> +dummy_event_port_preschedule_hint(__rte_unused void *port,
> +                            __rte_unused rte_event_dev_preschedule_type_t preschedule)
> +{
> +}
> +
>  void
>  event_dev_fp_ops_reset(struct rte_event_fp_ops *fp_op)
>  {
> @@ -124,12 +137,12 @@ event_dev_fp_ops_reset(struct rte_event_fp_ops *fp_op)
>                 .dequeue_burst = dummy_event_dequeue_burst,
>                 .maintain = dummy_event_maintain,
>                 .txa_enqueue = dummy_event_tx_adapter_enqueue,
> -               .txa_enqueue_same_dest =
> -                       dummy_event_tx_adapter_enqueue_same_dest,
> +               .txa_enqueue_same_dest = dummy_event_tx_adapter_enqueue_same_dest,
>                 .ca_enqueue = dummy_event_crypto_adapter_enqueue,
>                 .dma_enqueue = dummy_event_dma_adapter_enqueue,
>                 .profile_switch = dummy_event_port_profile_switch,
>                 .preschedule_modify = dummy_event_port_preschedule_modify,
> +               .preschedule = dummy_event_port_preschedule,
>                 .data = dummy_data,
>         };
>
> @@ -153,8 +166,12 @@ event_dev_fp_ops_set(struct rte_event_fp_ops *fp_op,
>         fp_op->dma_enqueue = dev->dma_enqueue;
>         fp_op->profile_switch = dev->profile_switch;
>         fp_op->preschedule_modify = dev->preschedule_modify;
> +       fp_op->preschedule = dev->preschedule;
>         fp_op->data = dev->data->ports;
>
>         if (fp_op->preschedule_modify == NULL)
>                 fp_op->preschedule_modify = dummy_event_port_preschedule_modify_hint;
> +
> +       if (fp_op->preschedule == NULL)
> +               fp_op->preschedule = dummy_event_port_preschedule_hint;
>  }
> diff --git a/lib/eventdev/eventdev_trace_points.c b/lib/eventdev/eventdev_trace_points.c
> index e41674123c..e7af1591f7 100644
> --- a/lib/eventdev/eventdev_trace_points.c
> +++ b/lib/eventdev/eventdev_trace_points.c
> @@ -52,6 +52,9 @@ RTE_TRACE_POINT_REGISTER(rte_eventdev_trace_port_profile_switch,
>  RTE_TRACE_POINT_REGISTER(rte_eventdev_trace_port_preschedule_modify,
>         lib.eventdev.port.preschedule.modify)
>
> +RTE_TRACE_POINT_REGISTER(rte_eventdev_trace_port_preschedule,
> +       lib.eventdev.port.preschedule)
> +
>  /* Eventdev Rx adapter trace points */
>  RTE_TRACE_POINT_REGISTER(rte_eventdev_trace_eth_rx_adapter_create,
>         lib.eventdev.rx.adapter.create)
> diff --git a/lib/eventdev/rte_eventdev.h b/lib/eventdev/rte_eventdev.h
> index 0add0093ac..8df6a8bee1 100644
> --- a/lib/eventdev/rte_eventdev.h
> +++ b/lib/eventdev/rte_eventdev.h
> @@ -480,6 +480,15 @@ struct rte_event;
>   * @see rte_event_port_preschedule_modify()
>   */
>
> +#define RTE_EVENT_DEV_CAP_SW_PRESCHEDULE (1ULL << 19)
> +/**< Event device supports software prescheduling.
> + *
> + * When this flag is set, the application can issue preschedule request on
> + * a event port.
> + *
> + * @see rte_event_port_preschedule()
> + */
> +
>  /* Event device priority levels */
>  #define RTE_EVENT_DEV_PRIORITY_HIGHEST   0
>  /**< Highest priority level for events and queues.
> @@ -2977,6 +2986,46 @@ rte_event_port_preschedule_modify(uint8_t dev_id, uint8_t port_id,
>         return fp_ops->preschedule_modify(port, type);
>  }
>
> +/**
> + * Provide a hint to the event device to pre-schedule events to event port .
> + *
> + * Hint the event device to pre-schedule events to the event port.
> + * The call doesn't not guarantee that the events will be pre-scheduleed.
> + * The call doesn't release the flow context currently held by the event port.
> + * The event device should support RTE_EVENT_DEV_CAP_SW_PRESCHEDULE capability.

Reword the comments.

> + *
> + * When pre-scheduling is enabled at an event device or event port level, the
> + * hint is ignored.
> + *
> + * Subsequent calls to rte_event_dequeue_burst() will dequeue the pre-schedule
> + * events but pre-schedule operation is not issued again.
> + *
> + * @param dev_id
> + *   The identifier of the device.
> + * @param port_id
> + *   The identifier of the event port.
> + * @param type
> + *   The pre-schedule type to use on the event port.
> + */
> +static inline void
> +rte_event_port_preschedule(uint8_t dev_id, uint8_t port_id, rte_event_dev_preschedule_type_t type)
> +{
> +       const struct rte_event_fp_ops *fp_ops;
> +       void *port;
> +
> +       fp_ops = &rte_event_fp_ops[dev_id];
> +       port = fp_ops->data[port_id];
> +
> +#ifdef RTE_LIBRTE_EVENTDEV_DEBUG
> +       if (dev_id >= RTE_EVENT_MAX_DEVS || port_id >= RTE_EVENT_MAX_PORTS_PER_DEV)
> +               return;
> +       if (port == NULL)
> +               return;
> +#endif
> +       rte_eventdev_trace_port_preschedule(dev_id, port_id, type);
> +
> +       fp_ops->preschedule(port, type);
> +}
>  #ifdef __cplusplus
>  }
>  #endif
> diff --git a/lib/eventdev/rte_eventdev_core.h b/lib/eventdev/rte_eventdev_core.h
> index 2275888a6b..21988abb4f 100644
> --- a/lib/eventdev/rte_eventdev_core.h
> +++ b/lib/eventdev/rte_eventdev_core.h
> @@ -53,6 +53,9 @@ typedef int (*event_preschedule_modify_t)(void *port,
>                                           rte_event_dev_preschedule_type_t preschedule_type);
>  /**< @internal Modify pre-schedule type on the event port. */
>
> +typedef void (*event_preschedule_t)(void *port, rte_event_dev_preschedule_type_t preschedule_type);
> +/**< @internal Issue pre-schedule on an event port. */
> +
>  struct __rte_cache_aligned rte_event_fp_ops {
>         void **data;
>         /**< points to array of internal port data pointers */
> @@ -82,6 +85,8 @@ struct __rte_cache_aligned rte_event_fp_ops {
>         /**< PMD Event switch profile function. */
>         event_preschedule_modify_t preschedule_modify;
>         /**< PMD Event port pre-schedule switch. */
> +       event_preschedule_t preschedule;
> +       /**< PMD Event port pre-schedule. */

Use reserved not to break ABI

>         uintptr_t reserved[4];
>  };