Re: [dpdk-dev] [PATCH 1/3] eventdev: allow for event devices requiring maintenance

[Jerin Jacob <jerinjacobk@gmail.com>]

On Tue, Oct 26, 2021 at 11:02 PM Mattias Rönnblom
<mattias.ronnblom@ericsson.com> wrote:
>
> Extend Eventdev API to allow for event devices which require various
> forms of internal processing to happen, even when events are not
> enqueued to or dequeued from a port.
>
> PATCH v1:
>   - Adapt to the move of fastpath function pointers out of
>     rte_eventdev struct
>   - Attempt to clarify how often the application is expected to
>     call rte_event_maintain()
>   - Add trace point
> RFC v2:
>   - Change rte_event_maintain() return type to be consistent
>     with the documentation.
>   - Remove unused typedef from eventdev_pmd.h.
>
> Signed-off-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>
> Tested-by: Richard Eklycke <richard.eklycke@ericsson.com>
> Tested-by: Liron Himi <lironh@marvell.com>
> ---
>
> +/**
> + * Maintain an event device.
> + *
> + * This function is only relevant for event devices which has the
> + * RTE_EVENT_DEV_CAP_REQUIRES_MAINT flag set. Such devices require the
> + * application to call rte_event_maintain() on a port during periods
> + * which it is neither enqueuing nor dequeuing events from that
> + * port.

# We need to add  "by the same core". Right? As other core such as
service core can not call rte_event_maintain()
# Also, Incase of Adapters enqueue() happens, right? If so, either
above text is not correct.
# @Erik Gabriel Carrillo  @Jayatheerthan, Jay @Gujjar, Abhinandan S
Please review 3/3 patch on adapter change.
Let me know you folks are OK with change or not or need more time to analyze.

If it need only for the adapter subsystem then can we make it an
internal API between DSW and adapters?


+  rte_event_maintain() is a low-overhead function and should be
> + * called at a high rate (e.g., in the applications poll loop).
> + *
> + * No port may be left unmaintained.
> + *
> + * rte_event_maintain() may be called on event devices which haven't
> + * set RTE_EVENT_DEV_CAP_REQUIRES_MAINT flag, in which case it is a
> + * no-operation.
> + *
> + * @param dev_id
> + *   The identifier of the device.
> + * @param port_id
> + *   The identifier of the event port.
> + * @return
> + *  - 0 on success.
> + *  - -EINVAL if *dev_id* or *port_id* is invalid
> + *
> + * @see RTE_EVENT_DEV_CAP_REQUIRES_MAINT
> + */
> +static inline int
> +rte_event_maintain(uint8_t dev_id, uint8_t port_id)
> +{
> +       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) {
> +               rte_errno = EINVAL;
> +               return 0;
> +       }
> +
> +       if (port == NULL) {
> +               rte_errno = EINVAL;
> +               return 0;
> +       }
> +#endif
> +       rte_eventdev_trace_maintain(dev_id, port_id);
> +
> +       if (fp_ops->maintain != NULL)
> +               fp_ops->maintain(port);
> +
> +       return 0;
> +}
> +
>  #ifdef __cplusplus
>  }
>  #endif
> diff --git a/lib/eventdev/rte_eventdev_core.h b/lib/eventdev/rte_eventdev_core.h
> index 61d5ebdc44..61fa65cab3 100644
> --- a/lib/eventdev/rte_eventdev_core.h
> +++ b/lib/eventdev/rte_eventdev_core.h
> @@ -29,6 +29,9 @@ typedef uint16_t (*event_dequeue_burst_t)(void *port, struct rte_event ev[],
>                                           uint64_t timeout_ticks);
>  /**< @internal Dequeue burst of events from port of a device */
>
> +typedef void (*event_maintain_t)(void *port);
> +/**< @internal Maintains a port */
> +
>  typedef uint16_t (*event_tx_adapter_enqueue_t)(void *port,
>                                                struct rte_event ev[],
>                                                uint16_t nb_events);
> @@ -54,6 +57,8 @@ struct rte_event_fp_ops {
>         /**< PMD dequeue function. */
>         event_dequeue_burst_t dequeue_burst;
>         /**< PMD dequeue burst function. */
> +       event_maintain_t maintain;
> +       /**< PMD port maintenance function. */
>         event_tx_adapter_enqueue_t txa_enqueue;
>         /**< PMD Tx adapter enqueue function. */
>         event_tx_adapter_enqueue_t txa_enqueue_same_dest;
> diff --git a/lib/eventdev/rte_eventdev_trace_fp.h b/lib/eventdev/rte_eventdev_trace_fp.h
> index 5639e0b83a..c5a79a14d8 100644
> --- a/lib/eventdev/rte_eventdev_trace_fp.h
> +++ b/lib/eventdev/rte_eventdev_trace_fp.h
> @@ -38,6 +38,13 @@ RTE_TRACE_POINT_FP(
>         rte_trace_point_emit_ptr(enq_mode_cb);
>  )
>
> +RTE_TRACE_POINT_FP(
> +       rte_eventdev_trace_maintain,
> +       RTE_TRACE_POINT_ARGS(uint8_t dev_id, uint8_t port_id),
> +       rte_trace_point_emit_u8(dev_id);
> +       rte_trace_point_emit_u8(port_id);
> +)
> +
>  RTE_TRACE_POINT_FP(
>         rte_eventdev_trace_eth_tx_adapter_enqueue,
>         RTE_TRACE_POINT_ARGS(uint8_t dev_id, uint8_t port_id, void *ev_table,
> --
> 2.25.1
>