Re: [PATCH v4 1/2] ethdev: add query_update sync and async function calls

[Thomas Monjalon <thomas@monjalon.net>]

18/01/2023 11:31, Gregory Etelson:
> Current API allows either query or update indirect flow action.
> If port hardware allows both update and query in a single operation,
> application still has to issue 2 separate hardware requests.
> 
> The patch adds `rte_flow_action_handle_query_update` function call,
> and it's async version `rte_flow_async_action_handle_query_update`
> to atomically query and update flow action.

What is the benefit?
Is it a performance optimization? How much?

> int
> rte_flow_action_handle_query_update
>        (uint16_t port_id, struct rte_flow_action_handle *handle,
>         const void *update, void *query,
>         enum rte_flow_query_update_mode mode,
>         struct rte_flow_error *error);
> 
> int
> rte_flow_async_action_handle_query_update
>        (uint16_t port_id, uint32_t queue_id,
>         const struct rte_flow_op_attr *op_attr,
>         struct rte_flow_action_handle *action_handle,
>         const void *update, void *query,
>         enum rte_flow_query_update_mode mode,
>         void *user_data, struct rte_flow_error *error);

No need to copy the functions in the commit log.

> Application can control query and update order, if that is supported
> by port hardware, by setting qu_mode parameter to
> RTE_FLOW_QU_QUERY_FIRST or RTE_FLOW_QU_UPDATE_FIRST.
> 
> RTE_FLOW_QU_QUERY and RTE_FLOW_QU_UPDATE parameter values provide
> query only and update only functionality for backward compatibility
> with existing API.

Why do we need such compatibility?
The existing functions will stay, isn't it?

[...]
> + * RTE_FLOW_QU_QUERY_FIRST
> + *   Force port to query action before update.
> + * RTE_FLOW_QU_UPDATE_FIRST
> + *   Force port to update action before update.

You mean "before query".
Anyway you don't need to repeat the enum in the comment.

> + *
> + * @see rte_flow_action_handle_query_update()
> + * @see rte_flow_async_action_handle_query_update()
> + */
> +enum rte_flow_query_update_mode {
> +	RTE_FLOW_QU_QUERY_FIRST,  /* query before update */
> +	RTE_FLOW_QU_UPDATE_FIRST, /* query after  update */
> +};
> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice.
> + *
> + * Query and/or update indirect flow action.
> + * If update parameter is NULL the function queries indirect action.
> + * If query parameter is NULL the function updates indirect action.
> + * If both query and update not NULL, the function atomically
> + * queries and updates indirect action. Query and update carried in order

"are" carried?

> + * specified in the mode parameter.
> + *
> + * @param port_id
> + *   Port identifier of Ethernet device.
> + * @param handle
> + *   Handle for the indirect action object to be updated.
> + * @param update
> + *   Update profile specification used to modify the action pointed by handle.
> + *   *update* could be with the same type of the immediate action corresponding

could be "of" the same type

> + *   to the *handle* argument when creating, or a wrapper structure includes
> + *   action configuration to be updated and bit fields to indicate the member
> + *   of fields inside the action to update.
> + * @param query
> + *   Pointer to storage for the associated query data type.
> + * @param mode
> + *   Operational mode.
> + * @param error
> + *   Perform verbose error reporting if not NULL.
> + *   PMDs initialize this structure in case of error only.
> + *
> + * @return
> + * 0 on success, a negative errno value otherwise and rte_errno is set.
> + * - (ENOTSUP) if underlying device does not support this functionality.
> + * - (EINVAL) - if *handle* invalid
> + */
> +__rte_experimental
> +int
> +rte_flow_action_handle_query_update(uint16_t port_id,
> +				    struct rte_flow_action_handle *handle,
> +				    const void *update, void *query,
> +				    enum rte_flow_query_update_mode mode,
> +				    struct rte_flow_error *error);
> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice.
> + *
> + * Enqueue async indirect flow action query and/or update
> + *
> + * @param port_id
> + *   Port identifier of Ethernet device.
> + * @param queue_id
> + *   Flow queue which is used to update the rule.
> + * @param attr
> + *   Indirect action update operation attributes.
> + * @param handle
> + *   Handle for the indirect action object to be updated.
> + * @param update
> + *   Update profile specification used to modify the action pointed by handle.
> + *   *update* could be with the same type of the immediate action corresponding
> + *   to the *handle* argument when creating, or a wrapper structure includes

includes -> including

> + *   action configuration to be updated and bit fields to indicate the member
> + *   of fields inside the action to update.

Where can we find how such wrapper should look like?

> + * @param query
> + *   Pointer to storage for the associated query data type.
> + *   Query result returned on async completion event.
> + * @param mode
> + *   Operational mode.
> + * @param user_data
> + *   The user data that will be returned on async completion event.
> + * @param error
> + *   Perform verbose error reporting if not NULL.
> + *   PMDs initialize this structure in case of error only.
> + *
> + * @return
> + *   0 on success, a negative errno value otherwise and rte_errno is set.
> + * - (ENOTSUP) if underlying device does not support this functionality.
> + * - (EINVAL) - if *handle* invalid
> + */
> +__rte_experimental
> +int
> +rte_flow_async_action_handle_query_update(uint16_t port_id, uint32_t queue_id,
> +					  const struct rte_flow_op_attr *attr,
> +					  struct rte_flow_action_handle *handle,
> +					  const void *update, void *query,
> +					  enum rte_flow_query_update_mode mode,
> +					  void *user_data,
> +					  struct rte_flow_error *error);

> --- a/lib/ethdev/version.map
> +++ b/lib/ethdev/version.map
> @@ -298,6 +298,11 @@ EXPERIMENTAL {
>  	rte_flow_get_q_aged_flows;
>  	rte_mtr_meter_policy_get;
>  	rte_mtr_meter_profile_get;
> +
> +	# future

It should be "# added in 23.03"

> +	rte_flow_action_handle_query_update;
> +	rte_flow_async_action_handle_query_update;