Re: [PATCH 4/4] ethdev: add traffic manager query function

[Ferruh Yigit <ferruh.yigit@amd.com>]

On 8/6/2024 4:24 PM, Bruce Richardson wrote:
> +/**
> + * Return information about a traffic management node
> + *
> + * Return information about a hierarchy node, using the same format of parameters
> + * as was passed to the rte_rm_node_add() function.
> + * Each of the "out" parameters pointers (except error) may be passed as NULL if the
> + * information is not needed by the caller. For example, to one may check if a node id
> + * is in use by:
> + *
> + *  struct rte_tm_error error;
> + *  int ret = rte_tm_node_query(port, node_id, NULL, NULL, NULL, NULL, NULL, &error);
> + *  if (ret == ENOENT) ...
> + *
> + * @param[in] port_id
> + *   The port identifier of the Ethernet device.
> + * @param[in] node_id
> + *   Node ID. Should be a valid node id.
> + * @param[out] parent_node_id
> + *   Parent node ID.
> + * @param[out] priority
> + *   Node priority. The highest node priority is zero. Used by the SP algorithm
> + *   running on the parent of the current node for scheduling this child node.
> + * @param[out] weight
> + *   Node weight. The node weight is relative to the weight sum of all siblings
> + *   that have the same priority. The lowest weight is one. Used by the WFQ
> + *   algorithm running on the parent of the current node for scheduling this
> + *   child node.
> + * @param[out] level_id
> + *   The node level in the scheduler hierarchy.
> + * @param[out] params
> + *   Node parameters, as would be used when creating the node.
> + * @param[out] error
> + *   Error details. Filled in only on error, when not NULL.
> + * @return
> + *   0 on success, non-zero error code otherwise.
> + *   -EINVAL - port or node id value is invalid
> + *   -ENOENT - no node exists with the provided id
> + */
> +int
> +rte_tm_node_query(uint16_t port_id,
> +	uint32_t node_id,
> +	uint32_t *parent_node_id,
> +	uint32_t *priority,
> +	uint32_t *weight,
> +	uint32_t *level_id,
> +	struct rte_tm_node_params *params,
> +	struct rte_tm_error *error);
> +
>

No objection to get an TM node query API overall, but it would be good
to get more comment on the what correct API should be, we are missing it.
Both because it is not discussed much, and it is first release, better
to add this API as experimental.

Also we should have an implementation in driver and a sample application
usage (testpmd?) with new API. Are these planned separately for this
release, or can it be available part of next version of this patch?

Finally, does it worth documenting this in release notes, as just a
query API I am not sure if this a notable feature, but just a reminder.