RE: [RFC PATCH] eventdev: adapter API to configure multiple Rx queues

[Shijith Thotton <sthotton@marvell.com>]

>> >>> This RFC introduces a new API,
>> >>> rte_event_eth_rx_adapter_queues_add(),
>> >>> designed to enhance the flexibility of configuring multiple Rx
>> >>> queues in eventdev Rx adapter.
>> >>>
>> >>> The existing rte_event_eth_rx_adapter_queue_add() API supports
>> >>> adding multiple queues by specifying rx_queue_id = -1, but it lacks
>> >>> the ability to
>> >apply
>> >>> specific configurations to each of the added queues.
>> >>>
>> >>
>> >>The application can still use the existing
>> >>rte_event_eth_rx_adapter_queue_add() API in a loop with different
>> >>configurations for different queues.
>> >>
>> >>The proposed API is not enabling new features that cannot be achieved
>> >>with the existing API.
>> >>Adding new APIs without much usefulness causes unnecessary
>> >>complexity/confusion for users.
>> >>
>> >
>> >The new API was introduced because the existing API does not support
>> >adding multiple queues with specific configurations. It serves as a
>> >burst variant of the existing API, like many other APIs in DPDK.
>> >
>
>The other burst APIs may be there for dataplane functionalities, but may not be
>for the control plane functionalities.
>

rte_acl_add_rules() is an example of burst API in control path.

>> >For better clarity, the API can be renamed to
>> >rte_event_eth_rx_adapter_queue_add_burst() if needed.
>> >
>> >In hardware, adding each queue individually incurs significant
>> >overheads, such as mailbox operations. A burst API helps to amortize
>> >this overhead. Since real- world applications often call the API with
>> >specific queue_ids, the burst API can provide considerable benefits.
>> >Testing shows a 75% reduction in time when adding multiple queues to
>> >the RX adapter using the burst API on our platform.
>> >
>
> As batching helps for a particular hardware device, this may not be applicable
>for all platforms/cases.
>	Since queue_add is a control plane operation, latency may not be a
>concern.

In certain use cases, these APIs can be considered semi-fast path. For instance,
in an application that hotplugs a port on demand, configuring all available
queues simultaneously can significantly reduce latency.

>How to specify a particular set(specific queue_ids) of rx_queues that has a non-
>zero start index with the new proposed API?

In the proposed API,
int rte_event_eth_rx_adapter_queues_add(
                        uint8_t id, uint16_t eth_dev_id, int32_t rx_queue_id[],
                        const struct rte_event_eth_rx_adapter_queue_conf conf[],
                        uint16_t nb_rx_queues);
rx_queues_id is an array containing the receive queues ids, which can start
from a non-zero value. The array index is used solely to locate the
corresponding queue_conf. For example, rx_queues_id[i] will use conf[i].

>	Since this is still not possible with the proposed API, the existing
>queue_add API needs to be used with specific queue_ids and their
>configurations.
>
>> >I can modify the old API implementation to act as a wrapper around the
>> >burst API, with number of queues equal to 1. If concerns remain, we can
>> >explore deprecation as an alternative.
>> >
>>
>> Please let me know if you have any suggestions/feedback on what I said
>> above.
>
>Still feel the new proposed API can be avoided as it looks like a different
>combination of existing API instead of adding some new features.
>
>> If not, I can go ahead and send v1.
>>
>> >>> The proposed API, rte_event_eth_rx_adapter_queues_add, addresses
>> >>> this limitation by:
>> >>>
>> >>> - Enabling users to specify an array of rx_queue_id values alongside
>> >>>   individual configurations for each queue.
>> >>>
>> >>> - Supporting a nb_rx_queues argument to define the number of queues
>to
>> >>>   configure. When set to 0, the API applies a common configuration to
>> >>>   all queues, similar to the existing rx_queue_id = -1 behavior.
>> >>>
>> >>> This enhancement allows for more granular control when configuring
>> >multiple
>> >>> Rx queues. Additionally, the API can act as a replacement for the
>> >>> older API, offering both flexibility and improved functionality.
>> >>>
>> >>> Signed-off-by: Shijith Thotton <sthotton@marvell.com>
>> >>> ---
>> >>>  lib/eventdev/eventdev_pmd.h             | 34
>> +++++++++++++++++++++++++
>> >>>  lib/eventdev/rte_event_eth_rx_adapter.h | 34
>> >>> +++++++++++++++++++++++++
>> >>>  2 files changed, 68 insertions(+)
>> >>>
>> >>> diff --git a/lib/eventdev/eventdev_pmd.h
>> >>> b/lib/eventdev/eventdev_pmd.h index 36148f8d86..2e458a9779
>> 100644
>> >>> --- a/lib/eventdev/eventdev_pmd.h
>> >>> +++ b/lib/eventdev/eventdev_pmd.h
>> >>> @@ -25,6 +25,7 @@
>> >>>  #include <rte_mbuf_dyn.h>
>> >>>
>> >>>  #include "event_timer_adapter_pmd.h"
>> >>> +#include "rte_event_eth_rx_adapter.h"
>> >>>  #include "rte_eventdev.h"
>> >>>
>> >>>  #ifdef __cplusplus
>> >>> @@ -708,6 +709,37 @@ typedef int
>> >>> (*eventdev_eth_rx_adapter_queue_add_t)(
>> >>>  		int32_t rx_queue_id,
>> >>>  		const struct rte_event_eth_rx_adapter_queue_conf
>> >>> *queue_conf);
>> >>>
>> >>> +/**
>> >>> + * Add ethernet Rx queues to event device. This callback is invoked
>> >>> +if
>> >>> + * the caps returned from rte_eventdev_eth_rx_adapter_caps_get(,
>> >>> +eth_port_id)
>> >>> + * has RTE_EVENT_ETH_RX_ADAPTER_CAP_INTERNAL_PORT set.
>> >>> + *
>> >>> + * @param dev
>> >>> + *   Event device pointer
>> >>> + *
>> >>> + * @param eth_dev
>> >>> + *   Ethernet device pointer
>> >>> + *
>> >>> + * @param rx_queue_id
>> >>> + *   Ethernet device receive queue index array
>> >>> + *
>> >>> + * @param queue_conf
>> >>> + *   Additional configuration structure array
>> >>> + *
>> >>> + * @param nb_rx_queues
>> >>> + *   Number of ethernet device receive queues
>> >>> + *
>> >>> + * @return
>> >>> + *   - 0: Success, ethernet receive queues added successfully.
>> >>> + *   - <0: Error code returned by the driver function.
>> >>> + */
>> >>> +typedef int (*eventdev_eth_rx_adapter_queues_add_t)(
>> >>> +		const struct rte_eventdev *dev,
>> >>> +		const struct rte_eth_dev *eth_dev,
>> >>> +		int32_t rx_queue_id[],
>> >>> +		const struct rte_event_eth_rx_adapter_queue_conf
>> >>> queue_conf[],
>> >>> +		uint16_t nb_rx_queues);
>> >>> +
>> >>>  /**
>> >>>   * Delete ethernet Rx queues from event device. This callback is invoked if
>> >>>   * the caps returned from eventdev_eth_rx_adapter_caps_get(,
>> >eth_port_id)
>> >>> @@ -1578,6 +1610,8 @@ struct eventdev_ops {
>> >>>  	/**< Get ethernet Rx adapter capabilities */
>> >>>  	eventdev_eth_rx_adapter_queue_add_t eth_rx_adapter_queue_add;
>> >>>  	/**< Add Rx queues to ethernet Rx adapter */
>> >>> +	eventdev_eth_rx_adapter_queues_add_t
>> >>> eth_rx_adapter_queues_add;
>> >>> +	/**< Add Rx queues to ethernet Rx adapter */
>> >>>  	eventdev_eth_rx_adapter_queue_del_t eth_rx_adapter_queue_del;
>> >>>  	/**< Delete Rx queues from ethernet Rx adapter */
>> >>>  	eventdev_eth_rx_adapter_queue_conf_get_t
>> >>> eth_rx_adapter_queue_conf_get; diff --git
>> >>> a/lib/eventdev/rte_event_eth_rx_adapter.h
>> >>> b/lib/eventdev/rte_event_eth_rx_adapter.h
>> >>> index 9237e198a7..9a5c560b67 100644
>> >>> --- a/lib/eventdev/rte_event_eth_rx_adapter.h
>> >>> +++ b/lib/eventdev/rte_event_eth_rx_adapter.h
>> >>> @@ -553,6 +553,40 @@ int
>> rte_event_eth_rx_adapter_queue_add(uint8_t
>> >>> id,
>> >>>  			int32_t rx_queue_id,
>> >>>  			const struct rte_event_eth_rx_adapter_queue_conf
>> >>> *conf);
>> >>>
>> >>> +/**
>> >>> + * Add multiple receive queues to an event adapter.
>> >>> + *
>> >>> + * @param id
>> >>> + *  Adapter identifier.
>> >>> + *
>> >>> + * @param eth_dev_id
>> >>> + *  Port identifier of Ethernet device.
>> >>> + *
>> >>> + * @param rx_queue_id
>> >>> + *  Array of Ethernet device receive queue indices.
>> >>> + *  If nb_rx_queues is 0, then rx_queue_id is ignored.
>> >>> + *
>> >>> + * @param conf
>> >>> + *  Array of additional configuration structures of type
>> >>> + *  *rte_event_eth_rx_adapter_queue_conf*. conf[i] is used for
>> >>> rx_queue_id[i].
>> >>> + *  If nb_rx_queues is 0, then conf[0] is used for all Rx queues.
>> >>> + *
>> >>> + * @param nb_rx_queues
>> >>> + *  Number of receive queues to add.
>> >>> + *  If nb_rx_queues is 0, then all Rx queues configured for
>> >>> + *  the device are added with the same configuration in conf[0].
>> >>> + * @see RTE_EVENT_ETH_RX_ADAPTER_CAP_MULTI_EVENTQ
>> >>> + *
>> >>> + * @return
>> >>> + *  - 0: Success, Receive queues added correctly.
>> >>> + *  - <0: Error code on failure.
>> >>> + */
>> >>> +__rte_experimental
>> >>> +int rte_event_eth_rx_adapter_queues_add(
>> >>> +			uint8_t id, uint16_t eth_dev_id, int32_t
>> >>> rx_queue_id[],
>> >>> +			const struct rte_event_eth_rx_adapter_queue_conf
>> >>> conf[],
>> >>> +			uint16_t nb_rx_queues);
>> >>> +
>> >>>  /**
>> >>>   * Delete receive queue from an event adapter.
>> >>>   *
>> >>> --
>> >>> 2.25.1