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.

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.

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.

Thanks,
Shijith

>> 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