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

["Naga Harish K, S V" <s.v.naga.harish.k@intel.com>]

> -----Original Message-----
> From: Shijith Thotton <sthotton@marvell.com>
> Sent: Monday, January 20, 2025 11:53 PM
> To: Naga Harish K, S V <s.v.naga.harish.k@intel.com>; dev@dpdk.org
> Cc: Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com>; Pathak,
> Pravin <pravin.pathak@intel.com>; Hemant Agrawal
> <hemant.agrawal@nxp.com>; Sachin Saxena <sachin.saxena@nxp.com>;
> Mattias R_nnblom <mattias.ronnblom@ericsson.com>; Jerin Jacob
> <jerinj@marvell.com>; Liang Ma <liangma@liangbit.com>; Mccarthy, Peter
> <peter.mccarthy@intel.com>; Van Haaren, Harry
> <harry.van.haaren@intel.com>; Carrillo, Erik G <erik.g.carrillo@intel.com>;
> Gujjar, Abhinandan S <abhinandan.gujjar@intel.com>; Amit Prakash Shukla
> <amitprakashs@marvell.com>; Burakov, Anatoly
> <anatoly.burakov@intel.com>
> Subject: RE: [RFC PATCH] eventdev: adapter API to configure multiple Rx
> queues
> 
> >> >> >>> 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 eth_rx_adapter_queue_add eventdev PMD operation can be updated to
> support burst mode. Internally, both the new and existing APIs can utilize this
> updated operation. This enables applications to use either API and achieve the
> same results while adding a single queue. For adding multiple RX queues to the
> adapter, the new API can be used as it is not supported by the old API.
> 

Not all platforms implement the eventdev PMD operation for eth_rx_adapter_queue_add, so this does not apply to all platforms.

> >> >> >
> >> >> >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.
> >>
> >
> >I mean, In general, burst APIs are for data-plane functions.
> >This may be one of the rare cases where a burst API is in the 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.
> >>
> >
> >As said earlier, this latency reduction (when trying to add multiple RX
> >queues to the Event Ethernet Rx adapter) may not apply to all
> platforms/cases.
> >This API is not for configuring queues but for adding the queues to the
> >RX adapter.
> >
> >> >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].
> >>
> >
> >Ok
> >
> >> >	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