Re: [PATCH 2/6] eventdev: add weight and affinity to queue attributes

["Mattias Rönnblom" <mattias.ronnblom@ericsson.com>]

On 2022-03-29 15:11, Shijith Thotton wrote:
> Extended eventdev queue QoS attributes to support weight and affinity.
> If queues are of same priority, events from the queue with highest
> weight will be scheduled first. Affinity indicates the number of times,
> the subsequent schedule calls from an event port will use the same event
> queue. Schedule call selects another queue if current queue goes empty
> or schedule count reaches affinity count.
>
> To avoid ABI break, weight and affinity attributes are not yet added to
> queue config structure and relies on PMD for managing it. New eventdev
> op queue_attr_get can be used to get it from the PMD.

Have you considered using a PMD-specific command line parameter as a 
stop-gap until you can extend the config struct?

> Signed-off-by: Shijith Thotton <sthotton@marvell.com>
> ---
>   lib/eventdev/eventdev_pmd.h | 22 ++++++++++++++++++++
>   lib/eventdev/rte_eventdev.c | 12 +++++++++++
>   lib/eventdev/rte_eventdev.h | 41 +++++++++++++++++++++++++++++++++----
>   3 files changed, 71 insertions(+), 4 deletions(-)
>
> diff --git a/lib/eventdev/eventdev_pmd.h b/lib/eventdev/eventdev_pmd.h
> index 6182749503..f19df98a7a 100644
> --- a/lib/eventdev/eventdev_pmd.h
> +++ b/lib/eventdev/eventdev_pmd.h
> @@ -341,6 +341,26 @@ typedef int (*eventdev_queue_setup_t)(struct rte_eventdev *dev,
>   typedef void (*eventdev_queue_release_t)(struct rte_eventdev *dev,
>   		uint8_t queue_id);
>   
> +/**
> + * Get an event queue attribute at runtime.
> + *
> + * @param dev
> + *   Event device pointer
> + * @param queue_id
> + *   Event queue index
> + * @param attr_id
> + *   Event queue attribute id
> + * @param[out] attr_value
> + *   Event queue attribute value
> + *
> + * @return
> + *  - 0: Success.
> + *  - <0: Error code on failure.
> + */
> +typedef int (*eventdev_queue_attr_get_t)(struct rte_eventdev *dev,
> +					 uint8_t queue_id, uint32_t attr_id,
> +					 uint32_t *attr_value);
> +
>   /**
>    * Set an event queue attribute at runtime.
>    *
> @@ -1231,6 +1251,8 @@ struct eventdev_ops {
>   	/**< Set up an event queue. */
>   	eventdev_queue_release_t queue_release;
>   	/**< Release an event queue. */
> +	eventdev_queue_attr_get_t queue_attr_get;
> +	/**< Get an event queue attribute. */
>   	eventdev_queue_attr_set_t queue_attr_set;
>   	/**< Set an event queue attribute. */
>   
> diff --git a/lib/eventdev/rte_eventdev.c b/lib/eventdev/rte_eventdev.c
> index 13c8af877e..37f0e54bf3 100644
> --- a/lib/eventdev/rte_eventdev.c
> +++ b/lib/eventdev/rte_eventdev.c
> @@ -838,6 +838,18 @@ rte_event_queue_attr_get(uint8_t dev_id, uint8_t queue_id, uint32_t attr_id,
>   
>   		*attr_value = conf->schedule_type;
>   		break;
> +	case RTE_EVENT_QUEUE_ATTR_WEIGHT:
> +		*attr_value = RTE_EVENT_QUEUE_WEIGHT_LOWEST;
> +		if (dev->dev_ops->queue_attr_get)
> +			return (*dev->dev_ops->queue_attr_get)(
> +				dev, queue_id, attr_id, attr_value);
> +		break;
> +	case RTE_EVENT_QUEUE_ATTR_AFFINITY:
> +		*attr_value = RTE_EVENT_QUEUE_AFFINITY_LOWEST;
> +		if (dev->dev_ops->queue_attr_get)
> +			return (*dev->dev_ops->queue_attr_get)(
> +				dev, queue_id, attr_id, attr_value);
> +		break;
>   	default:
>   		return -EINVAL;
>   	};
> diff --git a/lib/eventdev/rte_eventdev.h b/lib/eventdev/rte_eventdev.h
> index 19710cd0c5..fa16fc5dcb 100644
> --- a/lib/eventdev/rte_eventdev.h
> +++ b/lib/eventdev/rte_eventdev.h
> @@ -222,8 +222,14 @@ struct rte_event;
>   
>   /* Event device capability bitmap flags */
>   #define RTE_EVENT_DEV_CAP_QUEUE_QOS           (1ULL << 0)
> -/**< Event scheduling prioritization is based on the priority associated with
> - *  each event queue.
> +/**< Event scheduling prioritization is based on the priority and weight
> + * associated with each event queue. Events from a queue with highest priority
> + * is scheduled first. If the queues are of same priority, a queue with highest
> + * weight is selected. Subsequent schedules from an event port could see events
> + * from the same event queue if the queue is configured with an affinity count.
> + * Affinity count of a queue indicates the number of times, the subsequent
> + * schedule calls from an event port should use the same queue if the queue is
> + * non-empty.

Is this specifying something else than WRR scheduling for equal-priority 
queues?

What is a schedule call? I must say I don't understand this description. 
Is affinity the per-port batch size from the queue that is "next in 
line" for an opportunity to be scheduled to a port?

>    *
>    *  @see rte_event_queue_setup(), rte_event_queue_attr_set()
>    */
> @@ -331,6 +337,26 @@ struct rte_event;
>    * @see rte_event_port_link()
>    */
>   
> +/* Event queue scheduling weights */
> +#define RTE_EVENT_QUEUE_WEIGHT_HIGHEST   255
> +/**< Highest weight of an event queue
> + * @see rte_event_queue_attr_get(), rte_event_queue_attr_set()
> + */
> +#define RTE_EVENT_QUEUE_WEIGHT_LOWEST    0
> +/**< Lowest weight of an event queue
> + * @see rte_event_queue_attr_get(), rte_event_queue_attr_set()
> + */
> +
> +/* Event queue scheduling affinity */
> +#define RTE_EVENT_QUEUE_AFFINITY_HIGHEST   255
> +/**< Highest scheduling affinity of an event queue
> + * @see rte_event_queue_attr_get(), rte_event_queue_attr_set()
> + */
> +#define RTE_EVENT_QUEUE_AFFINITY_LOWEST    0
> +/**< Lowest scheduling affinity of an event queue
> + * @see rte_event_queue_attr_get(), rte_event_queue_attr_set()
> + */
> +
>   /**
>    * Get the total number of event devices that have been successfully
>    * initialised.
> @@ -684,11 +710,18 @@ rte_event_queue_setup(uint8_t dev_id, uint8_t queue_id,
>    * The schedule type of the queue.
>    */
>   #define RTE_EVENT_QUEUE_ATTR_SCHEDULE_TYPE 4
> -
> +/**
> + * The weight of the queue.
> + */
> +#define RTE_EVENT_QUEUE_ATTR_WEIGHT 5
> +/**
> + * Affinity of the queue.
> + */
> +#define RTE_EVENT_QUEUE_ATTR_AFFINITY 6
>   /**
>    * Maximum supported attribute ID.
>    */
> -#define RTE_EVENT_QUEUE_ATTR_MAX RTE_EVENT_QUEUE_ATTR_SCHEDULE_TYPE
> +#define RTE_EVENT_QUEUE_ATTR_MAX RTE_EVENT_QUEUE_ATTR_AFFINITY
>   

>   /**
>    * Get an attribute from a queue.