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

[Shijith Thotton <sthotton@marvell.com>]

>> 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?
>

It is WRR for equal-priority queues. I will update the text as follows. Please check.

/**< 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, weight of the queues
 * are used to select a queue in a weighted round robin fashion. Subsequent
 * dequeue calls 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 subsequent dequeue calls from an event port which
 * should use the same queue if the queue is non-empty.

>What is a schedule call? I must say I don't understand this description.
 
Schedule call indicates a dequeue call. I have updated the text to avoid confusion.

>Is affinity the per-port batch size from the queue that is "next in
>line" for an opportunity to be scheduled to a port?
>

Not exactly batch size. It is the number of subsequent dequeue calls which
should use the same queue. So the subsequent dequeue calls could return a max of
affinity * batch_size number of events from the same queue.

 >>    *
>>    *  @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.