Re: [dpdk-dev] [PATCH v3 1/7] ethdev: allocate max space for internal queue array

[Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com>]

>At queue configure stage always allocate space for maximum possible
>number (RTE_MAX_QUEUES_PER_PORT) of queue pointers.
>That will allow 'fast' inline functions (eth_rx_burst, etc.) to refer
>pointer to internal queue data without extra checking of current
>number
>of configured queues.
>That would help in future to hide rte_eth_dev and related structures.
>
>Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
>---
> lib/ethdev/rte_ethdev.c | 36 +++++++++---------------------------
> 1 file changed, 9 insertions(+), 27 deletions(-)
>
>diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
>index daf5ca9242..424bc260fa 100644
>--- a/lib/ethdev/rte_ethdev.c
>+++ b/lib/ethdev/rte_ethdev.c
>@@ -898,7 +898,8 @@ eth_dev_rx_queue_config(struct rte_eth_dev
>*dev, uint16_t nb_queues)
>
> 	if (dev->data->rx_queues == NULL && nb_queues != 0) { /*
>first time configuration */
> 		dev->data->rx_queues = rte_zmalloc("ethdev-
>>rx_queues",
>-				sizeof(dev->data->rx_queues[0]) *
>nb_queues,
>+				sizeof(dev->data->rx_queues[0]) *
>+				RTE_MAX_QUEUES_PER_PORT,
> 				RTE_CACHE_LINE_SIZE);
> 		if (dev->data->rx_queues == NULL) {
> 			dev->data->nb_rx_queues = 0;

We could get rid of this zmalloc by declaring rx_queues as array of 
pointers, it would make code much simpler.
I believe the original code dates back to "Initial" release.


>@@ -909,21 +910,11 @@ eth_dev_rx_queue_config(struct
>rte_eth_dev *dev, uint16_t nb_queues)
>
> 		rxq = dev->data->rx_queues;
>
>-		for (i = nb_queues; i < old_nb_queues; i++)
>+		for (i = nb_queues; i < old_nb_queues; i++) {
> 			(*dev->dev_ops->rx_queue_release)(rxq[i]);
>-		rxq = rte_realloc(rxq, sizeof(rxq[0]) * nb_queues,
>-				RTE_CACHE_LINE_SIZE);
>-		if (rxq == NULL)
>-			return -(ENOMEM);
>-		if (nb_queues > old_nb_queues) {
>-			uint16_t new_qs = nb_queues -
>old_nb_queues;
>-
>-			memset(rxq + old_nb_queues, 0,
>-				sizeof(rxq[0]) * new_qs);
>+			rxq[i] = NULL;
> 		}
>
>-		dev->data->rx_queues = rxq;
>-
> 	} else if (dev->data->rx_queues != NULL && nb_queues == 0) {
> 		RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops-
>>rx_queue_release, -ENOTSUP);
>
>@@ -1138,8 +1129,9 @@ eth_dev_tx_queue_config(struct
>rte_eth_dev *dev, uint16_t nb_queues)
>
> 	if (dev->data->tx_queues == NULL && nb_queues != 0) { /*
>first time configuration */
> 		dev->data->tx_queues = rte_zmalloc("ethdev-
>>tx_queues",
>-						   sizeof(dev->data-
>>tx_queues[0]) * nb_queues,
>-
>RTE_CACHE_LINE_SIZE);
>+				sizeof(dev->data->tx_queues[0]) *
>+				RTE_MAX_QUEUES_PER_PORT,
>+				RTE_CACHE_LINE_SIZE);
> 		if (dev->data->tx_queues == NULL) {
> 			dev->data->nb_tx_queues = 0;
> 			return -(ENOMEM);
>@@ -1149,21 +1141,11 @@ eth_dev_tx_queue_config(struct
>rte_eth_dev *dev, uint16_t nb_queues)
>
> 		txq = dev->data->tx_queues;
>
>-		for (i = nb_queues; i < old_nb_queues; i++)
>+		for (i = nb_queues; i < old_nb_queues; i++) {
> 			(*dev->dev_ops->tx_queue_release)(txq[i]);
>-		txq = rte_realloc(txq, sizeof(txq[0]) * nb_queues,
>-				  RTE_CACHE_LINE_SIZE);
>-		if (txq == NULL)
>-			return -ENOMEM;
>-		if (nb_queues > old_nb_queues) {
>-			uint16_t new_qs = nb_queues -
>old_nb_queues;
>-
>-			memset(txq + old_nb_queues, 0,
>-			       sizeof(txq[0]) * new_qs);
>+			txq[i] = NULL;
> 		}
>
>-		dev->data->tx_queues = txq;
>-
> 	} else if (dev->data->tx_queues != NULL && nb_queues == 0) {
> 		RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops-
>>tx_queue_release, -ENOTSUP);
>
>--
>2.26.3