[dpdk-dev] [PATCH v3 3/3] net/failsafe: improve Rx sub-devices iteration

[Matan Azrad <matan@mellanox.com>]

Connecting the sub-devices each other by cyclic linked list can help to
iterate over them by Rx burst functions because there is no need to
check the sub-devices ring wraparound.

Create the aforementioned linked-list and change the Rx burst functions
iteration accordingly.

Signed-off-by: Matan Azrad <matan@mellanox.com>
---
 drivers/net/failsafe/failsafe.c         |  5 ++++
 drivers/net/failsafe/failsafe_ops.c     |  1 +
 drivers/net/failsafe/failsafe_private.h |  5 ++--
 drivers/net/failsafe/failsafe_rxtx.c    | 50 ++++++++++-----------------------
 4 files changed, 24 insertions(+), 37 deletions(-)

diff --git a/drivers/net/failsafe/failsafe.c b/drivers/net/failsafe/failsafe.c
index 6bc5aba..d230c37 100644
--- a/drivers/net/failsafe/failsafe.c
+++ b/drivers/net/failsafe/failsafe.c
@@ -55,6 +55,7 @@
 {
 	uint8_t nb_subs;
 	int ret;
+	int i;
 
 	ret = failsafe_args_count_subdevice(dev, params);
 	if (ret)
@@ -72,6 +73,10 @@
 		ERROR("Could not allocate sub_devices");
 		return -ENOMEM;
 	}
+	/* Initiate static sub devices linked list. */
+	for (i = 1; i < nb_subs; i++)
+		PRIV(dev)->subs[i - 1].next = PRIV(dev)->subs + i;
+	PRIV(dev)->subs[i - 1].next = PRIV(dev)->subs;
 	return 0;
 }
 
diff --git a/drivers/net/failsafe/failsafe_ops.c b/drivers/net/failsafe/failsafe_ops.c
index e16a590..fe957ad 100644
--- a/drivers/net/failsafe/failsafe_ops.c
+++ b/drivers/net/failsafe/failsafe_ops.c
@@ -294,6 +294,7 @@
 	rxq->info.conf = *rx_conf;
 	rxq->info.nb_desc = nb_rx_desc;
 	rxq->priv = PRIV(dev);
+	rxq->sdev = PRIV(dev)->subs;
 	dev->data->rx_queues[rx_queue_id] = rxq;
 	FOREACH_SUBDEV_STATE(sdev, i, dev, DEV_ACTIVE) {
 		ret = rte_eth_rx_queue_setup(PORT_ID(sdev),
diff --git a/drivers/net/failsafe/failsafe_private.h b/drivers/net/failsafe/failsafe_private.h
index 4196ece..54b5b91 100644
--- a/drivers/net/failsafe/failsafe_private.h
+++ b/drivers/net/failsafe/failsafe_private.h
@@ -62,8 +62,8 @@
 struct rxq {
 	struct fs_priv *priv;
 	uint16_t qid;
-	/* id of last sub_device polled */
-	uint8_t last_polled;
+	/* next sub_device to poll */
+	struct sub_device *sdev;
 	unsigned int socket_id;
 	struct rte_eth_rxq_info info;
 	rte_atomic64_t refcnt[];
@@ -100,6 +100,7 @@ struct fs_stats {
 
 struct sub_device {
 	/* Exhaustive DPDK device description */
+	struct sub_device *next;
 	struct rte_devargs devargs;
 	struct rte_bus *bus;
 	struct rte_device *dev;
diff --git a/drivers/net/failsafe/failsafe_rxtx.c b/drivers/net/failsafe/failsafe_rxtx.c
index 178294c..0ebf06a 100644
--- a/drivers/net/failsafe/failsafe_rxtx.c
+++ b/drivers/net/failsafe/failsafe_rxtx.c
@@ -94,36 +94,27 @@
 		  struct rte_mbuf **rx_pkts,
 		  uint16_t nb_pkts)
 {
-	struct fs_priv *priv;
 	struct sub_device *sdev;
 	struct rxq *rxq;
 	void *sub_rxq;
 	uint16_t nb_rx;
-	uint8_t nb_polled, nb_subs;
-	uint8_t i;
 
 	rxq = queue;
-	priv = rxq->priv;
-	nb_subs = priv->subs_tail - priv->subs_head;
-	nb_polled = 0;
-	for (i = rxq->last_polled; nb_polled < nb_subs; nb_polled++) {
-		i++;
-		if (i == priv->subs_tail)
-			i = priv->subs_head;
-		sdev = &priv->subs[i];
-		if (fs_rx_unsafe(sdev))
+	sdev = rxq->sdev;
+	do {
+		if (fs_rx_unsafe(sdev)) {
+			nb_rx = 0;
 			continue;
+		}
 		sub_rxq = ETH(sdev)->data->rx_queues[rxq->qid];
 		FS_ATOMIC_P(rxq->refcnt[sdev->sid]);
 		nb_rx = ETH(sdev)->
 			rx_pkt_burst(sub_rxq, rx_pkts, nb_pkts);
 		FS_ATOMIC_V(rxq->refcnt[sdev->sid]);
-		if (nb_rx) {
-			rxq->last_polled = i;
-			return nb_rx;
-		}
-	}
-	return 0;
+		sdev = sdev->next;
+	} while (nb_rx == 0 && sdev != rxq->sdev);
+	rxq->sdev = sdev;
+	return nb_rx;
 }
 
 uint16_t
@@ -131,35 +122,24 @@
 			 struct rte_mbuf **rx_pkts,
 			 uint16_t nb_pkts)
 {
-	struct fs_priv *priv;
 	struct sub_device *sdev;
 	struct rxq *rxq;
 	void *sub_rxq;
 	uint16_t nb_rx;
-	uint8_t nb_polled, nb_subs;
-	uint8_t i;
 
 	rxq = queue;
-	priv = rxq->priv;
-	nb_subs = priv->subs_tail - priv->subs_head;
-	nb_polled = 0;
-	for (i = rxq->last_polled; nb_polled < nb_subs; nb_polled++) {
-		i++;
-		if (i == priv->subs_tail)
-			i = priv->subs_head;
-		sdev = &priv->subs[i];
+	sdev = rxq->sdev;
+	do {
 		RTE_ASSERT(!fs_rx_unsafe(sdev));
 		sub_rxq = ETH(sdev)->data->rx_queues[rxq->qid];
 		FS_ATOMIC_P(rxq->refcnt[sdev->sid]);
 		nb_rx = ETH(sdev)->
 			rx_pkt_burst(sub_rxq, rx_pkts, nb_pkts);
 		FS_ATOMIC_V(rxq->refcnt[sdev->sid]);
-		if (nb_rx) {
-			rxq->last_polled = i;
-			return nb_rx;
-		}
-	}
-	return 0;
+		sdev = sdev->next;
+	} while (nb_rx == 0 && sdev != rxq->sdev);
+	rxq->sdev = sdev;
+	return nb_rx;
 }
 
 uint16_t
-- 
1.8.3.1