[dpdk-dev] [PATCH v5 2/4] net/ice: cleanup Tx buffers

[Chenxu Di]

Add support to the ice driver for the API rte_eth_tx_done_cleanup
to force free consumed buffers on Tx ring.

Signed-off-by: Chenxu Di <chenxux.di at intel.com>
---
 drivers/net/ice/ice_ethdev.c |   1 +
 drivers/net/ice/ice_rxtx.c   | 123 +++++++++++++++++++++++++++++++++++
 drivers/net/ice/ice_rxtx.h   |   1 +
 3 files changed, 125 insertions(+)

diff --git a/drivers/net/ice/ice_ethdev.c b/drivers/net/ice/ice_ethdev.c
index de189daba..b55cdbf74 100644
--- a/drivers/net/ice/ice_ethdev.c
+++ b/drivers/net/ice/ice_ethdev.c
@@ -220,6 +220,7 @@ static const struct eth_dev_ops ice_eth_dev_ops = {
 	.filter_ctrl                  = ice_dev_filter_ctrl,
 	.udp_tunnel_port_add          = ice_dev_udp_tunnel_port_add,
 	.udp_tunnel_port_del          = ice_dev_udp_tunnel_port_del,
+	.tx_done_cleanup              = ice_tx_done_cleanup,
 };
 
 /* store statistics names and its offset in stats structure */
diff --git a/drivers/net/ice/ice_rxtx.c b/drivers/net/ice/ice_rxtx.c
index 2db174456..7e704d2d5 100644
--- a/drivers/net/ice/ice_rxtx.c
+++ b/drivers/net/ice/ice_rxtx.c
@@ -863,6 +863,129 @@ ice_fdir_tx_queue_stop(struct rte_eth_dev *dev, uint16_t tx_queue_id)
 	return 0;
 }
 
+
+int ice_tx_done_cleanup(void *q, uint32_t free_cnt)
+{
+	struct ice_tx_queue *txq = (struct ice_tx_queue *)q;
+	struct ice_tx_entry *sw_ring;
+	volatile struct ice_tx_desc *txr;
+	uint16_t tx_first; /* First segment analyzed. */
+	uint16_t tx_id;    /* Current segment being processed. */
+	uint16_t tx_last;  /* Last segment in the current packet. */
+	uint16_t tx_next;  /* First segment of the next packet. */
+	int count;
+
+	if (txq == NULL)
+		return -ENODEV;
+
+	count = 0;
+	sw_ring = txq->sw_ring;
+	txr = txq->tx_ring;
+
+	/*
+	 * tx_tail is the last sent packet on the sw_ring. Goto the end
+	 * of that packet (the last segment in the packet chain) and
+	 * then the next segment will be the start of the oldest segment
+	 * in the sw_ring. This is the first packet that will be
+	 * attempted to be freed.
+	 */
+
+	/* Get last segment in most recently added packet. */
+	tx_last = sw_ring[txq->tx_tail].last_id;
+
+	/* Get the next segment, which is the oldest segment in ring. */
+	tx_first = sw_ring[tx_last].next_id;
+
+	/* Set the current index to the first. */
+	tx_id = tx_first;
+
+	/*
+	 * Loop through each packet. For each packet, verify that an
+	 * mbuf exists and that the last segment is free. If so, free
+	 * it and move on.
+	 */
+	while (1) {
+		tx_last = sw_ring[tx_id].last_id;
+
+		if (sw_ring[tx_last].mbuf) {
+			if ((txr[tx_last].cmd_type_offset_bsz &
+				rte_cpu_to_le_64(ICE_TXD_QW1_DTYPE_M)) ==
+				rte_cpu_to_le_64(ICE_TX_DESC_DTYPE_DESC_DONE)) {
+				/* Get the start of the next packet. */
+				tx_next = sw_ring[tx_last].next_id;
+
+				/*
+				 * Loop through all segments in a
+				 * packet.
+				 */
+				do {
+					rte_pktmbuf_free_seg(sw_ring[tx_id].mbuf);
+					sw_ring[tx_id].mbuf = NULL;
+					sw_ring[tx_id].last_id = tx_id;
+
+					/* Move to next segment. */
+					tx_id = sw_ring[tx_id].next_id;
+
+				} while (tx_id != tx_next);
+
+				/*
+				 * Increment the number of packets
+				 * freed.
+				 */
+				count++;
+
+				if (unlikely(count == (int)free_cnt))
+					break;
+			} else {
+				/*
+				 * mbuf still in use, nothing left to
+				 * free.
+				 */
+				break;
+			}
+		} else {
+			/*
+			 * There are multiple reasons to be here:
+			 * 1) All the packets on the ring have been
+			 *    freed - tx_id is equal to tx_first
+			 *    and some packets have been freed.
+			 *    - Done, exit
+			 * 2) Interfaces has not sent a rings worth of
+			 *    packets yet, so the segment after tail is
+			 *    still empty. Or a previous call to this
+			 *    function freed some of the segments but
+			 *    not all so there is a hole in the list.
+			 *    Hopefully this is a rare case.
+			 *    - Walk the list and find the next mbuf. If
+			 *      there isn't one, then done.
+			 */
+			if (likely(tx_id == tx_first && count != 0))
+				break;
+
+			/*
+			 * Walk the list and find the next mbuf, if any.
+			 */
+			do {
+				/* Move to next segment. */
+				tx_id = sw_ring[tx_id].next_id;
+
+				if (sw_ring[tx_id].mbuf)
+					break;
+
+			} while (tx_id != tx_first);
+
+			/*
+			 * Determine why previous loop bailed. If there
+			 * is not an mbuf, done.
+			 */
+			if (sw_ring[tx_id].mbuf == NULL)
+				break;
+		}
+	}
+
+	return count;
+}
+
 int
 ice_rx_queue_setup(struct rte_eth_dev *dev,
 		   uint16_t queue_idx,
diff --git a/drivers/net/ice/ice_rxtx.h b/drivers/net/ice/ice_rxtx.h
index 9e3d2cd07..8d4232a61 100644
--- a/drivers/net/ice/ice_rxtx.h
+++ b/drivers/net/ice/ice_rxtx.h
@@ -183,6 +183,7 @@ int ice_rx_descriptor_status(void *rx_queue, uint16_t offset);
 int ice_tx_descriptor_status(void *tx_queue, uint16_t offset);
 void ice_set_default_ptype_table(struct rte_eth_dev *dev);
 const uint32_t *ice_dev_supported_ptypes_get(struct rte_eth_dev *dev);
+int ice_tx_done_cleanup(void *txq, uint32_t free_cnt);
 
 int ice_rx_vec_dev_check(struct rte_eth_dev *dev);
 int ice_tx_vec_dev_check(struct rte_eth_dev *dev);
-- 
2.17.1