[PATCH 31/35] net/ionic: allow client to specify Tx free threshold

[Andrew Boyer <andrew.boyer@amd.com>]

Some clients have opinions about how often to flush the
transmit ring.

The default value is the number of Tx descriptors minus the
default Tx burst size.

Signed-off-by: Andrew Boyer <andrew.boyer@amd.com>
---
 drivers/net/ionic/ionic_dev.h    |  1 +
 drivers/net/ionic/ionic_ethdev.c |  4 ++--
 drivers/net/ionic/ionic_lif.h    |  1 +
 drivers/net/ionic/ionic_rxtx.c   | 17 +++++++++++++++--
 4 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ionic/ionic_dev.h b/drivers/net/ionic/ionic_dev.h
index 6b0540f615..d696de45e0 100644
--- a/drivers/net/ionic/ionic_dev.h
+++ b/drivers/net/ionic/ionic_dev.h
@@ -20,6 +20,7 @@
 #define IONIC_MAX_RING_DESC		32768
 #define IONIC_MIN_RING_DESC		16
 #define IONIC_DEF_TXRX_DESC		4096
+#define IONIC_DEF_TXRX_BURST		32
 
 #define IONIC_DEVCMD_TIMEOUT		5	/* devcmd_timeout */
 #define IONIC_DEVCMD_CHECK_PERIOD_US	10	/* devcmd status chk period */
diff --git a/drivers/net/ionic/ionic_ethdev.c b/drivers/net/ionic/ionic_ethdev.c
index 36fb09b810..28297879cf 100644
--- a/drivers/net/ionic/ionic_ethdev.c
+++ b/drivers/net/ionic/ionic_ethdev.c
@@ -429,8 +429,8 @@ ionic_dev_info_get(struct rte_eth_dev *eth_dev,
 	dev_info->tx_desc_lim = tx_desc_lim_v1;
 
 	/* Driver-preferred Rx/Tx parameters */
-	dev_info->default_rxportconf.burst_size = 32;
-	dev_info->default_txportconf.burst_size = 32;
+	dev_info->default_rxportconf.burst_size = IONIC_DEF_TXRX_BURST;
+	dev_info->default_txportconf.burst_size = IONIC_DEF_TXRX_BURST;
 	dev_info->default_rxportconf.nb_queues = 1;
 	dev_info->default_txportconf.nb_queues = 1;
 	dev_info->default_rxportconf.ring_size = IONIC_DEF_TXRX_DESC;
diff --git a/drivers/net/ionic/ionic_lif.h b/drivers/net/ionic/ionic_lif.h
index ec9cb24a61..e4af138a51 100644
--- a/drivers/net/ionic/ionic_lif.h
+++ b/drivers/net/ionic/ionic_lif.h
@@ -104,6 +104,7 @@ struct ionic_tx_qcq {
 
 	/* cacheline2 */
 	uint16_t num_segs_fw;	/* # segs supported by current FW */
+	uint16_t free_thresh;
 	uint16_t flags;
 
 	struct ionic_tx_stats stats;
diff --git a/drivers/net/ionic/ionic_rxtx.c b/drivers/net/ionic/ionic_rxtx.c
index fceb8333f6..9a346f4143 100644
--- a/drivers/net/ionic/ionic_rxtx.c
+++ b/drivers/net/ionic/ionic_rxtx.c
@@ -223,6 +223,13 @@ ionic_dev_tx_queue_setup(struct rte_eth_dev *eth_dev, uint16_t tx_queue_id,
 	if (!rte_is_power_of_2(nb_desc) || nb_desc < IONIC_MIN_RING_DESC)
 		return -EINVAL; /* or use IONIC_DEFAULT_RING_DESC */
 
+	if (tx_conf->tx_free_thresh > nb_desc) {
+		IONIC_PRINT(ERR,
+			"tx_free_thresh must be less than nb_desc (%u)",
+			nb_desc);
+		return -EINVAL;
+	}
+
 	/* Free memory prior to re-allocation if needed... */
 	if (eth_dev->data->tx_queues[tx_queue_id] != NULL) {
 		ionic_dev_tx_queue_release(eth_dev, tx_queue_id);
@@ -252,6 +259,10 @@ ionic_dev_tx_queue_setup(struct rte_eth_dev *eth_dev, uint16_t tx_queue_id,
 	if (offloads & RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE)
 		txq->flags |= IONIC_QCQ_F_FAST_FREE;
 
+	txq->free_thresh =
+		tx_conf->tx_free_thresh ? tx_conf->tx_free_thresh :
+		nb_desc - IONIC_DEF_TXRX_BURST;
+
 	eth_dev->data->tx_queues[tx_queue_id] = txq;
 
 	return 0;
@@ -609,8 +620,10 @@ ionic_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 		rte_mbuf_prefetch_part2(tx_pkts[0]);
 	}
 
-	/* Cleaning old buffers */
-	ionic_tx_flush(txq);
+	if (unlikely(ionic_q_space_avail(q) < txq->free_thresh)) {
+		/* Cleaning old buffers */
+		ionic_tx_flush(txq);
+	}
 
 	nb_avail = ionic_q_space_avail(q);
 	if (unlikely(nb_avail < nb_pkts)) {
-- 
2.17.1