[dpdk-dev] [PATCH v2 16/32] net/sfc: support Rx free threshold

[Andrew Rybchenko <arybchenko@solarflare.com>]

Rx free threshold defines minimum number of free Rx descriptors
when Rx ring refill should be done.

Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
Reviewed-by: Andrew Lee <alee@solarflare.com>
Reviewed-by: Robert Stonehouse <rstonehouse@solarflare.com>
---
 drivers/net/sfc/sfc_ethdev.c |  1 +
 drivers/net/sfc/sfc_rx.c     | 16 ++++++++++++----
 drivers/net/sfc/sfc_rx.h     |  1 +
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/net/sfc/sfc_ethdev.c b/drivers/net/sfc/sfc_ethdev.c
index e67ca61..1d7993f 100644
--- a/drivers/net/sfc/sfc_ethdev.c
+++ b/drivers/net/sfc/sfc_ethdev.c
@@ -838,6 +838,7 @@ sfc_rx_queue_info_get(struct rte_eth_dev *dev, uint16_t rx_queue_id,
 	SFC_ASSERT(rxq != NULL);
 
 	qinfo->mp = rxq->refill_mb_pool;
+	qinfo->conf.rx_free_thresh = rxq->refill_threshold;
 	qinfo->conf.rx_drop_en = 1;
 	qinfo->nb_desc = rxq_info->entries;
 
diff --git a/drivers/net/sfc/sfc_rx.c b/drivers/net/sfc/sfc_rx.c
index be8fa23..278d583 100644
--- a/drivers/net/sfc/sfc_rx.c
+++ b/drivers/net/sfc/sfc_rx.c
@@ -87,6 +87,10 @@ sfc_rx_qrefill(struct sfc_rxq *rxq)
 
 	free_space = EFX_RXQ_LIMIT(rxq->ptr_mask + 1) -
 		(added - rxq->completed);
+
+	if (free_space < rxq->refill_threshold)
+		return;
+
 	bulks = free_space / RTE_DIM(objs);
 
 	id = added & rxq->ptr_mask;
@@ -410,9 +414,10 @@ sfc_rx_qstop(struct sfc_adapter *sa, unsigned int sw_index)
 }
 
 static int
-sfc_rx_qcheck_conf(struct sfc_adapter *sa,
+sfc_rx_qcheck_conf(struct sfc_adapter *sa, uint16_t nb_rx_desc,
 		   const struct rte_eth_rxconf *rx_conf)
 {
+	const uint16_t rx_free_thresh_max = EFX_RXQ_LIMIT(nb_rx_desc);
 	int rc = 0;
 
 	if (rx_conf->rx_thresh.pthresh != 0 ||
@@ -423,8 +428,10 @@ sfc_rx_qcheck_conf(struct sfc_adapter *sa,
 		rc = EINVAL;
 	}
 
-	if (rx_conf->rx_free_thresh != 0) {
-		sfc_err(sa, "RxQ free threshold is not supported");
+	if (rx_conf->rx_free_thresh > rx_free_thresh_max) {
+		sfc_err(sa,
+			"RxQ free threshold too large: %u vs maximum %u",
+			rx_conf->rx_free_thresh, rx_free_thresh_max);
 		rc = EINVAL;
 	}
 
@@ -555,7 +562,7 @@ sfc_rx_qinit(struct sfc_adapter *sa, unsigned int sw_index,
 	struct sfc_evq *evq;
 	struct sfc_rxq *rxq;
 
-	rc = sfc_rx_qcheck_conf(sa, rx_conf);
+	rc = sfc_rx_qcheck_conf(sa, nb_rx_desc, rx_conf);
 	if (rc != 0)
 		goto fail_bad_conf;
 
@@ -615,6 +622,7 @@ sfc_rx_qinit(struct sfc_adapter *sa, unsigned int sw_index,
 	evq->rxq = rxq;
 	rxq->evq = evq;
 	rxq->ptr_mask = rxq_info->entries - 1;
+	rxq->refill_threshold = rx_conf->rx_free_thresh;
 	rxq->refill_mb_pool = mb_pool;
 	rxq->buf_size = buf_size;
 	rxq->hw_index = sw_index;
diff --git a/drivers/net/sfc/sfc_rx.h b/drivers/net/sfc/sfc_rx.h
index e4385b9..69318ab 100644
--- a/drivers/net/sfc/sfc_rx.h
+++ b/drivers/net/sfc/sfc_rx.h
@@ -87,6 +87,7 @@ struct sfc_rxq {
 	/* Used on refill */
 	unsigned int		added;
 	unsigned int		pushed;
+	unsigned int		refill_threshold;
 	uint8_t			port_id;
 	uint16_t		buf_size;
 	struct rte_mempool	*refill_mb_pool;
-- 
2.5.5