ionic: batch rx buffer refilling

We don't need to refill the rx descriptors on every napi
if only a few were handled.  Waiting until we can batch up
a few together will save us a few Rx cycles.
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/pensando/ionic/ionic_dev.h

@@ -12,8 +12,10 @@
 
 #define IONIC_MAX_TX_DESC		8192
 #define IONIC_MAX_RX_DESC		16384
-#define IONIC_MIN_TXRX_DESC		16
+#define IONIC_MIN_TXRX_DESC		64
 #define IONIC_DEF_TXRX_DESC		4096
+#define IONIC_RX_FILL_THRESHOLD		16
+#define IONIC_RX_FILL_DIV		8
 #define IONIC_LIFS_MAX			1024
 #define IONIC_WATCHDOG_SECS		5
 #define IONIC_ITR_COAL_USEC_DEFAULT	64

drivers/net/ethernet/pensando/ionic/ionic_txrx.c

@@ -392,11 +392,6 @@ void ionic_rx_fill(struct ionic_queue *q)
 			 q->dbval | q->head_idx);
 }
 
-static void ionic_rx_fill_cb(void *arg)
-{
-	ionic_rx_fill(arg);
-}
-
 void ionic_rx_empty(struct ionic_queue *q)
 {
 	struct ionic_desc_info *desc_info;
@@ -480,6 +475,7 @@ int ionic_rx_napi(struct napi_struct *napi, int budget)
 	struct ionic_cq *cq = napi_to_cq(napi);
 	struct ionic_dev *idev;
 	struct ionic_lif *lif;
+	u16 rx_fill_threshold;
 	u32 work_done = 0;
 	u32 flags = 0;
 
@@ -489,7 +485,9 @@ int ionic_rx_napi(struct napi_struct *napi, int budget)
 	work_done = ionic_cq_service(cq, budget,
 				     ionic_rx_service, NULL, NULL);
 
-	if (work_done)
+	rx_fill_threshold = min_t(u16, IONIC_RX_FILL_THRESHOLD,
+				  cq->num_descs / IONIC_RX_FILL_DIV);
+	if (work_done && ionic_q_space_avail(cq->bound_q) >= rx_fill_threshold)
 		ionic_rx_fill(cq->bound_q);
 
 	if (work_done < budget && napi_complete_done(napi, work_done)) {
@@ -518,6 +516,7 @@ int ionic_txrx_napi(struct napi_struct *napi, int budget)
 	struct ionic_dev *idev;
 	struct ionic_lif *lif;
 	struct ionic_cq *txcq;
+	u16 rx_fill_threshold;
 	u32 rx_work_done = 0;
 	u32 tx_work_done = 0;
 	u32 flags = 0;
@@ -531,8 +530,11 @@ int ionic_txrx_napi(struct napi_struct *napi, int budget)
 
 	rx_work_done = ionic_cq_service(rxcq, budget,
 					ionic_rx_service, NULL, NULL);
-	if (rx_work_done)
-		ionic_rx_fill_cb(rxcq->bound_q);
+
+	rx_fill_threshold = min_t(u16, IONIC_RX_FILL_THRESHOLD,
+				  rxcq->num_descs / IONIC_RX_FILL_DIV);
+	if (rx_work_done && ionic_q_space_avail(rxcq->bound_q) >= rx_fill_threshold)
+		ionic_rx_fill(rxcq->bound_q);
 
 	if (rx_work_done < budget && napi_complete_done(napi, rx_work_done)) {
 		ionic_dim_update(qcq);