commit 6be5ed3fef568ad79f9519db4a336c725a089d51
author Claudiu Manoil <claudiu.manoil@freescale.com> Tue Mar 19 07:40:03 2013 +0000
committer David S. Miller <davem@davemloft.net> Wed Mar 20 13:21:52 2013 -0400
tree ac6f3c7e6780dcbacbd6d65d3ab43460d87d0e3a
parent c233cf4074e50933edd5e82c3c5826923f0c1b10

gianfar: Poll only active Rx queues

Split the napi budget fairly among the active queues only, instead
of dividing it by the total number of Rx queues assigned to the
given interrupt group.
Use the h/w indication field RXFi in rstat (receive status register)
to identify the active rx queues from the current interrupt group
(i.e. receive event occured on ring i, if ring i is part of the current
interrupt group). This indication field in rstat, RXFi i=0..7,
allows us to find out on which queues of the same interrupt group
do we have incomming traffic once we entered the polling routine for
the given interrupt group. After servicing the ring i, the corresponding
bit RXFi will be written with 1 to clear the active queue indication for
that ring.

Signed-off-by: Claudiu Manoil <claudiu.manoil@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/gianfar.c

diff --git a/drivers/net/ethernet/freescale/gianfar.c b/drivers/net/ethernet/freescale/gianfar.c
index 1e555a7..3f07dbd 100644
--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c
@@ -2835,15 +2835,20 @@
 	int work_done = 0, work_done_per_q = 0;
 	int i, budget_per_q;
 	int has_tx_work;
-	unsigned long serviced_queues = 0;
-	int num_queues = gfargrp->num_rx_queues;
+	unsigned long rstat_rxf;
+	int num_act_queues;
 
-	budget_per_q = budget/num_queues;
 	/* Clear IEVENT, so interrupts aren't called again
 	 * because of the packets that have already arrived
 	 */
 	gfar_write(&regs->ievent, IEVENT_RTX_MASK);
 
+	rstat_rxf = gfar_read(&regs->rstat) & RSTAT_RXF_MASK;
+
+	num_act_queues = bitmap_weight(&rstat_rxf, MAX_RX_QS);
+	if (num_act_queues)
+		budget_per_q = budget/num_act_queues;
+
 	while (1) {
 		has_tx_work = 0;
 		for_each_set_bit(i, &gfargrp->tx_bit_map, priv->num_tx_queues) {
@@ -2856,7 +2861,8 @@
 		}
 
 		for_each_set_bit(i, &gfargrp->rx_bit_map, priv->num_rx_queues) {
-			if (test_bit(i, &serviced_queues))
+			/* skip queue if not active */
+			if (!(rstat_rxf & (RSTAT_CLEAR_RXF0 >> i)))
 				continue;
 
 			rx_queue = priv->rx_queue[i];
@@ -2866,20 +2872,24 @@
 
 			/* finished processing this queue */
 			if (work_done_per_q < budget_per_q) {
-				set_bit(i, &serviced_queues);
-				num_queues--;
-				if (!num_queues)
+				/* clear active queue hw indication */
+				gfar_write(&regs->rstat,
+					   RSTAT_CLEAR_RXF0 >> i);
+				rstat_rxf &= ~(RSTAT_CLEAR_RXF0 >> i);
+				num_act_queues--;
+
+				if (!num_act_queues)
 					break;
 				/* recompute budget per Rx queue */
 				budget_per_q =
-					(budget - work_done) / num_queues;
+					(budget - work_done) / num_act_queues;
 			}
 		}
 
 		if (work_done >= budget)
 			break;
 
-		if (!num_queues && !has_tx_work) {
+		if (!num_act_queues && !has_tx_work) {
 
 			napi_complete(napi);