[PATCH 7/7] sky2: optimize receive restart

[Stephen Hemminger <shemminger@osdl.org>]

[-- Attachment #1: sky2-delay-put.patch --]
[-- Type: text/plain, Size: 2271 bytes --]

When the driver handles multiple packets per NAPI poll, it is
better to reload the receive ring, then tell the hardware. Otherwise,
under packet storm with flow control, the driver/hardware will degrade
down to one packet getting through per pause-exchange.

Likewise on transmit, don't wakeup until a little more than minimum
ring space is available.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>

--- sky2.orig/drivers/net/sky2.c	2006-07-12 14:07:05.000000000 -0700
+++ sky2/drivers/net/sky2.c	2006-07-12 14:27:34.000000000 -0700
@@ -65,6 +65,7 @@
 #define RX_MAX_PENDING		(RX_LE_SIZE/2 - 2)
 #define RX_DEF_PENDING		RX_MAX_PENDING
 #define RX_SKB_ALIGN		8
+#define RX_BUF_WRITE		16
 
 #define TX_RING_SIZE		512
 #define TX_DEF_PENDING		(TX_RING_SIZE - 1)
@@ -1390,7 +1391,7 @@
 	}
 
 	sky2->tx_cons = put;
-	if (tx_avail(sky2) > MAX_SKB_TX_LE)
+	if (tx_avail(sky2) > MAX_SKB_TX_LE + 4)
 		netif_wake_queue(dev);
 }
 
@@ -1889,9 +1890,6 @@
 	re->skb->ip_summed = CHECKSUM_NONE;
 	sky2_rx_add(sky2, re->mapaddr);
 
-	/* Tell receiver about new buffers. */
-	sky2_put_idx(sky2->hw, rxqaddr[sky2->port], sky2->rx_put);
-
 	return skb;
 
 oversize:
@@ -1938,7 +1936,9 @@
 /* Process status response ring */
 static int sky2_status_intr(struct sky2_hw *hw, int to_do)
 {
+	struct sky2_port *sky2;
 	int work_done = 0;
+	unsigned buf_write[2] = { 0, 0 };
 	u16 hwidx = sky2_read16(hw, STAT_PUT_IDX);
 
 	rmb();
@@ -1946,7 +1946,6 @@
 	while (hw->st_idx != hwidx) {
 		struct sky2_status_le *le  = hw->st_le + hw->st_idx;
 		struct net_device *dev;
-		struct sky2_port *sky2;
 		struct sk_buff *skb;
 		u32 status;
 		u16 length;
@@ -1979,6 +1978,14 @@
 #endif
 				netif_receive_skb(skb);
 
+			/* Update receiver after 16 frames */
+			if (++buf_write[le->link] == RX_BUF_WRITE) {
+				sky2_put_idx(hw, rxqaddr[le->link],
+					     sky2->rx_put);
+				buf_write[le->link] = 0;
+			}
+
+			/* Stop after net poll weight */
 			if (++work_done >= to_do)
 				goto exit_loop;
 			break;
@@ -2017,6 +2024,16 @@
 	}
 
 exit_loop:
+	if (buf_write[0]) {
+		sky2 = netdev_priv(hw->dev[0]);
+		sky2_put_idx(hw, Q_R1, sky2->rx_put);
+	}
+
+	if (buf_write[1]) {
+		sky2 = netdev_priv(hw->dev[1]);
+		sky2_put_idx(hw, Q_R2, sky2->rx_put);
+	}
+
 	return work_done;
 }
 

--