4 files changed, 42 insertions, 15 deletions

diff --git a/drivers/net/ethernet/marvell/skge.c b/drivers/net/ethernet/marvell/skge.c
index 3f7dab4..9b9c2ac 100644
--- a/drivers/net/ethernet/marvell/skge.c
+++ b/drivers/net/ethernet/marvell/skge.c
@@ -3189,7 +3189,7 @@ static int skge_poll(struct napi_struct *napi, int to_do)
 	if (work_done < to_do) {
 		unsigned long flags;
 
-		napi_gro_flush(napi);
+		napi_gro_flush(napi, false);
 		spin_lock_irqsave(&hw->hw_lock, flags);
 		__napi_complete(napi);
 		hw->intr_mask |= napimask[skge->port];
diff --git a/drivers/net/ethernet/realtek/8139cp.c b/drivers/net/ethernet/realtek/8139cp.c
index 995d0cf..1c81825 100644
--- a/drivers/net/ethernet/realtek/8139cp.c
+++ b/drivers/net/ethernet/realtek/8139cp.c
@@ -563,7 +563,7 @@ rx_next:
 		if (cpr16(IntrStatus) & cp_rx_intr_mask)
 			goto rx_status_loop;
 
-		napi_gro_flush(napi);
+		napi_gro_flush(napi, false);
 		spin_lock_irqsave(&cp->lock, flags);
 		__napi_complete(napi);
 		cpw16_f(IntrMask, cp_intr_mask);
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index a659fd0..0a36fff 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1497,19 +1497,22 @@ struct napi_gro_cb {
 	/* This indicates where we are processing relative to skb->data. */
 	int data_offset;
 
-	/* This is non-zero if the packet may be of the same flow. */
-	int same_flow;
-
 	/* This is non-zero if the packet cannot be merged with the new skb. */
 	int flush;
 
 	/* Number of segments aggregated. */
-	int count;
+	u16	count;
+
+	/* This is non-zero if the packet may be of the same flow. */
+	u8	same_flow;
 
 	/* Free the skb? */
-	int free;
+	u8	free;
 #define NAPI_GRO_FREE		  1
 #define NAPI_GRO_FREE_STOLEN_HEAD 2
+
+	/* jiffies when first packet was created/queued */
+	unsigned long age;
 };
 
 #define NAPI_GRO_CB(skb) ((struct napi_gro_cb *)(skb)->cb)
@@ -2156,7 +2159,7 @@ extern gro_result_t	dev_gro_receive(struct napi_struct *napi,
 extern gro_result_t	napi_skb_finish(gro_result_t ret, struct sk_buff *skb);
 extern gro_result_t	napi_gro_receive(struct napi_struct *napi,
 					 struct sk_buff *skb);
-extern void		napi_gro_flush(struct napi_struct *napi);
+extern void		napi_gro_flush(struct napi_struct *napi, bool flush_old);
 extern struct sk_buff *	napi_get_frags(struct napi_struct *napi);
 extern gro_result_t	napi_frags_finish(struct napi_struct *napi,
 					  struct sk_buff *skb,
diff --git a/net/core/dev.c b/net/core/dev.c
index de2bad7..d44668f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3471,17 +3471,31 @@ out:
 	return netif_receive_skb(skb);
 }
 
-inline void napi_gro_flush(struct napi_struct *napi)
+/* napi->gro_list contains packets ordered by age.
+ * youngest packets at the head of it.
+ * Complete skbs in reverse order to reduce latencies.
+ */
+void napi_gro_flush(struct napi_struct *napi, bool flush_old)
 {
-	struct sk_buff *skb, *next;
+	struct sk_buff *skb, *prev = NULL;
 
-	for (skb = napi->gro_list; skb; skb = next) {
-		next = skb->next;
+	/* scan list and build reverse chain */
+	for (skb = napi->gro_list; skb != NULL; skb = skb->next) {
+		skb->prev = prev;
+		prev = skb;
+	}
+
+	for (skb = prev; skb; skb = prev) {
 		skb->next = NULL;
+
+		if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)
+			return;
+
+		prev = skb->prev;
 		napi_gro_complete(skb);
+		napi->gro_count--;
 	}
 
-	napi->gro_count = 0;
 	napi->gro_list = NULL;
 }
 EXPORT_SYMBOL(napi_gro_flush);
@@ -3542,6 +3556,7 @@ enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 
 	napi->gro_count++;
 	NAPI_GRO_CB(skb)->count = 1;
+	NAPI_GRO_CB(skb)->age = jiffies;
 	skb_shinfo(skb)->gso_size = skb_gro_len(skb);
 	skb->next = napi->gro_list;
 	napi->gro_list = skb;
@@ -3878,7 +3893,7 @@ void napi_complete(struct napi_struct *n)
 	if (unlikely(test_bit(NAPI_STATE_NPSVC, &n->state)))
 		return;
 
-	napi_gro_flush(n);
+	napi_gro_flush(n, false);
 	local_irq_save(flags);
 	__napi_complete(n);
 	local_irq_restore(flags);
@@ -3983,8 +3998,17 @@ static void net_rx_action(struct softirq_action *h)
 				local_irq_enable();
 				napi_complete(n);
 				local_irq_disable();
-			} else
+			} else {
+				if (n->gro_list) {
+					/* flush too old packets
+					 * If HZ < 1000, flush all packets.
+					 */
+					local_irq_enable();
+					napi_gro_flush(n, HZ >= 1000);
+					local_irq_disable();
+				}
 				list_move_tail(&n->poll_list, &sd->poll_list);
+			}
 		}
 
 		netpoll_poll_unlock(have);