openwrtv3/target/linux/generic/patches-4.1/657-qdisc_reduce_truesize.patch

From bc9fec2f87d57bdbff30d296605e24504513f65c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dave=20T=C3=A4ht?= <dave.taht@bufferbloat.net>
Date: Mon, 17 Sep 2012 19:20:22 -0700
Subject: [PATCH 4/7] net: add skb_reduce_truesize support to common qdiscs

Reduce skb size under load when queues begin to fill on the
commont qdiscs.
---
 net/sched/sch_codel.c    |    2 ++
 net/sched/sch_fifo.c     |   12 ++++++++----
 net/sched/sch_fq_codel.c |    2 ++
 3 files changed, 12 insertions(+), 4 deletions(-)

--- a/net/sched/sch_codel.c
+++ b/net/sched/sch_codel.c
@@ -97,6 +97,8 @@ static int codel_qdisc_enqueue(struct sk
 	struct codel_sched_data *q;
 
 	if (likely(qdisc_qlen(sch) < sch->limit)) {
+		if(qdisc_qlen(sch) > 128)
+			skb = skb_reduce_truesize(skb);
 		codel_set_enqueue_time(skb);
 		return qdisc_enqueue_tail(skb, sch);
 	}
--- a/net/sched/sch_fifo.c
+++ b/net/sched/sch_fifo.c
@@ -29,17 +29,21 @@ static int bfifo_enqueue(struct sk_buff
 
 static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 {
-	if (likely(skb_queue_len(&sch->q) < sch->limit))
+	if (likely(skb_queue_len(&sch->q) < sch->limit)) {
+		if (skb_queue_len(&sch->q) > 128)
+			skb = skb_reduce_truesize(skb);
 		return qdisc_enqueue_tail(skb, sch);
-
+	}
 	return qdisc_reshape_fail(skb, sch);
 }
 
 static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 {
-	if (likely(skb_queue_len(&sch->q) < sch->limit))
+	if (likely(skb_queue_len(&sch->q) < sch->limit)) {
+		if (skb_queue_len(&sch->q) > 128)
+			skb = skb_reduce_truesize(skb);
 		return qdisc_enqueue_tail(skb, sch);
-
+	}
 	/* queue full, remove one skb to fulfill the limit */
 	__qdisc_queue_drop_head(sch, &sch->q);
 	qdisc_qstats_drop(sch);
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -185,6 +185,8 @@ static int fq_codel_enqueue(struct sk_bu
 		return ret;
 	}
 	idx--;
+	if (sch->q.qlen > 128)
+		skb = skb_reduce_truesize(skb);
 
 	codel_set_enqueue_time(skb);
 	flow = &q->flows[idx];