kernel: add patches by Dave Täht to reduce buffer size in longer queues to reduce memory pressure
Signed-off-by: Felix Fietkau <nbd@openwrt.org> SVN-Revision: 36301
This commit is contained in:
Felix Fietkau
parent
915969ff2c
commit
307965026a
4 changed files with 208 additions and 0 deletions
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@ -0,0 +1,41 @@
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From 4593a806e31119c5bd3faa00c7210ad862d515af Mon Sep 17 00:00:00 2001
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From: Dave Taht <dave.taht@bufferbloat.net>
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Date: Mon, 31 Dec 2012 10:02:21 -0800
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Subject: [PATCH 3/7] skb_reduce_truesize: helper function for shrinking skbs
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whenever needed
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On embedded devices in particular, large queues of small packets from the rx
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path with a large truesize can exist. Reducing their size can reduce
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memory pressure. skb_reduce_truesize is a helper function for doing this,
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when needed.
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---
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include/linux/skbuff.h | 18 ++++++++++++++++++
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1 file changed, 18 insertions(+)
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--- a/include/linux/skbuff.h
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+++ b/include/linux/skbuff.h
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@@ -1772,6 +1772,24 @@ static inline void pskb_trim_unique(stru
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BUG_ON(err);
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}
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+/*
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+ * Caller wants to reduce memory needs before queueing skb
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+ * The (expensive) copy should not be be done in fast path.
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+ */
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+static inline struct sk_buff *skb_reduce_truesize(struct sk_buff *skb)
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+{
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+ if (skb->truesize > 2 * SKB_TRUESIZE(skb->len)) {
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+ struct sk_buff *nskb;
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+ nskb = skb_copy_expand(skb, skb_headroom(skb), 0,
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+ GFP_ATOMIC | __GFP_NOWARN);
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+ if (nskb) {
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+ __kfree_skb(skb);
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+ skb = nskb;
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+ }
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+ }
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+ return skb;
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+}
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+
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/**
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* skb_orphan - orphan a buffer
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* @skb: buffer to orphan
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@ -0,0 +1,63 @@
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From bc9fec2f87d57bdbff30d296605e24504513f65c Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Dave=20T=C3=A4ht?= <dave.taht@bufferbloat.net>
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Date: Mon, 17 Sep 2012 19:20:22 -0700
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Subject: [PATCH 4/7] net: add skb_reduce_truesize support to common qdiscs
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Reduce skb size under load when queues begin to fill on the
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commont qdiscs.
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---
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net/sched/sch_codel.c | 2 ++
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net/sched/sch_fifo.c | 12 ++++++++----
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net/sched/sch_fq_codel.c | 2 ++
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3 files changed, 12 insertions(+), 4 deletions(-)
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--- a/net/sched/sch_codel.c
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+++ b/net/sched/sch_codel.c
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@@ -96,6 +96,8 @@ static int codel_qdisc_enqueue(struct sk
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struct codel_sched_data *q;
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if (likely(qdisc_qlen(sch) < sch->limit)) {
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+ if(qdisc_qlen(sch) > 128)
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+ skb = skb_reduce_truesize(skb);
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codel_set_enqueue_time(skb);
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return qdisc_enqueue_tail(skb, sch);
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}
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--- a/net/sched/sch_fifo.c
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+++ b/net/sched/sch_fifo.c
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@@ -29,17 +29,21 @@ static int bfifo_enqueue(struct sk_buff
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static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch)
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{
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- if (likely(skb_queue_len(&sch->q) < sch->limit))
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+ if (likely(skb_queue_len(&sch->q) < sch->limit)) {
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+ if (skb_queue_len(&sch->q) > 128)
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+ skb = skb_reduce_truesize(skb);
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return qdisc_enqueue_tail(skb, sch);
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-
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+ }
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return qdisc_reshape_fail(skb, sch);
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}
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static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch)
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{
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- if (likely(skb_queue_len(&sch->q) < sch->limit))
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+ if (likely(skb_queue_len(&sch->q) < sch->limit)) {
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+ if (skb_queue_len(&sch->q) > 128)
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+ skb = skb_reduce_truesize(skb);
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return qdisc_enqueue_tail(skb, sch);
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-
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+ }
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/* queue full, remove one skb to fulfill the limit */
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__qdisc_queue_drop_head(sch, &sch->q);
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sch->qstats.drops++;
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--- a/net/sched/sch_fq_codel.c
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+++ b/net/sched/sch_fq_codel.c
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@@ -182,6 +182,8 @@ static int fq_codel_enqueue(struct sk_bu
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return ret;
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}
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idx--;
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+ if (sch->q.qlen > 128)
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+ skb = skb_reduce_truesize(skb);
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codel_set_enqueue_time(skb);
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flow = &q->flows[idx];
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@ -0,0 +1,41 @@
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From 4593a806e31119c5bd3faa00c7210ad862d515af Mon Sep 17 00:00:00 2001
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From: Dave Taht <dave.taht@bufferbloat.net>
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Date: Mon, 31 Dec 2012 10:02:21 -0800
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Subject: [PATCH 3/7] skb_reduce_truesize: helper function for shrinking skbs
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whenever needed
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On embedded devices in particular, large queues of small packets from the rx
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path with a large truesize can exist. Reducing their size can reduce
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memory pressure. skb_reduce_truesize is a helper function for doing this,
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when needed.
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---
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include/linux/skbuff.h | 18 ++++++++++++++++++
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1 file changed, 18 insertions(+)
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--- a/include/linux/skbuff.h
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+++ b/include/linux/skbuff.h
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@@ -1801,6 +1801,24 @@ static inline void pskb_trim_unique(stru
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BUG_ON(err);
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}
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+/*
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+ * Caller wants to reduce memory needs before queueing skb
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+ * The (expensive) copy should not be be done in fast path.
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+ */
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+static inline struct sk_buff *skb_reduce_truesize(struct sk_buff *skb)
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+{
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+ if (skb->truesize > 2 * SKB_TRUESIZE(skb->len)) {
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+ struct sk_buff *nskb;
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+ nskb = skb_copy_expand(skb, skb_headroom(skb), 0,
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+ GFP_ATOMIC | __GFP_NOWARN);
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+ if (nskb) {
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+ __kfree_skb(skb);
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+ skb = nskb;
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+ }
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+ }
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+ return skb;
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+}
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+
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/**
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* skb_orphan - orphan a buffer
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* @skb: buffer to orphan
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@ -0,0 +1,63 @@
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From bc9fec2f87d57bdbff30d296605e24504513f65c Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Dave=20T=C3=A4ht?= <dave.taht@bufferbloat.net>
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Date: Mon, 17 Sep 2012 19:20:22 -0700
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Subject: [PATCH 4/7] net: add skb_reduce_truesize support to common qdiscs
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Reduce skb size under load when queues begin to fill on the
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commont qdiscs.
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---
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net/sched/sch_codel.c | 2 ++
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net/sched/sch_fifo.c | 12 ++++++++----
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net/sched/sch_fq_codel.c | 2 ++
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3 files changed, 12 insertions(+), 4 deletions(-)
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--- a/net/sched/sch_codel.c
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+++ b/net/sched/sch_codel.c
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@@ -96,6 +96,8 @@ static int codel_qdisc_enqueue(struct sk
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struct codel_sched_data *q;
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if (likely(qdisc_qlen(sch) < sch->limit)) {
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+ if(qdisc_qlen(sch) > 128)
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+ skb = skb_reduce_truesize(skb);
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codel_set_enqueue_time(skb);
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return qdisc_enqueue_tail(skb, sch);
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}
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--- a/net/sched/sch_fifo.c
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+++ b/net/sched/sch_fifo.c
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@@ -29,17 +29,21 @@ static int bfifo_enqueue(struct sk_buff
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static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch)
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{
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- if (likely(skb_queue_len(&sch->q) < sch->limit))
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+ if (likely(skb_queue_len(&sch->q) < sch->limit)) {
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+ if (skb_queue_len(&sch->q) > 128)
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+ skb = skb_reduce_truesize(skb);
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return qdisc_enqueue_tail(skb, sch);
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-
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+ }
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return qdisc_reshape_fail(skb, sch);
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}
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static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch)
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{
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- if (likely(skb_queue_len(&sch->q) < sch->limit))
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+ if (likely(skb_queue_len(&sch->q) < sch->limit)) {
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+ if (skb_queue_len(&sch->q) > 128)
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+ skb = skb_reduce_truesize(skb);
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return qdisc_enqueue_tail(skb, sch);
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-
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+ }
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/* queue full, remove one skb to fulfill the limit */
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__qdisc_queue_drop_head(sch, &sch->q);
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sch->qstats.drops++;
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--- a/net/sched/sch_fq_codel.c
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+++ b/net/sched/sch_fq_codel.c
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@@ -182,6 +182,8 @@ static int fq_codel_enqueue(struct sk_bu
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return ret;
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}
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idx--;
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+ if (sch->q.qlen > 128)
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+ skb = skb_reduce_truesize(skb);
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codel_set_enqueue_time(skb);
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flow = &q->flows[idx];
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