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authorFlorian Westphal <fw@strlen.de>2016-09-18 01:57:34 +0300
committerDavid S. Miller <davem@davemloft.net>2016-09-19 08:47:18 +0300
commit48da34b7a74201f15315cb1fc40bb9a7bd2b4940 (patch)
tree123595224534ee49f1175b6ef8371728b6d31538 /net/sched
parented760cb8aae7c2b84c193d4a7637b0c9e752f07e (diff)
downloadlinux-48da34b7a74201f15315cb1fc40bb9a7bd2b4940.tar.xz
sched: add and use qdisc_skb_head helpers
This change replaces sk_buff_head struct in Qdiscs with new qdisc_skb_head. Its similar to the skb_buff_head api, but does not use skb->prev pointers. Qdiscs will commonly enqueue at the tail of a list and dequeue at head. While skb_buff_head works fine for this, enqueue/dequeue needs to also adjust the prev pointer of next element. The ->prev pointer is not required for qdiscs so we can just leave it undefined and avoid one cacheline write access for en/dequeue. Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched')
-rw-r--r--net/sched/sch_generic.c21
-rw-r--r--net/sched/sch_htb.c24
-rw-r--r--net/sched/sch_netem.c14
3 files changed, 43 insertions, 16 deletions
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 73877d9c2bcb..6cfb6e9038c2 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -466,7 +466,7 @@ static const u8 prio2band[TC_PRIO_MAX + 1] = {
*/
struct pfifo_fast_priv {
u32 bitmap;
- struct sk_buff_head q[PFIFO_FAST_BANDS];
+ struct qdisc_skb_head q[PFIFO_FAST_BANDS];
};
/*
@@ -477,7 +477,7 @@ struct pfifo_fast_priv {
*/
static const int bitmap2band[] = {-1, 0, 1, 0, 2, 0, 1, 0};
-static inline struct sk_buff_head *band2list(struct pfifo_fast_priv *priv,
+static inline struct qdisc_skb_head *band2list(struct pfifo_fast_priv *priv,
int band)
{
return priv->q + band;
@@ -489,7 +489,7 @@ static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
if (qdisc->q.qlen < qdisc_dev(qdisc)->tx_queue_len) {
int band = prio2band[skb->priority & TC_PRIO_MAX];
struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
- struct sk_buff_head *list = band2list(priv, band);
+ struct qdisc_skb_head *list = band2list(priv, band);
priv->bitmap |= (1 << band);
qdisc->q.qlen++;
@@ -505,8 +505,8 @@ static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
int band = bitmap2band[priv->bitmap];
if (likely(band >= 0)) {
- struct sk_buff_head *list = band2list(priv, band);
- struct sk_buff *skb = __qdisc_dequeue_head(list);
+ struct qdisc_skb_head *qh = band2list(priv, band);
+ struct sk_buff *skb = __qdisc_dequeue_head(qh);
if (likely(skb != NULL)) {
qdisc_qstats_backlog_dec(qdisc, skb);
@@ -514,7 +514,7 @@ static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
}
qdisc->q.qlen--;
- if (skb_queue_empty(list))
+ if (qh->qlen == 0)
priv->bitmap &= ~(1 << band);
return skb;
@@ -529,9 +529,9 @@ static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
int band = bitmap2band[priv->bitmap];
if (band >= 0) {
- struct sk_buff_head *list = band2list(priv, band);
+ struct qdisc_skb_head *qh = band2list(priv, band);
- return skb_peek(list);
+ return qh->head;
}
return NULL;
@@ -569,7 +569,7 @@ static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
- __skb_queue_head_init(band2list(priv, prio));
+ qdisc_skb_head_init(band2list(priv, prio));
/* Can by-pass the queue discipline */
qdisc->flags |= TCQ_F_CAN_BYPASS;
@@ -617,7 +617,8 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
sch->padded = (char *) sch - (char *) p;
}
- skb_queue_head_init(&sch->q);
+ qdisc_skb_head_init(&sch->q);
+ spin_lock_init(&sch->q.lock);
spin_lock_init(&sch->busylock);
lockdep_set_class(&sch->busylock,
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 53dbfa187870..c798d0de8a9d 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -162,7 +162,7 @@ struct htb_sched {
struct work_struct work;
/* non shaped skbs; let them go directly thru */
- struct sk_buff_head direct_queue;
+ struct qdisc_skb_head direct_queue;
long direct_pkts;
struct qdisc_watchdog watchdog;
@@ -570,6 +570,22 @@ static inline void htb_deactivate(struct htb_sched *q, struct htb_class *cl)
list_del_init(&cl->un.leaf.drop_list);
}
+static void htb_enqueue_tail(struct sk_buff *skb, struct Qdisc *sch,
+ struct qdisc_skb_head *qh)
+{
+ struct sk_buff *last = qh->tail;
+
+ if (last) {
+ skb->next = NULL;
+ last->next = skb;
+ qh->tail = skb;
+ } else {
+ qh->tail = skb;
+ qh->head = skb;
+ }
+ qh->qlen++;
+}
+
static int htb_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
@@ -580,7 +596,7 @@ static int htb_enqueue(struct sk_buff *skb, struct Qdisc *sch,
if (cl == HTB_DIRECT) {
/* enqueue to helper queue */
if (q->direct_queue.qlen < q->direct_qlen) {
- __skb_queue_tail(&q->direct_queue, skb);
+ htb_enqueue_tail(skb, sch, &q->direct_queue);
q->direct_pkts++;
} else {
return qdisc_drop(skb, sch, to_free);
@@ -888,7 +904,7 @@ static struct sk_buff *htb_dequeue(struct Qdisc *sch)
unsigned long start_at;
/* try to dequeue direct packets as high prio (!) to minimize cpu work */
- skb = __skb_dequeue(&q->direct_queue);
+ skb = __qdisc_dequeue_head(&q->direct_queue);
if (skb != NULL) {
ok:
qdisc_bstats_update(sch, skb);
@@ -1019,7 +1035,7 @@ static int htb_init(struct Qdisc *sch, struct nlattr *opt)
qdisc_watchdog_init(&q->watchdog, sch);
INIT_WORK(&q->work, htb_work_func);
- __skb_queue_head_init(&q->direct_queue);
+ qdisc_skb_head_init(&q->direct_queue);
if (tb[TCA_HTB_DIRECT_QLEN])
q->direct_qlen = nla_get_u32(tb[TCA_HTB_DIRECT_QLEN]);
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 0a964b35f8c7..9f7b380cf0a3 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -413,6 +413,16 @@ static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch,
return segs;
}
+static void netem_enqueue_skb_head(struct qdisc_skb_head *qh, struct sk_buff *skb)
+{
+ skb->next = qh->head;
+
+ if (!qh->head)
+ qh->tail = skb;
+ qh->head = skb;
+ qh->qlen++;
+}
+
/*
* Insert one skb into qdisc.
* Note: parent depends on return value to account for queue length.
@@ -523,7 +533,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff *last;
if (sch->q.qlen)
- last = skb_peek_tail(&sch->q);
+ last = sch->q.tail;
else
last = netem_rb_to_skb(rb_last(&q->t_root));
if (last) {
@@ -552,7 +562,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
cb->time_to_send = psched_get_time();
q->counter = 0;
- __skb_queue_head(&sch->q, skb);
+ netem_enqueue_skb_head(&sch->q, skb);
sch->qstats.requeues++;
}