From 300ce174ebc2fcf2b5111a50fa42f79d891927dd Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Sun, 30 Oct 2005 13:47:34 -0800 Subject: [NETEM]: Support time based reordering Change netem to support packets getting reordered because of variations in delay. Introduce a special case version of FIFO that queues packets in order based on the netem delay. Since netem is classful, those users that don't want jitter based reordering can just insert a pfifo instead of the default. This required changes to generic skbuff code to allow finer grain manipulation of sk_buff_head. Insertion into the middle and reverse walk. Signed-off-by: Stephen Hemminger Signed-off-by: Arnaldo Carvalho de Melo --- net/sched/sch_netem.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 84 insertions(+), 1 deletion(-) (limited to 'net/sched/sch_netem.c') diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c index d871fe7f81a927..7c10ef3457d759 100644 --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -300,11 +300,16 @@ static void netem_reset(struct Qdisc *sch) del_timer_sync(&q->timer); } +/* Pass size change message down to embedded FIFO */ static int set_fifo_limit(struct Qdisc *q, int limit) { struct rtattr *rta; int ret = -ENOMEM; + /* Hack to avoid sending change message to non-FIFO */ + if (strncmp(q->ops->id + 1, "fifo", 4) != 0) + return 0; + rta = kmalloc(RTA_LENGTH(sizeof(struct tc_fifo_qopt)), GFP_KERNEL); if (rta) { rta->rta_type = RTM_NEWQDISC; @@ -436,6 +441,84 @@ static int netem_change(struct Qdisc *sch, struct rtattr *opt) return 0; } +/* + * Special case version of FIFO queue for use by netem. + * It queues in order based on timestamps in skb's + */ +struct fifo_sched_data { + u32 limit; +}; + +static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch) +{ + struct fifo_sched_data *q = qdisc_priv(sch); + struct sk_buff_head *list = &sch->q; + const struct netem_skb_cb *ncb + = (const struct netem_skb_cb *)nskb->cb; + struct sk_buff *skb; + + if (likely(skb_queue_len(list) < q->limit)) { + skb_queue_reverse_walk(list, skb) { + const struct netem_skb_cb *cb + = (const struct netem_skb_cb *)skb->cb; + + if (PSCHED_TLESS(cb->time_to_send, ncb->time_to_send)) + break; + } + + __skb_queue_after(list, skb, nskb); + + sch->qstats.backlog += nskb->len; + sch->bstats.bytes += nskb->len; + sch->bstats.packets++; + + return NET_XMIT_SUCCESS; + } + + return qdisc_drop(nskb, sch); +} + +static int tfifo_init(struct Qdisc *sch, struct rtattr *opt) +{ + struct fifo_sched_data *q = qdisc_priv(sch); + + if (opt) { + struct tc_fifo_qopt *ctl = RTA_DATA(opt); + if (RTA_PAYLOAD(opt) < sizeof(*ctl)) + return -EINVAL; + + q->limit = ctl->limit; + } else + q->limit = max_t(u32, sch->dev->tx_queue_len, 1); + + return 0; +} + +static int tfifo_dump(struct Qdisc *sch, struct sk_buff *skb) +{ + struct fifo_sched_data *q = qdisc_priv(sch); + struct tc_fifo_qopt opt = { .limit = q->limit }; + + RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt); + return skb->len; + +rtattr_failure: + return -1; +} + +static struct Qdisc_ops tfifo_qdisc_ops = { + .id = "tfifo", + .priv_size = sizeof(struct fifo_sched_data), + .enqueue = tfifo_enqueue, + .dequeue = qdisc_dequeue_head, + .requeue = qdisc_requeue, + .drop = qdisc_queue_drop, + .init = tfifo_init, + .reset = qdisc_reset_queue, + .change = tfifo_init, + .dump = tfifo_dump, +}; + static int netem_init(struct Qdisc *sch, struct rtattr *opt) { struct netem_sched_data *q = qdisc_priv(sch); @@ -448,7 +531,7 @@ static int netem_init(struct Qdisc *sch, struct rtattr *opt) q->timer.function = netem_watchdog; q->timer.data = (unsigned long) sch; - q->qdisc = qdisc_create_dflt(sch->dev, &pfifo_qdisc_ops); + q->qdisc = qdisc_create_dflt(sch->dev, &tfifo_qdisc_ops); if (!q->qdisc) { pr_debug("netem: qdisc create failed\n"); return -ENOMEM; -- cgit 1.2.3-korg