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[PKT_SCHED]: netetm: make qdisc friendly to outer disciplines 

Netem currently dumps packets into the queue when timer expires. This
patch makes work by self-clocking (more like TBF).  It fixes a bug
when 0 delay is requested (only doing loss or duplication).

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stephen Hemminger 2005-05-03 16:24:32 -07:00 committed by David S. Miller
parent 8cbe1d46d6
commit 771018e76a
1 changed files with 67 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

113
net/sched/sch_netem.c
View File

@ -138,38 +138,78 @@ static long tabledist(unsigned long mu, long sigma,
}
/* Put skb in the private delayed queue. */
static int delay_skb(struct Qdisc *sch, struct sk_buff *skb)
static int netem_delay(struct Qdisc *sch, struct sk_buff *skb)
{
struct netem_sched_data *q = qdisc_priv(sch);
struct netem_skb_cb *cb = (struct netem_skb_cb *)skb->cb;
psched_tdiff_t td;
psched_time_t now;
PSCHED_GET_TIME(now);
td = tabledist(q->latency, q->jitter, &q->delay_cor, q->delay_dist);
PSCHED_TADD2(now, td, cb->time_to_send);
/* Always queue at tail to keep packets in order */
if (likely(q->delayed.qlen < q->limit)) {
struct netem_skb_cb *cb = (struct netem_skb_cb *)skb->cb;
PSCHED_TADD2(now, td, cb->time_to_send);
pr_debug("netem_delay: skb=%p now=%llu tosend=%llu\n", skb,
now, cb->time_to_send);
__skb_queue_tail(&q->delayed, skb);
if (!timer_pending(&q->timer)) {
q->timer.expires = jiffies + PSCHED_US2JIFFIE(td);
add_timer(&q->timer);
}
return NET_XMIT_SUCCESS;
}
pr_debug("netem_delay: queue over limit %d\n", q->limit);
sch->qstats.overlimits++;
kfree_skb(skb);
return NET_XMIT_DROP;
}
/*
* Move a packet that is ready to send from the delay holding
* list to the underlying qdisc.
*/
static int netem_run(struct Qdisc *sch)
{
struct netem_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb;
psched_time_t now;
PSCHED_GET_TIME(now);
skb = skb_peek(&q->delayed);
if (skb) {
const struct netem_skb_cb *cb
= (const struct netem_skb_cb *)skb->cb;
long delay
= PSCHED_US2JIFFIE(PSCHED_TDIFF(cb->time_to_send, now));
pr_debug("netem_run: skb=%p delay=%ld\n", skb, delay);
/* if more time remaining? */
if (delay > 0) {
mod_timer(&q->timer, jiffies + delay);
return 1;
}
__skb_unlink(skb, &q->delayed);
if (q->qdisc->enqueue(skb, q->qdisc)) {
sch->q.qlen--;
sch->qstats.drops++;
}
}
return 0;
}
static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{
struct netem_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb2;
int ret;
pr_debug("netem_enqueue skb=%p @%lu\n", skb, jiffies);
pr_debug("netem_enqueue skb=%p\n", skb);
/* Random packet drop 0 => none, ~0 => all */
if (q->loss && q->loss >= get_crandom(&q->loss_cor)) {
@ -184,7 +224,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
&& (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
pr_debug("netem_enqueue: dup %p\n", skb2);
if (delay_skb(sch, skb2)) {
if (netem_delay(sch, skb2)) {
sch->q.qlen++;
sch->bstats.bytes += skb2->len;
sch->bstats.packets++;
@ -202,7 +242,8 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
ret = q->qdisc->enqueue(skb, q->qdisc);
} else {
q->counter = 0;
ret = delay_skb(sch, skb);
ret = netem_delay(sch, skb);
netem_run(sch);
}
if (likely(ret == NET_XMIT_SUCCESS)) {
@ -241,56 +282,35 @@ static unsigned int netem_drop(struct Qdisc* sch)
return len;
}
/* Dequeue packet.
* Move all packets that are ready to send from the delay holding
* list to the underlying qdisc, then just call dequeue
*/
static struct sk_buff *netem_dequeue(struct Qdisc *sch)
{
struct netem_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb;
int pending;
pending = netem_run(sch);
skb = q->qdisc->dequeue(q->qdisc);
if (skb)
if (skb) {
pr_debug("netem_dequeue: return skb=%p\n", skb);
sch->q.qlen--;
sch->flags &= ~TCQ_F_THROTTLED;
}
else if (pending) {
pr_debug("netem_dequeue: throttling\n");
sch->flags |= TCQ_F_THROTTLED;
}
return skb;
}
static void netem_watchdog(unsigned long arg)
{
struct Qdisc *sch = (struct Qdisc *)arg;
struct netem_sched_data *q = qdisc_priv(sch);
struct net_device *dev = sch->dev;
struct sk_buff *skb;
psched_time_t now;
pr_debug("netem_watchdog: fired @%lu\n", jiffies);
spin_lock_bh(&dev->queue_lock);
PSCHED_GET_TIME(now);
while ((skb = skb_peek(&q->delayed)) != NULL) {
const struct netem_skb_cb *cb
= (const struct netem_skb_cb *)skb->cb;
long delay
= PSCHED_US2JIFFIE(PSCHED_TDIFF(cb->time_to_send, now));
pr_debug("netem_watchdog: skb %p@%lu %ld\n",
skb, jiffies, delay);
/* if more time remaining? */
if (delay > 0) {
mod_timer(&q->timer, jiffies + delay);
break;
}
__skb_unlink(skb, &q->delayed);
if (q->qdisc->enqueue(skb, q->qdisc)) {
sch->q.qlen--;
sch->qstats.drops++;
}
}
qdisc_run(dev);
spin_unlock_bh(&dev->queue_lock);
pr_debug("netem_watchdog qlen=%d\n", sch->q.qlen);
sch->flags &= ~TCQ_F_THROTTLED;
netif_schedule(sch->dev);
}
static void netem_reset(struct Qdisc *sch)
@ -301,6 +321,7 @@ static void netem_reset(struct Qdisc *sch)
skb_queue_purge(&q->delayed);
sch->q.qlen = 0;
sch->flags &= ~TCQ_F_THROTTLED;
del_timer_sync(&q->timer);
}