On Fri, Oct 17, 2008 at 02:33:23PM +0200, Patrick McHardy wrote:

Jarek Poplawski wrote:

quoted

Patrick McHardy wrote, On 10/16/2008 02:38 PM:

quoted

Jarek Poplawski wrote:

...

quoted

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PS: after this patchset only netem_enqueue() needs qdisc->requeue(),
but I hope this won't take too long.

Assuming work-conserving qdiscs are used with netem, the currently
code will always send out a reorder packet immediately. This behaviour
is trivial to implement without ->requeue. The problematic case is
non-work-conserving inner qdiscs, but that doesn't seem important
at all since you'd usually add it as parent of netem, which still
works.

How about something like this (example only)?

@@ -233,7 +233,9 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 		 */
 		cb->time_to_send = psched_get_time();
 		q->counter = 0;
-		ret = q->qdisc->ops->requeue(skb, q->qdisc);
+		q->qdisc->flags |= TCQ_F_REQUEUE;
+		ret = qdisc_equeue(skb, q->qdisc);
+		q->qdisc->flags &= ~TCQ_F_REQUEUE;

Well, the inner qdisc would still need to logic to order packets
apprioriately.

I'm not sure I was understood: the idea is to do something like
in this example in tfifo_enqueue() in all leaf qdiscs like fifo
etc. too, so to redirect their ->enqueue() to their ->requeue()
which usually is qdisc_requeue() (or to it directly if needed).

Its probably not that hard, but as I said, I don't
think its necessary at all. It only makes a difference with a
non-work-conserving inner qdisc, but a lot of the functionality of
netem requires the inner tfifo anyways and rate-limiting is usually
done on top of netem. So I would suggest so either hard-wire the
tfifo qdisc or at least make the assumption that inner qdiscs are
work-conserving.

Of course, I can do it like this, but wouldn't it break backward
compatibility for some users?

Thanks,
Jarek P.