Lossless IP networks are not possible. Dropping packets is the
fastest way to get back to a target delay, and if that involves
dropping ECN marked packets, so be it. When a network is in a
more steady state, ECN is fine...
My choice of "2 * target" as a threshold for dropping ECN
marked packets is entirely arbitrary.
---
include/net/codel.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/include/net/codel.h b/include/net/codel.h
index 550debf..26944a0 100644
--- a/include/net/codel.h
+++ b/include/net/codel.h
@@ -280,7 +280,8 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
* since there is no more divide
*/
codel_Newton_step(vars);
- if (params->ecn && INET_ECN_set_ce(skb)) {
+ if (params->ecn && INET_ECN_set_ce(skb) &&
+ vars->ldelay <= 2 * params->target) {
stats->ecn_mark++;
vars->drop_next =
codel_control_law(vars->drop_next,
@@ -305,7 +306,8 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
}
}
} else if (drop) {
- if (params->ecn && INET_ECN_set_ce(skb)) {
+ if (params->ecn && INET_ECN_set_ce(skb) &&
+ vars->ldelay <= 2 * params->target) {
stats->ecn_mark++;
} else {
qdisc_drop(skb, sch);
--
1.7.9.5
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