fq_codel: should use qdisc backlog as threshold
codel_should_drop() logic allows a packet being not dropped if queue size is under max packet size. In fq_codel, we have two possible backlogs : The qdisc global one, and the flow local one. The meaningful one for codel_should_drop() should be the global backlog, not the per flow one, so that thin flows can have a non zero drop/mark probability. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Dave Taht <dave.taht@bufferbloat.net> Cc: Kathleen Nichols <nichols@pollere.com> Cc: Van Jacobson <van@pollere.net> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -205,7 +205,7 @@ static codel_time_t codel_control_law(codel_time_t t,
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static bool codel_should_drop(const struct sk_buff *skb,
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unsigned int *backlog,
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struct Qdisc *sch,
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struct codel_vars *vars,
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struct codel_params *params,
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struct codel_stats *stats,
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@ -219,13 +219,13 @@ static bool codel_should_drop(const struct sk_buff *skb,
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}
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vars->ldelay = now - codel_get_enqueue_time(skb);
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*backlog -= qdisc_pkt_len(skb);
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sch->qstats.backlog -= qdisc_pkt_len(skb);
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if (unlikely(qdisc_pkt_len(skb) > stats->maxpacket))
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stats->maxpacket = qdisc_pkt_len(skb);
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if (codel_time_before(vars->ldelay, params->target) ||
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*backlog <= stats->maxpacket) {
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sch->qstats.backlog <= stats->maxpacket) {
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/* went below - stay below for at least interval */
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vars->first_above_time = 0;
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return false;
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@ -249,8 +249,7 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
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struct codel_params *params,
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struct codel_vars *vars,
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struct codel_stats *stats,
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codel_skb_dequeue_t dequeue_func,
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u32 *backlog)
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codel_skb_dequeue_t dequeue_func)
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{
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struct sk_buff *skb = dequeue_func(vars, sch);
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codel_time_t now;
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@ -261,7 +260,7 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
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return skb;
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}
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now = codel_get_time();
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drop = codel_should_drop(skb, backlog, vars, params, stats, now);
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drop = codel_should_drop(skb, sch, vars, params, stats, now);
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if (vars->dropping) {
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if (!drop) {
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/* sojourn time below target - leave dropping state */
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@ -292,7 +291,7 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
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qdisc_drop(skb, sch);
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stats->drop_count++;
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skb = dequeue_func(vars, sch);
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if (!codel_should_drop(skb, backlog,
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if (!codel_should_drop(skb, sch,
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vars, params, stats, now)) {
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/* leave dropping state */
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vars->dropping = false;
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@ -313,7 +312,7 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
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stats->drop_count++;
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skb = dequeue_func(vars, sch);
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drop = codel_should_drop(skb, backlog, vars, params,
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drop = codel_should_drop(skb, sch, vars, params,
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stats, now);
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}
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vars->dropping = true;
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@ -77,8 +77,8 @@ static struct sk_buff *codel_qdisc_dequeue(struct Qdisc *sch)
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struct codel_sched_data *q = qdisc_priv(sch);
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struct sk_buff *skb;
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skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats,
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dequeue, &sch->qstats.backlog);
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skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats, dequeue);
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/* We cant call qdisc_tree_decrease_qlen() if our qlen is 0,
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* or HTB crashes. Defer it for next round.
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*/
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@ -217,13 +217,14 @@ static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch)
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*/
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static struct sk_buff *dequeue(struct codel_vars *vars, struct Qdisc *sch)
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{
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struct fq_codel_sched_data *q = qdisc_priv(sch);
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struct fq_codel_flow *flow;
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struct sk_buff *skb = NULL;
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flow = container_of(vars, struct fq_codel_flow, cvars);
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if (flow->head) {
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skb = dequeue_head(flow);
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sch->qstats.backlog -= qdisc_pkt_len(skb);
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q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
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sch->q.qlen--;
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}
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return skb;
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@ -256,7 +257,7 @@ begin:
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prev_ecn_mark = q->cstats.ecn_mark;
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skb = codel_dequeue(sch, &q->cparams, &flow->cvars, &q->cstats,
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dequeue, &q->backlogs[flow - q->flows]);
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dequeue);
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flow->dropped += q->cstats.drop_count - prev_drop_count;
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flow->dropped += q->cstats.ecn_mark - prev_ecn_mark;
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