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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>
This commit is contained in:
Eric Dumazet 2012-05-16 04:39:09 +00:00 committed by David S. Miller
parent c27b46e7f1
commit 865ec5523d
3 changed files with 12 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
include/net/codel.h
View File

@ -205,7 +205,7 @@ static codel_time_t codel_control_law(codel_time_t t,
static bool codel_should_drop(const struct sk_buff *skb,
unsigned int *backlog,
struct Qdisc *sch,
struct codel_vars *vars,
struct codel_params *params,
struct codel_stats *stats,
@ -219,13 +219,13 @@ static bool codel_should_drop(const struct sk_buff *skb,
}
vars->ldelay = now - codel_get_enqueue_time(skb);
*backlog -= qdisc_pkt_len(skb);
sch->qstats.backlog -= qdisc_pkt_len(skb);
if (unlikely(qdisc_pkt_len(skb) > stats->maxpacket))
stats->maxpacket = qdisc_pkt_len(skb);
if (codel_time_before(vars->ldelay, params->target) ||
*backlog <= stats->maxpacket) {
sch->qstats.backlog <= stats->maxpacket) {
/* went below - stay below for at least interval */
vars->first_above_time = 0;
return false;
@ -249,8 +249,7 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
struct codel_params *params,
struct codel_vars *vars,
struct codel_stats *stats,
codel_skb_dequeue_t dequeue_func,
u32 *backlog)
codel_skb_dequeue_t dequeue_func)
{
struct sk_buff *skb = dequeue_func(vars, sch);
codel_time_t now;
@ -261,7 +260,7 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
return skb;
}
now = codel_get_time();
drop = codel_should_drop(skb, backlog, vars, params, stats, now);
drop = codel_should_drop(skb, sch, vars, params, stats, now);
if (vars->dropping) {
if (!drop) {
/* sojourn time below target - leave dropping state */
@ -292,7 +291,7 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
qdisc_drop(skb, sch);
stats->drop_count++;
skb = dequeue_func(vars, sch);
if (!codel_should_drop(skb, backlog,
if (!codel_should_drop(skb, sch,
vars, params, stats, now)) {
/* leave dropping state */
vars->dropping = false;
@ -313,7 +312,7 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
stats->drop_count++;
skb = dequeue_func(vars, sch);
drop = codel_should_drop(skb, backlog, vars, params,
drop = codel_should_drop(skb, sch, vars, params,
stats, now);
}
vars->dropping = true;

4
net/sched/sch_codel.c
View File

@ -77,8 +77,8 @@ static struct sk_buff *codel_qdisc_dequeue(struct Qdisc *sch)
struct codel_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb;
skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats,
dequeue, &sch->qstats.backlog);
skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats, dequeue);
/* We cant call qdisc_tree_decrease_qlen() if our qlen is 0,
* or HTB crashes. Defer it for next round.
*/

5
net/sched/sch_fq_codel.c
View File

@ -217,13 +217,14 @@ static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch)
*/
static struct sk_buff *dequeue(struct codel_vars *vars, struct Qdisc *sch)
{
struct fq_codel_sched_data *q = qdisc_priv(sch);
struct fq_codel_flow *flow;
struct sk_buff *skb = NULL;
flow = container_of(vars, struct fq_codel_flow, cvars);
if (flow->head) {
skb = dequeue_head(flow);
sch->qstats.backlog -= qdisc_pkt_len(skb);
q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
sch->q.qlen--;
}
return skb;
@ -256,7 +257,7 @@ begin:
prev_ecn_mark = q->cstats.ecn_mark;
skb = codel_dequeue(sch, &q->cparams, &flow->cvars, &q->cstats,
dequeue, &q->backlogs[flow - q->flows]);
dequeue);
flow->dropped += q->cstats.drop_count - prev_drop_count;
flow->dropped += q->cstats.ecn_mark - prev_ecn_mark;