target/linux/generic/patches-3.3/046-fq_codel-qdisc-backlog.patch

   1 From: Eric Dumazet <edumazet@google.com>
   2
   3 codel_should_drop() logic allows a packet being not dropped if queue
   4 size is under max packet size.
   5
   6 In fq_codel, we have two possible backlogs : The qdisc global one, and
   7 the flow local one.
   8
   9 The meaningful one for codel_should_drop() should be the global backlog,
  10 not the per flow one, so that thin flows can have a non zero drop/mark
  11 probability.
  12
  13 Signed-off-by: Eric Dumazet <edumazet@google.com>
  14 Cc: Dave Taht <dave.taht@bufferbloat.net>
  15 Cc: Kathleen Nichols <nichols@pollere.com>
  16 Cc: Van Jacobson <van@pollere.net>
  17 ---
  18  include/net/codel.h      |   15 +++++++--------
  19  net/sched/sch_codel.c    |    4 ++--
  20  net/sched/sch_fq_codel.c |    5 +++--
  21  3 files changed, 12 insertions(+), 12 deletions(-)
  22
  23 --- a/include/net/codel.h
  24 +++ b/include/net/codel.h
  25 @@ -205,7 +205,7 @@ static codel_time_t codel_control_law(co
  26
  27
  28  static bool codel_should_drop(const struct sk_buff *skb,
  29 -                             unsigned int *backlog,
  30 +                             struct Qdisc *sch,
  31                               struct codel_vars *vars,
  32                               struct codel_params *params,
  33                               struct codel_stats *stats,
  34 @@ -219,13 +219,13 @@ static bool codel_should_drop(const stru
  35         }
  36
  37         vars->ldelay = now - codel_get_enqueue_time(skb);
  38 -       *backlog -= qdisc_pkt_len(skb);
  39 +       sch->qstats.backlog -= qdisc_pkt_len(skb);
  40
  41         if (unlikely(qdisc_pkt_len(skb) > stats->maxpacket))
  42                 stats->maxpacket = qdisc_pkt_len(skb);
  43
  44         if (codel_time_before(vars->ldelay, params->target) ||
  45 -           *backlog <= stats->maxpacket) {
  46 +           sch->qstats.backlog <= stats->maxpacket) {
  47                 /* went below - stay below for at least interval */
  48                 vars->first_above_time = 0;
  49                 return false;
  50 @@ -249,8 +249,7 @@ static struct sk_buff *codel_dequeue(str
  51                                      struct codel_params *params,
  52                                      struct codel_vars *vars,
  53                                      struct codel_stats *stats,
  54 -                                    codel_skb_dequeue_t dequeue_func,
  55 -                                    u32 *backlog)
  56 +                                    codel_skb_dequeue_t dequeue_func)
  57  {
  58         struct sk_buff *skb = dequeue_func(vars, sch);
  59         codel_time_t now;
  60 @@ -261,7 +260,7 @@ static struct sk_buff *codel_dequeue(str
  61                 return skb;
  62         }
  63         now = codel_get_time();
  64 -       drop = codel_should_drop(skb, backlog, vars, params, stats, now);
  65 +       drop = codel_should_drop(skb, sch, vars, params, stats, now);
  66         if (vars->dropping) {
  67                 if (!drop) {
  68                         /* sojourn time below target - leave dropping state */
  69 @@ -292,7 +291,7 @@ static struct sk_buff *codel_dequeue(str
  70                                 qdisc_drop(skb, sch);
  71                                 stats->drop_count++;
  72                                 skb = dequeue_func(vars, sch);
  73 -                               if (!codel_should_drop(skb, backlog,
  74 +                               if (!codel_should_drop(skb, sch,
  75                                                        vars, params, stats, now)) {
  76                                         /* leave dropping state */
  77                                         vars->dropping = false;
  78 @@ -313,7 +312,7 @@ static struct sk_buff *codel_dequeue(str
  79                         stats->drop_count++;
  80
  81                         skb = dequeue_func(vars, sch);
  82 -                       drop = codel_should_drop(skb, backlog, vars, params,
  83 +                       drop = codel_should_drop(skb, sch, vars, params,
  84                                                  stats, now);
  85                 }
  86                 vars->dropping = true;
  87 --- a/net/sched/sch_codel.c
  88 +++ b/net/sched/sch_codel.c
  89 @@ -77,8 +77,8 @@ static struct sk_buff *codel_qdisc_deque
  90         struct codel_sched_data *q = qdisc_priv(sch);
  91         struct sk_buff *skb;
  92
  93 -       skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats,
  94 -                           dequeue, &sch->qstats.backlog);
  95 +       skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats, dequeue);
  96 +
  97         /* We cant call qdisc_tree_decrease_qlen() if our qlen is 0,
  98          * or HTB crashes. Defer it for next round.
  99          */
 100 --- a/net/sched/sch_fq_codel.c
 101 +++ b/net/sched/sch_fq_codel.c
 102 @@ -217,13 +217,14 @@ static int fq_codel_enqueue(struct sk_bu
 103   */
 104  static struct sk_buff *dequeue(struct codel_vars *vars, struct Qdisc *sch)
 105  {
 106 +       struct fq_codel_sched_data *q = qdisc_priv(sch);
 107         struct fq_codel_flow *flow;
 108         struct sk_buff *skb = NULL;
 109
 110         flow = container_of(vars, struct fq_codel_flow, cvars);
 111         if (flow->head) {
 112                 skb = dequeue_head(flow);
 113 -               sch->qstats.backlog -= qdisc_pkt_len(skb);
 114 +               q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
 115                 sch->q.qlen--;
 116         }
 117         return skb;
 118 @@ -256,7 +257,7 @@ begin:
 119         prev_ecn_mark = q->cstats.ecn_mark;
 120
 121         skb = codel_dequeue(sch, &q->cparams, &flow->cvars, &q->cstats,
 122 -                           dequeue, &q->backlogs[flow - q->flows]);
 123 +                           dequeue);
 124
 125         flow->dropped += q->cstats.drop_count - prev_drop_count;
 126         flow->dropped += q->cstats.ecn_mark - prev_ecn_mark;