From aa3e219997e4b949be4199660936099ded0b401f Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 20 Dec 2010 13:18:16 -0800 Subject: [PATCH] net_sched: sch_sfq: fix allot handling When deploying SFQ/IFB here at work, I found the allot management was pretty wrong in sfq, even changing allot from short to int... We should init allot for each new flow, not using a previous value found in slot. Before patch, I saw bursts of several packets per flow, apparently denying the default "quantum 1514" limit I had on my SFQ class. class sfq 11:1 parent 11: (dropped 0, overlimits 0 requeues 0) backlog 0b 7p requeues 0 allot 11546 class sfq 11:46 parent 11: (dropped 0, overlimits 0 requeues 0) backlog 0b 1p requeues 0 allot -23873 class sfq 11:78 parent 11: (dropped 0, overlimits 0 requeues 0) backlog 0b 5p requeues 0 allot 11393 After patch, better fairness among each flow, allot limit being respected, allot is positive : class sfq 11:e parent 11: (dropped 0, overlimits 0 requeues 86) backlog 0b 3p requeues 86 allot 596 class sfq 11:94 parent 11: (dropped 0, overlimits 0 requeues 0) backlog 0b 3p requeues 0 allot 1468 class sfq 11:a4 parent 11: (dropped 0, overlimits 0 requeues 0) backlog 0b 4p requeues 0 allot 650 class sfq 11:bb parent 11: (dropped 0, overlimits 0 requeues 0) backlog 0b 3p requeues 0 allot 596 Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/sched/sch_sfq.c | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-) diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c index 3cf478d012d..7150705f1d0 100644 --- a/net/sched/sch_sfq.c +++ b/net/sched/sch_sfq.c @@ -270,7 +270,6 @@ static unsigned int sfq_drop(struct Qdisc *sch) /* It is difficult to believe, but ALL THE SLOTS HAVE LENGTH 1. */ d = q->next[q->tail]; q->next[q->tail] = q->next[d]; - q->allot[q->next[d]] += q->quantum; skb = q->qs[d].prev; len = qdisc_pkt_len(skb); __skb_unlink(skb, &q->qs[d]); @@ -321,14 +320,13 @@ sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch) sfq_inc(q, x); if (q->qs[x].qlen == 1) { /* The flow is new */ if (q->tail == SFQ_DEPTH) { /* It is the first flow */ - q->tail = x; q->next[x] = x; - q->allot[x] = q->quantum; } else { q->next[x] = q->next[q->tail]; q->next[q->tail] = x; - q->tail = x; } + q->tail = x; + q->allot[x] = q->quantum; } if (++sch->q.qlen <= q->limit) { sch->bstats.bytes += qdisc_pkt_len(skb); @@ -359,13 +357,13 @@ sfq_dequeue(struct Qdisc *sch) { struct sfq_sched_data *q = qdisc_priv(sch); struct sk_buff *skb; - sfq_index a, old_a; + sfq_index a, next_a; /* No active slots */ if (q->tail == SFQ_DEPTH) return NULL; - a = old_a = q->next[q->tail]; + a = q->next[q->tail]; /* Grab packet */ skb = __skb_dequeue(&q->qs[a]); @@ -376,17 +374,15 @@ sfq_dequeue(struct Qdisc *sch) /* Is the slot empty? */ if (q->qs[a].qlen == 0) { q->ht[q->hash[a]] = SFQ_DEPTH; - a = q->next[a]; - if (a == old_a) { + next_a = q->next[a]; + if (a == next_a) { q->tail = SFQ_DEPTH; return skb; } - q->next[q->tail] = a; - q->allot[a] += q->quantum; + q->next[q->tail] = next_a; } else if ((q->allot[a] -= qdisc_pkt_len(skb)) <= 0) { - q->tail = a; - a = q->next[a]; q->allot[a] += q->quantum; + q->tail = a; } return skb; } -- 2.20.1