From eeaeb068f1393b4db4861481bf594bcd1c3eda7a Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 28 Dec 2010 21:53:33 +0000 Subject: sch_sfq: allow big packets and be fair SFQ is currently 'limited' to small packets, because it uses a 15bit allotment number per flow. Introduce a scale by 8, so that we can handle full size TSO/GRO packets. Use appropriate handling to make sure allot is positive before a new packet is dequeued, so that fairness is respected. Signed-off-by: Eric Dumazet Acked-by: Jarek Poplawski Cc: Patrick McHardy Signed-off-by: David S. Miller --- net/sched/sch_sfq.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c index 6a2f88fea6d8..b76d46b71466 100644 --- a/net/sched/sch_sfq.c +++ b/net/sched/sch_sfq.c @@ -67,7 +67,7 @@ IMPLEMENTATION: This implementation limits maximal queue length to 128; - maximal mtu to 2^15-1; max 128 flows, number of hash buckets to 1024. + max mtu to 2^18-1; max 128 flows, number of hash buckets to 1024. The only goal of this restrictions was that all data fit into one 4K page on 32bit arches. @@ -77,6 +77,11 @@ #define SFQ_SLOTS 128 /* max number of flows */ #define SFQ_EMPTY_SLOT 255 #define SFQ_HASH_DIVISOR 1024 +/* We use 16 bits to store allot, and want to handle packets up to 64K + * Scale allot by 8 (1<<3) so that no overflow occurs. + */ +#define SFQ_ALLOT_SHIFT 3 +#define SFQ_ALLOT_SIZE(X) DIV_ROUND_UP(X, 1 << SFQ_ALLOT_SHIFT) /* This type should contain at least SFQ_DEPTH + SFQ_SLOTS values */ typedef unsigned char sfq_index; @@ -115,7 +120,7 @@ struct sfq_sched_data struct timer_list perturb_timer; u32 perturbation; sfq_index cur_depth; /* depth of longest slot */ - + unsigned short scaled_quantum; /* SFQ_ALLOT_SIZE(quantum) */ struct sfq_slot *tail; /* current slot in round */ sfq_index ht[SFQ_HASH_DIVISOR]; /* Hash table */ struct sfq_slot slots[SFQ_SLOTS]; @@ -395,7 +400,7 @@ sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch) q->tail->next = x; } q->tail = slot; - slot->allot = q->quantum; + slot->allot = q->scaled_quantum; } if (++sch->q.qlen <= q->limit) { sch->bstats.bytes += qdisc_pkt_len(skb); @@ -431,8 +436,14 @@ sfq_dequeue(struct Qdisc *sch) if (q->tail == NULL) return NULL; +next_slot: a = q->tail->next; slot = &q->slots[a]; + if (slot->allot <= 0) { + q->tail = slot; + slot->allot += q->scaled_quantum; + goto next_slot; + } skb = slot_dequeue_head(slot); sfq_dec(q, a); sch->q.qlen--; @@ -447,9 +458,8 @@ sfq_dequeue(struct Qdisc *sch) return skb; } q->tail->next = next_a; - } else if ((slot->allot -= qdisc_pkt_len(skb)) <= 0) { - q->tail = slot; - slot->allot += q->quantum; + } else { + slot->allot -= SFQ_ALLOT_SIZE(qdisc_pkt_len(skb)); } return skb; } @@ -485,6 +495,7 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt) sch_tree_lock(sch); q->quantum = ctl->quantum ? : psched_mtu(qdisc_dev(sch)); + q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum); q->perturb_period = ctl->perturb_period * HZ; if (ctl->limit) q->limit = min_t(u32, ctl->limit, SFQ_DEPTH - 1); @@ -525,6 +536,7 @@ static int sfq_init(struct Qdisc *sch, struct nlattr *opt) q->tail = NULL; if (opt == NULL) { q->quantum = psched_mtu(qdisc_dev(sch)); + q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum); q->perturb_period = 0; q->perturbation = net_random(); } else { @@ -617,7 +629,7 @@ static int sfq_dump_class_stats(struct Qdisc *sch, unsigned long cl, if (idx != SFQ_EMPTY_SLOT) { const struct sfq_slot *slot = &q->slots[idx]; - xstats.allot = slot->allot; + xstats.allot = slot->allot << SFQ_ALLOT_SHIFT; qs.qlen = slot->qlen; slot_queue_walk(slot, skb) qs.backlog += qdisc_pkt_len(skb); -- cgit v1.2.2