diff options
| author | Hagen Paul Pfeifer <hagen@jauu.net> | 2010-01-24 12:30:59 (GMT) |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-01-29 05:27:00 (GMT) |
| commit | 57dbb2d83d100ea601c54fe129bfde0678db5dee (patch) | |
| tree | 40305bcd986692f512b1b5e848c0b0f612968c6a /net/sched/sch_fifo.c | |
| parent | d74340d31bf1dbeb00acadddd8697666528a7846 (diff) | |
| download | linux-57dbb2d83d100ea601c54fe129bfde0678db5dee.tar.xz | |
sched: add head drop fifo queue
This adds an additional queuing strategy, called pfifo_head_drop,
to remove the oldest skb in the case of an overflow within the queue -
the head element - instead of the last skb (tail). To remove the oldest
skb in congested situations is useful for sensor network environments
where newer packets reflect the superior information.
Reviewed-by: Florian Westphal <fw@strlen.de>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/sch_fifo.c')
| -rw-r--r-- | net/sched/sch_fifo.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/net/sched/sch_fifo.c b/net/sched/sch_fifo.c index 69188e8..4b0a6cc 100644 --- a/net/sched/sch_fifo.c +++ b/net/sched/sch_fifo.c @@ -43,6 +43,26 @@ static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch) return qdisc_reshape_fail(skb, sch); } +static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc* sch) +{ + struct sk_buff *skb_head; + struct fifo_sched_data *q = qdisc_priv(sch); + + if (likely(skb_queue_len(&sch->q) < q->limit)) + return qdisc_enqueue_tail(skb, sch); + + /* queue full, remove one skb to fulfill the limit */ + skb_head = qdisc_dequeue_head(sch); + sch->bstats.bytes -= qdisc_pkt_len(skb_head); + sch->bstats.packets--; + sch->qstats.drops++; + kfree_skb(skb_head); + + qdisc_enqueue_tail(skb, sch); + + return NET_XMIT_CN; +} + static int fifo_init(struct Qdisc *sch, struct nlattr *opt) { struct fifo_sched_data *q = qdisc_priv(sch); @@ -108,6 +128,20 @@ struct Qdisc_ops bfifo_qdisc_ops __read_mostly = { }; EXPORT_SYMBOL(bfifo_qdisc_ops); +struct Qdisc_ops pfifo_head_drop_qdisc_ops __read_mostly = { + .id = "pfifo_head_drop", + .priv_size = sizeof(struct fifo_sched_data), + .enqueue = pfifo_tail_enqueue, + .dequeue = qdisc_dequeue_head, + .peek = qdisc_peek_head, + .drop = qdisc_queue_drop_head, + .init = fifo_init, + .reset = qdisc_reset_queue, + .change = fifo_init, + .dump = fifo_dump, + .owner = THIS_MODULE, +}; + /* Pass size change message down to embedded FIFO */ int fifo_set_limit(struct Qdisc *q, unsigned int limit) { |