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authorHagen Paul Pfeifer <hagen@jauu.net>2010-01-24 12:30:59 +0000
committerDavid S. Miller <davem@davemloft.net>2010-01-28 21:27:00 -0800
commit57dbb2d83d100ea601c54fe129bfde0678db5dee (patch)
tree40305bcd986692f512b1b5e848c0b0f612968c6a /net/sched/sch_fifo.c
parentd74340d31bf1dbeb00acadddd8697666528a7846 (diff)
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.c34
1 files changed, 34 insertions, 0 deletions
diff --git a/net/sched/sch_fifo.c b/net/sched/sch_fifo.c
index 69188e8358b4..4b0a6cc44c77 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)
{