| title: | Re PATCH 1 1 sched add head drop fifo que |
|
Hagen Paul Pfeifer wrote, On 01/18/2010 05:44 PM:
This add an additional queuing strategy, called pfifo_head_drop,
"This adds"...
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 a congested situations is useful for sensor network environments
"skb in congested situations"...
where newer packets reflects the superior information.
"where newer packets reflect"...
Reviewed-by: Florian Westphal <fw@xxxxxxxxx
Acked-by: Patrick McHardy <kaber@xxxxxxxxx
Signed-off-by: Hagen Paul Pfeifer <hagen@xxxxxxxx
---
include/net/pkt_sched.h | 1 +
net/sched/sch_api.c | 1 +
net/sched/sch_fifo.c | 36 ++++++++++++++++++++++++++++++++++++
3 files changed, 38 insertions(+), 0 deletions(-)
...
+static int pfifo_front_enqueue(struct sk_buff *skb, struct Qdisc* sch)
Why do you call it "front_enqueue" if always does "enqueue_tail"?
Btw, usually these methods take name from the qdisc.
+{
+ 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- q.qlen--;
I dont think this is needed; qdisc_dequeue_head() updated it already.
+ 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 +130,20 @@ 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_front_enqueue,
+ .dequeue = qdisc_dequeue_head,
+ .peek = qdisc_peek_head,
+ .drop = qdisc_queue_drop,
Probably it isnt used much, but it seems for consistency this drop
should be implemented as a head drop.
Jarek P.
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