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authorEric Dumazet <eric.dumazet@gmail.com>2011-01-05 10:35:02 +0000
committerDavid S. Miller <davem@davemloft.net>2011-01-05 13:39:17 -0800
commit44b8288308ac9da27eab7d7bdbf1375a568805c3 (patch)
tree47fc194f0ff73d2fdb7d62d3d8d6d268ca660316
parentdbbe68bb12b34f3e450da7a73c20e6fa1f85d63a (diff)
net_sched: pfifo_head_drop problem
commit 57dbb2d83d100ea (sched: add head drop fifo queue) introduced pfifo_head_drop, and broke the invariant that sch->bstats.bytes and sch->bstats.packets are COUNTER (increasing counters only) This can break estimators because est_timer() handles unsigned deltas only. A decreasing counter can then give a huge unsigned delta. My mid term suggestion would be to change things so that sch->bstats.bytes and sch->bstats.packets are incremented in dequeue() only, not at enqueue() time. We also could add drop_bytes/drop_packets and provide estimations of drop rates. It would be more sensible anyway for very low speeds, and big bursts. Right now, if we drop packets, they still are accounted in byte/packets abolute counters and rate estimators. Before this mid term change, this patch makes pfifo_head_drop behavior similar to other qdiscs in case of drops : Dont decrement sch->bstats.bytes and sch->bstats.packets Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Acked-by: Hagen Paul Pfeifer <hagen@jauu.net> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/sched/sch_fifo.c2
1 files changed, 0 insertions, 2 deletions
diff --git a/net/sched/sch_fifo.c b/net/sched/sch_fifo.c
index 4dfecb0cba37..aa4d6337e43c 100644
--- a/net/sched/sch_fifo.c
+++ b/net/sched/sch_fifo.c
@@ -54,8 +54,6 @@ static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc* 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);

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