net: sk_buff rbnode reorg
skb->rbnode shares space with skb->next, skb->prev and skb->tstamp
Current uses (TCP receive ofo queue and netem) need to save/restore
tstamp, while skb->dev is either NULL (TCP) or a constant for a given
queue (netem).
Since we plan using an RB tree for TCP retransmit queue to speedup SACK
processing with large BDP, this patch exchanges skb->dev and
skb->tstamp.
This saves some overhead in both TCP and netem.
v2: removes the swtstamp field from struct tcp_skb_cb
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Wei Wang <weiwan@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index b1266e7..063a4bd 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -146,7 +146,6 @@ struct netem_sched_data {
*/
struct netem_skb_cb {
psched_time_t time_to_send;
- ktime_t tstamp_save;
};
@@ -561,7 +560,6 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
}
cb->time_to_send = now + delay;
- cb->tstamp_save = skb->tstamp;
++q->counter;
tfifo_enqueue(skb, sch);
} else {
@@ -629,7 +627,10 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
qdisc_qstats_backlog_dec(sch, skb);
skb->next = NULL;
skb->prev = NULL;
- skb->tstamp = netem_skb_cb(skb)->tstamp_save;
+ /* skb->dev shares skb->rbnode area,
+ * we need to restore its value.
+ */
+ skb->dev = qdisc_dev(sch);
#ifdef CONFIG_NET_CLS_ACT
/*