Hi Peter,
Peter wrote on 11/13/2007 11:14:50 PM:
> @@ -134,7 +134,7 @@ static inline int qdisc_restart(struct net_device *dev)
> {
> struct Qdisc *q = dev->qdisc;
> struct sk_buff *skb;
> - int ret;
> + int ret = NETDEV_TX_BUSY;
>
> /* Dequeue packet */
> if (unlikely((skb = dev_dequeue_skb(dev, q)) == NULL))
> @@ -145,7 +145,8 @@ static inline int qdisc_restart(struct net_device *dev)
> spin_unlock(&dev->queue_lock);
>
> HARD_TX_LOCK(dev, smp_processor_id());
> - ret = dev_hard_start_xmit(skb, dev);
> + if (!netif_subqueue_stopped(dev, skb))
> + ret = dev_hard_start_xmit(skb, dev);
> HARD_TX_UNLOCK(dev);
You could optimize this by getting HARD_TX_LOCK after the check. I
assume that netif_stop_subqueue (from another CPU) would always be
called by the driver xmit, and that is not possible since we hold
the __LINK_STATE_QDISC_RUNNING bit. Does that sound correct?
PATCH
------
diff -ruNp 1/net/sched/sch_generic.c 2/net/sched/sch_generic.c
--- 1/net/sched/sch_generic.c 2007-11-14 11:14:10.000000000 +0530
+++ 2/net/sched/sch_generic.c 2007-11-14 11:18:27.000000000 +0530
@@ -144,10 +144,11 @@ static inline int qdisc_restart(struct n
/* And release queue */
spin_unlock(&dev->queue_lock);
- HARD_TX_LOCK(dev, smp_processor_id());
if (!netif_subqueue_stopped(dev, skb))
+ HARD_TX_LOCK(dev, smp_processor_id());
ret = dev_hard_start_xmit(skb, dev);
- HARD_TX_UNLOCK(dev);
+ HARD_TX_UNLOCK(dev);
+ }
spin_lock(&dev->queue_lock);
q = dev->qdisc;
Thanks,
- KK
-
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