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authorPeter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>2007-11-13 20:40:55 -0800
committerDavid S. Miller <davem@davemloft.net>2007-11-13 20:40:55 -0800
commit5f1a485d5905aa641f33009019b3699076666a4c (patch)
tree8bdcb81a47090cc3b34b1de7159b981e1c55b88b /net/sched
parent9418d5dc9ba40b88737580457bf3b7c63c60ec43 (diff)
downloadblackbird-op-linux-5f1a485d5905aa641f33009019b3699076666a4c.tar.gz
blackbird-op-linux-5f1a485d5905aa641f33009019b3699076666a4c.zip
[PKT_SCHED]: Check subqueue status before calling hard_start_xmit
The only qdiscs that check subqueue state before dequeue'ing are PRIO and RR. The other qdiscs, including the default pfifo_fast qdisc, will allow traffic bound for subqueue 0 through to hard_start_xmit. The check for netif_queue_stopped() is done above in pkt_sched.h, so it is unnecessary for qdisc_restart(). However, if the underlying driver is multiqueue capable, and only sets queue states on subqueues, this will allow packets to enter the driver when it's currently unable to process packets, resulting in expensive requeues and driver entries. This patch re-adds the check for the subqueue status before calling hard_start_xmit, so we can try and avoid the driver entry when the queues are stopped. Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched')
-rw-r--r--net/sched/sch_generic.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index fa1a6f45dc41..e595e6570ce0 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -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);
spin_lock(&dev->queue_lock);
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