summaryrefslogtreecommitdiff
path: root/net/sched/sch_generic.c
diff options
context:
space:
mode:
authorJohn Fastabend <john.fastabend@gmail.com>2017-12-07 09:54:47 -0800
committerDavid S. Miller <davem@davemloft.net>2017-12-08 13:32:25 -0500
commit29b86cdac00a82f88b81c16659e64cc624550216 (patch)
tree30cf667a3752f64da2af6d1c8511d6c2c025b9c6 /net/sched/sch_generic.c
parent6b3ba9146fe64b9bebb6346c9dcfe3b4851de2d7 (diff)
downloadlinux-sh-29b86cdac00a82f88b81c16659e64cc624550216.tar.gz
net: sched: remove remaining uses for qdisc_qlen in xmit path
sch_direct_xmit() uses qdisc_qlen as a return value but all call sites of the routine only check if it is zero or not. Simplify the logic so that we don't need to return an actual queue length value. This introduces a case now where sch_direct_xmit would have returned a qlen of zero but now it returns true. However in this case all call sites of sch_direct_xmit will implement a dequeue() and get a null skb and abort. This trades tracking qlen in the hotpath for an extra dequeue operation. Overall this seems to be good for performance. Signed-off-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/sch_generic.c')
-rw-r--r--net/sched/sch_generic.c28
1 files changed, 13 insertions, 15 deletions
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index ec757f66896a..cbc0a9a00e30 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -164,12 +164,12 @@ trace:
* only one CPU can execute this function.
*
* Returns to the caller:
- * 0 - queue is empty or throttled.
- * >0 - queue is not empty.
+ * false - hardware queue frozen backoff
+ * true - feel free to send more pkts
*/
-int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
- struct net_device *dev, struct netdev_queue *txq,
- spinlock_t *root_lock, bool validate)
+bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
+ struct net_device *dev, struct netdev_queue *txq,
+ spinlock_t *root_lock, bool validate)
{
int ret = NETDEV_TX_BUSY;
@@ -190,28 +190,26 @@ int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
} else {
if (root_lock)
spin_lock(root_lock);
- return qdisc_qlen(q);
+ return true;
}
if (root_lock)
spin_lock(root_lock);
- if (dev_xmit_complete(ret)) {
- /* Driver sent out skb successfully or skb was consumed */
- ret = qdisc_qlen(q);
- } else {
+ if (!dev_xmit_complete(ret)) {
/* Driver returned NETDEV_TX_BUSY - requeue skb */
if (unlikely(ret != NETDEV_TX_BUSY))
net_warn_ratelimited("BUG %s code %d qlen %d\n",
dev->name, ret, q->q.qlen);
- ret = dev_requeue_skb(skb, q);
+ dev_requeue_skb(skb, q);
+ return false;
}
if (ret && netif_xmit_frozen_or_stopped(txq))
- ret = 0;
+ return false;
- return ret;
+ return true;
}
/*
@@ -233,7 +231,7 @@ int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
* >0 - queue is not empty.
*
*/
-static inline int qdisc_restart(struct Qdisc *q, int *packets)
+static inline bool qdisc_restart(struct Qdisc *q, int *packets)
{
spinlock_t *root_lock = NULL;
struct netdev_queue *txq;
@@ -244,7 +242,7 @@ static inline int qdisc_restart(struct Qdisc *q, int *packets)
/* Dequeue packet */
skb = dequeue_skb(q, &validate, packets);
if (unlikely(!skb))
- return 0;
+ return false;
if (!(q->flags & TCQ_F_NOLOCK))
root_lock = qdisc_lock(q);