commit 1f27cde313d72d6b44a73ba89c8b2c6a99c628cf
author Eric Dumazet <edumazet@google.com> Wed Mar 02 08:21:43 2016 -0800
committer David S. Miller <davem@davemloft.net> Thu Mar 03 17:38:46 2016 -0500
tree 827ad853aec72793016f8f7302eb2a345bab2319
parent 799977d9aafbf0ca0b9c39b04cbfb16db71302c9

net: sched: use pfifo_fast for non real queues

Some devices declare a high number of TX queues, then set a much
lower real_num_tx_queues

This cause setups using fq_codel, sfq or fq as the default qdisc to consume
more memory than really needed.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sch_generic.h

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index e5bba89..46e55f0 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -345,6 +345,12 @@
 extern struct Qdisc_ops mq_qdisc_ops;
 extern struct Qdisc_ops noqueue_qdisc_ops;
 extern const struct Qdisc_ops *default_qdisc_ops;
+static inline const struct Qdisc_ops *
+get_default_qdisc_ops(const struct net_device *dev, int ntx)
+{
+	return ntx < dev->real_num_tx_queues ?
+			default_qdisc_ops : &pfifo_fast_ops;
+}
 
 struct Qdisc_class_common {
 	u32			classid;

net/sched/sch_generic.c

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 16bc83b..f18c350 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -567,6 +567,7 @@
 	.dump		=	pfifo_fast_dump,
 	.owner		=	THIS_MODULE,
 };
+EXPORT_SYMBOL(pfifo_fast_ops);
 
 static struct lock_class_key qdisc_tx_busylock;
 

net/sched/sch_mq.c

diff --git a/net/sched/sch_mq.c b/net/sched/sch_mq.c
index 3e82f04..56a77b8 100644
--- a/net/sched/sch_mq.c
+++ b/net/sched/sch_mq.c
@@ -57,7 +57,7 @@
 
 	for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
 		dev_queue = netdev_get_tx_queue(dev, ntx);
-		qdisc = qdisc_create_dflt(dev_queue, default_qdisc_ops,
+		qdisc = qdisc_create_dflt(dev_queue, get_default_qdisc_ops(dev, ntx),
 					  TC_H_MAKE(TC_H_MAJ(sch->handle),
 						    TC_H_MIN(ntx + 1)));
 		if (qdisc == NULL)

net/sched/sch_mqprio.c

diff --git a/net/sched/sch_mqprio.c b/net/sched/sch_mqprio.c
index 02ffb3f..b8002ce 100644
--- a/net/sched/sch_mqprio.c
+++ b/net/sched/sch_mqprio.c
@@ -125,7 +125,8 @@
 
 	for (i = 0; i < dev->num_tx_queues; i++) {
 		dev_queue = netdev_get_tx_queue(dev, i);
-		qdisc = qdisc_create_dflt(dev_queue, default_qdisc_ops,
+		qdisc = qdisc_create_dflt(dev_queue,
+					  get_default_qdisc_ops(dev, i),
 					  TC_H_MAKE(TC_H_MAJ(sch->handle),
 						    TC_H_MIN(i + 1)));
 		if (qdisc == NULL) {