net_sched: reduce fifo qdisc size

Because of various alignements [SLUB / qdisc], we use 512 bytes of
memory for one {p|b}fifo qdisc, instead of 256 bytes on 64bit arches and
192 bytes on 32bit ones.

Move the "u32 limit" inside "struct Qdisc" (no impact on other qdiscs)

Change qdisc_alloc(), first trying a regular allocation before an
oversized one.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 7 deletions

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 0da09d50873..a854cab03f1 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -550,21 +550,25 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 {
 	void *p;
 	struct Qdisc *sch;
-	unsigned int size;
+	unsigned int size = QDISC_ALIGN(sizeof(*sch)) + ops->priv_size;
 	int err = -ENOBUFS;
 
-	/* ensure that the Qdisc and the private data are 64-byte aligned */
-	size = QDISC_ALIGN(sizeof(*sch));
-	size += ops->priv_size + (QDISC_ALIGNTO - 1);
-
 	p = kzalloc_node(size, GFP_KERNEL,
 			 netdev_queue_numa_node_read(dev_queue));
 
 	if (!p)
 		goto errout;
 	sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
-	sch->padded = (char *) sch - (char *) p;
-
+	/* if we got non aligned memory, ask more and do alignment ourself */
+	if (sch != p) {
+		kfree(p);
+		p = kzalloc_node(size + QDISC_ALIGNTO - 1, GFP_KERNEL,
+				 netdev_queue_numa_node_read(dev_queue));
+		if (!p)
+			goto errout;
+		sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
+		sch->padded = (char *) sch - (char *) p;
+	}
 	INIT_LIST_HEAD(&sch->list);
 	skb_queue_head_init(&sch->q);
 	spin_lock_init(&sch->busylock);