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>

2 files changed, 22 insertions, 30 deletions

diff --git a/net/sched/sch_fifo.c b/net/sched/sch_fifo.c
index be33f9ddf9dd..66effe2da8e0 100644
--- a/net/sched/sch_fifo.c
+++ b/net/sched/sch_fifo.c
@@ -19,15 +19,9 @@
 
 /* 1 band FIFO pseudo-"scheduler" */
 
-struct fifo_sched_data {
-        u32 limit;
-};
-
 static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 {
-        struct fifo_sched_data *q = qdisc_priv(sch);
-
-        if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= q->limit))
+        if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit))
                 return qdisc_enqueue_tail(skb, sch);
 
         return qdisc_reshape_fail(skb, sch);
@@ -35,9 +29,7 @@ static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 
 static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 {
-        struct fifo_sched_data *q = qdisc_priv(sch);
-
-        if (likely(skb_queue_len(&sch->q) < q->limit))
+        if (likely(skb_queue_len(&sch->q) < sch->limit))
                 return qdisc_enqueue_tail(skb, sch);
 
         return qdisc_reshape_fail(skb, sch);
@@ -45,9 +37,7 @@ static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 
 static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 {
-        struct fifo_sched_data *q = qdisc_priv(sch);
-
-        if (likely(skb_queue_len(&sch->q) < q->limit))
+        if (likely(skb_queue_len(&sch->q) < sch->limit))
                 return qdisc_enqueue_tail(skb, sch);
 
         /* queue full, remove one skb to fulfill the limit */
@@ -60,7 +50,6 @@ static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 
 static int fifo_init(struct Qdisc *sch, struct nlattr *opt)
 {
-        struct fifo_sched_data *q = qdisc_priv(sch);
         bool bypass;
         bool is_bfifo = sch->ops == &bfifo_qdisc_ops;
 
@@ -70,20 +59,20 @@ static int fifo_init(struct Qdisc *sch, struct nlattr *opt)
                 if (is_bfifo)
                         limit *= psched_mtu(qdisc_dev(sch));
 
-                q->limit = limit;
+                sch->limit = limit;
         } else {
                 struct tc_fifo_qopt *ctl = nla_data(opt);
 
                 if (nla_len(opt) < sizeof(*ctl))
                         return -EINVAL;
 
-                q->limit = ctl->limit;
+                sch->limit = ctl->limit;
         }
 
         if (is_bfifo)
-                bypass = q->limit >= psched_mtu(qdisc_dev(sch));
+                bypass = sch->limit >= psched_mtu(qdisc_dev(sch));
         else
-                bypass = q->limit >= 1;
+                bypass = sch->limit >= 1;
 
         if (bypass)
                 sch->flags |= TCQ_F_CAN_BYPASS;
@@ -94,8 +83,7 @@ static int fifo_init(struct Qdisc *sch, struct nlattr *opt)
 
 static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb)
 {
-        struct fifo_sched_data *q = qdisc_priv(sch);
-        struct tc_fifo_qopt opt = { .limit = q->limit };
+        struct tc_fifo_qopt opt = { .limit = sch->limit };
 
         NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
         return skb->len;
@@ -106,7 +94,7 @@ nla_put_failure:
 
 struct Qdisc_ops pfifo_qdisc_ops __read_mostly = {
         .id             =       "pfifo",
-        .priv_size      =       sizeof(struct fifo_sched_data),
+        .priv_size      =       0,
         .enqueue        =       pfifo_enqueue,
         .dequeue        =       qdisc_dequeue_head,
         .peek           =       qdisc_peek_head,
@@ -121,7 +109,7 @@ EXPORT_SYMBOL(pfifo_qdisc_ops);
 
 struct Qdisc_ops bfifo_qdisc_ops __read_mostly = {
         .id             =       "bfifo",
-        .priv_size      =       sizeof(struct fifo_sched_data),
+        .priv_size      =       0,
         .enqueue        =       bfifo_enqueue,
         .dequeue        =       qdisc_dequeue_head,
         .peek           =       qdisc_peek_head,
@@ -136,7 +124,7 @@ EXPORT_SYMBOL(bfifo_qdisc_ops);
 
 struct Qdisc_ops pfifo_head_drop_qdisc_ops __read_mostly = {
         .id             =       "pfifo_head_drop",
-        .priv_size      =       sizeof(struct fifo_sched_data),
+        .priv_size      =       0,
         .enqueue        =       pfifo_tail_enqueue,
         .dequeue        =       qdisc_dequeue_head,
         .peek           =       qdisc_peek_head,
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 0da09d508737..a854cab03f1e 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);