[VLAN]: Avoid a 4-order allocation.
This patch splits the vlan_group struct into a multi-allocated struct. On
x86_64, the size of the original struct is a little more than 32KB, causing
a 4-order allocation, which is prune to problems caused by buddy-system
external fragmentation conditions.
I couldn't just use vmalloc() because vfree() cannot be called in the
softirq context of the RCU callback.
Signed-off-by: Dan Aloni <da-x@monatomic.org>
Acked-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index 35cb385..d103580 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -70,15 +70,34 @@
* depends on completely exhausting the VLAN identifier space. Thus
* it gives constant time look-up, but in many cases it wastes memory.
*/
-#define VLAN_GROUP_ARRAY_LEN 4096
+#define VLAN_GROUP_ARRAY_LEN 4096
+#define VLAN_GROUP_ARRAY_SPLIT_PARTS 8
+#define VLAN_GROUP_ARRAY_PART_LEN (VLAN_GROUP_ARRAY_LEN/VLAN_GROUP_ARRAY_SPLIT_PARTS)
struct vlan_group {
int real_dev_ifindex; /* The ifindex of the ethernet(like) device the vlan is attached to. */
struct hlist_node hlist; /* linked list */
- struct net_device *vlan_devices[VLAN_GROUP_ARRAY_LEN];
+ struct net_device **vlan_devices_arrays[VLAN_GROUP_ARRAY_SPLIT_PARTS];
struct rcu_head rcu;
};
+static inline struct net_device *vlan_group_get_device(struct vlan_group *vg, int vlan_id)
+{
+ struct net_device **array;
+ array = vg->vlan_devices_arrays[vlan_id / VLAN_GROUP_ARRAY_PART_LEN];
+ return array[vlan_id % VLAN_GROUP_ARRAY_PART_LEN];
+}
+
+static inline void vlan_group_set_device(struct vlan_group *vg, int vlan_id,
+ struct net_device *dev)
+{
+ struct net_device **array;
+ if (!vg)
+ return;
+ array = vg->vlan_devices_arrays[vlan_id / VLAN_GROUP_ARRAY_PART_LEN];
+ array[vlan_id % VLAN_GROUP_ARRAY_PART_LEN] = dev;
+}
+
struct vlan_priority_tci_mapping {
unsigned long priority;
unsigned short vlan_qos; /* This should be shifted when first set, so we only do it
@@ -160,7 +179,7 @@
return NET_RX_DROP;
}
- skb->dev = grp->vlan_devices[vlan_tag & VLAN_VID_MASK];
+ skb->dev = vlan_group_get_device(grp, vlan_tag & VLAN_VID_MASK);
if (skb->dev == NULL) {
dev_kfree_skb_any(skb);