From 67727184f28c38d06013c6659560bb046c1d9f9c Mon Sep 17 00:00:00 2001 From: Pavel Emelyanov Date: Wed, 26 Mar 2008 16:27:22 -0700 Subject: [VLAN]: Reduce memory consumed by vlan_groups Currently each vlan_groupd contains 8 pointers on arrays with 512 pointers on struct net_device each :) Such a construction "in many cases ... wastes memory". My proposal is to allow for some of these arrays pointers be NULL, meaning that there are no devices in it. When a new device is added to the vlan_group, the appropriate array is allocated. The check in vlan_group_get_device's is safe, since the pointer vg->vlan_devices_arrays[x] can only switch from NULL to not-NULL. The vlan_group_prealloc_vid() is guarded with rtnl lock and is also safe. I've checked (I hope that) all the places, that use these arrays and found, that the register_vlan_dev is the only place, that can put a vlan device on an empty vlan_group. Rough calculations shows, that after the patch a setup with a single vlan dev (or up to 512 vlans with sequential vids) will occupy approximately 8 times less memory. The question I have is - does this patch makes sense, or a totally new structures are required to store the vlan_devs? Signed-off-by: Pavel Emelyanov Signed-off-by: Patrick McHardy --- include/linux/if_vlan.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h index 79504b22a93..edd55af7ebd 100644 --- a/include/linux/if_vlan.h +++ b/include/linux/if_vlan.h @@ -93,7 +93,7 @@ static inline struct net_device *vlan_group_get_device(struct vlan_group *vg, { 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]; + return array ? array[vlan_id % VLAN_GROUP_ARRAY_PART_LEN] : NULL; } static inline void vlan_group_set_device(struct vlan_group *vg, -- cgit v1.2.3-70-g09d2