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| author | Pavel Emelyanov <xemul@openvz.org> | 2008-03-26 16:27:22 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2008-03-26 16:27:22 -0700 |
| commit | 67727184f28c38d06013c6659560bb046c1d9f9c (patch) | |
| tree | fce5871c7fe554e05aa61fcc2d2d86afe7befdbc /include | |
| parent | 789e41e6f496022ac1639aaae38ea1943606a9d0 (diff) | |
| download | lwn-67727184f28c38d06013c6659560bb046c1d9f9c.tar.gz lwn-67727184f28c38d06013c6659560bb046c1d9f9c.zip | |
[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 <xemul@openvz.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/if_vlan.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h index 79504b22a932..edd55af7ebd6 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, |