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authorPavel Emelyanov <xemul@openvz.org>2008-04-16 02:17:42 -0700
committerDavid S. Miller <davem@davemloft.net>2008-04-16 02:17:42 -0700
commitd0498d9ae1a5cebac363e38907266d5cd2eedf89 (patch)
tree7d138b369cfe61652844c964a8f0c6ca72a54bbd /net/core
parentf3005d7f4abe03ad41af33b1548602cd086d86a2 (diff)
downloadblackbird-op-linux-d0498d9ae1a5cebac363e38907266d5cd2eedf89.tar.gz
blackbird-op-linux-d0498d9ae1a5cebac363e38907266d5cd2eedf89.zip
[NET]: Do not allocate unneeded memory for dev->priv alignment.
The alloc_netdev_mq() tries to produce 32-bytes alignment for both the net_device itself and its private data. The second alignment is achieved by adding the NETDEV_ALIGN_CONST to the whole size of the memory to be allocated. However, for those devices that do not need the private area, this addition just makes the net_device weight 1024 + 32 = 1068 bytes, i.e. consume twice as much memory. Since loopback device is such (sizeof_priv == 0 for it), and each net namespace creates one, this can save a noticeable amount of memory for kernel with net namespaces turned on. After this set the lo device is actually allocated from a size-1024 kmem cache on i386 box even with NETPOLL and WIRELESS_EXT turned on. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/dev.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 77530e9a34fc..c16a07fde388 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4000,7 +4000,8 @@ struct net_device *alloc_netdev_mq(int sizeof_priv, const char *name,
alloc_size = (sizeof(*dev) + NETDEV_ALIGN_CONST +
(sizeof(struct net_device_subqueue) * (queue_count - 1))) &
~NETDEV_ALIGN_CONST;
- alloc_size += sizeof_priv + NETDEV_ALIGN_CONST;
+ if (sizeof_priv)
+ alloc_size += sizeof_priv + NETDEV_ALIGN_CONST;
p = kzalloc(alloc_size, GFP_KERNEL);
if (!p) {
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