From: Pavel Emelyanov Date: Wed, 16 Apr 2008 09:17:42 +0000 (-0700) Subject: [NET]: Do not allocate unneeded memory for dev->priv alignment. X-Git-Tag: v2.6.26-rc1~1138^2~14 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=d0498d9ae1a5cebac363e38907266d5cd2eedf89;p=linux-2.6-omap-h63xx.git [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 Signed-off-by: David S. Miller --- diff --git a/net/core/dev.c b/net/core/dev.c index 77530e9a34f..c16a07fde38 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) {