From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Emelyanov Subject: [PATCH net-2.6.26 2/2] Do not allocate unneeded memory for dev->priv alignment. Date: Mon, 07 Apr 2008 20:31:12 +0400 Message-ID: <47FA4C50.3080405@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Stephen Hemminger , Patrick McHardy To: Linux Netdev List Return-path: Received: from sacred.ru ([62.205.161.221]:42516 "EHLO sacred.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759101AbYDGQHk (ORCPT ); Mon, 7 Apr 2008 12:07:40 -0400 Sender: netdev-owner@vger.kernel.org List-ID: 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 --- net/core/dev.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 7aa0112..80e103a 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) { -- 1.5.3.4