[NETFILTER]: ULOG/nfnetlink_log: Use better default value for 'nlbufsiz'

Performance tests showed that ULOG may fail on heavy loaded systems
because of failed order-N allocations (N >= 1).

The default value of 4096 is not optimal in the sense that it actually
allocates _two_ contigous physical pages.  Reasoning: ULOG uses
alloc_skb(), which adds another ~300 bytes for skb_shared_info.

This patch sets the default value to NLMSG_GOODSIZE and adds some
documentation at the top.

Signed-off-by: Holger Eitzenberger <heitzenberger@astaro.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/bridge/netfilter/ebt_ulog.c b/net/bridge/netfilter/ebt_ulog.c
index ce617b3dbbb8..dbbf9f673b55 100644
--- a/net/bridge/netfilter/ebt_ulog.c
+++ b/net/bridge/netfilter/ebt_ulog.c
@@ -46,7 +46,7 @@
 #define PRINTR(format, args...) do { if (net_ratelimit()) \
                                 printk(format , ## args); } while (0)
 
-static unsigned int nlbufsiz = 4096;
+static unsigned int nlbufsiz = NLMSG_GOODSIZE;
 module_param(nlbufsiz, uint, 0600);
 MODULE_PARM_DESC(nlbufsiz, "netlink buffer size (number of bytes) "
                            "(defaults to 4096)");