Commit 91dd93f9 authored May 12, 2015 by Eric Dumazet Committed by David S. Miller May 14, 2015

netlink: move nl_table in read_mostly section



netlink sockets creation and deletion heavily modify nl_table_users
and nl_table_lock.

If nl_table is sharing one cache line with one of them, netlink
performance is really bad on SMP.

ffffffff81ff5f00 B nl_table
ffffffff81ff5f0c b nl_table_users

Putting nl_table in read_mostly section increased performance
of my open/delete netlink sockets test by about 80 %

This came up while diagnosing a getaddrinfo() problem.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent be346ffa

net/netlink/af_netlink.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -89,7 +89,7 @@ static inline int netlink_is_kernel(struct sock *sk)
		return nlk_sk(sk)->flags & NETLINK_KERNEL_SOCKET;
		}

		struct netlink_table *nl_table;
		struct netlink_table *nl_table __read_mostly;
		EXPORT_SYMBOL_GPL(nl_table);

		static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);