igmp: hash a hash table to speedup ip_check_mc_rcu()
After IP route cache removal, multicast applications using
a lot of multicast addresses hit a O(N) behavior in ip_check_mc_rcu()
Add a per in_device hash table to get faster lookup.
This hash table is created only if the number of items in mc_list is
above 4.
Reported-by: Shawn Bohrer <sbohrer@rgmadvisors.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Shawn Bohrer <sbohrer@rgmadvisors.com>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index ea1e3b8..b99cd23 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -50,12 +50,17 @@
DECLARE_BITMAP(state, IPV4_DEVCONF_MAX);
};
+#define MC_HASH_SZ_LOG 9
+
struct in_device {
struct net_device *dev;
atomic_t refcnt;
int dead;
struct in_ifaddr *ifa_list; /* IP ifaddr chain */
+
struct ip_mc_list __rcu *mc_list; /* IP multicast filter chain */
+ struct ip_mc_list __rcu * __rcu *mc_hash;
+
int mc_count; /* Number of installed mcasts */
spinlock_t mc_tomb_lock;
struct ip_mc_list *mc_tomb;