ipvs: optimize dst usage for real server
Currently when forwarding requests to real servers
we use dst_lock and atomic operations when cloning the
dst_cache value. As the dst_cache value does not change
most of the time it is better to use RCU and to lock
dst_lock only when we need to replace the obsoleted dst.
For this to work we keep dst_cache in new structure protected
by RCU. For packets to remote real servers we will use noref
version of dst_cache, it will be valid while we are in RCU
read-side critical section because now dst_release for replaced
dsts will be invoked after the grace period. Packets to
local real servers that are passed to local stack with
NF_ACCEPT need a dst clone.
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off by: Hans Schillstrom <hans@schillstrom.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
index 8ad73a8..a150ff5 100644
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -724,6 +724,13 @@
struct ip_vs_pe *pe;
};
+/* Information for cached dst */
+struct ip_vs_dest_dst {
+ struct dst_entry *dst_cache; /* destination cache entry */
+ u32 dst_cookie;
+ union nf_inet_addr dst_saddr;
+ struct rcu_head rcu_head;
+};
/*
* The real server destination forwarding entry
@@ -752,9 +759,7 @@
/* for destination cache */
spinlock_t dst_lock; /* lock of dst_cache */
- struct dst_entry *dst_cache; /* destination cache entry */
- u32 dst_cookie;
- union nf_inet_addr dst_saddr;
+ struct ip_vs_dest_dst __rcu *dest_dst; /* cached dst info */
/* for virtual service */
struct ip_vs_service *svc; /* service it belongs to */
@@ -1427,6 +1432,7 @@
extern int ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
struct ip_vs_protocol *pp, int offset,
unsigned int hooknum, struct ip_vs_iphdr *iph);
+extern void ip_vs_dest_dst_rcu_free(struct rcu_head *head);
#ifdef CONFIG_IP_VS_IPV6
extern int ip_vs_bypass_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,