[PATCH] ipvs: improved SH fallback strategy
From: Alexander Frolkin <hidden>
Date: 2013-09-23 12:22:54
Also in:
lkml, lvs-devel
Subsystem:
ipvs, netfilter, networking [general], the rest · Maintainers:
Simon Horman, Julian Anastasov, Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Improve the SH fallback realserver selection strategy. With sh and sh-fallback, if a realserver is down, this attempts to distribute the traffic that would have gone to that server evenly among the remaining servers. Signed-off-by: Alexander Frolkin <redacted> ---
diff --git a/net/netfilter/ipvs/ip_vs_sh.c b/net/netfilter/ipvs/ip_vs_sh.c
index f16c027..1676354 100644
--- a/net/netfilter/ipvs/ip_vs_sh.c
+++ b/net/netfilter/ipvs/ip_vs_sh.c@@ -120,22 +120,35 @@ static inline struct ip_vs_dest * ip_vs_sh_get_fallback(struct ip_vs_service *svc, struct ip_vs_sh_state *s, const union nf_inet_addr *addr, __be16 port) { - unsigned int offset; - unsigned int hash; + unsigned int offset, roffset; + unsigned int hash, ihash; struct ip_vs_dest *dest; - for (offset = 0; offset < IP_VS_SH_TAB_SIZE; offset++) { - hash = ip_vs_sh_hashkey(svc->af, addr, port, offset); - dest = rcu_dereference(s->buckets[hash].dest); - if (!dest) - break; - if (is_unavailable(dest)) - IP_VS_DBG_BUF(6, "SH: selected unavailable server " - "%s:%d (offset %d)", + ihash = ip_vs_sh_hashkey(svc->af, addr, port, 0); + dest = rcu_dereference(s->buckets[ihash].dest); + + if (!dest) + return NULL; + + if (is_unavailable(dest)) { + IP_VS_DBG_BUF(6, "SH: selected unavailable server " + "%s:%d, reselecting", + IP_VS_DBG_ADDR(svc->af, &dest->addr), + ntohs(dest->port)); + for (offset = 0; offset < IP_VS_SH_TAB_SIZE; offset++) { + roffset = (offset + ihash) % IP_VS_SH_TAB_SIZE; + hash = ip_vs_sh_hashkey(svc->af, addr, port, roffset); + dest = rcu_dereference(s->buckets[hash].dest); + if (is_unavailable(dest)) + IP_VS_DBG_BUF(6, "SH: selected unavailable " + "server %s:%d (offset %d), reselecting", IP_VS_DBG_ADDR(svc->af, &dest->addr), - ntohs(dest->port), offset); - else - return dest; + ntohs(dest->port), roffset); + else + return dest; + } + } else { + return dest; } return NULL;