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author | Alexander Frolkin <avf@eldamar.org.uk> | 2013-09-27 11:06:23 +0100 |
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committer | Simon Horman <horms@verge.net.au> | 2013-10-15 10:54:50 +0900 |
commit | 1255ce5f10dbb4646c8d43b8d59faab48ae4a6b2 (patch) | |
tree | e9246035c427a2d5ea7e494cc1e7b080a1c30d25 /net/netfilter/ipvs/ip_vs_sh.c | |
parent | 9e4e948a3edafd2b7f4dc14c395e146ffd0d9611 (diff) | |
download | op-kernel-dev-1255ce5f10dbb4646c8d43b8d59faab48ae4a6b2.zip op-kernel-dev-1255ce5f10dbb4646c8d43b8d59faab48ae4a6b2.tar.gz |
ipvs: improved SH fallback strategy
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 <avf@eldamar.org.uk>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
Diffstat (limited to 'net/netfilter/ipvs/ip_vs_sh.c')
-rw-r--r-- | net/netfilter/ipvs/ip_vs_sh.c | 39 |
1 files changed, 29 insertions, 10 deletions
diff --git a/net/netfilter/ipvs/ip_vs_sh.c b/net/netfilter/ipvs/ip_vs_sh.c index 3588fae..cc65b2f 100644 --- a/net/netfilter/ipvs/ip_vs_sh.c +++ b/net/netfilter/ipvs/ip_vs_sh.c @@ -115,27 +115,46 @@ ip_vs_sh_get(struct ip_vs_service *svc, struct ip_vs_sh_state *s, } -/* As ip_vs_sh_get, but with fallback if selected server is unavailable */ +/* As ip_vs_sh_get, but with fallback if selected server is unavailable + * + * The fallback strategy loops around the table starting from a "random" + * point (in fact, it is chosen to be the original hash value to make the + * algorithm deterministic) to find a new server. + */ 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; + /* first try the dest it's supposed to go to */ + 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)) + return dest; + + IP_VS_DBG_BUF(6, "SH: selected unavailable server %s:%d, reselecting", + IP_VS_DBG_ADDR(svc->af, &dest->addr), ntohs(dest->port)); + + /* if the original dest is unavailable, loop around the table + * starting from ihash to find a new dest + */ for (offset = 0; offset < IP_VS_SH_TAB_SIZE; offset++) { - hash = ip_vs_sh_hashkey(svc->af, addr, port, 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 (!dest) break; - if (is_unavailable(dest)) - IP_VS_DBG_BUF(6, "SH: selected unavailable server " - "%s:%d (offset %d)", - IP_VS_DBG_ADDR(svc->af, &dest->addr), - ntohs(dest->port), offset); - else + if (!is_unavailable(dest)) return 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), roffset); } return NULL; |