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ipvs: SH fallback and L4 hashing
By default the SH scheduler rejects connections that are hashed onto a realserver of weight 0. This patch adds a flag to make SH choose a different realserver in this case, instead of rejecting the connection. The patch also adds a flag to make SH include the source port (TCP, UDP, SCTP) in the hash as well as the source address. This basically allows for deterministic round-robin load balancing (i.e., where any director in a cluster of directors with identical config will send the same packet the same way). The flags are service flags (IP_VS_SVC_F_SCHED*) so that these options can be set per service. They are set using a new option to ipvsadm. 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>
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commit
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2 changed files with 91 additions and 15 deletions
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@ -20,6 +20,12 @@
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#define IP_VS_SVC_F_PERSISTENT 0x0001 /* persistent port */
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#define IP_VS_SVC_F_HASHED 0x0002 /* hashed entry */
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#define IP_VS_SVC_F_ONEPACKET 0x0004 /* one-packet scheduling */
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#define IP_VS_SVC_F_SCHED1 0x0008 /* scheduler flag 1 */
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#define IP_VS_SVC_F_SCHED2 0x0010 /* scheduler flag 2 */
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#define IP_VS_SVC_F_SCHED3 0x0020 /* scheduler flag 3 */
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#define IP_VS_SVC_F_SCHED_SH_FALLBACK IP_VS_SVC_F_SCHED1 /* SH fallback */
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#define IP_VS_SVC_F_SCHED_SH_PORT IP_VS_SVC_F_SCHED2 /* SH use port */
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/*
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* Destination Server Flags
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@ -48,6 +48,10 @@
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#include <net/ip_vs.h>
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#include <net/tcp.h>
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#include <linux/udp.h>
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#include <linux/sctp.h>
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/*
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* IPVS SH bucket
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@ -71,10 +75,19 @@ struct ip_vs_sh_state {
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struct ip_vs_sh_bucket buckets[IP_VS_SH_TAB_SIZE];
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};
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/* Helper function to determine if server is unavailable */
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static inline bool is_unavailable(struct ip_vs_dest *dest)
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{
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return atomic_read(&dest->weight) <= 0 ||
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dest->flags & IP_VS_DEST_F_OVERLOAD;
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}
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/*
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* Returns hash value for IPVS SH entry
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*/
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static inline unsigned int ip_vs_sh_hashkey(int af, const union nf_inet_addr *addr)
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static inline unsigned int
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ip_vs_sh_hashkey(int af, const union nf_inet_addr *addr,
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__be16 port, unsigned int offset)
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{
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__be32 addr_fold = addr->ip;
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@ -83,7 +96,8 @@ static inline unsigned int ip_vs_sh_hashkey(int af, const union nf_inet_addr *ad
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addr_fold = addr->ip6[0]^addr->ip6[1]^
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addr->ip6[2]^addr->ip6[3];
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#endif
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return (ntohl(addr_fold)*2654435761UL) & IP_VS_SH_TAB_MASK;
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return (offset + (ntohs(port) + ntohl(addr_fold))*2654435761UL) &
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IP_VS_SH_TAB_MASK;
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}
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@ -91,12 +105,42 @@ static inline unsigned int ip_vs_sh_hashkey(int af, const union nf_inet_addr *ad
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* Get ip_vs_dest associated with supplied parameters.
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*/
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static inline struct ip_vs_dest *
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ip_vs_sh_get(int af, struct ip_vs_sh_state *s, const union nf_inet_addr *addr)
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ip_vs_sh_get(struct ip_vs_service *svc, struct ip_vs_sh_state *s,
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const union nf_inet_addr *addr, __be16 port)
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{
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return rcu_dereference(s->buckets[ip_vs_sh_hashkey(af, addr)].dest);
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unsigned int hash = ip_vs_sh_hashkey(svc->af, addr, port, 0);
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struct ip_vs_dest *dest = rcu_dereference(s->buckets[hash].dest);
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return (!dest || is_unavailable(dest)) ? NULL : dest;
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}
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/* As ip_vs_sh_get, but with fallback if selected server is unavailable */
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static inline struct ip_vs_dest *
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ip_vs_sh_get_fallback(struct ip_vs_service *svc, struct ip_vs_sh_state *s,
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const union nf_inet_addr *addr, __be16 port)
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{
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unsigned int offset;
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unsigned int hash;
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struct ip_vs_dest *dest;
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for (offset = 0; offset < IP_VS_SH_TAB_SIZE; offset++) {
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hash = ip_vs_sh_hashkey(svc->af, addr, port, offset);
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dest = rcu_dereference(s->buckets[hash].dest);
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if (!dest)
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break;
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if (is_unavailable(dest))
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IP_VS_DBG_BUF(6, "SH: selected unavailable server "
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"%s:%d (offset %d)",
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IP_VS_DBG_ADDR(svc->af, &dest->addr),
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ntohs(dest->port), offset);
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else
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return dest;
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}
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return NULL;
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}
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/*
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* Assign all the hash buckets of the specified table with the service.
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*/
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@ -213,13 +257,33 @@ static int ip_vs_sh_dest_changed(struct ip_vs_service *svc,
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}
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/*
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* If the dest flags is set with IP_VS_DEST_F_OVERLOAD,
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* consider that the server is overloaded here.
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*/
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static inline int is_overloaded(struct ip_vs_dest *dest)
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/* Helper function to get port number */
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static inline __be16
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ip_vs_sh_get_port(const struct sk_buff *skb, struct ip_vs_iphdr *iph)
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{
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return dest->flags & IP_VS_DEST_F_OVERLOAD;
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__be16 port;
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struct tcphdr _tcph, *th;
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struct udphdr _udph, *uh;
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sctp_sctphdr_t _sctph, *sh;
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switch (iph->protocol) {
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case IPPROTO_TCP:
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th = skb_header_pointer(skb, iph->len, sizeof(_tcph), &_tcph);
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port = th->source;
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break;
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case IPPROTO_UDP:
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uh = skb_header_pointer(skb, iph->len, sizeof(_udph), &_udph);
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port = uh->source;
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break;
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case IPPROTO_SCTP:
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sh = skb_header_pointer(skb, iph->len, sizeof(_sctph), &_sctph);
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port = sh->source;
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break;
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default:
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port = 0;
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}
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return port;
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}
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@ -232,15 +296,21 @@ ip_vs_sh_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
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{
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struct ip_vs_dest *dest;
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struct ip_vs_sh_state *s;
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__be16 port = 0;
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IP_VS_DBG(6, "ip_vs_sh_schedule(): Scheduling...\n");
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if (svc->flags & IP_VS_SVC_F_SCHED_SH_PORT)
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port = ip_vs_sh_get_port(skb, iph);
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s = (struct ip_vs_sh_state *) svc->sched_data;
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dest = ip_vs_sh_get(svc->af, s, &iph->saddr);
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if (!dest
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|| !(dest->flags & IP_VS_DEST_F_AVAILABLE)
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|| atomic_read(&dest->weight) <= 0
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|| is_overloaded(dest)) {
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if (svc->flags & IP_VS_SVC_F_SCHED_SH_FALLBACK)
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dest = ip_vs_sh_get_fallback(svc, s, &iph->saddr, port);
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else
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dest = ip_vs_sh_get(svc, s, &iph->saddr, port);
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if (!dest) {
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ip_vs_scheduler_err(svc, "no destination available");
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return NULL;
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}
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