Commit eba3b5a7 authored by Alexander Frolkin's avatar Alexander Frolkin Committed by Simon Horman
Browse files

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: default avatarAlexander Frolkin <>
Acked-by: default avatarJulian Anastasov <>
Signed-off-by: default avatarSimon Horman <>
parent acaac5d8
......@@ -20,6 +20,12 @@
#define IP_VS_SVC_F_PERSISTENT 0x0001 /* persistent port */
#define IP_VS_SVC_F_HASHED 0x0002 /* hashed entry */
#define IP_VS_SVC_F_ONEPACKET 0x0004 /* one-packet scheduling */
#define IP_VS_SVC_F_SCHED1 0x0008 /* scheduler flag 1 */
#define IP_VS_SVC_F_SCHED2 0x0010 /* scheduler flag 2 */
#define IP_VS_SVC_F_SCHED3 0x0020 /* scheduler flag 3 */
#define IP_VS_SVC_F_SCHED_SH_PORT IP_VS_SVC_F_SCHED2 /* SH use port */
* Destination Server Flags
......@@ -48,6 +48,10 @@
#include <net/ip_vs.h>
#include <net/tcp.h>
#include <linux/udp.h>
#include <linux/sctp.h>
* IPVS SH bucket
......@@ -71,10 +75,19 @@ struct ip_vs_sh_state {
struct ip_vs_sh_bucket buckets[IP_VS_SH_TAB_SIZE];
/* Helper function to determine if server is unavailable */
static inline bool is_unavailable(struct ip_vs_dest *dest)
return atomic_read(&dest->weight) <= 0 ||
dest->flags & IP_VS_DEST_F_OVERLOAD;
* Returns hash value for IPVS SH entry
static inline unsigned int ip_vs_sh_hashkey(int af, const union nf_inet_addr *addr)
static inline unsigned int
ip_vs_sh_hashkey(int af, const union nf_inet_addr *addr,
__be16 port, unsigned int offset)
__be32 addr_fold = addr->ip;
......@@ -83,7 +96,8 @@ static inline unsigned int ip_vs_sh_hashkey(int af, const union nf_inet_addr *ad
addr_fold = addr->ip6[0]^addr->ip6[1]^
return (ntohl(addr_fold)*2654435761UL) & IP_VS_SH_TAB_MASK;
return (offset + (ntohs(port) + ntohl(addr_fold))*2654435761UL) &
......@@ -91,12 +105,42 @@ static inline unsigned int ip_vs_sh_hashkey(int af, const union nf_inet_addr *ad
* Get ip_vs_dest associated with supplied parameters.
static inline struct ip_vs_dest *
ip_vs_sh_get(int af, struct ip_vs_sh_state *s, const union nf_inet_addr *addr)
ip_vs_sh_get(struct ip_vs_service *svc, struct ip_vs_sh_state *s,
const union nf_inet_addr *addr, __be16 port)
return rcu_dereference(s->buckets[ip_vs_sh_hashkey(af, addr)].dest);
unsigned int hash = ip_vs_sh_hashkey(svc->af, addr, port, 0);
struct ip_vs_dest *dest = rcu_dereference(s->buckets[hash].dest);
return (!dest || is_unavailable(dest)) ? NULL : dest;
/* As ip_vs_sh_get, but with fallback if selected server is unavailable */
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;
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)
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);
return dest;
return NULL;
* Assign all the hash buckets of the specified table with the service.
......@@ -213,13 +257,33 @@ static int ip_vs_sh_dest_changed(struct ip_vs_service *svc,
* If the dest flags is set with IP_VS_DEST_F_OVERLOAD,
* consider that the server is overloaded here.
static inline int is_overloaded(struct ip_vs_dest *dest)
/* Helper function to get port number */
static inline __be16
ip_vs_sh_get_port(const struct sk_buff *skb, struct ip_vs_iphdr *iph)
return dest->flags & IP_VS_DEST_F_OVERLOAD;
__be16 port;
struct tcphdr _tcph, *th;
struct udphdr _udph, *uh;
sctp_sctphdr_t _sctph, *sh;
switch (iph->protocol) {
th = skb_header_pointer(skb, iph->len, sizeof(_tcph), &_tcph);
port = th->source;
uh = skb_header_pointer(skb, iph->len, sizeof(_udph), &_udph);
port = uh->source;
sh = skb_header_pointer(skb, iph->len, sizeof(_sctph), &_sctph);
port = sh->source;
port = 0;
return port;
......@@ -232,15 +296,21 @@ ip_vs_sh_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
struct ip_vs_dest *dest;
struct ip_vs_sh_state *s;
__be16 port = 0;
IP_VS_DBG(6, "ip_vs_sh_schedule(): Scheduling...\n");
if (svc->flags & IP_VS_SVC_F_SCHED_SH_PORT)
port = ip_vs_sh_get_port(skb, iph);
s = (struct ip_vs_sh_state *) svc->sched_data;
dest = ip_vs_sh_get(svc->af, s, &iph->saddr);
if (!dest
|| !(dest->flags & IP_VS_DEST_F_AVAILABLE)
|| atomic_read(&dest->weight) <= 0
|| is_overloaded(dest)) {
if (svc->flags & IP_VS_SVC_F_SCHED_SH_FALLBACK)
dest = ip_vs_sh_get_fallback(svc, s, &iph->saddr, port);
dest = ip_vs_sh_get(svc, s, &iph->saddr, port);
if (!dest) {
ip_vs_scheduler_err(svc, "no destination available");
return NULL;
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment