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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>
This commit is contained in:
Alexander Frolkin 2013-06-19 10:54:25 +01:00 committed by Simon Horman
parent acaac5d8bb
commit eba3b5a787
2 changed files with 91 additions and 15 deletions
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6
include/uapi/linux/ip_vs.h
View File

@ -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_FALLBACK IP_VS_SVC_F_SCHED1 /* SH fallback */
#define IP_VS_SVC_F_SCHED_SH_PORT IP_VS_SVC_F_SCHED2 /* SH use port */
/*
* Destination Server Flags

100
net/netfilter/ipvs/ip_vs_sh.c
View File

@ -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]^
addr->ip6[2]^addr->ip6[3];
#endif
return (ntohl(addr_fold)*2654435761UL) & IP_VS_SH_TAB_MASK;
return (offset + (ntohs(port) + ntohl(addr_fold))*2654435761UL) &
IP_VS_SH_TAB_MASK;
}
@ -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)
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
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) {
case IPPROTO_TCP:
th = skb_header_pointer(skb, iph->len, sizeof(_tcph), &_tcph);
port = th->source;
break;
case IPPROTO_UDP:
uh = skb_header_pointer(skb, iph->len, sizeof(_udph), &_udph);
port = uh->source;
break;
case IPPROTO_SCTP:
sh = skb_header_pointer(skb, iph->len, sizeof(_sctph), &_sctph);
port = sh->source;
break;
default:
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);
else
dest = ip_vs_sh_get(svc, s, &iph->saddr, port);
if (!dest) {
ip_vs_scheduler_err(svc, "no destination available");
return NULL;
}