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Message-ID: <20130619095425.GA20145@eldamar.org.uk>
Date: Wed, 19 Jun 2013 10:54:25 +0100
From: Alexander Frolkin <avf@...amar.org.uk>
To: Julian Anastasov <ja@....bg>, lvs-devel@...r.kernel.org
Cc: Wensong Zhang <wensong@...ux-vs.org>,
Simon Horman <horms@...ge.net.au>, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH] 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@...amar.org.uk>
---
The patch is against the ipvs-next tree.
diff --git a/include/uapi/linux/ip_vs.h b/include/uapi/linux/ip_vs.h
index a245377..2945822 100644
--- a/include/uapi/linux/ip_vs.h
+++ b/include/uapi/linux/ip_vs.h
@@ -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
diff --git a/net/netfilter/ipvs/ip_vs_sh.c b/net/netfilter/ipvs/ip_vs_sh.c
index e0130f8..b7e2c5a 100644
--- a/net/netfilter/ipvs/ip_vs_sh.c
+++ b/net/netfilter/ipvs/ip_vs_sh.c
@@ -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 rcu_head rcu_head;
};
+/* 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;
}
--
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