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Date: Wed, 19 Jun 2013 22:45:43 +0300 (EEST)
From: Julian Anastasov <ja@....bg>
To: Alexander Frolkin <avf@...amar.org.uk>
cc: lvs-devel@...r.kernel.org, Wensong Zhang <wensong@...ux-vs.org>,
Simon Horman <horms@...ge.net.au>, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ipvs: SH fallback and L4 hashing
Hello,
On Wed, 19 Jun 2013, Alexander Frolkin wrote:
> 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>
Thanks! Looks good to me.
Acked-by: Julian Anastasov <ja@....bg>
> ---
> The patch is against the ipvs-next tree.
Still, I see one warning:
patching file include/uapi/linux/ip_vs.h
patching file net/netfilter/ipvs/ip_vs_sh.c
Hunk #2 succeeded at 75 with fuzz 1.
May be because you are missing the
"ipvs: ip_vs_sh: fix build" change, not sure where is
the fault, may be the change is not in ipvs-next,
Simon can tell how to proceed with applying this patch.
> 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;
> }
Regards
--
Julian Anastasov <ja@....bg>
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