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1da177e4 LT |
1 | /* |
2 | * IPVS: Source Hashing scheduling module | |
3 | * | |
1da177e4 LT |
4 | * Authors: Wensong Zhang <wensong@gnuchina.org> |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | * | |
11 | * Changes: | |
12 | * | |
13 | */ | |
14 | ||
15 | /* | |
16 | * The sh algorithm is to select server by the hash key of source IP | |
17 | * address. The pseudo code is as follows: | |
18 | * | |
19 | * n <- servernode[src_ip]; | |
20 | * if (n is dead) OR | |
21 | * (n is overloaded) or (n.weight <= 0) then | |
22 | * return NULL; | |
23 | * | |
24 | * return n; | |
25 | * | |
26 | * Notes that servernode is a 256-bucket hash table that maps the hash | |
27 | * index derived from packet source IP address to the current server | |
28 | * array. If the sh scheduler is used in cache cluster, it is good to | |
29 | * combine it with cache_bypass feature. When the statically assigned | |
30 | * server is dead or overloaded, the load balancer can bypass the cache | |
31 | * server and send requests to the original server directly. | |
32 | * | |
33 | */ | |
34 | ||
9aada7ac HE |
35 | #define KMSG_COMPONENT "IPVS" |
36 | #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt | |
37 | ||
14c85021 | 38 | #include <linux/ip.h> |
1da177e4 LT |
39 | #include <linux/module.h> |
40 | #include <linux/kernel.h> | |
14c85021 | 41 | #include <linux/skbuff.h> |
1da177e4 LT |
42 | |
43 | #include <net/ip_vs.h> | |
44 | ||
45 | ||
46 | /* | |
47 | * IPVS SH bucket | |
48 | */ | |
49 | struct ip_vs_sh_bucket { | |
50 | struct ip_vs_dest *dest; /* real server (cache) */ | |
51 | }; | |
52 | ||
53 | /* | |
54 | * for IPVS SH entry hash table | |
55 | */ | |
56 | #ifndef CONFIG_IP_VS_SH_TAB_BITS | |
57 | #define CONFIG_IP_VS_SH_TAB_BITS 8 | |
58 | #endif | |
59 | #define IP_VS_SH_TAB_BITS CONFIG_IP_VS_SH_TAB_BITS | |
60 | #define IP_VS_SH_TAB_SIZE (1 << IP_VS_SH_TAB_BITS) | |
61 | #define IP_VS_SH_TAB_MASK (IP_VS_SH_TAB_SIZE - 1) | |
62 | ||
63 | ||
64 | /* | |
65 | * Returns hash value for IPVS SH entry | |
66 | */ | |
20971a0a | 67 | static inline unsigned ip_vs_sh_hashkey(int af, const union nf_inet_addr *addr) |
1da177e4 | 68 | { |
20971a0a JV |
69 | __be32 addr_fold = addr->ip; |
70 | ||
71 | #ifdef CONFIG_IP_VS_IPV6 | |
72 | if (af == AF_INET6) | |
73 | addr_fold = addr->ip6[0]^addr->ip6[1]^ | |
74 | addr->ip6[2]^addr->ip6[3]; | |
75 | #endif | |
76 | return (ntohl(addr_fold)*2654435761UL) & IP_VS_SH_TAB_MASK; | |
1da177e4 LT |
77 | } |
78 | ||
79 | ||
80 | /* | |
81 | * Get ip_vs_dest associated with supplied parameters. | |
82 | */ | |
83 | static inline struct ip_vs_dest * | |
20971a0a JV |
84 | ip_vs_sh_get(int af, struct ip_vs_sh_bucket *tbl, |
85 | const union nf_inet_addr *addr) | |
1da177e4 | 86 | { |
20971a0a | 87 | return (tbl[ip_vs_sh_hashkey(af, addr)]).dest; |
1da177e4 LT |
88 | } |
89 | ||
90 | ||
91 | /* | |
92 | * Assign all the hash buckets of the specified table with the service. | |
93 | */ | |
94 | static int | |
95 | ip_vs_sh_assign(struct ip_vs_sh_bucket *tbl, struct ip_vs_service *svc) | |
96 | { | |
97 | int i; | |
98 | struct ip_vs_sh_bucket *b; | |
99 | struct list_head *p; | |
100 | struct ip_vs_dest *dest; | |
101 | ||
102 | b = tbl; | |
103 | p = &svc->destinations; | |
104 | for (i=0; i<IP_VS_SH_TAB_SIZE; i++) { | |
105 | if (list_empty(p)) { | |
106 | b->dest = NULL; | |
107 | } else { | |
108 | if (p == &svc->destinations) | |
109 | p = p->next; | |
110 | ||
111 | dest = list_entry(p, struct ip_vs_dest, n_list); | |
112 | atomic_inc(&dest->refcnt); | |
113 | b->dest = dest; | |
114 | ||
115 | p = p->next; | |
116 | } | |
117 | b++; | |
118 | } | |
119 | return 0; | |
120 | } | |
121 | ||
122 | ||
123 | /* | |
124 | * Flush all the hash buckets of the specified table. | |
125 | */ | |
126 | static void ip_vs_sh_flush(struct ip_vs_sh_bucket *tbl) | |
127 | { | |
128 | int i; | |
129 | struct ip_vs_sh_bucket *b; | |
130 | ||
131 | b = tbl; | |
132 | for (i=0; i<IP_VS_SH_TAB_SIZE; i++) { | |
133 | if (b->dest) { | |
134 | atomic_dec(&b->dest->refcnt); | |
135 | b->dest = NULL; | |
136 | } | |
137 | b++; | |
138 | } | |
139 | } | |
140 | ||
141 | ||
142 | static int ip_vs_sh_init_svc(struct ip_vs_service *svc) | |
143 | { | |
144 | struct ip_vs_sh_bucket *tbl; | |
145 | ||
146 | /* allocate the SH table for this service */ | |
147 | tbl = kmalloc(sizeof(struct ip_vs_sh_bucket)*IP_VS_SH_TAB_SIZE, | |
148 | GFP_ATOMIC); | |
149 | if (tbl == NULL) { | |
1e3e238e | 150 | pr_err("%s(): no memory\n", __func__); |
1da177e4 LT |
151 | return -ENOMEM; |
152 | } | |
153 | svc->sched_data = tbl; | |
154 | IP_VS_DBG(6, "SH hash table (memory=%Zdbytes) allocated for " | |
155 | "current service\n", | |
156 | sizeof(struct ip_vs_sh_bucket)*IP_VS_SH_TAB_SIZE); | |
157 | ||
158 | /* assign the hash buckets with the updated service */ | |
159 | ip_vs_sh_assign(tbl, svc); | |
160 | ||
161 | return 0; | |
162 | } | |
163 | ||
164 | ||
165 | static int ip_vs_sh_done_svc(struct ip_vs_service *svc) | |
166 | { | |
167 | struct ip_vs_sh_bucket *tbl = svc->sched_data; | |
168 | ||
169 | /* got to clean up hash buckets here */ | |
170 | ip_vs_sh_flush(tbl); | |
171 | ||
172 | /* release the table itself */ | |
173 | kfree(svc->sched_data); | |
174 | IP_VS_DBG(6, "SH hash table (memory=%Zdbytes) released\n", | |
175 | sizeof(struct ip_vs_sh_bucket)*IP_VS_SH_TAB_SIZE); | |
176 | ||
177 | return 0; | |
178 | } | |
179 | ||
180 | ||
181 | static int ip_vs_sh_update_svc(struct ip_vs_service *svc) | |
182 | { | |
183 | struct ip_vs_sh_bucket *tbl = svc->sched_data; | |
184 | ||
185 | /* got to clean up hash buckets here */ | |
186 | ip_vs_sh_flush(tbl); | |
187 | ||
188 | /* assign the hash buckets with the updated service */ | |
189 | ip_vs_sh_assign(tbl, svc); | |
190 | ||
191 | return 0; | |
192 | } | |
193 | ||
194 | ||
195 | /* | |
196 | * If the dest flags is set with IP_VS_DEST_F_OVERLOAD, | |
197 | * consider that the server is overloaded here. | |
198 | */ | |
199 | static inline int is_overloaded(struct ip_vs_dest *dest) | |
200 | { | |
201 | return dest->flags & IP_VS_DEST_F_OVERLOAD; | |
202 | } | |
203 | ||
204 | ||
205 | /* | |
206 | * Source Hashing scheduling | |
207 | */ | |
208 | static struct ip_vs_dest * | |
209 | ip_vs_sh_schedule(struct ip_vs_service *svc, const struct sk_buff *skb) | |
210 | { | |
211 | struct ip_vs_dest *dest; | |
212 | struct ip_vs_sh_bucket *tbl; | |
20971a0a JV |
213 | struct ip_vs_iphdr iph; |
214 | ||
215 | ip_vs_fill_iphdr(svc->af, skb_network_header(skb), &iph); | |
1da177e4 LT |
216 | |
217 | IP_VS_DBG(6, "ip_vs_sh_schedule(): Scheduling...\n"); | |
218 | ||
219 | tbl = (struct ip_vs_sh_bucket *)svc->sched_data; | |
20971a0a | 220 | dest = ip_vs_sh_get(svc->af, tbl, &iph.saddr); |
1da177e4 LT |
221 | if (!dest |
222 | || !(dest->flags & IP_VS_DEST_F_AVAILABLE) | |
223 | || atomic_read(&dest->weight) <= 0 | |
224 | || is_overloaded(dest)) { | |
68888d10 | 225 | IP_VS_ERR_RL("SH: no destination available\n"); |
1da177e4 LT |
226 | return NULL; |
227 | } | |
228 | ||
20971a0a JV |
229 | IP_VS_DBG_BUF(6, "SH: source IP address %s --> server %s:%d\n", |
230 | IP_VS_DBG_ADDR(svc->af, &iph.saddr), | |
231 | IP_VS_DBG_ADDR(svc->af, &dest->addr), | |
232 | ntohs(dest->port)); | |
1da177e4 LT |
233 | |
234 | return dest; | |
235 | } | |
236 | ||
237 | ||
238 | /* | |
239 | * IPVS SH Scheduler structure | |
240 | */ | |
241 | static struct ip_vs_scheduler ip_vs_sh_scheduler = | |
242 | { | |
243 | .name = "sh", | |
244 | .refcnt = ATOMIC_INIT(0), | |
245 | .module = THIS_MODULE, | |
d149ccc9 | 246 | .n_list = LIST_HEAD_INIT(ip_vs_sh_scheduler.n_list), |
1da177e4 LT |
247 | .init_service = ip_vs_sh_init_svc, |
248 | .done_service = ip_vs_sh_done_svc, | |
249 | .update_service = ip_vs_sh_update_svc, | |
250 | .schedule = ip_vs_sh_schedule, | |
251 | }; | |
252 | ||
253 | ||
254 | static int __init ip_vs_sh_init(void) | |
255 | { | |
1da177e4 LT |
256 | return register_ip_vs_scheduler(&ip_vs_sh_scheduler); |
257 | } | |
258 | ||
259 | ||
260 | static void __exit ip_vs_sh_cleanup(void) | |
261 | { | |
262 | unregister_ip_vs_scheduler(&ip_vs_sh_scheduler); | |
263 | } | |
264 | ||
265 | ||
266 | module_init(ip_vs_sh_init); | |
267 | module_exit(ip_vs_sh_cleanup); | |
268 | MODULE_LICENSE("GPL"); |