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1da177e4 LT |
1 | /* |
2 | * IPVS: Weighted Least-Connection Scheduling module | |
3 | * | |
1da177e4 LT |
4 | * Authors: Wensong Zhang <wensong@linuxvirtualserver.org> |
5 | * Peter Kese <peter.kese@ijs.si> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License | |
9 | * as published by the Free Software Foundation; either version | |
10 | * 2 of the License, or (at your option) any later version. | |
11 | * | |
12 | * Changes: | |
13 | * Wensong Zhang : changed the ip_vs_wlc_schedule to return dest | |
14 | * Wensong Zhang : changed to use the inactconns in scheduling | |
15 | * Wensong Zhang : changed some comestics things for debugging | |
16 | * Wensong Zhang : changed for the d-linked destination list | |
17 | * Wensong Zhang : added the ip_vs_wlc_update_svc | |
18 | * Wensong Zhang : added any dest with weight=0 is quiesced | |
19 | * | |
20 | */ | |
21 | ||
22 | #include <linux/module.h> | |
23 | #include <linux/kernel.h> | |
24 | ||
25 | #include <net/ip_vs.h> | |
26 | ||
27 | ||
28 | static int | |
29 | ip_vs_wlc_init_svc(struct ip_vs_service *svc) | |
30 | { | |
31 | return 0; | |
32 | } | |
33 | ||
34 | ||
35 | static int | |
36 | ip_vs_wlc_done_svc(struct ip_vs_service *svc) | |
37 | { | |
38 | return 0; | |
39 | } | |
40 | ||
41 | ||
42 | static int | |
43 | ip_vs_wlc_update_svc(struct ip_vs_service *svc) | |
44 | { | |
45 | return 0; | |
46 | } | |
47 | ||
48 | ||
49 | static inline unsigned int | |
50 | ip_vs_wlc_dest_overhead(struct ip_vs_dest *dest) | |
51 | { | |
52 | /* | |
53 | * We think the overhead of processing active connections is 256 | |
54 | * times higher than that of inactive connections in average. (This | |
55 | * 256 times might not be accurate, we will change it later) We | |
56 | * use the following formula to estimate the overhead now: | |
57 | * dest->activeconns*256 + dest->inactconns | |
58 | */ | |
59 | return (atomic_read(&dest->activeconns) << 8) + | |
60 | atomic_read(&dest->inactconns); | |
61 | } | |
62 | ||
63 | ||
64 | /* | |
65 | * Weighted Least Connection scheduling | |
66 | */ | |
67 | static struct ip_vs_dest * | |
68 | ip_vs_wlc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb) | |
69 | { | |
70 | struct ip_vs_dest *dest, *least; | |
71 | unsigned int loh, doh; | |
72 | ||
73 | IP_VS_DBG(6, "ip_vs_wlc_schedule(): Scheduling...\n"); | |
74 | ||
75 | /* | |
76 | * We calculate the load of each dest server as follows: | |
77 | * (dest overhead) / dest->weight | |
78 | * | |
79 | * Remember -- no floats in kernel mode!!! | |
80 | * The comparison of h1*w2 > h2*w1 is equivalent to that of | |
81 | * h1/w1 > h2/w2 | |
82 | * if every weight is larger than zero. | |
83 | * | |
84 | * The server with weight=0 is quiesced and will not receive any | |
85 | * new connections. | |
86 | */ | |
87 | ||
88 | list_for_each_entry(dest, &svc->destinations, n_list) { | |
89 | if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && | |
90 | atomic_read(&dest->weight) > 0) { | |
91 | least = dest; | |
92 | loh = ip_vs_wlc_dest_overhead(least); | |
93 | goto nextstage; | |
94 | } | |
95 | } | |
96 | return NULL; | |
97 | ||
98 | /* | |
99 | * Find the destination with the least load. | |
100 | */ | |
101 | nextstage: | |
102 | list_for_each_entry_continue(dest, &svc->destinations, n_list) { | |
103 | if (dest->flags & IP_VS_DEST_F_OVERLOAD) | |
104 | continue; | |
105 | doh = ip_vs_wlc_dest_overhead(dest); | |
106 | if (loh * atomic_read(&dest->weight) > | |
107 | doh * atomic_read(&least->weight)) { | |
108 | least = dest; | |
109 | loh = doh; | |
110 | } | |
111 | } | |
112 | ||
113 | IP_VS_DBG(6, "WLC: server %u.%u.%u.%u:%u " | |
114 | "activeconns %d refcnt %d weight %d overhead %d\n", | |
115 | NIPQUAD(least->addr), ntohs(least->port), | |
116 | atomic_read(&least->activeconns), | |
117 | atomic_read(&least->refcnt), | |
118 | atomic_read(&least->weight), loh); | |
119 | ||
120 | return least; | |
121 | } | |
122 | ||
123 | ||
124 | static struct ip_vs_scheduler ip_vs_wlc_scheduler = | |
125 | { | |
126 | .name = "wlc", | |
127 | .refcnt = ATOMIC_INIT(0), | |
128 | .module = THIS_MODULE, | |
d149ccc9 | 129 | .n_list = LIST_HEAD_INIT(ip_vs_wlc_scheduler.n_list), |
1da177e4 LT |
130 | .init_service = ip_vs_wlc_init_svc, |
131 | .done_service = ip_vs_wlc_done_svc, | |
132 | .update_service = ip_vs_wlc_update_svc, | |
133 | .schedule = ip_vs_wlc_schedule, | |
134 | }; | |
135 | ||
136 | ||
137 | static int __init ip_vs_wlc_init(void) | |
138 | { | |
1da177e4 LT |
139 | return register_ip_vs_scheduler(&ip_vs_wlc_scheduler); |
140 | } | |
141 | ||
142 | static void __exit ip_vs_wlc_cleanup(void) | |
143 | { | |
144 | unregister_ip_vs_scheduler(&ip_vs_wlc_scheduler); | |
145 | } | |
146 | ||
147 | module_init(ip_vs_wlc_init); | |
148 | module_exit(ip_vs_wlc_cleanup); | |
149 | MODULE_LICENSE("GPL"); |