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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 | ||
9aada7ac HE |
22 | #define KMSG_COMPONENT "IPVS" |
23 | #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt | |
24 | ||
1da177e4 LT |
25 | #include <linux/module.h> |
26 | #include <linux/kernel.h> | |
27 | ||
28 | #include <net/ip_vs.h> | |
29 | ||
30 | ||
1da177e4 LT |
31 | static inline unsigned int |
32 | ip_vs_wlc_dest_overhead(struct ip_vs_dest *dest) | |
33 | { | |
34 | /* | |
35 | * We think the overhead of processing active connections is 256 | |
36 | * times higher than that of inactive connections in average. (This | |
37 | * 256 times might not be accurate, we will change it later) We | |
38 | * use the following formula to estimate the overhead now: | |
39 | * dest->activeconns*256 + dest->inactconns | |
40 | */ | |
41 | return (atomic_read(&dest->activeconns) << 8) + | |
42 | atomic_read(&dest->inactconns); | |
43 | } | |
44 | ||
45 | ||
46 | /* | |
47 | * Weighted Least Connection scheduling | |
48 | */ | |
49 | static struct ip_vs_dest * | |
50 | ip_vs_wlc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb) | |
51 | { | |
52 | struct ip_vs_dest *dest, *least; | |
53 | unsigned int loh, doh; | |
54 | ||
55 | IP_VS_DBG(6, "ip_vs_wlc_schedule(): Scheduling...\n"); | |
56 | ||
57 | /* | |
58 | * We calculate the load of each dest server as follows: | |
59 | * (dest overhead) / dest->weight | |
60 | * | |
61 | * Remember -- no floats in kernel mode!!! | |
62 | * The comparison of h1*w2 > h2*w1 is equivalent to that of | |
63 | * h1/w1 > h2/w2 | |
64 | * if every weight is larger than zero. | |
65 | * | |
66 | * The server with weight=0 is quiesced and will not receive any | |
67 | * new connections. | |
68 | */ | |
69 | ||
70 | list_for_each_entry(dest, &svc->destinations, n_list) { | |
71 | if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && | |
72 | atomic_read(&dest->weight) > 0) { | |
73 | least = dest; | |
74 | loh = ip_vs_wlc_dest_overhead(least); | |
75 | goto nextstage; | |
76 | } | |
77 | } | |
68888d10 | 78 | IP_VS_ERR_RL("WLC: no destination available\n"); |
1da177e4 LT |
79 | return NULL; |
80 | ||
81 | /* | |
82 | * Find the destination with the least load. | |
83 | */ | |
84 | nextstage: | |
85 | list_for_each_entry_continue(dest, &svc->destinations, n_list) { | |
86 | if (dest->flags & IP_VS_DEST_F_OVERLOAD) | |
87 | continue; | |
88 | doh = ip_vs_wlc_dest_overhead(dest); | |
89 | if (loh * atomic_read(&dest->weight) > | |
90 | doh * atomic_read(&least->weight)) { | |
91 | least = dest; | |
92 | loh = doh; | |
93 | } | |
94 | } | |
95 | ||
b14198f6 JV |
96 | IP_VS_DBG_BUF(6, "WLC: server %s:%u " |
97 | "activeconns %d refcnt %d weight %d overhead %d\n", | |
98 | IP_VS_DBG_ADDR(svc->af, &least->addr), ntohs(least->port), | |
99 | atomic_read(&least->activeconns), | |
100 | atomic_read(&least->refcnt), | |
101 | atomic_read(&least->weight), loh); | |
1da177e4 LT |
102 | |
103 | return least; | |
104 | } | |
105 | ||
106 | ||
107 | static struct ip_vs_scheduler ip_vs_wlc_scheduler = | |
108 | { | |
109 | .name = "wlc", | |
110 | .refcnt = ATOMIC_INIT(0), | |
111 | .module = THIS_MODULE, | |
d149ccc9 | 112 | .n_list = LIST_HEAD_INIT(ip_vs_wlc_scheduler.n_list), |
1da177e4 LT |
113 | .schedule = ip_vs_wlc_schedule, |
114 | }; | |
115 | ||
116 | ||
117 | static int __init ip_vs_wlc_init(void) | |
118 | { | |
1da177e4 LT |
119 | return register_ip_vs_scheduler(&ip_vs_wlc_scheduler); |
120 | } | |
121 | ||
122 | static void __exit ip_vs_wlc_cleanup(void) | |
123 | { | |
124 | unregister_ip_vs_scheduler(&ip_vs_wlc_scheduler); | |
125 | } | |
126 | ||
127 | module_init(ip_vs_wlc_init); | |
128 | module_exit(ip_vs_wlc_cleanup); | |
129 | MODULE_LICENSE("GPL"); |