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1da177e4 LT |
1 | /* |
2 | * IPVS: Least-Connection Scheduling module | |
3 | * | |
1da177e4 LT |
4 | * Authors: Wensong Zhang <wensong@linuxvirtualserver.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 | * Wensong Zhang : added the ip_vs_lc_update_svc | |
13 | * Wensong Zhang : added any dest with weight=0 is quiesced | |
14 | * | |
15 | */ | |
16 | ||
9aada7ac HE |
17 | #define KMSG_COMPONENT "IPVS" |
18 | #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt | |
19 | ||
1da177e4 LT |
20 | #include <linux/module.h> |
21 | #include <linux/kernel.h> | |
22 | ||
23 | #include <net/ip_vs.h> | |
24 | ||
25 | ||
1da177e4 LT |
26 | static inline unsigned int |
27 | ip_vs_lc_dest_overhead(struct ip_vs_dest *dest) | |
28 | { | |
29 | /* | |
30 | * We think the overhead of processing active connections is 256 | |
31 | * times higher than that of inactive connections in average. (This | |
32 | * 256 times might not be accurate, we will change it later) We | |
33 | * use the following formula to estimate the overhead now: | |
34 | * dest->activeconns*256 + dest->inactconns | |
35 | */ | |
36 | return (atomic_read(&dest->activeconns) << 8) + | |
37 | atomic_read(&dest->inactconns); | |
38 | } | |
39 | ||
40 | ||
41 | /* | |
42 | * Least Connection scheduling | |
43 | */ | |
44 | static struct ip_vs_dest * | |
45 | ip_vs_lc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb) | |
46 | { | |
47 | struct ip_vs_dest *dest, *least = NULL; | |
48 | unsigned int loh = 0, doh; | |
49 | ||
1e3e238e | 50 | IP_VS_DBG(6, "%s(): Scheduling...\n", __func__); |
1da177e4 LT |
51 | |
52 | /* | |
53 | * Simply select the server with the least number of | |
54 | * (activeconns<<5) + inactconns | |
55 | * Except whose weight is equal to zero. | |
56 | * If the weight is equal to zero, it means that the server is | |
57 | * quiesced, the existing connections to the server still get | |
58 | * served, but no new connection is assigned to the server. | |
59 | */ | |
60 | ||
61 | list_for_each_entry(dest, &svc->destinations, n_list) { | |
62 | if ((dest->flags & IP_VS_DEST_F_OVERLOAD) || | |
63 | atomic_read(&dest->weight) == 0) | |
64 | continue; | |
65 | doh = ip_vs_lc_dest_overhead(dest); | |
66 | if (!least || doh < loh) { | |
67 | least = dest; | |
68 | loh = doh; | |
69 | } | |
70 | } | |
71 | ||
68888d10 SH |
72 | if (!least) |
73 | IP_VS_ERR_RL("LC: no destination available\n"); | |
74 | else | |
75 | IP_VS_DBG_BUF(6, "LC: server %s:%u activeconns %d " | |
76 | "inactconns %d\n", | |
77 | IP_VS_DBG_ADDR(svc->af, &least->addr), | |
78 | ntohs(least->port), | |
79 | atomic_read(&least->activeconns), | |
80 | atomic_read(&least->inactconns)); | |
1da177e4 LT |
81 | |
82 | return least; | |
83 | } | |
84 | ||
85 | ||
86 | static struct ip_vs_scheduler ip_vs_lc_scheduler = { | |
87 | .name = "lc", | |
88 | .refcnt = ATOMIC_INIT(0), | |
89 | .module = THIS_MODULE, | |
d149ccc9 | 90 | .n_list = LIST_HEAD_INIT(ip_vs_lc_scheduler.n_list), |
1da177e4 LT |
91 | .schedule = ip_vs_lc_schedule, |
92 | }; | |
93 | ||
94 | ||
95 | static int __init ip_vs_lc_init(void) | |
96 | { | |
1da177e4 LT |
97 | return register_ip_vs_scheduler(&ip_vs_lc_scheduler) ; |
98 | } | |
99 | ||
100 | static void __exit ip_vs_lc_cleanup(void) | |
101 | { | |
102 | unregister_ip_vs_scheduler(&ip_vs_lc_scheduler); | |
103 | } | |
104 | ||
105 | module_init(ip_vs_lc_init); | |
106 | module_exit(ip_vs_lc_cleanup); | |
107 | MODULE_LICENSE("GPL"); |