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1 | // SPDX-License-Identifier: GPL-2.0-or-later | |
2 | /* | |
3 | * IPVS: Least-Connection Scheduling module | |
4 | * | |
5 | * Authors: Wensong Zhang <wensong@linuxvirtualserver.org> | |
6 | * | |
7 | * Changes: | |
8 | * Wensong Zhang : added the ip_vs_lc_update_svc | |
9 | * Wensong Zhang : added any dest with weight=0 is quiesced | |
10 | */ | |
11 | ||
12 | #define KMSG_COMPONENT "IPVS" | |
13 | #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt | |
14 | ||
15 | #include <linux/module.h> | |
16 | #include <linux/kernel.h> | |
17 | ||
18 | #include <net/ip_vs.h> | |
19 | ||
20 | /* | |
21 | * Least Connection scheduling | |
22 | */ | |
23 | static struct ip_vs_dest * | |
24 | ip_vs_lc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb, | |
25 | struct ip_vs_iphdr *iph) | |
26 | { | |
27 | struct ip_vs_dest *dest, *least = NULL; | |
28 | unsigned int loh = 0, doh; | |
29 | ||
30 | IP_VS_DBG(6, "%s(): Scheduling...\n", __func__); | |
31 | ||
32 | /* | |
33 | * Simply select the server with the least number of | |
34 | * (activeconns<<5) + inactconns | |
35 | * Except whose weight is equal to zero. | |
36 | * If the weight is equal to zero, it means that the server is | |
37 | * quiesced, the existing connections to the server still get | |
38 | * served, but no new connection is assigned to the server. | |
39 | */ | |
40 | ||
41 | list_for_each_entry_rcu(dest, &svc->destinations, n_list) { | |
42 | if ((dest->flags & IP_VS_DEST_F_OVERLOAD) || | |
43 | atomic_read(&dest->weight) == 0) | |
44 | continue; | |
45 | doh = ip_vs_dest_conn_overhead(dest); | |
46 | if (!least || doh < loh) { | |
47 | least = dest; | |
48 | loh = doh; | |
49 | } | |
50 | } | |
51 | ||
52 | if (!least) | |
53 | ip_vs_scheduler_err(svc, "no destination available"); | |
54 | else | |
55 | IP_VS_DBG_BUF(6, "LC: server %s:%u activeconns %d " | |
56 | "inactconns %d\n", | |
57 | IP_VS_DBG_ADDR(least->af, &least->addr), | |
58 | ntohs(least->port), | |
59 | atomic_read(&least->activeconns), | |
60 | atomic_read(&least->inactconns)); | |
61 | ||
62 | return least; | |
63 | } | |
64 | ||
65 | ||
66 | static struct ip_vs_scheduler ip_vs_lc_scheduler = { | |
67 | .name = "lc", | |
68 | .refcnt = ATOMIC_INIT(0), | |
69 | .module = THIS_MODULE, | |
70 | .n_list = LIST_HEAD_INIT(ip_vs_lc_scheduler.n_list), | |
71 | .schedule = ip_vs_lc_schedule, | |
72 | }; | |
73 | ||
74 | ||
75 | static int __init ip_vs_lc_init(void) | |
76 | { | |
77 | return register_ip_vs_scheduler(&ip_vs_lc_scheduler) ; | |
78 | } | |
79 | ||
80 | static void __exit ip_vs_lc_cleanup(void) | |
81 | { | |
82 | unregister_ip_vs_scheduler(&ip_vs_lc_scheduler); | |
83 | synchronize_rcu(); | |
84 | } | |
85 | ||
86 | module_init(ip_vs_lc_init); | |
87 | module_exit(ip_vs_lc_cleanup); | |
88 | MODULE_LICENSE("GPL"); |