1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * IPVS: Overflow-Connection Scheduling module |
4 | * |
5 | * Authors: Raducu Deaconu <rhadoo_io@yahoo.com> |
6 | * |
7 | * Scheduler implements "overflow" loadbalancing according to number of active |
8 | * connections , will keep all connections to the node with the highest weight |
9 | * and overflow to the next node if the number of connections exceeds the node's |
10 | * weight. |
11 | * Note that this scheduler might not be suitable for UDP because it only uses |
12 | * active connections |
13 | */ |
14 | |
15 | #define KMSG_COMPONENT "IPVS" |
16 | #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt |
17 | |
18 | #include <linux/module.h> |
19 | #include <linux/kernel.h> |
20 | |
21 | #include <net/ip_vs.h> |
22 | |
23 | /* OVF Connection scheduling */ |
24 | static struct ip_vs_dest * |
25 | ip_vs_ovf_schedule(struct ip_vs_service *svc, const struct sk_buff *skb, |
26 | struct ip_vs_iphdr *iph) |
27 | { |
28 | struct ip_vs_dest *dest, *h = NULL; |
29 | int hw = 0, w; |
30 | |
31 | IP_VS_DBG(6, "ip_vs_ovf_schedule(): Scheduling...\n" ); |
32 | /* select the node with highest weight, go to next in line if active |
33 | * connections exceed weight |
34 | */ |
35 | list_for_each_entry_rcu(dest, &svc->destinations, n_list) { |
36 | w = atomic_read(v: &dest->weight); |
37 | if ((dest->flags & IP_VS_DEST_F_OVERLOAD) || |
38 | atomic_read(v: &dest->activeconns) > w || |
39 | w == 0) |
40 | continue; |
41 | if (!h || w > hw) { |
42 | h = dest; |
43 | hw = w; |
44 | } |
45 | } |
46 | |
47 | if (h) { |
48 | IP_VS_DBG_BUF(6, "OVF: server %s:%u active %d w %d\n" , |
49 | IP_VS_DBG_ADDR(h->af, &h->addr), |
50 | ntohs(h->port), |
51 | atomic_read(&h->activeconns), |
52 | atomic_read(&h->weight)); |
53 | return h; |
54 | } |
55 | |
56 | ip_vs_scheduler_err(svc, msg: "no destination available" ); |
57 | return NULL; |
58 | } |
59 | |
60 | static struct ip_vs_scheduler ip_vs_ovf_scheduler = { |
61 | .name = "ovf" , |
62 | .refcnt = ATOMIC_INIT(0), |
63 | .module = THIS_MODULE, |
64 | .n_list = LIST_HEAD_INIT(ip_vs_ovf_scheduler.n_list), |
65 | .schedule = ip_vs_ovf_schedule, |
66 | }; |
67 | |
68 | static int __init ip_vs_ovf_init(void) |
69 | { |
70 | return register_ip_vs_scheduler(scheduler: &ip_vs_ovf_scheduler); |
71 | } |
72 | |
73 | static void __exit ip_vs_ovf_cleanup(void) |
74 | { |
75 | unregister_ip_vs_scheduler(scheduler: &ip_vs_ovf_scheduler); |
76 | synchronize_rcu(); |
77 | } |
78 | |
79 | module_init(ip_vs_ovf_init); |
80 | module_exit(ip_vs_ovf_cleanup); |
81 | MODULE_LICENSE("GPL" ); |
82 | MODULE_DESCRIPTION("ipvs overflow connection scheduler" ); |
83 | |