1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * IPVS: Weighted Least-Connection Scheduling module |
4 | * |
5 | * Authors: Wensong Zhang <wensong@linuxvirtualserver.org> |
6 | * Peter Kese <peter.kese@ijs.si> |
7 | * |
8 | * Changes: |
9 | * Wensong Zhang : changed the ip_vs_wlc_schedule to return dest |
10 | * Wensong Zhang : changed to use the inactconns in scheduling |
11 | * Wensong Zhang : changed some comestics things for debugging |
12 | * Wensong Zhang : changed for the d-linked destination list |
13 | * Wensong Zhang : added the ip_vs_wlc_update_svc |
14 | * Wensong Zhang : added any dest with weight=0 is quiesced |
15 | */ |
16 | |
17 | #define KMSG_COMPONENT "IPVS" |
18 | #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt |
19 | |
20 | #include <linux/module.h> |
21 | #include <linux/kernel.h> |
22 | |
23 | #include <net/ip_vs.h> |
24 | |
25 | /* |
26 | * Weighted Least Connection scheduling |
27 | */ |
28 | static struct ip_vs_dest * |
29 | ip_vs_wlc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb, |
30 | struct ip_vs_iphdr *iph) |
31 | { |
32 | struct ip_vs_dest *dest, *least; |
33 | int loh, doh; |
34 | |
35 | IP_VS_DBG(6, "ip_vs_wlc_schedule(): Scheduling...\n" ); |
36 | |
37 | /* |
38 | * We calculate the load of each dest server as follows: |
39 | * (dest overhead) / dest->weight |
40 | * |
41 | * Remember -- no floats in kernel mode!!! |
42 | * The comparison of h1*w2 > h2*w1 is equivalent to that of |
43 | * h1/w1 > h2/w2 |
44 | * if every weight is larger than zero. |
45 | * |
46 | * The server with weight=0 is quiesced and will not receive any |
47 | * new connections. |
48 | */ |
49 | |
50 | list_for_each_entry_rcu(dest, &svc->destinations, n_list) { |
51 | if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && |
52 | atomic_read(v: &dest->weight) > 0) { |
53 | least = dest; |
54 | loh = ip_vs_dest_conn_overhead(dest: least); |
55 | goto nextstage; |
56 | } |
57 | } |
58 | ip_vs_scheduler_err(svc, msg: "no destination available" ); |
59 | return NULL; |
60 | |
61 | /* |
62 | * Find the destination with the least load. |
63 | */ |
64 | nextstage: |
65 | list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { |
66 | if (dest->flags & IP_VS_DEST_F_OVERLOAD) |
67 | continue; |
68 | doh = ip_vs_dest_conn_overhead(dest); |
69 | if ((__s64)loh * atomic_read(v: &dest->weight) > |
70 | (__s64)doh * atomic_read(v: &least->weight)) { |
71 | least = dest; |
72 | loh = doh; |
73 | } |
74 | } |
75 | |
76 | IP_VS_DBG_BUF(6, "WLC: server %s:%u " |
77 | "activeconns %d refcnt %d weight %d overhead %d\n" , |
78 | IP_VS_DBG_ADDR(least->af, &least->addr), |
79 | ntohs(least->port), |
80 | atomic_read(&least->activeconns), |
81 | refcount_read(&least->refcnt), |
82 | atomic_read(&least->weight), loh); |
83 | |
84 | return least; |
85 | } |
86 | |
87 | |
88 | static struct ip_vs_scheduler ip_vs_wlc_scheduler = |
89 | { |
90 | .name = "wlc" , |
91 | .refcnt = ATOMIC_INIT(0), |
92 | .module = THIS_MODULE, |
93 | .n_list = LIST_HEAD_INIT(ip_vs_wlc_scheduler.n_list), |
94 | .schedule = ip_vs_wlc_schedule, |
95 | }; |
96 | |
97 | |
98 | static int __init ip_vs_wlc_init(void) |
99 | { |
100 | return register_ip_vs_scheduler(scheduler: &ip_vs_wlc_scheduler); |
101 | } |
102 | |
103 | static void __exit ip_vs_wlc_cleanup(void) |
104 | { |
105 | unregister_ip_vs_scheduler(scheduler: &ip_vs_wlc_scheduler); |
106 | synchronize_rcu(); |
107 | } |
108 | |
109 | module_init(ip_vs_wlc_init); |
110 | module_exit(ip_vs_wlc_cleanup); |
111 | MODULE_LICENSE("GPL" ); |
112 | MODULE_DESCRIPTION("ipvs weighted least connection scheduler" ); |
113 | |