1 /*
2 * IPVS: Least-Connection Scheduling module
3 *
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
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 * Least Connection scheduling
27 */
28 static struct ip_vs_dest *
ip_vs_lc_schedule(struct ip_vs_service * svc,const struct sk_buff * skb)29 ip_vs_lc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
30 {
31 struct ip_vs_dest *dest, *least = NULL;
32 unsigned int loh = 0, doh;
33
34 IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
35
36 /*
37 * Simply select the server with the least number of
38 * (activeconns<<5) + inactconns
39 * Except whose weight is equal to zero.
40 * If the weight is equal to zero, it means that the server is
41 * quiesced, the existing connections to the server still get
42 * served, but no new connection is assigned to the server.
43 */
44
45 list_for_each_entry(dest, &svc->destinations, n_list) {
46 if ((dest->flags & IP_VS_DEST_F_OVERLOAD) ||
47 atomic_read(&dest->weight) == 0)
48 continue;
49 doh = ip_vs_dest_conn_overhead(dest);
50 if (!least || doh < loh) {
51 least = dest;
52 loh = doh;
53 }
54 }
55
56 if (!least)
57 ip_vs_scheduler_err(svc, "no destination available");
58 else
59 IP_VS_DBG_BUF(6, "LC: server %s:%u activeconns %d "
60 "inactconns %d\n",
61 IP_VS_DBG_ADDR(svc->af, &least->addr),
62 ntohs(least->port),
63 atomic_read(&least->activeconns),
64 atomic_read(&least->inactconns));
65
66 return least;
67 }
68
69
70 static struct ip_vs_scheduler ip_vs_lc_scheduler = {
71 .name = "lc",
72 .refcnt = ATOMIC_INIT(0),
73 .module = THIS_MODULE,
74 .n_list = LIST_HEAD_INIT(ip_vs_lc_scheduler.n_list),
75 .schedule = ip_vs_lc_schedule,
76 };
77
78
ip_vs_lc_init(void)79 static int __init ip_vs_lc_init(void)
80 {
81 return register_ip_vs_scheduler(&ip_vs_lc_scheduler) ;
82 }
83
ip_vs_lc_cleanup(void)84 static void __exit ip_vs_lc_cleanup(void)
85 {
86 unregister_ip_vs_scheduler(&ip_vs_lc_scheduler);
87 }
88
89 module_init(ip_vs_lc_init);
90 module_exit(ip_vs_lc_cleanup);
91 MODULE_LICENSE("GPL");
92