2 * IPVS: Weighted Least-Connection Scheduling module
4 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
5 * Peter Kese <peter.kese@ijs.si>
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
13 * Wensong Zhang : changed the ip_vs_wlc_schedule to return dest
14 * Wensong Zhang : changed to use the inactconns in scheduling
15 * Wensong Zhang : changed some comestics things for debugging
16 * Wensong Zhang : changed for the d-linked destination list
17 * Wensong Zhang : added the ip_vs_wlc_update_svc
18 * Wensong Zhang : added any dest with weight=0 is quiesced
22 #define KMSG_COMPONENT "IPVS"
23 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
25 #include <linux/module.h>
26 #include <linux/kernel.h>
28 #include <net/ip_vs.h>
31 * Weighted Least Connection scheduling
33 static struct ip_vs_dest *
34 ip_vs_wlc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
35 struct ip_vs_iphdr *iph)
37 struct ip_vs_dest *dest, *least;
40 IP_VS_DBG(6, "ip_vs_wlc_schedule(): Scheduling...\n");
43 * We calculate the load of each dest server as follows:
44 * (dest overhead) / dest->weight
46 * Remember -- no floats in kernel mode!!!
47 * The comparison of h1*w2 > h2*w1 is equivalent to that of
49 * if every weight is larger than zero.
51 * The server with weight=0 is quiesced and will not receive any
55 list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
56 if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
57 atomic_read(&dest->weight) > 0) {
59 loh = ip_vs_dest_conn_overhead(least);
63 ip_vs_scheduler_err(svc, "no destination available");
67 * Find the destination with the least load.
70 list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) {
71 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
73 doh = ip_vs_dest_conn_overhead(dest);
74 if ((__s64)loh * atomic_read(&dest->weight) >
75 (__s64)doh * atomic_read(&least->weight)) {
81 IP_VS_DBG_BUF(6, "WLC: server %s:%u "
82 "activeconns %d refcnt %d weight %d overhead %d\n",
83 IP_VS_DBG_ADDR(svc->af, &least->addr), ntohs(least->port),
84 atomic_read(&least->activeconns),
85 atomic_read(&least->refcnt),
86 atomic_read(&least->weight), loh);
92 static struct ip_vs_scheduler ip_vs_wlc_scheduler =
95 .refcnt = ATOMIC_INIT(0),
96 .module = THIS_MODULE,
97 .n_list = LIST_HEAD_INIT(ip_vs_wlc_scheduler.n_list),
98 .schedule = ip_vs_wlc_schedule,
102 static int __init ip_vs_wlc_init(void)
104 return register_ip_vs_scheduler(&ip_vs_wlc_scheduler);
107 static void __exit ip_vs_wlc_cleanup(void)
109 unregister_ip_vs_scheduler(&ip_vs_wlc_scheduler);
113 module_init(ip_vs_wlc_init);
114 module_exit(ip_vs_wlc_cleanup);
115 MODULE_LICENSE("GPL");