2 * IPVS: Least-Connection Scheduling module
4 * Version: $Id: ip_vs_lc.c,v 1.8.2.1 2003/04/11 14:02:35 wensong Exp $
6 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
14 * Wensong Zhang : added the ip_vs_lc_update_svc
15 * Wensong Zhang : added any dest with weight=0 is quiesced
19 #include <linux/module.h>
20 #include <linux/kernel.h>
22 #include <net/ip_vs.h>
25 static int ip_vs_lc_init_svc(struct ip_vs_service *svc)
31 static int ip_vs_lc_done_svc(struct ip_vs_service *svc)
37 static int ip_vs_lc_update_svc(struct ip_vs_service *svc)
43 static inline unsigned int
44 ip_vs_lc_dest_overhead(struct ip_vs_dest *dest)
47 * We think the overhead of processing active connections is 256
48 * times higher than that of inactive connections in average. (This
49 * 256 times might not be accurate, we will change it later) We
50 * use the following formula to estimate the overhead now:
51 * dest->activeconns*256 + dest->inactconns
53 return (atomic_read(&dest->activeconns) << 8) +
54 atomic_read(&dest->inactconns);
59 * Least Connection scheduling
61 static struct ip_vs_dest *
62 ip_vs_lc_schedule(struct ip_vs_service *svc, struct iphdr *iph)
64 struct list_head *l, *e;
65 struct ip_vs_dest *dest, *least;
66 unsigned int loh, doh;
68 IP_VS_DBG(6, "ip_vs_lc_schedule(): Scheduling...\n");
71 * Simply select the server with the least number of
72 * (activeconns<<5) + inactconns
73 * Except whose weight is equal to zero.
74 * If the weight is equal to zero, it means that the server is
75 * quiesced, the existing connections to the server still get
76 * served, but no new connection is assigned to the server.
79 l = &svc->destinations;
80 for (e=l->next; e!=l; e=e->next) {
81 least = list_entry (e, struct ip_vs_dest, n_list);
82 if (atomic_read(&least->weight) > 0) {
83 loh = ip_vs_lc_dest_overhead(least);
90 * Find the destination with the least load.
93 for (e=e->next; e!=l; e=e->next) {
94 dest = list_entry(e, struct ip_vs_dest, n_list);
95 if (atomic_read(&dest->weight) == 0)
97 doh = ip_vs_lc_dest_overhead(dest);
104 IP_VS_DBG(6, "LC: server %u.%u.%u.%u:%u activeconns %d inactconns %d\n",
105 NIPQUAD(least->addr), ntohs(least->port),
106 atomic_read(&least->activeconns),
107 atomic_read(&least->inactconns));
113 static struct ip_vs_scheduler ip_vs_lc_scheduler = {
116 ATOMIC_INIT(0), /* refcnt */
117 THIS_MODULE, /* this module */
118 ip_vs_lc_init_svc, /* service initializer */
119 ip_vs_lc_done_svc, /* service done */
120 ip_vs_lc_update_svc, /* service updater */
121 ip_vs_lc_schedule, /* select a server from the destination list */
125 static int __init ip_vs_lc_init(void)
127 INIT_LIST_HEAD(&ip_vs_lc_scheduler.n_list);
128 return register_ip_vs_scheduler(&ip_vs_lc_scheduler) ;
131 static void __exit ip_vs_lc_cleanup(void)
133 unregister_ip_vs_scheduler(&ip_vs_lc_scheduler);
136 module_init(ip_vs_lc_init);
137 module_exit(ip_vs_lc_cleanup);
138 MODULE_LICENSE("GPL");