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
)
36 struct ip_vs_dest
*dest
, *least
;
37 unsigned int loh
, doh
;
39 IP_VS_DBG(6, "ip_vs_wlc_schedule(): Scheduling...\n");
42 * We calculate the load of each dest server as follows:
43 * (dest overhead) / dest->weight
45 * Remember -- no floats in kernel mode!!!
46 * The comparison of h1*w2 > h2*w1 is equivalent to that of
48 * if every weight is larger than zero.
50 * The server with weight=0 is quiesced and will not receive any
54 list_for_each_entry(dest
, &svc
->destinations
, n_list
) {
55 if (!(dest
->flags
& IP_VS_DEST_F_OVERLOAD
) &&
56 atomic_read(&dest
->weight
) > 0) {
58 loh
= ip_vs_dest_conn_overhead(least
);
62 ip_vs_scheduler_err(svc
, "no destination available");
66 * Find the destination with the least load.
69 list_for_each_entry_continue(dest
, &svc
->destinations
, n_list
) {
70 if (dest
->flags
& IP_VS_DEST_F_OVERLOAD
)
72 doh
= ip_vs_dest_conn_overhead(dest
);
73 if (loh
* atomic_read(&dest
->weight
) >
74 doh
* atomic_read(&least
->weight
)) {
80 IP_VS_DBG_BUF(6, "WLC: server %s:%u "
81 "activeconns %d refcnt %d weight %d overhead %d\n",
82 IP_VS_DBG_ADDR(svc
->af
, &least
->addr
), ntohs(least
->port
),
83 atomic_read(&least
->activeconns
),
84 atomic_read(&least
->refcnt
),
85 atomic_read(&least
->weight
), loh
);
91 static struct ip_vs_scheduler ip_vs_wlc_scheduler
=
94 .refcnt
= ATOMIC_INIT(0),
95 .module
= THIS_MODULE
,
96 .n_list
= LIST_HEAD_INIT(ip_vs_wlc_scheduler
.n_list
),
97 .schedule
= ip_vs_wlc_schedule
,
101 static int __init
ip_vs_wlc_init(void)
103 return register_ip_vs_scheduler(&ip_vs_wlc_scheduler
);
106 static void __exit
ip_vs_wlc_cleanup(void)
108 unregister_ip_vs_scheduler(&ip_vs_wlc_scheduler
);
111 module_init(ip_vs_wlc_init
);
112 module_exit(ip_vs_wlc_cleanup
);
113 MODULE_LICENSE("GPL");