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 static inline unsigned int
32 ip_vs_wlc_dest_overhead(struct ip_vs_dest
*dest
)
35 * We think the overhead of processing active connections is 256
36 * times higher than that of inactive connections in average. (This
37 * 256 times might not be accurate, we will change it later) We
38 * use the following formula to estimate the overhead now:
39 * dest->activeconns*256 + dest->inactconns
41 return (atomic_read(&dest
->activeconns
) << 8) +
42 atomic_read(&dest
->inactconns
);
47 * Weighted Least Connection scheduling
49 static struct ip_vs_dest
*
50 ip_vs_wlc_schedule(struct ip_vs_service
*svc
, const struct sk_buff
*skb
)
52 struct ip_vs_dest
*dest
, *least
;
53 unsigned int loh
, doh
;
55 IP_VS_DBG(6, "ip_vs_wlc_schedule(): Scheduling...\n");
58 * We calculate the load of each dest server as follows:
59 * (dest overhead) / dest->weight
61 * Remember -- no floats in kernel mode!!!
62 * The comparison of h1*w2 > h2*w1 is equivalent to that of
64 * if every weight is larger than zero.
66 * The server with weight=0 is quiesced and will not receive any
70 list_for_each_entry(dest
, &svc
->destinations
, n_list
) {
71 if (!(dest
->flags
& IP_VS_DEST_F_OVERLOAD
) &&
72 atomic_read(&dest
->weight
) > 0) {
74 loh
= ip_vs_wlc_dest_overhead(least
);
78 IP_VS_ERR_RL("WLC: no destination available\n");
82 * Find the destination with the least load.
85 list_for_each_entry_continue(dest
, &svc
->destinations
, n_list
) {
86 if (dest
->flags
& IP_VS_DEST_F_OVERLOAD
)
88 doh
= ip_vs_wlc_dest_overhead(dest
);
89 if (loh
* atomic_read(&dest
->weight
) >
90 doh
* atomic_read(&least
->weight
)) {
96 IP_VS_DBG_BUF(6, "WLC: server %s:%u "
97 "activeconns %d refcnt %d weight %d overhead %d\n",
98 IP_VS_DBG_ADDR(svc
->af
, &least
->addr
), ntohs(least
->port
),
99 atomic_read(&least
->activeconns
),
100 atomic_read(&least
->refcnt
),
101 atomic_read(&least
->weight
), loh
);
107 static struct ip_vs_scheduler ip_vs_wlc_scheduler
=
110 .refcnt
= ATOMIC_INIT(0),
111 .module
= THIS_MODULE
,
112 .n_list
= LIST_HEAD_INIT(ip_vs_wlc_scheduler
.n_list
),
113 .schedule
= ip_vs_wlc_schedule
,
117 static int __init
ip_vs_wlc_init(void)
119 return register_ip_vs_scheduler(&ip_vs_wlc_scheduler
);
122 static void __exit
ip_vs_wlc_cleanup(void)
124 unregister_ip_vs_scheduler(&ip_vs_wlc_scheduler
);
127 module_init(ip_vs_wlc_init
);
128 module_exit(ip_vs_wlc_cleanup
);
129 MODULE_LICENSE("GPL");