2 * IPVS: Weighted Round-Robin Scheduling module
4 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
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.
12 * Wensong Zhang : changed the ip_vs_wrr_schedule to return dest
13 * Wensong Zhang : changed some comestics things for debugging
14 * Wensong Zhang : changed for the d-linked destination list
15 * Wensong Zhang : added the ip_vs_wrr_update_svc
16 * Julian Anastasov : fixed the bug of returning destination
17 * with weight 0 when all weights are zero
21 #define KMSG_COMPONENT "IPVS"
22 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
24 #include <linux/module.h>
25 #include <linux/kernel.h>
26 #include <linux/slab.h>
27 #include <linux/net.h>
28 #include <linux/gcd.h>
30 #include <net/ip_vs.h>
33 * current destination pointer for weighted round-robin scheduling
35 struct ip_vs_wrr_mark
{
36 struct list_head
*cl
; /* current list head */
37 int cw
; /* current weight */
38 int mw
; /* maximum weight */
39 int di
; /* decreasing interval */
43 static int ip_vs_wrr_gcd_weight(struct ip_vs_service
*svc
)
45 struct ip_vs_dest
*dest
;
49 list_for_each_entry(dest
, &svc
->destinations
, n_list
) {
50 weight
= atomic_read(&dest
->weight
);
63 * Get the maximum weight of the service destinations.
65 static int ip_vs_wrr_max_weight(struct ip_vs_service
*svc
)
67 struct ip_vs_dest
*dest
;
68 int new_weight
, weight
= 0;
70 list_for_each_entry(dest
, &svc
->destinations
, n_list
) {
71 new_weight
= atomic_read(&dest
->weight
);
72 if (new_weight
> weight
)
80 static int ip_vs_wrr_init_svc(struct ip_vs_service
*svc
)
82 struct ip_vs_wrr_mark
*mark
;
85 * Allocate the mark variable for WRR scheduling
87 mark
= kmalloc(sizeof(struct ip_vs_wrr_mark
), GFP_ATOMIC
);
91 mark
->cl
= &svc
->destinations
;
93 mark
->mw
= ip_vs_wrr_max_weight(svc
);
94 mark
->di
= ip_vs_wrr_gcd_weight(svc
);
95 svc
->sched_data
= mark
;
101 static int ip_vs_wrr_done_svc(struct ip_vs_service
*svc
)
104 * Release the mark variable
106 kfree(svc
->sched_data
);
112 static int ip_vs_wrr_update_svc(struct ip_vs_service
*svc
)
114 struct ip_vs_wrr_mark
*mark
= svc
->sched_data
;
116 mark
->cl
= &svc
->destinations
;
117 mark
->mw
= ip_vs_wrr_max_weight(svc
);
118 mark
->di
= ip_vs_wrr_gcd_weight(svc
);
119 if (mark
->cw
> mark
->mw
)
126 * Weighted Round-Robin Scheduling
128 static struct ip_vs_dest
*
129 ip_vs_wrr_schedule(struct ip_vs_service
*svc
, const struct sk_buff
*skb
)
131 struct ip_vs_dest
*dest
;
132 struct ip_vs_wrr_mark
*mark
= svc
->sched_data
;
135 IP_VS_DBG(6, "%s(): Scheduling...\n", __func__
);
138 * This loop will always terminate, because mark->cw in (0, max_weight]
139 * and at least one server has its weight equal to max_weight.
141 write_lock(&svc
->sched_lock
);
144 if (mark
->cl
== &svc
->destinations
) {
145 /* it is at the head of the destination list */
147 if (mark
->cl
== mark
->cl
->next
) {
149 ip_vs_scheduler_err(svc
,
150 "no destination available: "
151 "no destinations present");
156 mark
->cl
= svc
->destinations
.next
;
157 mark
->cw
-= mark
->di
;
161 * Still zero, which means no available servers.
164 mark
->cl
= &svc
->destinations
;
165 ip_vs_scheduler_err(svc
,
166 "no destination available");
172 mark
->cl
= mark
->cl
->next
;
174 if (mark
->cl
!= &svc
->destinations
) {
175 /* not at the head of the list */
176 dest
= list_entry(mark
->cl
, struct ip_vs_dest
, n_list
);
177 if (!(dest
->flags
& IP_VS_DEST_F_OVERLOAD
) &&
178 atomic_read(&dest
->weight
) >= mark
->cw
) {
184 if (mark
->cl
== p
&& mark
->cw
== mark
->di
) {
185 /* back to the start, and no dest is found.
186 It is only possible when all dests are OVERLOADED */
188 ip_vs_scheduler_err(svc
,
189 "no destination available: "
190 "all destinations are overloaded");
195 IP_VS_DBG_BUF(6, "WRR: server %s:%u "
196 "activeconns %d refcnt %d weight %d\n",
197 IP_VS_DBG_ADDR(svc
->af
, &dest
->addr
), ntohs(dest
->port
),
198 atomic_read(&dest
->activeconns
),
199 atomic_read(&dest
->refcnt
),
200 atomic_read(&dest
->weight
));
203 write_unlock(&svc
->sched_lock
);
208 static struct ip_vs_scheduler ip_vs_wrr_scheduler
= {
210 .refcnt
= ATOMIC_INIT(0),
211 .module
= THIS_MODULE
,
212 .n_list
= LIST_HEAD_INIT(ip_vs_wrr_scheduler
.n_list
),
213 .init_service
= ip_vs_wrr_init_svc
,
214 .done_service
= ip_vs_wrr_done_svc
,
215 .update_service
= ip_vs_wrr_update_svc
,
216 .schedule
= ip_vs_wrr_schedule
,
219 static int __init
ip_vs_wrr_init(void)
221 return register_ip_vs_scheduler(&ip_vs_wrr_scheduler
) ;
224 static void __exit
ip_vs_wrr_cleanup(void)
226 unregister_ip_vs_scheduler(&ip_vs_wrr_scheduler
);
229 module_init(ip_vs_wrr_init
);
230 module_exit(ip_vs_wrr_cleanup
);
231 MODULE_LICENSE("GPL");