ip_vs_ovf.c

 1// SPDX-License-Identifier: GPL-2.0-or-later
 2/*
 3 * IPVS:        Overflow-Connection Scheduling module
 4 *
 5 * Authors:     Raducu Deaconu <rhadoo_io@yahoo.com>
 6 *
 7 * Scheduler implements "overflow" loadbalancing according to number of active
 8 * connections , will keep all connections to the node with the highest weight
 9 * and overflow to the next node if the number of connections exceeds the node's
10 * weight.
11 * Note that this scheduler might not be suitable for UDP because it only uses
12 * active connections
13 */
14
15#define pr_fmt(fmt) "IPVS: " fmt
16
17#include <linux/module.h>
18#include <linux/kernel.h>
19
20#include <net/ip_vs.h>
21
22/* OVF Connection scheduling  */
23static struct ip_vs_dest *
24ip_vs_ovf_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
25		   struct ip_vs_iphdr *iph)
26{
27	struct ip_vs_dest *dest, *h = NULL;
28	int hw = 0, w;
29
30	IP_VS_DBG(6, "ip_vs_ovf_schedule(): Scheduling...\n");
31	/* select the node with highest weight, go to next in line if active
32	* connections exceed weight
33	*/
34	list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
35		w = atomic_read(&dest->weight);
36		if ((dest->flags & IP_VS_DEST_F_OVERLOAD) ||
37		    atomic_read(&dest->activeconns) > w ||
38		    w == 0)
39			continue;
40		if (!h || w > hw) {
41			h = dest;
42			hw = w;
43		}
44	}
45
46	if (h) {
47		IP_VS_DBG_BUF(6, "OVF: server %s:%u active %d w %d\n",
48			      IP_VS_DBG_ADDR(h->af, &h->addr),
49			      ntohs(h->port),
50			      atomic_read(&h->activeconns),
51			      atomic_read(&h->weight));
52		return h;
53	}
54
55	ip_vs_scheduler_err(svc, "no destination available");
56	return NULL;
57}
58
59static struct ip_vs_scheduler ip_vs_ovf_scheduler = {
60	.name =			"ovf",
61	.refcnt =		ATOMIC_INIT(0),
62	.module =		THIS_MODULE,
63	.n_list =		LIST_HEAD_INIT(ip_vs_ovf_scheduler.n_list),
64	.schedule =		ip_vs_ovf_schedule,
65};
66
67static int __init ip_vs_ovf_init(void)
68{
69	return register_ip_vs_scheduler(&ip_vs_ovf_scheduler);
70}
71
72static void __exit ip_vs_ovf_cleanup(void)
73{
74	unregister_ip_vs_scheduler(&ip_vs_ovf_scheduler);
75	synchronize_rcu();
76}
77
78module_init(ip_vs_ovf_init);
79module_exit(ip_vs_ovf_cleanup);
80MODULE_LICENSE("GPL");
81MODULE_DESCRIPTION("ipvs overflow connection scheduler");