12874c5fdSThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later
2cb7f6a7bSJulius Volz /*
3cb7f6a7bSJulius Volz * IPVS: Least-Connection Scheduling module
4cb7f6a7bSJulius Volz *
5cb7f6a7bSJulius Volz * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
6cb7f6a7bSJulius Volz *
7cb7f6a7bSJulius Volz * Changes:
8cb7f6a7bSJulius Volz * Wensong Zhang : added the ip_vs_lc_update_svc
9cb7f6a7bSJulius Volz * Wensong Zhang : added any dest with weight=0 is quiesced
10cb7f6a7bSJulius Volz */
11cb7f6a7bSJulius Volz
129aada7acSHannes Eder #define KMSG_COMPONENT "IPVS"
139aada7acSHannes Eder #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
149aada7acSHannes Eder
15cb7f6a7bSJulius Volz #include <linux/module.h>
16cb7f6a7bSJulius Volz #include <linux/kernel.h>
17cb7f6a7bSJulius Volz
18cb7f6a7bSJulius Volz #include <net/ip_vs.h>
19cb7f6a7bSJulius Volz
20cb7f6a7bSJulius Volz /*
21cb7f6a7bSJulius Volz * Least Connection scheduling
22cb7f6a7bSJulius Volz */
23cb7f6a7bSJulius Volz static struct ip_vs_dest *
ip_vs_lc_schedule(struct ip_vs_service * svc,const struct sk_buff * skb,struct ip_vs_iphdr * iph)24bba54de5SJulian Anastasov ip_vs_lc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
25bba54de5SJulian Anastasov struct ip_vs_iphdr *iph)
26cb7f6a7bSJulius Volz {
27cb7f6a7bSJulius Volz struct ip_vs_dest *dest, *least = NULL;
28cb7f6a7bSJulius Volz unsigned int loh = 0, doh;
29cb7f6a7bSJulius Volz
301e3e238eSHannes Eder IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
31cb7f6a7bSJulius Volz
32cb7f6a7bSJulius Volz /*
33cb7f6a7bSJulius Volz * Simply select the server with the least number of
34cb7f6a7bSJulius Volz * (activeconns<<5) + inactconns
35cb7f6a7bSJulius Volz * Except whose weight is equal to zero.
36cb7f6a7bSJulius Volz * If the weight is equal to zero, it means that the server is
37cb7f6a7bSJulius Volz * quiesced, the existing connections to the server still get
38cb7f6a7bSJulius Volz * served, but no new connection is assigned to the server.
39cb7f6a7bSJulius Volz */
40cb7f6a7bSJulius Volz
414ebd288bSJulian Anastasov list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
42cb7f6a7bSJulius Volz if ((dest->flags & IP_VS_DEST_F_OVERLOAD) ||
43cb7f6a7bSJulius Volz atomic_read(&dest->weight) == 0)
44cb7f6a7bSJulius Volz continue;
45b552f7e3SChangli Gao doh = ip_vs_dest_conn_overhead(dest);
46cb7f6a7bSJulius Volz if (!least || doh < loh) {
47cb7f6a7bSJulius Volz least = dest;
48cb7f6a7bSJulius Volz loh = doh;
49cb7f6a7bSJulius Volz }
50cb7f6a7bSJulius Volz }
51cb7f6a7bSJulius Volz
5268888d10SSimon Horman if (!least)
5341ac51eeSPatrick Schaaf ip_vs_scheduler_err(svc, "no destination available");
5468888d10SSimon Horman else
5568888d10SSimon Horman IP_VS_DBG_BUF(6, "LC: server %s:%u activeconns %d "
5668888d10SSimon Horman "inactconns %d\n",
574d316f3fSJulian Anastasov IP_VS_DBG_ADDR(least->af, &least->addr),
5868888d10SSimon Horman ntohs(least->port),
59cb7f6a7bSJulius Volz atomic_read(&least->activeconns),
60cb7f6a7bSJulius Volz atomic_read(&least->inactconns));
61cb7f6a7bSJulius Volz
62cb7f6a7bSJulius Volz return least;
63cb7f6a7bSJulius Volz }
64cb7f6a7bSJulius Volz
65cb7f6a7bSJulius Volz
66cb7f6a7bSJulius Volz static struct ip_vs_scheduler ip_vs_lc_scheduler = {
67cb7f6a7bSJulius Volz .name = "lc",
68cb7f6a7bSJulius Volz .refcnt = ATOMIC_INIT(0),
69cb7f6a7bSJulius Volz .module = THIS_MODULE,
70cb7f6a7bSJulius Volz .n_list = LIST_HEAD_INIT(ip_vs_lc_scheduler.n_list),
71cb7f6a7bSJulius Volz .schedule = ip_vs_lc_schedule,
72cb7f6a7bSJulius Volz };
73cb7f6a7bSJulius Volz
74cb7f6a7bSJulius Volz
ip_vs_lc_init(void)75cb7f6a7bSJulius Volz static int __init ip_vs_lc_init(void)
76cb7f6a7bSJulius Volz {
77cb7f6a7bSJulius Volz return register_ip_vs_scheduler(&ip_vs_lc_scheduler) ;
78cb7f6a7bSJulius Volz }
79cb7f6a7bSJulius Volz
ip_vs_lc_cleanup(void)80cb7f6a7bSJulius Volz static void __exit ip_vs_lc_cleanup(void)
81cb7f6a7bSJulius Volz {
82cb7f6a7bSJulius Volz unregister_ip_vs_scheduler(&ip_vs_lc_scheduler);
83ceec4c38SJulian Anastasov synchronize_rcu();
84cb7f6a7bSJulius Volz }
85cb7f6a7bSJulius Volz
86cb7f6a7bSJulius Volz module_init(ip_vs_lc_init);
87cb7f6a7bSJulius Volz module_exit(ip_vs_lc_cleanup);
88cb7f6a7bSJulius Volz MODULE_LICENSE("GPL");
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