// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* IPVS: Overflow-Connection Scheduling module
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*
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* Authors: Raducu Deaconu <rhadoo_io@yahoo.com>
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*
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* Scheduler implements "overflow" loadbalancing according to number of active
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* connections , will keep all connections to the node with the highest weight
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* and overflow to the next node if the number of connections exceeds the node's
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* weight.
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* Note that this scheduler might not be suitable for UDP because it only uses
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* active connections
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*/
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#define KMSG_COMPONENT "IPVS"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <net/ip_vs.h>
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/* OVF Connection scheduling */
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static struct ip_vs_dest *
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ip_vs_ovf_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
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struct ip_vs_iphdr *iph)
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{
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struct ip_vs_dest *dest, *h = NULL;
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int hw = 0, w;
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IP_VS_DBG(6, "ip_vs_ovf_schedule(): Scheduling...\n");
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/* select the node with highest weight, go to next in line if active
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* connections exceed weight
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*/
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list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
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w = atomic_read(&dest->weight);
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if ((dest->flags & IP_VS_DEST_F_OVERLOAD) ||
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atomic_read(&dest->activeconns) > w ||
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w == 0)
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continue;
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if (!h || w > hw) {
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h = dest;
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hw = w;
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}
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}
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if (h) {
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IP_VS_DBG_BUF(6, "OVF: server %s:%u active %d w %d\n",
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IP_VS_DBG_ADDR(h->af, &h->addr),
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ntohs(h->port),
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atomic_read(&h->activeconns),
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atomic_read(&h->weight));
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return h;
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}
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ip_vs_scheduler_err(svc, "no destination available");
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return NULL;
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}
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static struct ip_vs_scheduler ip_vs_ovf_scheduler = {
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.name = "ovf",
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.refcnt = ATOMIC_INIT(0),
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.module = THIS_MODULE,
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.n_list = LIST_HEAD_INIT(ip_vs_ovf_scheduler.n_list),
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.schedule = ip_vs_ovf_schedule,
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};
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static int __init ip_vs_ovf_init(void)
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{
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return register_ip_vs_scheduler(&ip_vs_ovf_scheduler);
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}
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static void __exit ip_vs_ovf_cleanup(void)
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{
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unregister_ip_vs_scheduler(&ip_vs_ovf_scheduler);
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synchronize_rcu();
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}
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module_init(ip_vs_ovf_init);
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module_exit(ip_vs_ovf_cleanup);
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MODULE_LICENSE("GPL");
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