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