// SPDX-License-Identifier: GPL-2.0-or-later
/*
* IPVS: Least-Connection Scheduling module
*
* Authors: Wensong Zhang <[email protected]>
*
* Changes:
* Wensong Zhang : added the ip_vs_lc_update_svc
* Wensong Zhang : added any dest with weight=0 is quiesced
*/
#define KMSG_COMPONENT "IPVS"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/module.h>
#include <linux/kernel.h>
#include <net/ip_vs.h>
/*
* Least Connection scheduling
*/
static struct ip_vs_dest *
ip_vs_lc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
struct ip_vs_iphdr *iph)
{
struct ip_vs_dest *dest, *least = NULL;
unsigned int loh = 0, doh;
IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
/*
* Simply select the server with the least number of
* (activeconns<<5) + inactconns
* Except whose weight is equal to zero.
* If the weight is equal to zero, it means that the server is
* quiesced, the existing connections to the server still get
* served, but no new connection is assigned to the server.
*/
list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
if ((dest->flags & IP_VS_DEST_F_OVERLOAD) ||
atomic_read(&dest->weight) == 0)
continue;
doh = ip_vs_dest_conn_overhead(dest);
if (!least || doh < loh) {
least = dest;
loh = doh;
}
}
if (!least)
ip_vs_scheduler_err(svc, "no destination available");
else
IP_VS_DBG_BUF(6, "LC: server %s:%u activeconns %d "
"inactconns %d\n",
IP_VS_DBG_ADDR(least->af, &least->addr),
ntohs(least->port),
atomic_read(&least->activeconns),
atomic_read(&least->inactconns));
return least;
}
static struct ip_vs_scheduler ip_vs_lc_scheduler = {
.name = "lc",
.refcnt = ATOMIC_INIT(0),
.module = THIS_MODULE,
.n_list = LIST_HEAD_INIT(ip_vs_lc_scheduler.n_list),
.schedule = ip_vs_lc_schedule,
};
static int __init ip_vs_lc_init(void)
{
return register_ip_vs_scheduler(&ip_vs_lc_scheduler) ;
}
static void __exit ip_vs_lc_cleanup(void)
{
unregister_ip_vs_scheduler(&ip_vs_lc_scheduler);
synchronize_rcu();
}
module_init(ip_vs_lc_init);
module_exit(ip_vs_lc_cleanup);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ipvs least connection scheduler");