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/*
* IPVS: Least-Connection Scheduling module
*
* Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Changes:
* Wensong Zhang : added the ip_vs_lc_update_svc
* Wensong Zhang : added any dest with weight=0 is quiesced
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <net/ip_vs.h>
static inline unsigned int
ip_vs_lc_dest_overhead(struct ip_vs_dest *dest)
{
/*
* We think the overhead of processing active connections is 256
* times higher than that of inactive connections in average. (This
* 256 times might not be accurate, we will change it later) We
* use the following formula to estimate the overhead now:
* dest->activeconns*256 + dest->inactconns
*/
return (atomic_read(&dest->activeconns) << 8) +
atomic_read(&dest->inactconns);
}
/*
* 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_dest *dest, *least = NULL;
unsigned int loh = 0, doh;
IP_VS_DBG(6, "ip_vs_lc_schedule(): Scheduling...\n");
/*
* 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(dest, &svc->destinations, n_list) {
if ((dest->flags & IP_VS_DEST_F_OVERLOAD) ||
atomic_read(&dest->weight) == 0)
continue;
doh = ip_vs_lc_dest_overhead(dest);
if (!least || doh < loh) {
least = dest;
loh = doh;
}
}
if (least)
IP_VS_DBG_BUF(6, "LC: server %s:%u activeconns %d inactconns %d\n",
IP_VS_DBG_ADDR(svc->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),
#ifdef CONFIG_IP_VS_IPV6
.supports_ipv6 = 1,
#endif
.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);
}
module_init(ip_vs_lc_init);
module_exit(ip_vs_lc_cleanup);
MODULE_LICENSE("GPL");
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