LXR linux/net/netfilter/ipvs/ip_vs

   1/*
   2 * IPVS:        Overflow-Connection Scheduling module
   3 *
   4 * Authors:     Raducu Deaconu <rhadoo_io@yahoo.com>
   5 *
   6 *              This program is free software; you can redistribute it and/or
   7 *              modify it under the terms of the GNU General Public License
   8 *              as published by the Free Software Foundation; either version
   9 *              2 of the License, or (at your option) any later version.
  10 *
  11 * Scheduler implements "overflow" loadbalancing according to number of active
  12 * connections , will keep all conections to the node with the highest weight
  13 * and overflow to the next node if the number of connections exceeds the node's
  14 * weight.
  15 * Note that this scheduler might not be suitable for UDP because it only uses
  16 * active connections
  17 *
  18 */
  19
  20#define KMSG_COMPONENT "IPVS"
  21#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  22
  23#include <linux/module.h>
  24#include <linux/kernel.h>
  25
  26#include <net/ip_vs.h>
  27
  28/* OVF Connection scheduling  */
  29static struct ip_vs_dest *
  30ip_vs_ovf_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
  31                   struct ip_vs_iphdr *iph)
  32{
  33        struct ip_vs_dest *dest, *h = NULL;
  34        int hw = 0, w;
  35
  36        IP_VS_DBG(6, "ip_vs_ovf_schedule(): Scheduling...\n");
  37        /* select the node with highest weight, go to next in line if active
  38        * connections exceed weight
  39        */
  40        list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
  41                w = atomic_read(&dest->weight);
  42                if ((dest->flags & IP_VS_DEST_F_OVERLOAD) ||
  43                    atomic_read(&dest->activeconns) > w ||
  44                    w == 0)
  45                        continue;
  46                if (!h || w > hw) {
  47                        h = dest;
  48                        hw = w;
  49                }
  50        }
  51
  52        if (h) {
  53                IP_VS_DBG_BUF(6, "OVF: server %s:%u active %d w %d\n",
  54                              IP_VS_DBG_ADDR(h->af, &h->addr),
  55                              ntohs(h->port),
  56                              atomic_read(&h->activeconns),
  57                              atomic_read(&h->weight));
  58                return h;
  59        }
  60
  61        ip_vs_scheduler_err(svc, "no destination available");
  62        return NULL;
  63}
  64
  65static struct ip_vs_scheduler ip_vs_ovf_scheduler = {
  66        .name =                 "ovf",
  67        .refcnt =               ATOMIC_INIT(0),
  68        .module =               THIS_MODULE,
  69        .n_list =               LIST_HEAD_INIT(ip_vs_ovf_scheduler.n_list),
  70        .schedule =             ip_vs_ovf_schedule,
  71};
  72
  73static int __init ip_vs_ovf_init(void)
  74{
  75        return register_ip_vs_scheduler(&ip_vs_ovf_scheduler);
  76}
  77
  78static void __exit ip_vs_ovf_cleanup(void)
  79{
  80        unregister_ip_vs_scheduler(&ip_vs_ovf_scheduler);
  81        synchronize_rcu();
  82}
  83
  84module_init(ip_vs_ovf_init);
  85module_exit(ip_vs_ovf_cleanup);
  86MODULE_LICENSE("GPL");
  87