kernel/net/netfilter/ipvs/ip_vs_ovf.c

   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  */
  29 static struct ip_vs_dest *
  30 ip_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
  65 static 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
  73 static int __init ip_vs_ovf_init(void)
  74 {
  75         return register_ip_vs_scheduler(&ip_vs_ovf_scheduler);
  76 }
  77
  78 static void __exit ip_vs_ovf_cleanup(void)
  79 {
  80         unregister_ip_vs_scheduler(&ip_vs_ovf_scheduler);
  81         synchronize_rcu();
  82 }
  83
  84 module_init(ip_vs_ovf_init);
  85 module_exit(ip_vs_ovf_cleanup);
  86 MODULE_LICENSE("GPL");