LXR linux/net/netfilter/ipvs/ip_vs

   1/*
   2 * IPVS:        Weighted Least-Connection Scheduling module
   3 *
   4 * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
   5 *              Peter Kese <peter.kese@ijs.si>
   6 *
   7 *              This program is free software; you can redistribute it and/or
   8 *              modify it under the terms of the GNU General Public License
   9 *              as published by the Free Software Foundation; either version
  10 *              2 of the License, or (at your option) any later version.
  11 *
  12 * Changes:
  13 *     Wensong Zhang            :     changed the ip_vs_wlc_schedule to return dest
  14 *     Wensong Zhang            :     changed to use the inactconns in scheduling
  15 *     Wensong Zhang            :     changed some comestics things for debugging
  16 *     Wensong Zhang            :     changed for the d-linked destination list
  17 *     Wensong Zhang            :     added the ip_vs_wlc_update_svc
  18 *     Wensong Zhang            :     added any dest with weight=0 is quiesced
  19 *
  20 */
  21
  22#define KMSG_COMPONENT "IPVS"
  23#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  24
  25#include <linux/module.h>
  26#include <linux/kernel.h>
  27
  28#include <net/ip_vs.h>
  29
  30/*
  31 *      Weighted Least Connection scheduling
  32 */
  33static struct ip_vs_dest *
  34ip_vs_wlc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
  35{
  36        struct ip_vs_dest *dest, *least;
  37        unsigned int loh, doh;
  38
  39        IP_VS_DBG(6, "ip_vs_wlc_schedule(): Scheduling...\n");
  40
  41        /*
  42         * We calculate the load of each dest server as follows:
  43         *                (dest overhead) / dest->weight
  44         *
  45         * Remember -- no floats in kernel mode!!!
  46         * The comparison of h1*w2 > h2*w1 is equivalent to that of
  47         *                h1/w1 > h2/w2
  48         * if every weight is larger than zero.
  49         *
  50         * The server with weight=0 is quiesced and will not receive any
  51         * new connections.
  52         */
  53
  54        list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
  55                if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
  56                    atomic_read(&dest->weight) > 0) {
  57                        least = dest;
  58                        loh = ip_vs_dest_conn_overhead(least);
  59                        goto nextstage;
  60                }
  61        }
  62        ip_vs_scheduler_err(svc, "no destination available");
  63        return NULL;
  64
  65        /*
  66         *    Find the destination with the least load.
  67         */
  68  nextstage:
  69        list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) {
  70                if (dest->flags & IP_VS_DEST_F_OVERLOAD)
  71                        continue;
  72                doh = ip_vs_dest_conn_overhead(dest);
  73                if (loh * atomic_read(&dest->weight) >
  74                    doh * atomic_read(&least->weight)) {
  75                        least = dest;
  76                        loh = doh;
  77                }
  78        }
  79
  80        IP_VS_DBG_BUF(6, "WLC: server %s:%u "
  81                      "activeconns %d refcnt %d weight %d overhead %d\n",
  82                      IP_VS_DBG_ADDR(svc->af, &least->addr), ntohs(least->port),
  83                      atomic_read(&least->activeconns),
  84                      atomic_read(&least->refcnt),
  85                      atomic_read(&least->weight), loh);
  86
  87        return least;
  88}
  89
  90
  91static struct ip_vs_scheduler ip_vs_wlc_scheduler =
  92{
  93        .name =                 "wlc",
  94        .refcnt =               ATOMIC_INIT(0),
  95        .module =               THIS_MODULE,
  96        .n_list =               LIST_HEAD_INIT(ip_vs_wlc_scheduler.n_list),
  97        .schedule =             ip_vs_wlc_schedule,
  98};
  99
 100
 101static int __init ip_vs_wlc_init(void)
 102{
 103        return register_ip_vs_scheduler(&ip_vs_wlc_scheduler);
 104}
 105
 106static void __exit ip_vs_wlc_cleanup(void)
 107{
 108        unregister_ip_vs_scheduler(&ip_vs_wlc_scheduler);
 109        synchronize_rcu();
 110}
 111
 112module_init(ip_vs_wlc_init);
 113module_exit(ip_vs_wlc_cleanup);
 114MODULE_LICENSE("GPL");
 115