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                   struct ip_vs_iphdr *iph)
  36{
  37        struct ip_vs_dest *dest, *least;
  38        int loh, doh;
  39
  40        IP_VS_DBG(6, "ip_vs_wlc_schedule(): Scheduling...\n");
  41
  42        /*
  43         * We calculate the load of each dest server as follows:
  44         *                (dest overhead) / dest->weight
  45         *
  46         * Remember -- no floats in kernel mode!!!
  47         * The comparison of h1*w2 > h2*w1 is equivalent to that of
  48         *                h1/w1 > h2/w2
  49         * if every weight is larger than zero.
  50         *
  51         * The server with weight=0 is quiesced and will not receive any
  52         * new connections.
  53         */
  54
  55        list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
  56                if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
  57                    atomic_read(&dest->weight) > 0) {
  58                        least = dest;
  59                        loh = ip_vs_dest_conn_overhead(least);
  60                        goto nextstage;
  61                }
  62        }
  63        ip_vs_scheduler_err(svc, "no destination available");
  64        return NULL;
  65
  66        /*
  67         *    Find the destination with the least load.
  68         */
  69  nextstage:
  70        list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) {
  71                if (dest->flags & IP_VS_DEST_F_OVERLOAD)
  72                        continue;
  73                doh = ip_vs_dest_conn_overhead(dest);
  74                if ((__s64)loh * atomic_read(&dest->weight) >
  75                    (__s64)doh * atomic_read(&least->weight)) {
  76                        least = dest;
  77                        loh = doh;
  78                }
  79        }
  80
  81        IP_VS_DBG_BUF(6, "WLC: server %s:%u "
  82                      "activeconns %d refcnt %d weight %d overhead %d\n",
  83                      IP_VS_DBG_ADDR(least->af, &least->addr),
  84                      ntohs(least->port),
  85                      atomic_read(&least->activeconns),
  86                      atomic_read(&least->refcnt),
  87                      atomic_read(&least->weight), loh);
  88
  89        return least;
  90}
  91
  92
  93static struct ip_vs_scheduler ip_vs_wlc_scheduler =
  94{
  95        .name =                 "wlc",
  96        .refcnt =               ATOMIC_INIT(0),
  97        .module =               THIS_MODULE,
  98        .n_list =               LIST_HEAD_INIT(ip_vs_wlc_scheduler.n_list),
  99        .schedule =             ip_vs_wlc_schedule,
 100};
 101
 102
 103static int __init ip_vs_wlc_init(void)
 104{
 105        return register_ip_vs_scheduler(&ip_vs_wlc_scheduler);
 106}
 107
 108static void __exit ip_vs_wlc_cleanup(void)
 109{
 110        unregister_ip_vs_scheduler(&ip_vs_wlc_scheduler);
 111        synchronize_rcu();
 112}
 113
 114module_init(ip_vs_wlc_init);
 115module_exit(ip_vs_wlc_cleanup);
 116MODULE_LICENSE("GPL");
 117