LXR linux/net/ipv4/ipvs/ip_vs

   1/*
   2 * IPVS:        Least-Connection Scheduling module
   3 *
   4 * Version:     $Id: ip_vs_lc.c,v 1.10 2003/04/18 09:03:16 wensong Exp $
   5 *
   6 * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
   7 *
   8 *              This program is free software; you can redistribute it and/or
   9 *              modify it under the terms of the GNU General Public License
  10 *              as published by the Free Software Foundation; either version
  11 *              2 of the License, or (at your option) any later version.
  12 *
  13 * Changes:
  14 *     Wensong Zhang            :     added the ip_vs_lc_update_svc
  15 *     Wensong Zhang            :     added any dest with weight=0 is quiesced
  16 *
  17 */
  18
  19#include <linux/module.h>
  20#include <linux/kernel.h>
  21
  22#include <net/ip_vs.h>
  23
  24
  25static int ip_vs_lc_init_svc(struct ip_vs_service *svc)
  26{
  27        return 0;
  28}
  29
  30
  31static int ip_vs_lc_done_svc(struct ip_vs_service *svc)
  32{
  33        return 0;
  34}
  35
  36
  37static int ip_vs_lc_update_svc(struct ip_vs_service *svc)
  38{
  39        return 0;
  40}
  41
  42
  43static inline unsigned int
  44ip_vs_lc_dest_overhead(struct ip_vs_dest *dest)
  45{
  46        /*
  47         * We think the overhead of processing active connections is 256
  48         * times higher than that of inactive connections in average. (This
  49         * 256 times might not be accurate, we will change it later) We
  50         * use the following formula to estimate the overhead now:
  51         *                dest->activeconns*256 + dest->inactconns
  52         */
  53        return (atomic_read(&dest->activeconns) << 8) +
  54                atomic_read(&dest->inactconns);
  55}
  56
  57
  58/*
  59 *      Least Connection scheduling
  60 */
  61static struct ip_vs_dest *
  62ip_vs_lc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
  63{
  64        struct ip_vs_dest *dest, *least = NULL;
  65        unsigned int loh = 0, doh;
  66
  67        IP_VS_DBG(6, "ip_vs_lc_schedule(): Scheduling...\n");
  68
  69        /*
  70         * Simply select the server with the least number of
  71         *        (activeconns<<5) + inactconns
  72         * Except whose weight is equal to zero.
  73         * If the weight is equal to zero, it means that the server is
  74         * quiesced, the existing connections to the server still get
  75         * served, but no new connection is assigned to the server.
  76         */
  77
  78        list_for_each_entry(dest, &svc->destinations, n_list) {
  79                if ((dest->flags & IP_VS_DEST_F_OVERLOAD) ||
  80                    atomic_read(&dest->weight) == 0)
  81                        continue;
  82                doh = ip_vs_lc_dest_overhead(dest);
  83                if (!least || doh < loh) {
  84                        least = dest;
  85                        loh = doh;
  86                }
  87        }
  88
  89        if (least)
  90        IP_VS_DBG(6, "LC: server %u.%u.%u.%u:%u activeconns %d inactconns %d\n",
  91                  NIPQUAD(least->addr), ntohs(least->port),
  92                  atomic_read(&least->activeconns),
  93                  atomic_read(&least->inactconns));
  94
  95        return least;
  96}
  97
  98
  99static struct ip_vs_scheduler ip_vs_lc_scheduler = {
 100        .name =                 "lc",
 101        .refcnt =               ATOMIC_INIT(0),
 102        .module =               THIS_MODULE,
 103        .init_service =         ip_vs_lc_init_svc,
 104        .done_service =         ip_vs_lc_done_svc,
 105        .update_service =       ip_vs_lc_update_svc,
 106        .schedule =             ip_vs_lc_schedule,
 107};
 108
 109
 110static int __init ip_vs_lc_init(void)
 111{
 112        INIT_LIST_HEAD(&ip_vs_lc_scheduler.n_list);
 113        return register_ip_vs_scheduler(&ip_vs_lc_scheduler) ;
 114}
 115
 116static void __exit ip_vs_lc_cleanup(void)
 117{
 118        unregister_ip_vs_scheduler(&ip_vs_lc_scheduler);
 119}
 120
 121module_init(ip_vs_lc_init);
 122module_exit(ip_vs_lc_cleanup);
 123MODULE_LICENSE("GPL");
 124