net/netfilter/ipvs/ip_vs_wlc.c

   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  */
  33 static struct ip_vs_dest *
  34 ip_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(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(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
  91 static 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
 101 static int __init ip_vs_wlc_init(void)
 102 {
 103         return register_ip_vs_scheduler(&ip_vs_wlc_scheduler);
 104 }
 105
 106 static void __exit ip_vs_wlc_cleanup(void)
 107 {
 108         unregister_ip_vs_scheduler(&ip_vs_wlc_scheduler);
 109 }
 110
 111 module_init(ip_vs_wlc_init);
 112 module_exit(ip_vs_wlc_cleanup);
 113 MODULE_LICENSE("GPL");