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_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 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 synchronize_rcu(); 110 } 111 112 module_init(ip_vs_wlc_init); 113 module_exit(ip_vs_wlc_cleanup); 114 MODULE_LICENSE("GPL"); 115