1/* 2 * IPVS: Least-Connection Scheduling module 3 * 4 * Version: $Id: ip_vs_lc.c,v 1.1.1.1 2007/08/03 18:53:51 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