1 /* 2 * IPVS: Least-Connection Scheduling module 3 * 4 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 * 11 * Changes: 12 * Wensong Zhang : added the ip_vs_lc_update_svc 13 * Wensong Zhang : added any dest with weight=0 is quiesced 14 * 15 */ 16 17 #define KMSG_COMPONENT "IPVS" 18 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt 19 20 #include <linux/module.h> 21 #include <linux/kernel.h> 22 23 #include <net/ip_vs.h> 24 25 /* 26 * Least Connection scheduling 27 */ 28 static struct ip_vs_dest * 29 ip_vs_lc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb, 30 struct ip_vs_iphdr *iph) 31 { 32 struct ip_vs_dest *dest, *least = NULL; 33 unsigned int loh = 0, doh; 34 35 IP_VS_DBG(6, "%s(): Scheduling...\n", __func__); 36 37 /* 38 * Simply select the server with the least number of 39 * (activeconns<<5) + inactconns 40 * Except whose weight is equal to zero. 41 * If the weight is equal to zero, it means that the server is 42 * quiesced, the existing connections to the server still get 43 * served, but no new connection is assigned to the server. 44 */ 45 46 list_for_each_entry_rcu(dest, &svc->destinations, n_list) { 47 if ((dest->flags & IP_VS_DEST_F_OVERLOAD) || 48 atomic_read(&dest->weight) == 0) 49 continue; 50 doh = ip_vs_dest_conn_overhead(dest); 51 if (!least || doh < loh) { 52 least = dest; 53 loh = doh; 54 } 55 } 56 57 if (!least) 58 ip_vs_scheduler_err(svc, "no destination available"); 59 else 60 IP_VS_DBG_BUF(6, "LC: server %s:%u activeconns %d " 61 "inactconns %d\n", 62 IP_VS_DBG_ADDR(least->af, &least->addr), 63 ntohs(least->port), 64 atomic_read(&least->activeconns), 65 atomic_read(&least->inactconns)); 66 67 return least; 68 } 69 70 71 static struct ip_vs_scheduler ip_vs_lc_scheduler = { 72 .name = "lc", 73 .refcnt = ATOMIC_INIT(0), 74 .module = THIS_MODULE, 75 .n_list = LIST_HEAD_INIT(ip_vs_lc_scheduler.n_list), 76 .schedule = ip_vs_lc_schedule, 77 }; 78 79 80 static int __init ip_vs_lc_init(void) 81 { 82 return register_ip_vs_scheduler(&ip_vs_lc_scheduler) ; 83 } 84 85 static void __exit ip_vs_lc_cleanup(void) 86 { 87 unregister_ip_vs_scheduler(&ip_vs_lc_scheduler); 88 synchronize_rcu(); 89 } 90 91 module_init(ip_vs_lc_init); 92 module_exit(ip_vs_lc_cleanup); 93 MODULE_LICENSE("GPL"); 94