1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * IPVS: Least-Connection Scheduling module 4 * 5 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org> 6 * 7 * Changes: 8 * Wensong Zhang : added the ip_vs_lc_update_svc 9 * Wensong Zhang : added any dest with weight=0 is quiesced 10 */ 11 12 #define KMSG_COMPONENT "IPVS" 13 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt 14 15 #include <linux/module.h> 16 #include <linux/kernel.h> 17 18 #include <net/ip_vs.h> 19 20 /* 21 * Least Connection scheduling 22 */ 23 static struct ip_vs_dest * 24 ip_vs_lc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb, 25 struct ip_vs_iphdr *iph) 26 { 27 struct ip_vs_dest *dest, *least = NULL; 28 unsigned int loh = 0, doh; 29 30 IP_VS_DBG(6, "%s(): Scheduling...\n", __func__); 31 32 /* 33 * Simply select the server with the least number of 34 * (activeconns<<5) + inactconns 35 * Except whose weight is equal to zero. 36 * If the weight is equal to zero, it means that the server is 37 * quiesced, the existing connections to the server still get 38 * served, but no new connection is assigned to the server. 39 */ 40 41 list_for_each_entry_rcu(dest, &svc->destinations, n_list) { 42 if ((dest->flags & IP_VS_DEST_F_OVERLOAD) || 43 atomic_read(&dest->weight) == 0) 44 continue; 45 doh = ip_vs_dest_conn_overhead(dest); 46 if (!least || doh < loh) { 47 least = dest; 48 loh = doh; 49 } 50 } 51 52 if (!least) 53 ip_vs_scheduler_err(svc, "no destination available"); 54 else 55 IP_VS_DBG_BUF(6, "LC: server %s:%u activeconns %d " 56 "inactconns %d\n", 57 IP_VS_DBG_ADDR(least->af, &least->addr), 58 ntohs(least->port), 59 atomic_read(&least->activeconns), 60 atomic_read(&least->inactconns)); 61 62 return least; 63 } 64 65 66 static struct ip_vs_scheduler ip_vs_lc_scheduler = { 67 .name = "lc", 68 .refcnt = ATOMIC_INIT(0), 69 .module = THIS_MODULE, 70 .n_list = LIST_HEAD_INIT(ip_vs_lc_scheduler.n_list), 71 .schedule = ip_vs_lc_schedule, 72 }; 73 74 75 static int __init ip_vs_lc_init(void) 76 { 77 return register_ip_vs_scheduler(&ip_vs_lc_scheduler) ; 78 } 79 80 static void __exit ip_vs_lc_cleanup(void) 81 { 82 unregister_ip_vs_scheduler(&ip_vs_lc_scheduler); 83 synchronize_rcu(); 84 } 85 86 module_init(ip_vs_lc_init); 87 module_exit(ip_vs_lc_cleanup); 88 MODULE_LICENSE("GPL"); 89