1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * IPVS: Overflow-Connection Scheduling module 4 * 5 * Authors: Raducu Deaconu <rhadoo_io@yahoo.com> 6 * 7 * Scheduler implements "overflow" loadbalancing according to number of active 8 * connections , will keep all connections to the node with the highest weight 9 * and overflow to the next node if the number of connections exceeds the node's 10 * weight. 11 * Note that this scheduler might not be suitable for UDP because it only uses 12 * active connections 13 */ 14 15 #define KMSG_COMPONENT "IPVS" 16 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt 17 18 #include <linux/module.h> 19 #include <linux/kernel.h> 20 21 #include <net/ip_vs.h> 22 23 /* OVF Connection scheduling */ 24 static struct ip_vs_dest * 25 ip_vs_ovf_schedule(struct ip_vs_service *svc, const struct sk_buff *skb, 26 struct ip_vs_iphdr *iph) 27 { 28 struct ip_vs_dest *dest, *h = NULL; 29 int hw = 0, w; 30 31 IP_VS_DBG(6, "ip_vs_ovf_schedule(): Scheduling...\n"); 32 /* select the node with highest weight, go to next in line if active 33 * connections exceed weight 34 */ 35 list_for_each_entry_rcu(dest, &svc->destinations, n_list) { 36 w = atomic_read(&dest->weight); 37 if ((dest->flags & IP_VS_DEST_F_OVERLOAD) || 38 atomic_read(&dest->activeconns) > w || 39 w == 0) 40 continue; 41 if (!h || w > hw) { 42 h = dest; 43 hw = w; 44 } 45 } 46 47 if (h) { 48 IP_VS_DBG_BUF(6, "OVF: server %s:%u active %d w %d\n", 49 IP_VS_DBG_ADDR(h->af, &h->addr), 50 ntohs(h->port), 51 atomic_read(&h->activeconns), 52 atomic_read(&h->weight)); 53 return h; 54 } 55 56 ip_vs_scheduler_err(svc, "no destination available"); 57 return NULL; 58 } 59 60 static struct ip_vs_scheduler ip_vs_ovf_scheduler = { 61 .name = "ovf", 62 .refcnt = ATOMIC_INIT(0), 63 .module = THIS_MODULE, 64 .n_list = LIST_HEAD_INIT(ip_vs_ovf_scheduler.n_list), 65 .schedule = ip_vs_ovf_schedule, 66 }; 67 68 static int __init ip_vs_ovf_init(void) 69 { 70 return register_ip_vs_scheduler(&ip_vs_ovf_scheduler); 71 } 72 73 static void __exit ip_vs_ovf_cleanup(void) 74 { 75 unregister_ip_vs_scheduler(&ip_vs_ovf_scheduler); 76 synchronize_rcu(); 77 } 78 79 module_init(ip_vs_ovf_init); 80 module_exit(ip_vs_ovf_cleanup); 81 MODULE_LICENSE("GPL"); 82