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 31static inline unsigned int 32ip_vs_wlc_dest_overhead(struct ip_vs_dest *dest) 33{ 34 /* 35 * We think the overhead of processing active connections is 256 36 * times higher than that of inactive connections in average. (This 37 * 256 times might not be accurate, we will change it later) We 38 * use the following formula to estimate the overhead now: 39 * dest->activeconns*256 + dest->inactconns 40 */ 41 return (atomic_read(&dest->activeconns) << 8) + 42 atomic_read(&dest->inactconns); 43} 44 45 46/* 47 * Weighted Least Connection scheduling 48 */ 49static struct ip_vs_dest * 50ip_vs_wlc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb) 51{ 52 struct ip_vs_dest *dest, *least; 53 unsigned int loh, doh; 54 55 IP_VS_DBG(6, "ip_vs_wlc_schedule(): Scheduling...\n"); 56 57 /* 58 * We calculate the load of each dest server as follows: 59 * (dest overhead) / dest->weight 60 * 61 * Remember -- no floats in kernel mode!!! 62 * The comparison of h1*w2 > h2*w1 is equivalent to that of 63 * h1/w1 > h2/w2 64 * if every weight is larger than zero. 65 * 66 * The server with weight=0 is quiesced and will not receive any 67 * new connections. 68 */ 69 70 list_for_each_entry(dest, &svc->destinations, n_list) { 71 if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && 72 atomic_read(&dest->weight) > 0) { 73 least = dest; 74 loh = ip_vs_wlc_dest_overhead(least); 75 goto nextstage; 76 } 77 } 78 IP_VS_ERR_RL("WLC: no destination available\n"); 79 return NULL; 80 81 /* 82 * Find the destination with the least load. 83 */ 84 nextstage: 85 list_for_each_entry_continue(dest, &svc->destinations, n_list) { 86 if (dest->flags & IP_VS_DEST_F_OVERLOAD) 87 continue; 88 doh = ip_vs_wlc_dest_overhead(dest); 89 if (loh * atomic_read(&dest->weight) > 90 doh * atomic_read(&least->weight)) { 91 least = dest; 92 loh = doh; 93 } 94 } 95 96 IP_VS_DBG_BUF(6, "WLC: server %s:%u " 97 "activeconns %d refcnt %d weight %d overhead %d\n", 98 IP_VS_DBG_ADDR(svc->af, &least->addr), ntohs(least->port), 99 atomic_read(&least->activeconns), 100 atomic_read(&least->refcnt), 101 atomic_read(&least->weight), loh); 102 103 return least; 104} 105 106 107static struct ip_vs_scheduler ip_vs_wlc_scheduler = 108{ 109 .name = "wlc", 110 .refcnt = ATOMIC_INIT(0), 111 .module = THIS_MODULE, 112 .n_list = LIST_HEAD_INIT(ip_vs_wlc_scheduler.n_list), 113 .schedule = ip_vs_wlc_schedule, 114}; 115 116 117static int __init ip_vs_wlc_init(void) 118{ 119 return register_ip_vs_scheduler(&ip_vs_wlc_scheduler); 120} 121 122static void __exit ip_vs_wlc_cleanup(void) 123{ 124 unregister_ip_vs_scheduler(&ip_vs_wlc_scheduler); 125} 126 127module_init(ip_vs_wlc_init); 128module_exit(ip_vs_wlc_cleanup); 129MODULE_LICENSE("GPL"); 130