Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * IPVS: Least-Connection Scheduling module |
| 3 | * |
| 4 | * Version: $Id: ip_vs_lc.c,v 1.10 2003/04/18 09:03:16 wensong 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 | |
| 25 | static int ip_vs_lc_init_svc(struct ip_vs_service *svc) |
| 26 | { |
| 27 | return 0; |
| 28 | } |
| 29 | |
| 30 | |
| 31 | static int ip_vs_lc_done_svc(struct ip_vs_service *svc) |
| 32 | { |
| 33 | return 0; |
| 34 | } |
| 35 | |
| 36 | |
| 37 | static int ip_vs_lc_update_svc(struct ip_vs_service *svc) |
| 38 | { |
| 39 | return 0; |
| 40 | } |
| 41 | |
| 42 | |
| 43 | static inline unsigned int |
| 44 | ip_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 | */ |
| 61 | static struct ip_vs_dest * |
| 62 | ip_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 | |
| 99 | static 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 | |
| 110 | static 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 | |
| 116 | static void __exit ip_vs_lc_cleanup(void) |
| 117 | { |
| 118 | unregister_ip_vs_scheduler(&ip_vs_lc_scheduler); |
| 119 | } |
| 120 | |
| 121 | module_init(ip_vs_lc_init); |
| 122 | module_exit(ip_vs_lc_cleanup); |
| 123 | MODULE_LICENSE("GPL"); |