Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * IPVS: Weighted Least-Connection Scheduling module |
| 3 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
Hannes Eder | 9aada7a | 2009-07-30 14:29:44 -0700 | [diff] [blame^] | 22 | #define KMSG_COMPONENT "IPVS" |
| 23 | #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt |
| 24 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 25 | #include <linux/module.h> |
| 26 | #include <linux/kernel.h> |
| 27 | |
| 28 | #include <net/ip_vs.h> |
| 29 | |
| 30 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | static inline unsigned int |
| 32 | ip_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 | */ |
| 49 | static struct ip_vs_dest * |
| 50 | ip_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 | } |
Simon Horman | 68888d1 | 2008-12-29 18:37:36 -0800 | [diff] [blame] | 78 | IP_VS_ERR_RL("WLC: no destination available\n"); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
Julius Volz | b14198f | 2008-09-02 15:55:39 +0200 | [diff] [blame] | 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); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 102 | |
| 103 | return least; |
| 104 | } |
| 105 | |
| 106 | |
| 107 | static struct ip_vs_scheduler ip_vs_wlc_scheduler = |
| 108 | { |
| 109 | .name = "wlc", |
| 110 | .refcnt = ATOMIC_INIT(0), |
| 111 | .module = THIS_MODULE, |
Sven Wegener | d149ccc | 2008-08-10 09:18:02 +0000 | [diff] [blame] | 112 | .n_list = LIST_HEAD_INIT(ip_vs_wlc_scheduler.n_list), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 113 | .schedule = ip_vs_wlc_schedule, |
| 114 | }; |
| 115 | |
| 116 | |
| 117 | static int __init ip_vs_wlc_init(void) |
| 118 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 119 | return register_ip_vs_scheduler(&ip_vs_wlc_scheduler); |
| 120 | } |
| 121 | |
| 122 | static void __exit ip_vs_wlc_cleanup(void) |
| 123 | { |
| 124 | unregister_ip_vs_scheduler(&ip_vs_wlc_scheduler); |
| 125 | } |
| 126 | |
| 127 | module_init(ip_vs_wlc_init); |
| 128 | module_exit(ip_vs_wlc_cleanup); |
| 129 | MODULE_LICENSE("GPL"); |