| /* |
| * IPVS: Weighted Least-Connection Scheduling module |
| * |
| * Authors: Wensong Zhang <wensong@linuxvirtualserver.org> |
| * Peter Kese <peter.kese@ijs.si> |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| * |
| * Changes: |
| * Wensong Zhang : changed the ip_vs_wlc_schedule to return dest |
| * Wensong Zhang : changed to use the inactconns in scheduling |
| * Wensong Zhang : changed some comestics things for debugging |
| * Wensong Zhang : changed for the d-linked destination list |
| * Wensong Zhang : added the ip_vs_wlc_update_svc |
| * Wensong Zhang : added any dest with weight=0 is quiesced |
| * |
| */ |
| |
| #define KMSG_COMPONENT "IPVS" |
| #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt |
| |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| |
| #include <net/ip_vs.h> |
| |
| |
| static inline unsigned int |
| ip_vs_wlc_dest_overhead(struct ip_vs_dest *dest) |
| { |
| /* |
| * We think the overhead of processing active connections is 256 |
| * times higher than that of inactive connections in average. (This |
| * 256 times might not be accurate, we will change it later) We |
| * use the following formula to estimate the overhead now: |
| * dest->activeconns*256 + dest->inactconns |
| */ |
| return (atomic_read(&dest->activeconns) << 8) + |
| atomic_read(&dest->inactconns); |
| } |
| |
| |
| /* |
| * Weighted Least Connection scheduling |
| */ |
| static struct ip_vs_dest * |
| ip_vs_wlc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb) |
| { |
| struct ip_vs_dest *dest, *least; |
| unsigned int loh, doh; |
| |
| IP_VS_DBG(6, "ip_vs_wlc_schedule(): Scheduling...\n"); |
| |
| /* |
| * We calculate the load of each dest server as follows: |
| * (dest overhead) / dest->weight |
| * |
| * Remember -- no floats in kernel mode!!! |
| * The comparison of h1*w2 > h2*w1 is equivalent to that of |
| * h1/w1 > h2/w2 |
| * if every weight is larger than zero. |
| * |
| * The server with weight=0 is quiesced and will not receive any |
| * new connections. |
| */ |
| |
| list_for_each_entry(dest, &svc->destinations, n_list) { |
| if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && |
| atomic_read(&dest->weight) > 0) { |
| least = dest; |
| loh = ip_vs_wlc_dest_overhead(least); |
| goto nextstage; |
| } |
| } |
| IP_VS_ERR_RL("WLC: no destination available\n"); |
| return NULL; |
| |
| /* |
| * Find the destination with the least load. |
| */ |
| nextstage: |
| list_for_each_entry_continue(dest, &svc->destinations, n_list) { |
| if (dest->flags & IP_VS_DEST_F_OVERLOAD) |
| continue; |
| doh = ip_vs_wlc_dest_overhead(dest); |
| if (loh * atomic_read(&dest->weight) > |
| doh * atomic_read(&least->weight)) { |
| least = dest; |
| loh = doh; |
| } |
| } |
| |
| IP_VS_DBG_BUF(6, "WLC: server %s:%u " |
| "activeconns %d refcnt %d weight %d overhead %d\n", |
| IP_VS_DBG_ADDR(svc->af, &least->addr), ntohs(least->port), |
| atomic_read(&least->activeconns), |
| atomic_read(&least->refcnt), |
| atomic_read(&least->weight), loh); |
| |
| return least; |
| } |
| |
| |
| static struct ip_vs_scheduler ip_vs_wlc_scheduler = |
| { |
| .name = "wlc", |
| .refcnt = ATOMIC_INIT(0), |
| .module = THIS_MODULE, |
| .n_list = LIST_HEAD_INIT(ip_vs_wlc_scheduler.n_list), |
| .schedule = ip_vs_wlc_schedule, |
| }; |
| |
| |
| static int __init ip_vs_wlc_init(void) |
| { |
| return register_ip_vs_scheduler(&ip_vs_wlc_scheduler); |
| } |
| |
| static void __exit ip_vs_wlc_cleanup(void) |
| { |
| unregister_ip_vs_scheduler(&ip_vs_wlc_scheduler); |
| } |
| |
| module_init(ip_vs_wlc_init); |
| module_exit(ip_vs_wlc_cleanup); |
| MODULE_LICENSE("GPL"); |