/* * IPVS: Weighted Least-Connection Scheduling module * * Version: $Id: ip_vs_wlc.c,v 1.13 2003/04/18 09:03:16 wensong Exp $ * * 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 * */ #include <linux/module.h> #include <linux/kernel.h> #include <net/ip_vs.h> static int ip_vs_wlc_init_svc(struct ip_vs_service *svc) { return 0; } static int ip_vs_wlc_done_svc(struct ip_vs_service *svc) { return 0; } static int ip_vs_wlc_update_svc(struct ip_vs_service *svc) { return 0; } 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; } } 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(6, "WLC: server %u.%u.%u.%u:%u " "activeconns %d refcnt %d weight %d overhead %d\n", NIPQUAD(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, .init_service = ip_vs_wlc_init_svc, .done_service = ip_vs_wlc_done_svc, .update_service = ip_vs_wlc_update_svc, .schedule = ip_vs_wlc_schedule, }; static int __init ip_vs_wlc_init(void) { INIT_LIST_HEAD(&ip_vs_wlc_scheduler.n_list); 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");