/* * IPVS: Least-Connection Scheduling module * * Version: $Id: ip_vs_lc.c,v 1.10 2003/04/18 09:03:16 wensong Exp $ * * Authors: Wensong Zhang <wensong@linuxvirtualserver.org> * * 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 : added the ip_vs_lc_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_lc_init_svc(struct ip_vs_service *svc) { return 0; } static int ip_vs_lc_done_svc(struct ip_vs_service *svc) { return 0; } static int ip_vs_lc_update_svc(struct ip_vs_service *svc) { return 0; } static inline unsigned int ip_vs_lc_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); } /* * Least Connection scheduling */ static struct ip_vs_dest * ip_vs_lc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb) { struct ip_vs_dest *dest, *least = NULL; unsigned int loh = 0, doh; IP_VS_DBG(6, "ip_vs_lc_schedule(): Scheduling...\n"); /* * Simply select the server with the least number of * (activeconns<<5) + inactconns * Except whose weight is equal to zero. * If the weight is equal to zero, it means that the server is * quiesced, the existing connections to the server still get * served, but no new connection is assigned to the server. */ list_for_each_entry(dest, &svc->destinations, n_list) { if ((dest->flags & IP_VS_DEST_F_OVERLOAD) || atomic_read(&dest->weight) == 0) continue; doh = ip_vs_lc_dest_overhead(dest); if (!least || doh < loh) { least = dest; loh = doh; } } if (least) IP_VS_DBG(6, "LC: server %u.%u.%u.%u:%u activeconns %d inactconns %d\n", NIPQUAD(least->addr), ntohs(least->port), atomic_read(&least->activeconns), atomic_read(&least->inactconns)); return least; } static struct ip_vs_scheduler ip_vs_lc_scheduler = { .name = "lc", .refcnt = ATOMIC_INIT(0), .module = THIS_MODULE, .init_service = ip_vs_lc_init_svc, .done_service = ip_vs_lc_done_svc, .update_service = ip_vs_lc_update_svc, .schedule = ip_vs_lc_schedule, }; static int __init ip_vs_lc_init(void) { INIT_LIST_HEAD(&ip_vs_lc_scheduler.n_list); return register_ip_vs_scheduler(&ip_vs_lc_scheduler) ; } static void __exit ip_vs_lc_cleanup(void) { unregister_ip_vs_scheduler(&ip_vs_lc_scheduler); } module_init(ip_vs_lc_init); module_exit(ip_vs_lc_cleanup); MODULE_LICENSE("GPL");