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Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
235 lines
5.3 KiB
C
235 lines
5.3 KiB
C
/*
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* IPVS: Weighted Round-Robin Scheduling module
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*
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* Version: $Id: ip_vs_wrr.c,v 1.12 2002/09/15 08:14:08 wensong Exp $
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*
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* Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Changes:
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* Wensong Zhang : changed the ip_vs_wrr_schedule to return dest
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* Wensong Zhang : changed some comestics things for debugging
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* Wensong Zhang : changed for the d-linked destination list
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* Wensong Zhang : added the ip_vs_wrr_update_svc
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* Julian Anastasov : fixed the bug of returning destination
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* with weight 0 when all weights are zero
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*
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <net/ip_vs.h>
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/*
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* current destination pointer for weighted round-robin scheduling
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*/
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struct ip_vs_wrr_mark {
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struct list_head *cl; /* current list head */
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int cw; /* current weight */
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int mw; /* maximum weight */
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int di; /* decreasing interval */
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};
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/*
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* Get the gcd of server weights
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*/
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static int gcd(int a, int b)
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{
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int c;
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while ((c = a % b)) {
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a = b;
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b = c;
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}
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return b;
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}
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static int ip_vs_wrr_gcd_weight(struct ip_vs_service *svc)
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{
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struct ip_vs_dest *dest;
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int weight;
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int g = 0;
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list_for_each_entry(dest, &svc->destinations, n_list) {
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weight = atomic_read(&dest->weight);
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if (weight > 0) {
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if (g > 0)
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g = gcd(weight, g);
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else
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g = weight;
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}
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}
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return g ? g : 1;
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}
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/*
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* Get the maximum weight of the service destinations.
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*/
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static int ip_vs_wrr_max_weight(struct ip_vs_service *svc)
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{
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struct ip_vs_dest *dest;
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int weight = 0;
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list_for_each_entry(dest, &svc->destinations, n_list) {
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if (atomic_read(&dest->weight) > weight)
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weight = atomic_read(&dest->weight);
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}
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return weight;
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}
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static int ip_vs_wrr_init_svc(struct ip_vs_service *svc)
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{
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struct ip_vs_wrr_mark *mark;
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/*
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* Allocate the mark variable for WRR scheduling
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*/
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mark = kmalloc(sizeof(struct ip_vs_wrr_mark), GFP_ATOMIC);
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if (mark == NULL) {
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IP_VS_ERR("ip_vs_wrr_init_svc(): no memory\n");
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return -ENOMEM;
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}
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mark->cl = &svc->destinations;
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mark->cw = 0;
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mark->mw = ip_vs_wrr_max_weight(svc);
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mark->di = ip_vs_wrr_gcd_weight(svc);
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svc->sched_data = mark;
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return 0;
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}
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static int ip_vs_wrr_done_svc(struct ip_vs_service *svc)
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{
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/*
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* Release the mark variable
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*/
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kfree(svc->sched_data);
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return 0;
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}
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static int ip_vs_wrr_update_svc(struct ip_vs_service *svc)
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{
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struct ip_vs_wrr_mark *mark = svc->sched_data;
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mark->cl = &svc->destinations;
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mark->mw = ip_vs_wrr_max_weight(svc);
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mark->di = ip_vs_wrr_gcd_weight(svc);
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if (mark->cw > mark->mw)
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mark->cw = 0;
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return 0;
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}
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/*
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* Weighted Round-Robin Scheduling
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*/
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static struct ip_vs_dest *
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ip_vs_wrr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
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{
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struct ip_vs_dest *dest;
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struct ip_vs_wrr_mark *mark = svc->sched_data;
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struct list_head *p;
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IP_VS_DBG(6, "ip_vs_wrr_schedule(): Scheduling...\n");
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/*
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* This loop will always terminate, because mark->cw in (0, max_weight]
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* and at least one server has its weight equal to max_weight.
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*/
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write_lock(&svc->sched_lock);
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p = mark->cl;
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while (1) {
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if (mark->cl == &svc->destinations) {
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/* it is at the head of the destination list */
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if (mark->cl == mark->cl->next) {
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/* no dest entry */
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dest = NULL;
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goto out;
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}
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mark->cl = svc->destinations.next;
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mark->cw -= mark->di;
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if (mark->cw <= 0) {
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mark->cw = mark->mw;
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/*
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* Still zero, which means no available servers.
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*/
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if (mark->cw == 0) {
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mark->cl = &svc->destinations;
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IP_VS_INFO("ip_vs_wrr_schedule(): "
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"no available servers\n");
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dest = NULL;
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goto out;
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}
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}
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} else
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mark->cl = mark->cl->next;
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if (mark->cl != &svc->destinations) {
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/* not at the head of the list */
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dest = list_entry(mark->cl, struct ip_vs_dest, n_list);
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if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
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atomic_read(&dest->weight) >= mark->cw) {
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/* got it */
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break;
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}
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}
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if (mark->cl == p && mark->cw == mark->di) {
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/* back to the start, and no dest is found.
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It is only possible when all dests are OVERLOADED */
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dest = NULL;
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goto out;
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}
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}
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IP_VS_DBG(6, "WRR: server %u.%u.%u.%u:%u "
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"activeconns %d refcnt %d weight %d\n",
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NIPQUAD(dest->addr), ntohs(dest->port),
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atomic_read(&dest->activeconns),
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atomic_read(&dest->refcnt),
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atomic_read(&dest->weight));
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out:
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write_unlock(&svc->sched_lock);
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return dest;
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}
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static struct ip_vs_scheduler ip_vs_wrr_scheduler = {
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.name = "wrr",
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.refcnt = ATOMIC_INIT(0),
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.module = THIS_MODULE,
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.init_service = ip_vs_wrr_init_svc,
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.done_service = ip_vs_wrr_done_svc,
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.update_service = ip_vs_wrr_update_svc,
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.schedule = ip_vs_wrr_schedule,
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};
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static int __init ip_vs_wrr_init(void)
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{
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INIT_LIST_HEAD(&ip_vs_wrr_scheduler.n_list);
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return register_ip_vs_scheduler(&ip_vs_wrr_scheduler) ;
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}
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static void __exit ip_vs_wrr_cleanup(void)
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{
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unregister_ip_vs_scheduler(&ip_vs_wrr_scheduler);
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}
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module_init(ip_vs_wrr_init);
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module_exit(ip_vs_wrr_cleanup);
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MODULE_LICENSE("GPL");
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