patch-2.4.23 linux-2.4.23/net/ipv4/ipvs/ip_vs_wrr.c

• Lines: 241
• Date: 2003-11-28 10:26:21.000000000 -0800
• Orig file: linux-2.4.22/net/ipv4/ipvs/ip_vs_wrr.c
• Orig date: 1969-12-31 16:00:00.000000000 -0800

diff -urN linux-2.4.22/net/ipv4/ipvs/ip_vs_wrr.c linux-2.4.23/net/ipv4/ipvs/ip_vs_wrr.c
@@ -0,0 +1,240 @@
+/*
+ * IPVS:        Weighted Round-Robin Scheduling module
+ *
+ * Version:     $Id: ip_vs_wrr.c,v 1.11 2002/03/25 12:44:35 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            :     changed the ip_vs_wrr_schedule to return dest
+ *     Wensong Zhang            :     changed some comestics things for debugging
+ *     Wensong Zhang            :     changed for the d-linked destination list
+ *     Wensong Zhang            :     added the ip_vs_wrr_update_svc
+ *     Julian Anastasov         :     fixed the bug of returning destination
+ *                                    with weight 0 when all weights are zero
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+
+#include <net/ip_vs.h>
+
+/*
+ * current destination pointer for weighted round-robin scheduling
+ */
+struct ip_vs_wrr_mark {
+	struct list_head *cl;	/* current list head */
+	int cw;			/* current weight */
+	int mw;			/* maximum weight */
+	int di;			/* decreasing interval */
+};
+
+
+/*
+ *    Get the gcd of server weights
+ */
+static int gcd(int a, int b)
+{
+	int c;
+
+	while ((c = a % b)) {
+		a = b;
+		b = c;
+	}
+	return b;
+}
+
+static int ip_vs_wrr_gcd_weight(struct ip_vs_service *svc)
+{
+	register struct list_head *l, *e;
+	struct ip_vs_dest *dest;
+	int weight;
+	int g = 1;
+
+	l = &svc->destinations;
+	for (e=l->next; e!=l; e=e->next) {
+		dest = list_entry(e, struct ip_vs_dest, n_list);
+		weight = atomic_read(&dest->weight);
+		if (weight > 0) {
+			g = weight;
+			break;
+		}
+	}
+	if (e == l)
+		return g;
+
+	for (e=e->next; e!=l; e=e->next) {
+		dest = list_entry(e, struct ip_vs_dest, n_list);
+		weight = atomic_read(&dest->weight);
+		if (weight > 0)
+			g = gcd(weight, g);
+	}
+
+	return g;
+}
+
+
+/*
+ *    Get the maximum weight of the service destinations.
+ */
+static int ip_vs_wrr_max_weight(struct ip_vs_service *svc)
+{
+	register struct list_head *l, *e;
+	struct ip_vs_dest *dest;
+	int weight = 0;
+
+	l = &svc->destinations;
+	for (e=l->next; e!=l; e=e->next) {
+		dest = list_entry(e, struct ip_vs_dest, n_list);
+		if (atomic_read(&dest->weight) > weight)
+			weight = atomic_read(&dest->weight);
+	}
+
+	return weight;
+}
+
+
+static int ip_vs_wrr_init_svc(struct ip_vs_service *svc)
+{
+	struct ip_vs_wrr_mark *mark;
+
+	/*
+	 *    Allocate the mark variable for WRR scheduling
+	 */
+	mark = kmalloc(sizeof(struct ip_vs_wrr_mark), GFP_ATOMIC);
+	if (mark == NULL) {
+		IP_VS_ERR("ip_vs_wrr_init_svc(): no memory\n");
+		return -ENOMEM;
+	}
+	mark->cl = &svc->destinations;
+	mark->cw = 0;
+	mark->mw = ip_vs_wrr_max_weight(svc);
+	mark->di = ip_vs_wrr_gcd_weight(svc);
+	svc->sched_data = mark;
+
+	return 0;
+}
+
+
+static int ip_vs_wrr_done_svc(struct ip_vs_service *svc)
+{
+	/*
+	 *    Release the mark variable
+	 */
+	kfree(svc->sched_data);
+
+	return 0;
+}
+
+
+static int ip_vs_wrr_update_svc(struct ip_vs_service *svc)
+{
+	struct ip_vs_wrr_mark *mark = svc->sched_data;
+
+	mark->cl = &svc->destinations;
+	mark->mw = ip_vs_wrr_max_weight(svc);
+	mark->di = ip_vs_wrr_gcd_weight(svc);
+	return 0;
+}
+
+
+/*
+ *    Weighted Round-Robin Scheduling
+ */
+static struct ip_vs_dest *
+ip_vs_wrr_schedule(struct ip_vs_service *svc, struct iphdr *iph)
+{
+	struct ip_vs_dest *dest;
+	struct ip_vs_wrr_mark *mark = svc->sched_data;
+
+	IP_VS_DBG(6, "ip_vs_wrr_schedule(): Scheduling...\n");
+
+	/*
+	 * This loop will always terminate, because 0<mark->cw<max_weight,
+	 * and at least one server has its weight equal to max_weight.
+	 */
+	write_lock(&svc->sched_lock);
+	while (1) {
+		if (mark->cl == &svc->destinations) {
+			/* it is at the head of the destination list */
+
+			if (mark->cl == mark->cl->next) {
+				/* no dest entry */
+				write_unlock(&svc->sched_lock);
+				return NULL;
+			}
+
+			mark->cl = svc->destinations.next;
+			mark->cw -= mark->di;
+			if (mark->cw <= 0) {
+				mark->cw = mark->mw;
+				/*
+				 * Still zero, which means no availabe servers.
+				 */
+				if (mark->cw == 0) {
+					mark->cl = &svc->destinations;
+					write_unlock(&svc->sched_lock);
+					IP_VS_INFO("ip_vs_wrr_schedule(): "
+						   "no available servers\n");
+					return NULL;
+				}
+			}
+		}
+		else mark->cl = mark->cl->next;
+
+		if (mark->cl != &svc->destinations) {
+			/* not at the head of the list */
+			dest = list_entry(mark->cl, struct ip_vs_dest, n_list);
+			if (atomic_read(&dest->weight) >= mark->cw) {
+				write_unlock(&svc->sched_lock);
+				break;
+			}
+		}
+	}
+
+	IP_VS_DBG(6, "WRR: server %u.%u.%u.%u:%u "
+		  "activeconns %d refcnt %d weight %d\n",
+		  NIPQUAD(dest->addr), ntohs(dest->port),
+		  atomic_read(&dest->activeconns),
+		  atomic_read(&dest->refcnt),
+		  atomic_read(&dest->weight));
+
+	return	dest;
+}
+
+
+static struct ip_vs_scheduler ip_vs_wrr_scheduler = {
+	{0},			/* n_list */
+	"wrr",			/* name */
+	ATOMIC_INIT(0),		/* refcnt */
+	THIS_MODULE,		/* this module */
+	ip_vs_wrr_init_svc,	/* service initializer */
+	ip_vs_wrr_done_svc,	/* service done */
+	ip_vs_wrr_update_svc,	/* service updater */
+	ip_vs_wrr_schedule,	/* select a server from the destination list */
+};
+
+static int __init ip_vs_wrr_init(void)
+{
+	INIT_LIST_HEAD(&ip_vs_wrr_scheduler.n_list);
+	return register_ip_vs_scheduler(&ip_vs_wrr_scheduler) ;
+}
+
+static void __exit ip_vs_wrr_cleanup(void)
+{
+	unregister_ip_vs_scheduler(&ip_vs_wrr_scheduler);
+}
+
+module_init(ip_vs_wrr_init);
+module_exit(ip_vs_wrr_cleanup);
+MODULE_LICENSE("GPL");