[deliverable/linux.git] / net / ipv4 / ipvs / ip_vs_wlc.c

/*
 * 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
 *
 */

#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");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* IPVS: Weighted Least-Connection Scheduling module
	3	*
1da177e4 LT	4	* Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
	5	* Peter Kese <peter.kese@ijs.si>
	6	*
	7	* This program is free software; you can redistribute it and/or
	8	* modify it under the terms of the GNU General Public License
	9	* as published by the Free Software Foundation; either version
	10	* 2 of the License, or (at your option) any later version.
	11	*
	12	* Changes:
	13	* Wensong Zhang : changed the ip_vs_wlc_schedule to return dest
	14	* Wensong Zhang : changed to use the inactconns in scheduling
	15	* Wensong Zhang : changed some comestics things for debugging
	16	* Wensong Zhang : changed for the d-linked destination list
	17	* Wensong Zhang : added the ip_vs_wlc_update_svc
	18	* Wensong Zhang : added any dest with weight=0 is quiesced
	19	*
	20	*/
	21
	22	#include <linux/module.h>
	23	#include <linux/kernel.h>
	24
	25	#include <net/ip_vs.h>
	26
	27
	28	static int
	29	ip_vs_wlc_init_svc(struct ip_vs_service *svc)
	30	{
	31	return 0;
	32	}
	33
	34
	35	static int
	36	ip_vs_wlc_done_svc(struct ip_vs_service *svc)
	37	{
	38	return 0;
	39	}
	40
	41
	42	static int
	43	ip_vs_wlc_update_svc(struct ip_vs_service *svc)
	44	{
	45	return 0;
	46	}
	47
	48
	49	static inline unsigned int
	50	ip_vs_wlc_dest_overhead(struct ip_vs_dest *dest)
	51	{
	52	/*
	53	* We think the overhead of processing active connections is 256
	54	* times higher than that of inactive connections in average. (This
	55	* 256 times might not be accurate, we will change it later) We
	56	* use the following formula to estimate the overhead now:
	57	* dest->activeconns*256 + dest->inactconns
	58	*/
	59	return (atomic_read(&dest->activeconns) << 8) +
	60	atomic_read(&dest->inactconns);
	61	}
	62
	63
	64	/*
	65	* Weighted Least Connection scheduling
	66	*/
	67	static struct ip_vs_dest *
68	ip_vs_wlc_schedule(struct ip_vs_service svc, const struct sk_buff skb)
69	{
70	struct ip_vs_dest dest, least;
71	unsigned int loh, doh;
72
73	IP_VS_DBG(6, "ip_vs_wlc_schedule(): Scheduling...\n");
74
75	/*
76	* We calculate the load of each dest server as follows:
77	* (dest overhead) / dest->weight
78	*
79	* Remember -- no floats in kernel mode!!!
80	* The comparison of h1w2 > h2w1 is equivalent to that of
81	* h1/w1 > h2/w2
82	* if every weight is larger than zero.
83	*
84	* The server with weight=0 is quiesced and will not receive any
85	* new connections.
86	*/
87
88	list_for_each_entry(dest, &svc->destinations, n_list) {
89	if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
90	atomic_read(&dest->weight) > 0) {
91	least = dest;
92	loh = ip_vs_wlc_dest_overhead(least);
93	goto nextstage;
94	}
95	}
96	return NULL;
97
98	/*
99	* Find the destination with the least load.
100	*/
101	nextstage:
102	list_for_each_entry_continue(dest, &svc->destinations, n_list) {
103	if (dest->flags & IP_VS_DEST_F_OVERLOAD)
104	continue;
105	doh = ip_vs_wlc_dest_overhead(dest);
106	if (loh * atomic_read(&dest->weight) >
107	doh * atomic_read(&least->weight)) {
108	least = dest;
109	loh = doh;
110	}
111	}
112
113	IP_VS_DBG(6, "WLC: server %u.%u.%u.%u:%u "
114	"activeconns %d refcnt %d weight %d overhead %d\n",
115	NIPQUAD(least->addr), ntohs(least->port),
116	atomic_read(&least->activeconns),
117	atomic_read(&least->refcnt),
118	atomic_read(&least->weight), loh);
119
120	return least;
121	}
122
123
124	static struct ip_vs_scheduler ip_vs_wlc_scheduler =
125	{
126	.name = "wlc",
127	.refcnt = ATOMIC_INIT(0),
128	.module = THIS_MODULE,
129	.init_service = ip_vs_wlc_init_svc,
130	.done_service = ip_vs_wlc_done_svc,
131	.update_service = ip_vs_wlc_update_svc,
132	.schedule = ip_vs_wlc_schedule,
133	};
134
135
136	static int __init ip_vs_wlc_init(void)
137	{
138	INIT_LIST_HEAD(&ip_vs_wlc_scheduler.n_list);
139	return register_ip_vs_scheduler(&ip_vs_wlc_scheduler);
140	}
141
142	static void __exit ip_vs_wlc_cleanup(void)
143	{
144	unregister_ip_vs_scheduler(&ip_vs_wlc_scheduler);
145	}
146
147	module_init(ip_vs_wlc_init);
148	module_exit(ip_vs_wlc_cleanup);
149	MODULE_LICENSE("GPL");