[net-next-2.6.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 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,
	.n_list =		LIST_HEAD_INIT(ip_vs_wlc_scheduler.n_list),
	.schedule =		ip_vs_wlc_schedule,
};


static int __init ip_vs_wlc_init(void)
{
	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
1da177e4 LT	28	static inline unsigned int
	29	ip_vs_wlc_dest_overhead(struct ip_vs_dest *dest)
	30	{
	31	/*
	32	* We think the overhead of processing active connections is 256
	33	* times higher than that of inactive connections in average. (This
	34	* 256 times might not be accurate, we will change it later) We
	35	* use the following formula to estimate the overhead now:
	36	* dest->activeconns*256 + dest->inactconns
	37	*/
	38	return (atomic_read(&dest->activeconns) << 8) +
	39	atomic_read(&dest->inactconns);
	40	}
	41
	42
	43	/*
	44	* Weighted Least Connection scheduling
	45	*/
	46	static struct ip_vs_dest *
	47	ip_vs_wlc_schedule(struct ip_vs_service svc, const struct sk_buff skb)
	48	{
	49	struct ip_vs_dest dest, least;
	50	unsigned int loh, doh;
	51
	52	IP_VS_DBG(6, "ip_vs_wlc_schedule(): Scheduling...\n");
	53
	54	/*
	55	* We calculate the load of each dest server as follows:
	56	* (dest overhead) / dest->weight
	57	*
	58	* Remember -- no floats in kernel mode!!!
	59	* The comparison of h1w2 > h2w1 is equivalent to that of
	60	* h1/w1 > h2/w2
	61	* if every weight is larger than zero.
	62	*
	63	* The server with weight=0 is quiesced and will not receive any
	64	* new connections.
	65	*/
	66
	67	list_for_each_entry(dest, &svc->destinations, n_list) {
	68	if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
	69	atomic_read(&dest->weight) > 0) {
	70	least = dest;
	71	loh = ip_vs_wlc_dest_overhead(least);
	72	goto nextstage;
	73	}
	74	}
	75	return NULL;
	76
	77	/*
	78	* Find the destination with the least load.
	79	*/
	80	nextstage:
	81	list_for_each_entry_continue(dest, &svc->destinations, n_list) {
	82	if (dest->flags & IP_VS_DEST_F_OVERLOAD)
	83	continue;
	84	doh = ip_vs_wlc_dest_overhead(dest);
	85	if (loh * atomic_read(&dest->weight) >
	86	doh * atomic_read(&least->weight)) {
	87	least = dest;
	88	loh = doh;
	89	}
	90	}
	91
92	IP_VS_DBG(6, "WLC: server %u.%u.%u.%u:%u "
93	"activeconns %d refcnt %d weight %d overhead %d\n",
94	NIPQUAD(least->addr), ntohs(least->port),
95	atomic_read(&least->activeconns),
96	atomic_read(&least->refcnt),
97	atomic_read(&least->weight), loh);
98
99	return least;
100	}
101
102
103	static struct ip_vs_scheduler ip_vs_wlc_scheduler =
104	{
105	.name = "wlc",
106	.refcnt = ATOMIC_INIT(0),
107	.module = THIS_MODULE,
d149ccc9	108	.n_list = LIST_HEAD_INIT(ip_vs_wlc_scheduler.n_list),
1da177e4 LT	109	.schedule = ip_vs_wlc_schedule,
	110	};
	111
	112
	113	static int __init ip_vs_wlc_init(void)
	114	{
1da177e4 LT	115	return register_ip_vs_scheduler(&ip_vs_wlc_scheduler);
	116	}
	117
	118	static void __exit ip_vs_wlc_cleanup(void)
	119	{
	120	unregister_ip_vs_scheduler(&ip_vs_wlc_scheduler);
	121	}
	122
	123	module_init(ip_vs_wlc_init);
	124	module_exit(ip_vs_wlc_cleanup);
	125	MODULE_LICENSE("GPL");