ip_vs_lblc.c

linux-2.4.29操作系统的源码

	}
	tbl->rover = j;
}


/*
 *      Periodical timer handler for IPVS lblc table
 *      It is used to collect stale entries when the number of entries
 *      exceeds the maximum size of the table.
 *
 *      Fixme: we probably need more complicated algorithm to collect
 *             entries that have not been used for a long time even
 *             if the number of entries doesn't exceed the maximum size
 *             of the table.
 *      The full expiration check is for this purpose now.
 */
static void ip_vs_lblc_check_expire(unsigned long data)
{
	struct ip_vs_lblc_table *tbl;
	unsigned long now = jiffies;
	int goal;
	int i, j;
	struct list_head *l, *e;
	struct ip_vs_lblc_entry *en;

	tbl = (struct ip_vs_lblc_table *)data;

	if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
		/* do full expiration check */
		ip_vs_lblc_full_check(tbl);
		tbl->counter = 1;
		goto out;
	}

	if (atomic_read(&tbl->entries) <= tbl->max_size) {
		tbl->counter++;
		goto out;
	}

	goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3;
	if (goal > tbl->max_size/2)
		goal = tbl->max_size/2;

	for (i=0, j=tbl->rover; i<IP_VS_LBLC_TAB_SIZE; i++) {
		j = (j + 1) & IP_VS_LBLC_TAB_MASK;
		e = l = &tbl->bucket[j];
		write_lock(&tbl->lock);
		while (e->next != l) {
			en = list_entry(e->next,
					struct ip_vs_lblc_entry, list);
			if ((now - en->lastuse) < ENTRY_TIMEOUT) {
				e = e->next;
				continue;
			}
			ip_vs_lblc_free(en);
			atomic_dec(&tbl->entries);
			goal--;
		}
		write_unlock(&tbl->lock);
		if (goal <= 0)
			break;
	}
	tbl->rover = j;

  out:
	mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL);
}


static int ip_vs_lblc_init_svc(struct ip_vs_service *svc)
{
	int i;
	struct ip_vs_lblc_table *tbl;

	/*
	 *    Allocate the ip_vs_lblc_table for this service
	 */
	tbl = kmalloc(sizeof(struct ip_vs_lblc_table), GFP_ATOMIC);
	if (tbl == NULL) {
		IP_VS_ERR("ip_vs_lblc_init_svc(): no memory\n");
		return -ENOMEM;
	}
	svc->sched_data = tbl;
	IP_VS_DBG(6, "LBLC hash table (memory=%dbytes) allocated for "
		  "current service\n",
		  sizeof(struct ip_vs_lblc_table));

	/*
	 *    Initialize the hash buckets
	 */
	for (i=0; i<IP_VS_LBLC_TAB_SIZE; i++) {
		INIT_LIST_HEAD(&tbl->bucket[i]);
	}
	tbl->lock = RW_LOCK_UNLOCKED;
	tbl->max_size = IP_VS_LBLC_TAB_SIZE*16;
	tbl->rover = 0;
	tbl->counter = 1;

	/*
	 *    Hook periodic timer for garbage collection
	 */
	init_timer(&tbl->periodic_timer);
	tbl->periodic_timer.data = (unsigned long)tbl;
	tbl->periodic_timer.function = ip_vs_lblc_check_expire;
	tbl->periodic_timer.expires = jiffies+CHECK_EXPIRE_INTERVAL;
	add_timer(&tbl->periodic_timer);

	return 0;
}


static int ip_vs_lblc_done_svc(struct ip_vs_service *svc)
{
	struct ip_vs_lblc_table *tbl = svc->sched_data;

	/* remove periodic timer */
	del_timer_sync(&tbl->periodic_timer);

	/* got to clean up table entries here */
	ip_vs_lblc_flush(tbl);

	/* release the table itself */
	kfree(svc->sched_data);
	IP_VS_DBG(6, "LBLC hash table (memory=%dbytes) released\n",
		  sizeof(struct ip_vs_lblc_table));

	return 0;
}


static int ip_vs_lblc_update_svc(struct ip_vs_service *svc)
{
	return 0;
}


static inline struct ip_vs_dest *
__ip_vs_wlc_schedule(struct ip_vs_service *svc, struct iphdr *iph)
{
	register struct list_head *l, *e;
	struct ip_vs_dest *dest, *least;
	int loh, doh;

	/*
	 * We think the overhead of processing active connections is fifty
	 * times higher than that of inactive connections in average. (This
	 * fifty times might not be accurate, we will change it later.) We
	 * use the following formula to estimate the overhead:
	 *                dest->activeconns*50 + dest->inactconns
	 * and the load:
	 *                (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 connection.
	 */

	l = &svc->destinations;
	for (e=l->next; e!=l; e=e->next) {
		least = list_entry(e, struct ip_vs_dest, n_list);
		if (atomic_read(&least->weight) > 0) {
			loh = atomic_read(&least->activeconns) * 50
				+ atomic_read(&least->inactconns);
			goto nextstage;
		}
	}
	return NULL;

	/*
	 *    Find the destination with the least load.
	 */
  nextstage:
	for (e=e->next; e!=l; e=e->next) {
		dest = list_entry(e, struct ip_vs_dest, n_list);
		doh = atomic_read(&dest->activeconns) * 50
			+ atomic_read(&dest->inactconns);
		if (loh * atomic_read(&dest->weight) >
		    doh * atomic_read(&least->weight)) {
			least = dest;
			loh = doh;
		}
	}

	IP_VS_DBG(6, "LBLC: server %d.%d.%d.%d:%d "
		  "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;
}


/*
 *   If this destination server is overloaded and there is a less loaded
 *   server, then return true.
 */
static inline int
is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc)
{
	if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {
		register struct list_head *l, *e;
		struct ip_vs_dest *d;

		l = &svc->destinations;
		for (e=l->next; e!=l; e=e->next) {
			d = list_entry(e, struct ip_vs_dest, n_list);
			if (atomic_read(&d->activeconns)*2
			    < atomic_read(&d->weight)) {
				return 1;
			}
		}
	}
	return 0;
}


/*
 *    Locality-Based (weighted) Least-Connection scheduling
 */
static struct ip_vs_dest *
ip_vs_lblc_schedule(struct ip_vs_service *svc, struct iphdr *iph)
{
	struct ip_vs_dest *dest;
	struct ip_vs_lblc_table *tbl;
	struct ip_vs_lblc_entry *en;

	IP_VS_DBG(6, "ip_vs_lblc_schedule(): Scheduling...\n");

	tbl = (struct ip_vs_lblc_table *)svc->sched_data;
	en = ip_vs_lblc_get(tbl, iph->daddr);
	if (en == NULL) {
		dest = __ip_vs_wlc_schedule(svc, iph);
		if (dest == NULL) {
			IP_VS_DBG(1, "no destination available\n");
			return NULL;
		}
		en = ip_vs_lblc_new(iph->daddr, dest);
		if (en == NULL) {
			return NULL;
		}
		ip_vs_lblc_hash(tbl, en);
	} else {
		dest = en->dest;
		if (!(dest->flags & IP_VS_DEST_F_AVAILABLE)
		    || atomic_read(&dest->weight) <= 0
		    || is_overloaded(dest, svc)) {
			dest = __ip_vs_wlc_schedule(svc, iph);
			if (dest == NULL) {
				IP_VS_DBG(1, "no destination available\n");
				return NULL;
			}
			atomic_dec(&en->dest->refcnt);
			atomic_inc(&dest->refcnt);
			en->dest = dest;
		}
	}
	en->lastuse = jiffies;

	IP_VS_DBG(6, "LBLC: destination IP address %u.%u.%u.%u "
		  "--> server %u.%u.%u.%u:%d\n",
		  NIPQUAD(en->addr),
		  NIPQUAD(dest->addr),
		  ntohs(dest->port));

	return dest;
}


/*
 *      IPVS LBLC Scheduler structure
 */
static struct ip_vs_scheduler ip_vs_lblc_scheduler =
{
	{0},                    /* n_list */
	"lblc",                 /* name */
	ATOMIC_INIT(0),         /* refcnt */
	THIS_MODULE,		/* this module */
	ip_vs_lblc_init_svc,    /* service initializer */
	ip_vs_lblc_done_svc,    /* service done */
	ip_vs_lblc_update_svc,  /* service updater */
	ip_vs_lblc_schedule,    /* select a server from the destination list */
};


static int __init ip_vs_lblc_init(void)
{
	INIT_LIST_HEAD(&ip_vs_lblc_scheduler.n_list);
	lblc_sysctl_table.sysctl_header =
		register_sysctl_table(lblc_sysctl_table.root_dir, 0);
	return register_ip_vs_scheduler(&ip_vs_lblc_scheduler);
}


static void __exit ip_vs_lblc_cleanup(void)
{
	unregister_sysctl_table(lblc_sysctl_table.sysctl_header);
	unregister_ip_vs_scheduler(&ip_vs_lblc_scheduler);
}


module_init(ip_vs_lblc_init);
module_exit(ip_vs_lblc_cleanup);
MODULE_LICENSE("GPL");