2 * IPVS: Locality-Based Least-Connection with Replication scheduler
4 * Authors: Wensong Zhang <wensong@gnuchina.org>
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
12 * Julian Anastasov : Added the missing (dest->weight>0)
13 * condition in the ip_vs_dest_set_max.
18 * The lblc/r algorithm is as follows (pseudo code):
20 * if serverSet[dest_ip] is null then
21 * n, serverSet[dest_ip] <- {weighted least-conn node};
23 * n <- {least-conn (alive) node in serverSet[dest_ip]};
25 * (n.conns>n.weight AND
26 * there is a node m with m.conns<m.weight/2) then
27 * n <- {weighted least-conn node};
28 * add n to serverSet[dest_ip];
29 * if |serverSet[dest_ip]| > 1 AND
30 * now - serverSet[dest_ip].lastMod > T then
31 * m <- {most conn node in serverSet[dest_ip]};
32 * remove m from serverSet[dest_ip];
33 * if serverSet[dest_ip] changed then
34 * serverSet[dest_ip].lastMod <- now;
40 #define KMSG_COMPONENT "IPVS"
41 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
44 #include <linux/module.h>
45 #include <linux/kernel.h>
46 #include <linux/skbuff.h>
47 #include <linux/jiffies.h>
48 #include <linux/list.h>
49 #include <linux/slab.h>
53 #include <linux/sysctl.h>
54 #include <net/net_namespace.h>
56 #include <net/ip_vs.h>
60 * It is for garbage collection of stale IPVS lblcr entries,
61 * when the table is full.
63 #define CHECK_EXPIRE_INTERVAL (60*HZ)
64 #define ENTRY_TIMEOUT (6*60*HZ)
67 * It is for full expiration check.
68 * When there is no partial expiration check (garbage collection)
69 * in a half hour, do a full expiration check to collect stale
70 * entries that haven't been touched for a day.
72 #define COUNT_FOR_FULL_EXPIRATION 30
73 static int sysctl_ip_vs_lblcr_expiration = 24*60*60*HZ;
77 * for IPVS lblcr entry hash table
79 #ifndef CONFIG_IP_VS_LBLCR_TAB_BITS
80 #define CONFIG_IP_VS_LBLCR_TAB_BITS 10
82 #define IP_VS_LBLCR_TAB_BITS CONFIG_IP_VS_LBLCR_TAB_BITS
83 #define IP_VS_LBLCR_TAB_SIZE (1 << IP_VS_LBLCR_TAB_BITS)
84 #define IP_VS_LBLCR_TAB_MASK (IP_VS_LBLCR_TAB_SIZE - 1)
88 * IPVS destination set structure and operations
90 struct ip_vs_dest_set_elem {
91 struct list_head list; /* list link */
92 struct ip_vs_dest *dest; /* destination server */
95 struct ip_vs_dest_set {
96 atomic_t size; /* set size */
97 unsigned long lastmod; /* last modified time */
98 struct list_head list; /* destination list */
99 rwlock_t lock; /* lock for this list */
103 static struct ip_vs_dest_set_elem *
104 ip_vs_dest_set_insert(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
106 struct ip_vs_dest_set_elem *e;
108 list_for_each_entry(e, &set->list, list) {
110 /* already existed */
114 e = kmalloc(sizeof(*e), GFP_ATOMIC);
116 pr_err("%s(): no memory\n", __func__);
120 atomic_inc(&dest->refcnt);
123 list_add(&e->list, &set->list);
124 atomic_inc(&set->size);
126 set->lastmod = jiffies;
131 ip_vs_dest_set_erase(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
133 struct ip_vs_dest_set_elem *e;
135 list_for_each_entry(e, &set->list, list) {
136 if (e->dest == dest) {
138 atomic_dec(&set->size);
139 set->lastmod = jiffies;
140 atomic_dec(&e->dest->refcnt);
148 static void ip_vs_dest_set_eraseall(struct ip_vs_dest_set *set)
150 struct ip_vs_dest_set_elem *e, *ep;
152 write_lock(&set->lock);
153 list_for_each_entry_safe(e, ep, &set->list, list) {
155 * We don't kfree dest because it is refered either
156 * by its service or by the trash dest list.
158 atomic_dec(&e->dest->refcnt);
162 write_unlock(&set->lock);
165 /* get weighted least-connection node in the destination set */
166 static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
168 register struct ip_vs_dest_set_elem *e;
169 struct ip_vs_dest *dest, *least;
175 /* select the first destination server, whose weight > 0 */
176 list_for_each_entry(e, &set->list, list) {
178 if (least->flags & IP_VS_DEST_F_OVERLOAD)
181 if ((atomic_read(&least->weight) > 0)
182 && (least->flags & IP_VS_DEST_F_AVAILABLE)) {
183 loh = atomic_read(&least->activeconns) * 50
184 + atomic_read(&least->inactconns);
190 /* find the destination with the weighted least load */
192 list_for_each_entry(e, &set->list, list) {
194 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
197 doh = atomic_read(&dest->activeconns) * 50
198 + atomic_read(&dest->inactconns);
199 if ((loh * atomic_read(&dest->weight) >
200 doh * atomic_read(&least->weight))
201 && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
207 IP_VS_DBG_BUF(6, "%s(): server %s:%d "
208 "activeconns %d refcnt %d weight %d overhead %d\n",
210 IP_VS_DBG_ADDR(least->af, &least->addr),
212 atomic_read(&least->activeconns),
213 atomic_read(&least->refcnt),
214 atomic_read(&least->weight), loh);
219 /* get weighted most-connection node in the destination set */
220 static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
222 register struct ip_vs_dest_set_elem *e;
223 struct ip_vs_dest *dest, *most;
229 /* select the first destination server, whose weight > 0 */
230 list_for_each_entry(e, &set->list, list) {
232 if (atomic_read(&most->weight) > 0) {
233 moh = atomic_read(&most->activeconns) * 50
234 + atomic_read(&most->inactconns);
240 /* find the destination with the weighted most load */
242 list_for_each_entry(e, &set->list, list) {
244 doh = atomic_read(&dest->activeconns) * 50
245 + atomic_read(&dest->inactconns);
246 /* moh/mw < doh/dw ==> moh*dw < doh*mw, where mw,dw>0 */
247 if ((moh * atomic_read(&dest->weight) <
248 doh * atomic_read(&most->weight))
249 && (atomic_read(&dest->weight) > 0)) {
255 IP_VS_DBG_BUF(6, "%s(): server %s:%d "
256 "activeconns %d refcnt %d weight %d overhead %d\n",
258 IP_VS_DBG_ADDR(most->af, &most->addr), ntohs(most->port),
259 atomic_read(&most->activeconns),
260 atomic_read(&most->refcnt),
261 atomic_read(&most->weight), moh);
267 * IPVS lblcr entry represents an association between destination
268 * IP address and its destination server set
270 struct ip_vs_lblcr_entry {
271 struct list_head list;
272 int af; /* address family */
273 union nf_inet_addr addr; /* destination IP address */
274 struct ip_vs_dest_set set; /* destination server set */
275 unsigned long lastuse; /* last used time */
280 * IPVS lblcr hash table
282 struct ip_vs_lblcr_table {
283 struct list_head bucket[IP_VS_LBLCR_TAB_SIZE]; /* hash bucket */
284 atomic_t entries; /* number of entries */
285 int max_size; /* maximum size of entries */
286 struct timer_list periodic_timer; /* collect stale entries */
287 int rover; /* rover for expire check */
288 int counter; /* counter for no expire */
293 * IPVS LBLCR sysctl table
296 static ctl_table vs_vars_table[] = {
298 .procname = "lblcr_expiration",
299 .data = &sysctl_ip_vs_lblcr_expiration,
300 .maxlen = sizeof(int),
302 .proc_handler = proc_dointvec_jiffies,
307 static struct ctl_table_header * sysctl_header;
309 static inline void ip_vs_lblcr_free(struct ip_vs_lblcr_entry *en)
312 ip_vs_dest_set_eraseall(&en->set);
318 * Returns hash value for IPVS LBLCR entry
320 static inline unsigned
321 ip_vs_lblcr_hashkey(int af, const union nf_inet_addr *addr)
323 __be32 addr_fold = addr->ip;
325 #ifdef CONFIG_IP_VS_IPV6
327 addr_fold = addr->ip6[0]^addr->ip6[1]^
328 addr->ip6[2]^addr->ip6[3];
330 return (ntohl(addr_fold)*2654435761UL) & IP_VS_LBLCR_TAB_MASK;
335 * Hash an entry in the ip_vs_lblcr_table.
336 * returns bool success.
339 ip_vs_lblcr_hash(struct ip_vs_lblcr_table *tbl, struct ip_vs_lblcr_entry *en)
341 unsigned hash = ip_vs_lblcr_hashkey(en->af, &en->addr);
343 list_add(&en->list, &tbl->bucket[hash]);
344 atomic_inc(&tbl->entries);
349 * Get ip_vs_lblcr_entry associated with supplied parameters. Called under
352 static inline struct ip_vs_lblcr_entry *
353 ip_vs_lblcr_get(int af, struct ip_vs_lblcr_table *tbl,
354 const union nf_inet_addr *addr)
356 unsigned hash = ip_vs_lblcr_hashkey(af, addr);
357 struct ip_vs_lblcr_entry *en;
359 list_for_each_entry(en, &tbl->bucket[hash], list)
360 if (ip_vs_addr_equal(af, &en->addr, addr))
368 * Create or update an ip_vs_lblcr_entry, which is a mapping of a destination
369 * IP address to a server. Called under write lock.
371 static inline struct ip_vs_lblcr_entry *
372 ip_vs_lblcr_new(struct ip_vs_lblcr_table *tbl, const union nf_inet_addr *daddr,
373 struct ip_vs_dest *dest)
375 struct ip_vs_lblcr_entry *en;
377 en = ip_vs_lblcr_get(dest->af, tbl, daddr);
379 en = kmalloc(sizeof(*en), GFP_ATOMIC);
381 pr_err("%s(): no memory\n", __func__);
386 ip_vs_addr_copy(dest->af, &en->addr, daddr);
387 en->lastuse = jiffies;
389 /* initilize its dest set */
390 atomic_set(&(en->set.size), 0);
391 INIT_LIST_HEAD(&en->set.list);
392 rwlock_init(&en->set.lock);
394 ip_vs_lblcr_hash(tbl, en);
397 write_lock(&en->set.lock);
398 ip_vs_dest_set_insert(&en->set, dest);
399 write_unlock(&en->set.lock);
406 * Flush all the entries of the specified table.
408 static void ip_vs_lblcr_flush(struct ip_vs_lblcr_table *tbl)
411 struct ip_vs_lblcr_entry *en, *nxt;
413 /* No locking required, only called during cleanup. */
414 for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
415 list_for_each_entry_safe(en, nxt, &tbl->bucket[i], list) {
416 ip_vs_lblcr_free(en);
422 static inline void ip_vs_lblcr_full_check(struct ip_vs_service *svc)
424 struct ip_vs_lblcr_table *tbl = svc->sched_data;
425 unsigned long now = jiffies;
427 struct ip_vs_lblcr_entry *en, *nxt;
429 for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
430 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
432 write_lock(&svc->sched_lock);
433 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
434 if (time_after(en->lastuse+sysctl_ip_vs_lblcr_expiration,
438 ip_vs_lblcr_free(en);
439 atomic_dec(&tbl->entries);
441 write_unlock(&svc->sched_lock);
448 * Periodical timer handler for IPVS lblcr table
449 * It is used to collect stale entries when the number of entries
450 * exceeds the maximum size of the table.
452 * Fixme: we probably need more complicated algorithm to collect
453 * entries that have not been used for a long time even
454 * if the number of entries doesn't exceed the maximum size
456 * The full expiration check is for this purpose now.
458 static void ip_vs_lblcr_check_expire(unsigned long data)
460 struct ip_vs_service *svc = (struct ip_vs_service *) data;
461 struct ip_vs_lblcr_table *tbl = svc->sched_data;
462 unsigned long now = jiffies;
465 struct ip_vs_lblcr_entry *en, *nxt;
467 if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
468 /* do full expiration check */
469 ip_vs_lblcr_full_check(svc);
474 if (atomic_read(&tbl->entries) <= tbl->max_size) {
479 goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3;
480 if (goal > tbl->max_size/2)
481 goal = tbl->max_size/2;
483 for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
484 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
486 write_lock(&svc->sched_lock);
487 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
488 if (time_before(now, en->lastuse+ENTRY_TIMEOUT))
491 ip_vs_lblcr_free(en);
492 atomic_dec(&tbl->entries);
495 write_unlock(&svc->sched_lock);
502 mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL);
505 static int ip_vs_lblcr_init_svc(struct ip_vs_service *svc)
508 struct ip_vs_lblcr_table *tbl;
511 * Allocate the ip_vs_lblcr_table for this service
513 tbl = kmalloc(sizeof(*tbl), GFP_ATOMIC);
515 pr_err("%s(): no memory\n", __func__);
518 svc->sched_data = tbl;
519 IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) allocated for "
520 "current service\n", sizeof(*tbl));
523 * Initialize the hash buckets
525 for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
526 INIT_LIST_HEAD(&tbl->bucket[i]);
528 tbl->max_size = IP_VS_LBLCR_TAB_SIZE*16;
533 * Hook periodic timer for garbage collection
535 setup_timer(&tbl->periodic_timer, ip_vs_lblcr_check_expire,
537 mod_timer(&tbl->periodic_timer, jiffies + CHECK_EXPIRE_INTERVAL);
543 static int ip_vs_lblcr_done_svc(struct ip_vs_service *svc)
545 struct ip_vs_lblcr_table *tbl = svc->sched_data;
547 /* remove periodic timer */
548 del_timer_sync(&tbl->periodic_timer);
550 /* got to clean up table entries here */
551 ip_vs_lblcr_flush(tbl);
553 /* release the table itself */
555 IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) released\n",
562 static inline struct ip_vs_dest *
563 __ip_vs_lblcr_schedule(struct ip_vs_service *svc)
565 struct ip_vs_dest *dest, *least;
569 * We think the overhead of processing active connections is fifty
570 * times higher than that of inactive connections in average. (This
571 * fifty times might not be accurate, we will change it later.) We
572 * use the following formula to estimate the overhead:
573 * dest->activeconns*50 + dest->inactconns
575 * (dest overhead) / dest->weight
577 * Remember -- no floats in kernel mode!!!
578 * The comparison of h1*w2 > h2*w1 is equivalent to that of
580 * if every weight is larger than zero.
582 * The server with weight=0 is quiesced and will not receive any
585 list_for_each_entry(dest, &svc->destinations, n_list) {
586 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
589 if (atomic_read(&dest->weight) > 0) {
591 loh = atomic_read(&least->activeconns) * 50
592 + atomic_read(&least->inactconns);
599 * Find the destination with the least load.
602 list_for_each_entry_continue(dest, &svc->destinations, n_list) {
603 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
606 doh = atomic_read(&dest->activeconns) * 50
607 + atomic_read(&dest->inactconns);
608 if (loh * atomic_read(&dest->weight) >
609 doh * atomic_read(&least->weight)) {
615 IP_VS_DBG_BUF(6, "LBLCR: server %s:%d "
616 "activeconns %d refcnt %d weight %d overhead %d\n",
617 IP_VS_DBG_ADDR(least->af, &least->addr),
619 atomic_read(&least->activeconns),
620 atomic_read(&least->refcnt),
621 atomic_read(&least->weight), loh);
628 * If this destination server is overloaded and there is a less loaded
629 * server, then return true.
632 is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc)
634 if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {
635 struct ip_vs_dest *d;
637 list_for_each_entry(d, &svc->destinations, n_list) {
638 if (atomic_read(&d->activeconns)*2
639 < atomic_read(&d->weight)) {
649 * Locality-Based (weighted) Least-Connection scheduling
651 static struct ip_vs_dest *
652 ip_vs_lblcr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
654 struct ip_vs_lblcr_table *tbl = svc->sched_data;
655 struct ip_vs_iphdr iph;
656 struct ip_vs_dest *dest = NULL;
657 struct ip_vs_lblcr_entry *en;
659 ip_vs_fill_iphdr(svc->af, skb_network_header(skb), &iph);
661 IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
663 /* First look in our cache */
664 read_lock(&svc->sched_lock);
665 en = ip_vs_lblcr_get(svc->af, tbl, &iph.daddr);
667 /* We only hold a read lock, but this is atomic */
668 en->lastuse = jiffies;
670 /* Get the least loaded destination */
671 read_lock(&en->set.lock);
672 dest = ip_vs_dest_set_min(&en->set);
673 read_unlock(&en->set.lock);
675 /* More than one destination + enough time passed by, cleanup */
676 if (atomic_read(&en->set.size) > 1 &&
677 time_after(jiffies, en->set.lastmod +
678 sysctl_ip_vs_lblcr_expiration)) {
679 struct ip_vs_dest *m;
681 write_lock(&en->set.lock);
682 m = ip_vs_dest_set_max(&en->set);
684 ip_vs_dest_set_erase(&en->set, m);
685 write_unlock(&en->set.lock);
688 /* If the destination is not overloaded, use it */
689 if (dest && !is_overloaded(dest, svc)) {
690 read_unlock(&svc->sched_lock);
694 /* The cache entry is invalid, time to schedule */
695 dest = __ip_vs_lblcr_schedule(svc);
697 IP_VS_ERR_RL("LBLCR: no destination available\n");
698 read_unlock(&svc->sched_lock);
702 /* Update our cache entry */
703 write_lock(&en->set.lock);
704 ip_vs_dest_set_insert(&en->set, dest);
705 write_unlock(&en->set.lock);
707 read_unlock(&svc->sched_lock);
712 /* No cache entry, time to schedule */
713 dest = __ip_vs_lblcr_schedule(svc);
715 IP_VS_DBG(1, "no destination available\n");
719 /* If we fail to create a cache entry, we'll just use the valid dest */
720 write_lock(&svc->sched_lock);
721 ip_vs_lblcr_new(tbl, &iph.daddr, dest);
722 write_unlock(&svc->sched_lock);
725 IP_VS_DBG_BUF(6, "LBLCR: destination IP address %s --> server %s:%d\n",
726 IP_VS_DBG_ADDR(svc->af, &iph.daddr),
727 IP_VS_DBG_ADDR(svc->af, &dest->addr), ntohs(dest->port));
734 * IPVS LBLCR Scheduler structure
736 static struct ip_vs_scheduler ip_vs_lblcr_scheduler =
739 .refcnt = ATOMIC_INIT(0),
740 .module = THIS_MODULE,
741 .n_list = LIST_HEAD_INIT(ip_vs_lblcr_scheduler.n_list),
742 .init_service = ip_vs_lblcr_init_svc,
743 .done_service = ip_vs_lblcr_done_svc,
744 .schedule = ip_vs_lblcr_schedule,
748 static int __init ip_vs_lblcr_init(void)
752 sysctl_header = register_sysctl_paths(net_vs_ctl_path, vs_vars_table);
753 ret = register_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
755 unregister_sysctl_table(sysctl_header);
760 static void __exit ip_vs_lblcr_cleanup(void)
762 unregister_sysctl_table(sysctl_header);
763 unregister_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
767 module_init(ip_vs_lblcr_init);
768 module_exit(ip_vs_lblcr_cleanup);
769 MODULE_LICENSE("GPL");