2 * IPVS: Locality-Based Least-Connection scheduling module
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 * Martin Hamilton : fixed the terrible locking bugs
13 * *lock(tbl->lock) ==> *lock(&tbl->lock)
14 * Wensong Zhang : fixed the uninitialized tbl->lock bug
15 * Wensong Zhang : added doing full expiration check to
16 * collect stale entries of 24+ hours when
17 * no partial expire check in a half hour
18 * Julian Anastasov : replaced del_timer call with del_timer_sync
19 * to avoid the possible race between timer
20 * handler and del_timer thread in SMP
25 * The lblc algorithm is as follows (pseudo code):
27 * if cachenode[dest_ip] is null then
28 * n, cachenode[dest_ip] <- {weighted least-conn node};
30 * n <- cachenode[dest_ip];
32 * (n.conns>n.weight AND
33 * there is a node m with m.conns<m.weight/2) then
34 * n, cachenode[dest_ip] <- {weighted least-conn node};
38 * Thanks must go to Wenzhuo Zhang for talking WCCP to me and pushing
39 * me to write this module.
42 #define KMSG_COMPONENT "IPVS"
43 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
46 #include <linux/slab.h>
47 #include <linux/module.h>
48 #include <linux/kernel.h>
49 #include <linux/skbuff.h>
50 #include <linux/jiffies.h>
54 #include <linux/sysctl.h>
56 #include <net/ip_vs.h>
60 * It is for garbage collection of stale IPVS lblc entries,
61 * when the table is full.
63 #define CHECK_EXPIRE_INTERVAL (60*HZ)
64 #define ENTRY_TIMEOUT (6*60*HZ)
66 #define DEFAULT_EXPIRATION (24*60*60*HZ)
69 * It is for full expiration check.
70 * When there is no partial expiration check (garbage collection)
71 * in a half hour, do a full expiration check to collect stale
72 * entries that haven't been touched for a day.
74 #define COUNT_FOR_FULL_EXPIRATION 30
78 * for IPVS lblc entry hash table
80 #ifndef CONFIG_IP_VS_LBLC_TAB_BITS
81 #define CONFIG_IP_VS_LBLC_TAB_BITS 10
83 #define IP_VS_LBLC_TAB_BITS CONFIG_IP_VS_LBLC_TAB_BITS
84 #define IP_VS_LBLC_TAB_SIZE (1 << IP_VS_LBLC_TAB_BITS)
85 #define IP_VS_LBLC_TAB_MASK (IP_VS_LBLC_TAB_SIZE - 1)
89 * IPVS lblc entry represents an association between destination
90 * IP address and its destination server
92 struct ip_vs_lblc_entry
{
93 struct hlist_node list
;
94 int af
; /* address family */
95 union nf_inet_addr addr
; /* destination IP address */
96 struct ip_vs_dest
*dest
; /* real server (cache) */
97 unsigned long lastuse
; /* last used time */
98 struct rcu_head rcu_head
;
103 * IPVS lblc hash table
105 struct ip_vs_lblc_table
{
106 struct rcu_head rcu_head
;
107 struct hlist_head bucket
[IP_VS_LBLC_TAB_SIZE
]; /* hash bucket */
108 struct timer_list periodic_timer
; /* collect stale entries */
109 struct ip_vs_service
*svc
; /* pointer back to service */
110 atomic_t entries
; /* number of entries */
111 int max_size
; /* maximum size of entries */
112 int rover
; /* rover for expire check */
113 int counter
; /* counter for no expire */
119 * IPVS LBLC sysctl table
122 static struct ctl_table vs_vars_table
[] = {
124 .procname
= "lblc_expiration",
126 .maxlen
= sizeof(int),
128 .proc_handler
= proc_dointvec_jiffies
,
134 static void ip_vs_lblc_rcu_free(struct rcu_head
*head
)
136 struct ip_vs_lblc_entry
*en
= container_of(head
,
137 struct ip_vs_lblc_entry
,
140 ip_vs_dest_put_and_free(en
->dest
);
144 static inline void ip_vs_lblc_del(struct ip_vs_lblc_entry
*en
)
146 hlist_del_rcu(&en
->list
);
147 call_rcu(&en
->rcu_head
, ip_vs_lblc_rcu_free
);
151 * Returns hash value for IPVS LBLC entry
153 static inline unsigned int
154 ip_vs_lblc_hashkey(int af
, const union nf_inet_addr
*addr
)
156 __be32 addr_fold
= addr
->ip
;
158 #ifdef CONFIG_IP_VS_IPV6
160 addr_fold
= addr
->ip6
[0]^addr
->ip6
[1]^
161 addr
->ip6
[2]^addr
->ip6
[3];
163 return (ntohl(addr_fold
)*2654435761UL) & IP_VS_LBLC_TAB_MASK
;
168 * Hash an entry in the ip_vs_lblc_table.
169 * returns bool success.
172 ip_vs_lblc_hash(struct ip_vs_lblc_table
*tbl
, struct ip_vs_lblc_entry
*en
)
174 unsigned int hash
= ip_vs_lblc_hashkey(en
->af
, &en
->addr
);
176 hlist_add_head_rcu(&en
->list
, &tbl
->bucket
[hash
]);
177 atomic_inc(&tbl
->entries
);
181 /* Get ip_vs_lblc_entry associated with supplied parameters. */
182 static inline struct ip_vs_lblc_entry
*
183 ip_vs_lblc_get(int af
, struct ip_vs_lblc_table
*tbl
,
184 const union nf_inet_addr
*addr
)
186 unsigned int hash
= ip_vs_lblc_hashkey(af
, addr
);
187 struct ip_vs_lblc_entry
*en
;
189 hlist_for_each_entry_rcu(en
, &tbl
->bucket
[hash
], list
)
190 if (ip_vs_addr_equal(af
, &en
->addr
, addr
))
198 * Create or update an ip_vs_lblc_entry, which is a mapping of a destination IP
199 * address to a server. Called under spin lock.
201 static inline struct ip_vs_lblc_entry
*
202 ip_vs_lblc_new(struct ip_vs_lblc_table
*tbl
, const union nf_inet_addr
*daddr
,
203 u16 af
, struct ip_vs_dest
*dest
)
205 struct ip_vs_lblc_entry
*en
;
207 en
= ip_vs_lblc_get(af
, tbl
, daddr
);
209 if (en
->dest
== dest
)
213 en
= kmalloc(sizeof(*en
), GFP_ATOMIC
);
218 ip_vs_addr_copy(af
, &en
->addr
, daddr
);
219 en
->lastuse
= jiffies
;
221 ip_vs_dest_hold(dest
);
224 ip_vs_lblc_hash(tbl
, en
);
231 * Flush all the entries of the specified table.
233 static void ip_vs_lblc_flush(struct ip_vs_service
*svc
)
235 struct ip_vs_lblc_table
*tbl
= svc
->sched_data
;
236 struct ip_vs_lblc_entry
*en
;
237 struct hlist_node
*next
;
240 spin_lock_bh(&svc
->sched_lock
);
242 for (i
= 0; i
< IP_VS_LBLC_TAB_SIZE
; i
++) {
243 hlist_for_each_entry_safe(en
, next
, &tbl
->bucket
[i
], list
) {
245 atomic_dec(&tbl
->entries
);
248 spin_unlock_bh(&svc
->sched_lock
);
251 static int sysctl_lblc_expiration(struct ip_vs_service
*svc
)
254 return svc
->ipvs
->sysctl_lblc_expiration
;
256 return DEFAULT_EXPIRATION
;
260 static inline void ip_vs_lblc_full_check(struct ip_vs_service
*svc
)
262 struct ip_vs_lblc_table
*tbl
= svc
->sched_data
;
263 struct ip_vs_lblc_entry
*en
;
264 struct hlist_node
*next
;
265 unsigned long now
= jiffies
;
268 for (i
= 0, j
= tbl
->rover
; i
< IP_VS_LBLC_TAB_SIZE
; i
++) {
269 j
= (j
+ 1) & IP_VS_LBLC_TAB_MASK
;
271 spin_lock(&svc
->sched_lock
);
272 hlist_for_each_entry_safe(en
, next
, &tbl
->bucket
[j
], list
) {
275 sysctl_lblc_expiration(svc
)))
279 atomic_dec(&tbl
->entries
);
281 spin_unlock(&svc
->sched_lock
);
288 * Periodical timer handler for IPVS lblc table
289 * It is used to collect stale entries when the number of entries
290 * exceeds the maximum size of the table.
292 * Fixme: we probably need more complicated algorithm to collect
293 * entries that have not been used for a long time even
294 * if the number of entries doesn't exceed the maximum size
296 * The full expiration check is for this purpose now.
298 static void ip_vs_lblc_check_expire(struct timer_list
*t
)
300 struct ip_vs_lblc_table
*tbl
= from_timer(tbl
, t
, periodic_timer
);
301 struct ip_vs_service
*svc
= tbl
->svc
;
302 unsigned long now
= jiffies
;
305 struct ip_vs_lblc_entry
*en
;
306 struct hlist_node
*next
;
308 if ((tbl
->counter
% COUNT_FOR_FULL_EXPIRATION
) == 0) {
309 /* do full expiration check */
310 ip_vs_lblc_full_check(svc
);
315 if (atomic_read(&tbl
->entries
) <= tbl
->max_size
) {
320 goal
= (atomic_read(&tbl
->entries
) - tbl
->max_size
)*4/3;
321 if (goal
> tbl
->max_size
/2)
322 goal
= tbl
->max_size
/2;
324 for (i
= 0, j
= tbl
->rover
; i
< IP_VS_LBLC_TAB_SIZE
; i
++) {
325 j
= (j
+ 1) & IP_VS_LBLC_TAB_MASK
;
327 spin_lock(&svc
->sched_lock
);
328 hlist_for_each_entry_safe(en
, next
, &tbl
->bucket
[j
], list
) {
329 if (time_before(now
, en
->lastuse
+ ENTRY_TIMEOUT
))
333 atomic_dec(&tbl
->entries
);
336 spin_unlock(&svc
->sched_lock
);
343 mod_timer(&tbl
->periodic_timer
, jiffies
+ CHECK_EXPIRE_INTERVAL
);
347 static int ip_vs_lblc_init_svc(struct ip_vs_service
*svc
)
350 struct ip_vs_lblc_table
*tbl
;
353 * Allocate the ip_vs_lblc_table for this service
355 tbl
= kmalloc(sizeof(*tbl
), GFP_KERNEL
);
359 svc
->sched_data
= tbl
;
360 IP_VS_DBG(6, "LBLC hash table (memory=%zdbytes) allocated for "
361 "current service\n", sizeof(*tbl
));
364 * Initialize the hash buckets
366 for (i
= 0; i
< IP_VS_LBLC_TAB_SIZE
; i
++) {
367 INIT_HLIST_HEAD(&tbl
->bucket
[i
]);
369 tbl
->max_size
= IP_VS_LBLC_TAB_SIZE
*16;
376 * Hook periodic timer for garbage collection
378 timer_setup(&tbl
->periodic_timer
, ip_vs_lblc_check_expire
, 0);
379 mod_timer(&tbl
->periodic_timer
, jiffies
+ CHECK_EXPIRE_INTERVAL
);
385 static void ip_vs_lblc_done_svc(struct ip_vs_service
*svc
)
387 struct ip_vs_lblc_table
*tbl
= svc
->sched_data
;
389 /* remove periodic timer */
390 del_timer_sync(&tbl
->periodic_timer
);
392 /* got to clean up table entries here */
393 ip_vs_lblc_flush(svc
);
395 /* release the table itself */
396 kfree_rcu(tbl
, rcu_head
);
397 IP_VS_DBG(6, "LBLC hash table (memory=%zdbytes) released\n",
402 static inline struct ip_vs_dest
*
403 __ip_vs_lblc_schedule(struct ip_vs_service
*svc
)
405 struct ip_vs_dest
*dest
, *least
;
409 * We use the following formula to estimate the load:
410 * (dest overhead) / dest->weight
412 * Remember -- no floats in kernel mode!!!
413 * The comparison of h1*w2 > h2*w1 is equivalent to that of
415 * if every weight is larger than zero.
417 * The server with weight=0 is quiesced and will not receive any
420 list_for_each_entry_rcu(dest
, &svc
->destinations
, n_list
) {
421 if (dest
->flags
& IP_VS_DEST_F_OVERLOAD
)
423 if (atomic_read(&dest
->weight
) > 0) {
425 loh
= ip_vs_dest_conn_overhead(least
);
432 * Find the destination with the least load.
435 list_for_each_entry_continue_rcu(dest
, &svc
->destinations
, n_list
) {
436 if (dest
->flags
& IP_VS_DEST_F_OVERLOAD
)
439 doh
= ip_vs_dest_conn_overhead(dest
);
440 if ((__s64
)loh
* atomic_read(&dest
->weight
) >
441 (__s64
)doh
* atomic_read(&least
->weight
)) {
447 IP_VS_DBG_BUF(6, "LBLC: server %s:%d "
448 "activeconns %d refcnt %d weight %d overhead %d\n",
449 IP_VS_DBG_ADDR(least
->af
, &least
->addr
),
451 atomic_read(&least
->activeconns
),
452 refcount_read(&least
->refcnt
),
453 atomic_read(&least
->weight
), loh
);
460 * If this destination server is overloaded and there is a less loaded
461 * server, then return true.
464 is_overloaded(struct ip_vs_dest
*dest
, struct ip_vs_service
*svc
)
466 if (atomic_read(&dest
->activeconns
) > atomic_read(&dest
->weight
)) {
467 struct ip_vs_dest
*d
;
469 list_for_each_entry_rcu(d
, &svc
->destinations
, n_list
) {
470 if (atomic_read(&d
->activeconns
)*2
471 < atomic_read(&d
->weight
)) {
481 * Locality-Based (weighted) Least-Connection scheduling
483 static struct ip_vs_dest
*
484 ip_vs_lblc_schedule(struct ip_vs_service
*svc
, const struct sk_buff
*skb
,
485 struct ip_vs_iphdr
*iph
)
487 struct ip_vs_lblc_table
*tbl
= svc
->sched_data
;
488 struct ip_vs_dest
*dest
= NULL
;
489 struct ip_vs_lblc_entry
*en
;
491 IP_VS_DBG(6, "%s(): Scheduling...\n", __func__
);
493 /* First look in our cache */
494 en
= ip_vs_lblc_get(svc
->af
, tbl
, &iph
->daddr
);
496 /* We only hold a read lock, but this is atomic */
497 en
->lastuse
= jiffies
;
500 * If the destination is not available, i.e. it's in the trash,
501 * we must ignore it, as it may be removed from under our feet,
502 * if someone drops our reference count. Our caller only makes
503 * sure that destinations, that are not in the trash, are not
504 * moved to the trash, while we are scheduling. But anyone can
505 * free up entries from the trash at any time.
509 if ((dest
->flags
& IP_VS_DEST_F_AVAILABLE
) &&
510 atomic_read(&dest
->weight
) > 0 && !is_overloaded(dest
, svc
))
514 /* No cache entry or it is invalid, time to schedule */
515 dest
= __ip_vs_lblc_schedule(svc
);
517 ip_vs_scheduler_err(svc
, "no destination available");
521 /* If we fail to create a cache entry, we'll just use the valid dest */
522 spin_lock_bh(&svc
->sched_lock
);
524 ip_vs_lblc_new(tbl
, &iph
->daddr
, svc
->af
, dest
);
525 spin_unlock_bh(&svc
->sched_lock
);
528 IP_VS_DBG_BUF(6, "LBLC: destination IP address %s --> server %s:%d\n",
529 IP_VS_DBG_ADDR(svc
->af
, &iph
->daddr
),
530 IP_VS_DBG_ADDR(dest
->af
, &dest
->addr
), ntohs(dest
->port
));
537 * IPVS LBLC Scheduler structure
539 static struct ip_vs_scheduler ip_vs_lblc_scheduler
= {
541 .refcnt
= ATOMIC_INIT(0),
542 .module
= THIS_MODULE
,
543 .n_list
= LIST_HEAD_INIT(ip_vs_lblc_scheduler
.n_list
),
544 .init_service
= ip_vs_lblc_init_svc
,
545 .done_service
= ip_vs_lblc_done_svc
,
546 .schedule
= ip_vs_lblc_schedule
,
553 static int __net_init
__ip_vs_lblc_init(struct net
*net
)
555 struct netns_ipvs
*ipvs
= net_ipvs(net
);
560 if (!net_eq(net
, &init_net
)) {
561 ipvs
->lblc_ctl_table
= kmemdup(vs_vars_table
,
562 sizeof(vs_vars_table
),
564 if (ipvs
->lblc_ctl_table
== NULL
)
567 /* Don't export sysctls to unprivileged users */
568 if (net
->user_ns
!= &init_user_ns
)
569 ipvs
->lblc_ctl_table
[0].procname
= NULL
;
572 ipvs
->lblc_ctl_table
= vs_vars_table
;
573 ipvs
->sysctl_lblc_expiration
= DEFAULT_EXPIRATION
;
574 ipvs
->lblc_ctl_table
[0].data
= &ipvs
->sysctl_lblc_expiration
;
576 ipvs
->lblc_ctl_header
=
577 register_net_sysctl(net
, "net/ipv4/vs", ipvs
->lblc_ctl_table
);
578 if (!ipvs
->lblc_ctl_header
) {
579 if (!net_eq(net
, &init_net
))
580 kfree(ipvs
->lblc_ctl_table
);
587 static void __net_exit
__ip_vs_lblc_exit(struct net
*net
)
589 struct netns_ipvs
*ipvs
= net_ipvs(net
);
591 unregister_net_sysctl_table(ipvs
->lblc_ctl_header
);
593 if (!net_eq(net
, &init_net
))
594 kfree(ipvs
->lblc_ctl_table
);
599 static int __net_init
__ip_vs_lblc_init(struct net
*net
) { return 0; }
600 static void __net_exit
__ip_vs_lblc_exit(struct net
*net
) { }
604 static struct pernet_operations ip_vs_lblc_ops
= {
605 .init
= __ip_vs_lblc_init
,
606 .exit
= __ip_vs_lblc_exit
,
610 static int __init
ip_vs_lblc_init(void)
614 ret
= register_pernet_subsys(&ip_vs_lblc_ops
);
618 ret
= register_ip_vs_scheduler(&ip_vs_lblc_scheduler
);
620 unregister_pernet_subsys(&ip_vs_lblc_ops
);
624 static void __exit
ip_vs_lblc_cleanup(void)
626 unregister_ip_vs_scheduler(&ip_vs_lblc_scheduler
);
627 unregister_pernet_subsys(&ip_vs_lblc_ops
);
632 module_init(ip_vs_lblc_init
);
633 module_exit(ip_vs_lblc_cleanup
);
634 MODULE_LICENSE("GPL");