2 * IPVS: Locality-Based Least-Connection scheduling module
4 * Version: $Id: ip_vs_lblc.c,v 1.10 2002/09/15 08:14:08 wensong Exp $
6 * Authors: Wensong Zhang <wensong@gnuchina.org>
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
14 * Martin Hamilton : fixed the terrible locking bugs
15 * *lock(tbl->lock) ==> *lock(&tbl->lock)
16 * Wensong Zhang : fixed the uninitilized tbl->lock bug
17 * Wensong Zhang : added doing full expiration check to
18 * collect stale entries of 24+ hours when
19 * no partial expire check in a half hour
20 * Julian Anastasov : replaced del_timer call with del_timer_sync
21 * to avoid the possible race between timer
22 * handler and del_timer thread in SMP
27 * The lblc algorithm is as follows (pseudo code):
29 * if cachenode[dest_ip] is null then
30 * n, cachenode[dest_ip] <- {weighted least-conn node};
32 * n <- cachenode[dest_ip];
34 * (n.conns>n.weight AND
35 * there is a node m with m.conns<m.weight/2) then
36 * n, cachenode[dest_ip] <- {weighted least-conn node};
40 * Thanks must go to Wenzhuo Zhang for talking WCCP to me and pushing
41 * me to write this module.
45 #include <linux/module.h>
46 #include <linux/kernel.h>
47 #include <linux/skbuff.h>
48 #include <linux/jiffies.h>
52 #include <linux/sysctl.h>
54 #include <net/ip_vs.h>
58 * It is for garbage collection of stale IPVS lblc entries,
59 * when the table is full.
61 #define CHECK_EXPIRE_INTERVAL (60*HZ)
62 #define ENTRY_TIMEOUT (6*60*HZ)
65 * It is for full expiration check.
66 * When there is no partial expiration check (garbage collection)
67 * in a half hour, do a full expiration check to collect stale
68 * entries that haven't been touched for a day.
70 #define COUNT_FOR_FULL_EXPIRATION 30
71 static int sysctl_ip_vs_lblc_expiration
= 24*60*60*HZ
;
75 * for IPVS lblc entry hash table
77 #ifndef CONFIG_IP_VS_LBLC_TAB_BITS
78 #define CONFIG_IP_VS_LBLC_TAB_BITS 10
80 #define IP_VS_LBLC_TAB_BITS CONFIG_IP_VS_LBLC_TAB_BITS
81 #define IP_VS_LBLC_TAB_SIZE (1 << IP_VS_LBLC_TAB_BITS)
82 #define IP_VS_LBLC_TAB_MASK (IP_VS_LBLC_TAB_SIZE - 1)
86 * IPVS lblc entry represents an association between destination
87 * IP address and its destination server
89 struct ip_vs_lblc_entry
{
90 struct list_head list
;
91 __be32 addr
; /* destination IP address */
92 struct ip_vs_dest
*dest
; /* real server (cache) */
93 unsigned long lastuse
; /* last used time */
98 * IPVS lblc hash table
100 struct ip_vs_lblc_table
{
101 rwlock_t lock
; /* lock for this table */
102 struct list_head bucket
[IP_VS_LBLC_TAB_SIZE
]; /* hash bucket */
103 atomic_t entries
; /* number of entries */
104 int max_size
; /* maximum size of entries */
105 struct timer_list periodic_timer
; /* collect stale entries */
106 int rover
; /* rover for expire check */
107 int counter
; /* counter for no expire */
112 * IPVS LBLC sysctl table
115 static ctl_table vs_vars_table
[] = {
117 .ctl_name
= NET_IPV4_VS_LBLC_EXPIRE
,
118 .procname
= "lblc_expiration",
119 .data
= &sysctl_ip_vs_lblc_expiration
,
120 .maxlen
= sizeof(int),
122 .proc_handler
= &proc_dointvec_jiffies
,
127 static ctl_table vs_table
[] = {
129 .ctl_name
= NET_IPV4_VS
,
132 .child
= vs_vars_table
137 static ctl_table ipvs_ipv4_table
[] = {
139 .ctl_name
= NET_IPV4
,
147 static ctl_table lblc_root_table
[] = {
152 .child
= ipvs_ipv4_table
157 static struct ctl_table_header
* sysctl_header
;
160 * new/free a ip_vs_lblc_entry, which is a mapping of a destionation
161 * IP address to a server.
163 static inline struct ip_vs_lblc_entry
*
164 ip_vs_lblc_new(__be32 daddr
, struct ip_vs_dest
*dest
)
166 struct ip_vs_lblc_entry
*en
;
168 en
= kmalloc(sizeof(struct ip_vs_lblc_entry
), GFP_ATOMIC
);
170 IP_VS_ERR("ip_vs_lblc_new(): no memory\n");
174 INIT_LIST_HEAD(&en
->list
);
177 atomic_inc(&dest
->refcnt
);
184 static inline void ip_vs_lblc_free(struct ip_vs_lblc_entry
*en
)
188 * We don't kfree dest because it is refered either by its service
189 * or the trash dest list.
191 atomic_dec(&en
->dest
->refcnt
);
197 * Returns hash value for IPVS LBLC entry
199 static inline unsigned ip_vs_lblc_hashkey(__be32 addr
)
201 return (ntohl(addr
)*2654435761UL) & IP_VS_LBLC_TAB_MASK
;
206 * Hash an entry in the ip_vs_lblc_table.
207 * returns bool success.
210 ip_vs_lblc_hash(struct ip_vs_lblc_table
*tbl
, struct ip_vs_lblc_entry
*en
)
214 if (!list_empty(&en
->list
)) {
215 IP_VS_ERR("ip_vs_lblc_hash(): request for already hashed, "
216 "called from %p\n", __builtin_return_address(0));
221 * Hash by destination IP address
223 hash
= ip_vs_lblc_hashkey(en
->addr
);
225 write_lock(&tbl
->lock
);
226 list_add(&en
->list
, &tbl
->bucket
[hash
]);
227 atomic_inc(&tbl
->entries
);
228 write_unlock(&tbl
->lock
);
235 * Get ip_vs_lblc_entry associated with supplied parameters.
237 static inline struct ip_vs_lblc_entry
*
238 ip_vs_lblc_get(struct ip_vs_lblc_table
*tbl
, __be32 addr
)
241 struct ip_vs_lblc_entry
*en
;
243 hash
= ip_vs_lblc_hashkey(addr
);
245 read_lock(&tbl
->lock
);
247 list_for_each_entry(en
, &tbl
->bucket
[hash
], list
) {
248 if (en
->addr
== addr
) {
250 read_unlock(&tbl
->lock
);
255 read_unlock(&tbl
->lock
);
262 * Flush all the entries of the specified table.
264 static void ip_vs_lblc_flush(struct ip_vs_lblc_table
*tbl
)
267 struct ip_vs_lblc_entry
*en
, *nxt
;
269 for (i
=0; i
<IP_VS_LBLC_TAB_SIZE
; i
++) {
270 write_lock(&tbl
->lock
);
271 list_for_each_entry_safe(en
, nxt
, &tbl
->bucket
[i
], list
) {
273 atomic_dec(&tbl
->entries
);
275 write_unlock(&tbl
->lock
);
280 static inline void ip_vs_lblc_full_check(struct ip_vs_lblc_table
*tbl
)
282 unsigned long now
= jiffies
;
284 struct ip_vs_lblc_entry
*en
, *nxt
;
286 for (i
=0, j
=tbl
->rover
; i
<IP_VS_LBLC_TAB_SIZE
; i
++) {
287 j
= (j
+ 1) & IP_VS_LBLC_TAB_MASK
;
289 write_lock(&tbl
->lock
);
290 list_for_each_entry_safe(en
, nxt
, &tbl
->bucket
[j
], list
) {
292 en
->lastuse
+ sysctl_ip_vs_lblc_expiration
))
296 atomic_dec(&tbl
->entries
);
298 write_unlock(&tbl
->lock
);
305 * Periodical timer handler for IPVS lblc table
306 * It is used to collect stale entries when the number of entries
307 * exceeds the maximum size of the table.
309 * Fixme: we probably need more complicated algorithm to collect
310 * entries that have not been used for a long time even
311 * if the number of entries doesn't exceed the maximum size
313 * The full expiration check is for this purpose now.
315 static void ip_vs_lblc_check_expire(unsigned long data
)
317 struct ip_vs_lblc_table
*tbl
;
318 unsigned long now
= jiffies
;
321 struct ip_vs_lblc_entry
*en
, *nxt
;
323 tbl
= (struct ip_vs_lblc_table
*)data
;
325 if ((tbl
->counter
% COUNT_FOR_FULL_EXPIRATION
) == 0) {
326 /* do full expiration check */
327 ip_vs_lblc_full_check(tbl
);
332 if (atomic_read(&tbl
->entries
) <= tbl
->max_size
) {
337 goal
= (atomic_read(&tbl
->entries
) - tbl
->max_size
)*4/3;
338 if (goal
> tbl
->max_size
/2)
339 goal
= tbl
->max_size
/2;
341 for (i
=0, j
=tbl
->rover
; i
<IP_VS_LBLC_TAB_SIZE
; i
++) {
342 j
= (j
+ 1) & IP_VS_LBLC_TAB_MASK
;
344 write_lock(&tbl
->lock
);
345 list_for_each_entry_safe(en
, nxt
, &tbl
->bucket
[j
], list
) {
346 if (time_before(now
, en
->lastuse
+ ENTRY_TIMEOUT
))
350 atomic_dec(&tbl
->entries
);
353 write_unlock(&tbl
->lock
);
360 mod_timer(&tbl
->periodic_timer
, jiffies
+CHECK_EXPIRE_INTERVAL
);
364 static int ip_vs_lblc_init_svc(struct ip_vs_service
*svc
)
367 struct ip_vs_lblc_table
*tbl
;
370 * Allocate the ip_vs_lblc_table for this service
372 tbl
= kmalloc(sizeof(struct ip_vs_lblc_table
), GFP_ATOMIC
);
374 IP_VS_ERR("ip_vs_lblc_init_svc(): no memory\n");
377 svc
->sched_data
= tbl
;
378 IP_VS_DBG(6, "LBLC hash table (memory=%Zdbytes) allocated for "
380 sizeof(struct ip_vs_lblc_table
));
383 * Initialize the hash buckets
385 for (i
=0; i
<IP_VS_LBLC_TAB_SIZE
; i
++) {
386 INIT_LIST_HEAD(&tbl
->bucket
[i
]);
388 rwlock_init(&tbl
->lock
);
389 tbl
->max_size
= IP_VS_LBLC_TAB_SIZE
*16;
394 * Hook periodic timer for garbage collection
396 init_timer(&tbl
->periodic_timer
);
397 tbl
->periodic_timer
.data
= (unsigned long)tbl
;
398 tbl
->periodic_timer
.function
= ip_vs_lblc_check_expire
;
399 tbl
->periodic_timer
.expires
= jiffies
+CHECK_EXPIRE_INTERVAL
;
400 add_timer(&tbl
->periodic_timer
);
406 static int ip_vs_lblc_done_svc(struct ip_vs_service
*svc
)
408 struct ip_vs_lblc_table
*tbl
= svc
->sched_data
;
410 /* remove periodic timer */
411 del_timer_sync(&tbl
->periodic_timer
);
413 /* got to clean up table entries here */
414 ip_vs_lblc_flush(tbl
);
416 /* release the table itself */
417 kfree(svc
->sched_data
);
418 IP_VS_DBG(6, "LBLC hash table (memory=%Zdbytes) released\n",
419 sizeof(struct ip_vs_lblc_table
));
425 static int ip_vs_lblc_update_svc(struct ip_vs_service
*svc
)
431 static inline struct ip_vs_dest
*
432 __ip_vs_wlc_schedule(struct ip_vs_service
*svc
, struct iphdr
*iph
)
434 struct ip_vs_dest
*dest
, *least
;
438 * We think the overhead of processing active connections is fifty
439 * times higher than that of inactive connections in average. (This
440 * fifty times might not be accurate, we will change it later.) We
441 * use the following formula to estimate the overhead:
442 * dest->activeconns*50 + dest->inactconns
444 * (dest overhead) / dest->weight
446 * Remember -- no floats in kernel mode!!!
447 * The comparison of h1*w2 > h2*w1 is equivalent to that of
449 * if every weight is larger than zero.
451 * The server with weight=0 is quiesced and will not receive any
454 list_for_each_entry(dest
, &svc
->destinations
, n_list
) {
455 if (dest
->flags
& IP_VS_DEST_F_OVERLOAD
)
457 if (atomic_read(&dest
->weight
) > 0) {
459 loh
= atomic_read(&least
->activeconns
) * 50
460 + atomic_read(&least
->inactconns
);
467 * Find the destination with the least load.
470 list_for_each_entry_continue(dest
, &svc
->destinations
, n_list
) {
471 if (dest
->flags
& IP_VS_DEST_F_OVERLOAD
)
474 doh
= atomic_read(&dest
->activeconns
) * 50
475 + atomic_read(&dest
->inactconns
);
476 if (loh
* atomic_read(&dest
->weight
) >
477 doh
* atomic_read(&least
->weight
)) {
483 IP_VS_DBG(6, "LBLC: server %d.%d.%d.%d:%d "
484 "activeconns %d refcnt %d weight %d overhead %d\n",
485 NIPQUAD(least
->addr
), ntohs(least
->port
),
486 atomic_read(&least
->activeconns
),
487 atomic_read(&least
->refcnt
),
488 atomic_read(&least
->weight
), loh
);
495 * If this destination server is overloaded and there is a less loaded
496 * server, then return true.
499 is_overloaded(struct ip_vs_dest
*dest
, struct ip_vs_service
*svc
)
501 if (atomic_read(&dest
->activeconns
) > atomic_read(&dest
->weight
)) {
502 struct ip_vs_dest
*d
;
504 list_for_each_entry(d
, &svc
->destinations
, n_list
) {
505 if (atomic_read(&d
->activeconns
)*2
506 < atomic_read(&d
->weight
)) {
516 * Locality-Based (weighted) Least-Connection scheduling
518 static struct ip_vs_dest
*
519 ip_vs_lblc_schedule(struct ip_vs_service
*svc
, const struct sk_buff
*skb
)
521 struct ip_vs_dest
*dest
;
522 struct ip_vs_lblc_table
*tbl
;
523 struct ip_vs_lblc_entry
*en
;
524 struct iphdr
*iph
= ip_hdr(skb
);
526 IP_VS_DBG(6, "ip_vs_lblc_schedule(): Scheduling...\n");
528 tbl
= (struct ip_vs_lblc_table
*)svc
->sched_data
;
529 en
= ip_vs_lblc_get(tbl
, iph
->daddr
);
531 dest
= __ip_vs_wlc_schedule(svc
, iph
);
533 IP_VS_DBG(1, "no destination available\n");
536 en
= ip_vs_lblc_new(iph
->daddr
, dest
);
540 ip_vs_lblc_hash(tbl
, en
);
543 if (!(dest
->flags
& IP_VS_DEST_F_AVAILABLE
)
544 || atomic_read(&dest
->weight
) <= 0
545 || is_overloaded(dest
, svc
)) {
546 dest
= __ip_vs_wlc_schedule(svc
, iph
);
548 IP_VS_DBG(1, "no destination available\n");
551 atomic_dec(&en
->dest
->refcnt
);
552 atomic_inc(&dest
->refcnt
);
556 en
->lastuse
= jiffies
;
558 IP_VS_DBG(6, "LBLC: destination IP address %u.%u.%u.%u "
559 "--> server %u.%u.%u.%u:%d\n",
569 * IPVS LBLC Scheduler structure
571 static struct ip_vs_scheduler ip_vs_lblc_scheduler
=
574 .refcnt
= ATOMIC_INIT(0),
575 .module
= THIS_MODULE
,
576 .init_service
= ip_vs_lblc_init_svc
,
577 .done_service
= ip_vs_lblc_done_svc
,
578 .update_service
= ip_vs_lblc_update_svc
,
579 .schedule
= ip_vs_lblc_schedule
,
583 static int __init
ip_vs_lblc_init(void)
585 INIT_LIST_HEAD(&ip_vs_lblc_scheduler
.n_list
);
586 sysctl_header
= register_sysctl_table(lblc_root_table
);
587 return register_ip_vs_scheduler(&ip_vs_lblc_scheduler
);
591 static void __exit
ip_vs_lblc_cleanup(void)
593 unregister_sysctl_table(sysctl_header
);
594 unregister_ip_vs_scheduler(&ip_vs_lblc_scheduler
);
598 module_init(ip_vs_lblc_init
);
599 module_exit(ip_vs_lblc_cleanup
);
600 MODULE_LICENSE("GPL");