Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * IPVS: Locality-Based Least-Connection scheduling module | |
3 | * | |
1da177e4 LT |
4 | * Authors: Wensong Zhang <wensong@gnuchina.org> |
5 | * | |
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. | |
10 | * | |
11 | * Changes: | |
12 | * Martin Hamilton : fixed the terrible locking bugs | |
13 | * *lock(tbl->lock) ==> *lock(&tbl->lock) | |
14 | * Wensong Zhang : fixed the uninitilized 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 | |
21 | * | |
22 | */ | |
23 | ||
24 | /* | |
25 | * The lblc algorithm is as follows (pseudo code): | |
26 | * | |
27 | * if cachenode[dest_ip] is null then | |
28 | * n, cachenode[dest_ip] <- {weighted least-conn node}; | |
29 | * else | |
30 | * n <- cachenode[dest_ip]; | |
31 | * if (n is dead) OR | |
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}; | |
35 | * | |
36 | * return n; | |
37 | * | |
38 | * Thanks must go to Wenzhuo Zhang for talking WCCP to me and pushing | |
39 | * me to write this module. | |
40 | */ | |
41 | ||
14c85021 | 42 | #include <linux/ip.h> |
1da177e4 LT |
43 | #include <linux/module.h> |
44 | #include <linux/kernel.h> | |
14c85021 | 45 | #include <linux/skbuff.h> |
d7fe0f24 | 46 | #include <linux/jiffies.h> |
1da177e4 LT |
47 | |
48 | /* for sysctl */ | |
49 | #include <linux/fs.h> | |
50 | #include <linux/sysctl.h> | |
51 | ||
52 | #include <net/ip_vs.h> | |
53 | ||
54 | ||
55 | /* | |
56 | * It is for garbage collection of stale IPVS lblc entries, | |
57 | * when the table is full. | |
58 | */ | |
59 | #define CHECK_EXPIRE_INTERVAL (60*HZ) | |
60 | #define ENTRY_TIMEOUT (6*60*HZ) | |
61 | ||
62 | /* | |
63 | * It is for full expiration check. | |
64 | * When there is no partial expiration check (garbage collection) | |
65 | * in a half hour, do a full expiration check to collect stale | |
66 | * entries that haven't been touched for a day. | |
67 | */ | |
68 | #define COUNT_FOR_FULL_EXPIRATION 30 | |
69 | static int sysctl_ip_vs_lblc_expiration = 24*60*60*HZ; | |
70 | ||
71 | ||
72 | /* | |
73 | * for IPVS lblc entry hash table | |
74 | */ | |
75 | #ifndef CONFIG_IP_VS_LBLC_TAB_BITS | |
76 | #define CONFIG_IP_VS_LBLC_TAB_BITS 10 | |
77 | #endif | |
78 | #define IP_VS_LBLC_TAB_BITS CONFIG_IP_VS_LBLC_TAB_BITS | |
79 | #define IP_VS_LBLC_TAB_SIZE (1 << IP_VS_LBLC_TAB_BITS) | |
80 | #define IP_VS_LBLC_TAB_MASK (IP_VS_LBLC_TAB_SIZE - 1) | |
81 | ||
82 | ||
83 | /* | |
84 | * IPVS lblc entry represents an association between destination | |
85 | * IP address and its destination server | |
86 | */ | |
87 | struct ip_vs_lblc_entry { | |
88 | struct list_head list; | |
014d730d | 89 | __be32 addr; /* destination IP address */ |
1da177e4 LT |
90 | struct ip_vs_dest *dest; /* real server (cache) */ |
91 | unsigned long lastuse; /* last used time */ | |
92 | }; | |
93 | ||
94 | ||
95 | /* | |
96 | * IPVS lblc hash table | |
97 | */ | |
98 | struct ip_vs_lblc_table { | |
99 | rwlock_t lock; /* lock for this table */ | |
100 | struct list_head bucket[IP_VS_LBLC_TAB_SIZE]; /* hash bucket */ | |
101 | atomic_t entries; /* number of entries */ | |
102 | int max_size; /* maximum size of entries */ | |
103 | struct timer_list periodic_timer; /* collect stale entries */ | |
104 | int rover; /* rover for expire check */ | |
105 | int counter; /* counter for no expire */ | |
106 | }; | |
107 | ||
108 | ||
109 | /* | |
110 | * IPVS LBLC sysctl table | |
111 | */ | |
112 | ||
113 | static ctl_table vs_vars_table[] = { | |
114 | { | |
1da177e4 LT |
115 | .procname = "lblc_expiration", |
116 | .data = &sysctl_ip_vs_lblc_expiration, | |
117 | .maxlen = sizeof(int), | |
e905a9ed | 118 | .mode = 0644, |
1da177e4 LT |
119 | .proc_handler = &proc_dointvec_jiffies, |
120 | }, | |
121 | { .ctl_name = 0 } | |
122 | }; | |
123 | ||
1da177e4 LT |
124 | static struct ctl_table_header * sysctl_header; |
125 | ||
126 | /* | |
127 | * new/free a ip_vs_lblc_entry, which is a mapping of a destionation | |
128 | * IP address to a server. | |
129 | */ | |
130 | static inline struct ip_vs_lblc_entry * | |
014d730d | 131 | ip_vs_lblc_new(__be32 daddr, struct ip_vs_dest *dest) |
1da177e4 LT |
132 | { |
133 | struct ip_vs_lblc_entry *en; | |
134 | ||
135 | en = kmalloc(sizeof(struct ip_vs_lblc_entry), GFP_ATOMIC); | |
136 | if (en == NULL) { | |
137 | IP_VS_ERR("ip_vs_lblc_new(): no memory\n"); | |
138 | return NULL; | |
139 | } | |
140 | ||
141 | INIT_LIST_HEAD(&en->list); | |
142 | en->addr = daddr; | |
143 | ||
144 | atomic_inc(&dest->refcnt); | |
145 | en->dest = dest; | |
146 | ||
147 | return en; | |
148 | } | |
149 | ||
150 | ||
151 | static inline void ip_vs_lblc_free(struct ip_vs_lblc_entry *en) | |
152 | { | |
153 | list_del(&en->list); | |
154 | /* | |
155 | * We don't kfree dest because it is refered either by its service | |
156 | * or the trash dest list. | |
157 | */ | |
158 | atomic_dec(&en->dest->refcnt); | |
159 | kfree(en); | |
160 | } | |
161 | ||
162 | ||
163 | /* | |
164 | * Returns hash value for IPVS LBLC entry | |
165 | */ | |
014d730d | 166 | static inline unsigned ip_vs_lblc_hashkey(__be32 addr) |
1da177e4 LT |
167 | { |
168 | return (ntohl(addr)*2654435761UL) & IP_VS_LBLC_TAB_MASK; | |
169 | } | |
170 | ||
171 | ||
172 | /* | |
173 | * Hash an entry in the ip_vs_lblc_table. | |
174 | * returns bool success. | |
175 | */ | |
176 | static int | |
177 | ip_vs_lblc_hash(struct ip_vs_lblc_table *tbl, struct ip_vs_lblc_entry *en) | |
178 | { | |
179 | unsigned hash; | |
180 | ||
181 | if (!list_empty(&en->list)) { | |
182 | IP_VS_ERR("ip_vs_lblc_hash(): request for already hashed, " | |
183 | "called from %p\n", __builtin_return_address(0)); | |
184 | return 0; | |
185 | } | |
186 | ||
187 | /* | |
188 | * Hash by destination IP address | |
189 | */ | |
190 | hash = ip_vs_lblc_hashkey(en->addr); | |
191 | ||
192 | write_lock(&tbl->lock); | |
193 | list_add(&en->list, &tbl->bucket[hash]); | |
194 | atomic_inc(&tbl->entries); | |
195 | write_unlock(&tbl->lock); | |
196 | ||
197 | return 1; | |
198 | } | |
199 | ||
200 | ||
1da177e4 LT |
201 | /* |
202 | * Get ip_vs_lblc_entry associated with supplied parameters. | |
203 | */ | |
204 | static inline struct ip_vs_lblc_entry * | |
014d730d | 205 | ip_vs_lblc_get(struct ip_vs_lblc_table *tbl, __be32 addr) |
1da177e4 LT |
206 | { |
207 | unsigned hash; | |
208 | struct ip_vs_lblc_entry *en; | |
209 | ||
210 | hash = ip_vs_lblc_hashkey(addr); | |
211 | ||
212 | read_lock(&tbl->lock); | |
213 | ||
214 | list_for_each_entry(en, &tbl->bucket[hash], list) { | |
215 | if (en->addr == addr) { | |
216 | /* HIT */ | |
217 | read_unlock(&tbl->lock); | |
218 | return en; | |
219 | } | |
220 | } | |
221 | ||
222 | read_unlock(&tbl->lock); | |
223 | ||
224 | return NULL; | |
225 | } | |
226 | ||
227 | ||
228 | /* | |
229 | * Flush all the entries of the specified table. | |
230 | */ | |
231 | static void ip_vs_lblc_flush(struct ip_vs_lblc_table *tbl) | |
232 | { | |
233 | int i; | |
234 | struct ip_vs_lblc_entry *en, *nxt; | |
235 | ||
236 | for (i=0; i<IP_VS_LBLC_TAB_SIZE; i++) { | |
237 | write_lock(&tbl->lock); | |
238 | list_for_each_entry_safe(en, nxt, &tbl->bucket[i], list) { | |
239 | ip_vs_lblc_free(en); | |
240 | atomic_dec(&tbl->entries); | |
241 | } | |
242 | write_unlock(&tbl->lock); | |
243 | } | |
244 | } | |
245 | ||
246 | ||
247 | static inline void ip_vs_lblc_full_check(struct ip_vs_lblc_table *tbl) | |
248 | { | |
249 | unsigned long now = jiffies; | |
250 | int i, j; | |
251 | struct ip_vs_lblc_entry *en, *nxt; | |
252 | ||
253 | for (i=0, j=tbl->rover; i<IP_VS_LBLC_TAB_SIZE; i++) { | |
254 | j = (j + 1) & IP_VS_LBLC_TAB_MASK; | |
255 | ||
256 | write_lock(&tbl->lock); | |
257 | list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) { | |
e905a9ed | 258 | if (time_before(now, |
1da177e4 LT |
259 | en->lastuse + sysctl_ip_vs_lblc_expiration)) |
260 | continue; | |
261 | ||
262 | ip_vs_lblc_free(en); | |
263 | atomic_dec(&tbl->entries); | |
264 | } | |
265 | write_unlock(&tbl->lock); | |
266 | } | |
267 | tbl->rover = j; | |
268 | } | |
269 | ||
270 | ||
271 | /* | |
272 | * Periodical timer handler for IPVS lblc table | |
273 | * It is used to collect stale entries when the number of entries | |
274 | * exceeds the maximum size of the table. | |
275 | * | |
276 | * Fixme: we probably need more complicated algorithm to collect | |
277 | * entries that have not been used for a long time even | |
278 | * if the number of entries doesn't exceed the maximum size | |
279 | * of the table. | |
280 | * The full expiration check is for this purpose now. | |
281 | */ | |
282 | static void ip_vs_lblc_check_expire(unsigned long data) | |
283 | { | |
284 | struct ip_vs_lblc_table *tbl; | |
285 | unsigned long now = jiffies; | |
286 | int goal; | |
287 | int i, j; | |
288 | struct ip_vs_lblc_entry *en, *nxt; | |
289 | ||
290 | tbl = (struct ip_vs_lblc_table *)data; | |
291 | ||
292 | if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) { | |
293 | /* do full expiration check */ | |
294 | ip_vs_lblc_full_check(tbl); | |
295 | tbl->counter = 1; | |
296 | goto out; | |
297 | } | |
298 | ||
299 | if (atomic_read(&tbl->entries) <= tbl->max_size) { | |
300 | tbl->counter++; | |
301 | goto out; | |
302 | } | |
303 | ||
304 | goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3; | |
305 | if (goal > tbl->max_size/2) | |
306 | goal = tbl->max_size/2; | |
307 | ||
308 | for (i=0, j=tbl->rover; i<IP_VS_LBLC_TAB_SIZE; i++) { | |
309 | j = (j + 1) & IP_VS_LBLC_TAB_MASK; | |
310 | ||
311 | write_lock(&tbl->lock); | |
312 | list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) { | |
313 | if (time_before(now, en->lastuse + ENTRY_TIMEOUT)) | |
314 | continue; | |
315 | ||
316 | ip_vs_lblc_free(en); | |
317 | atomic_dec(&tbl->entries); | |
318 | goal--; | |
319 | } | |
320 | write_unlock(&tbl->lock); | |
321 | if (goal <= 0) | |
322 | break; | |
323 | } | |
324 | tbl->rover = j; | |
325 | ||
326 | out: | |
327 | mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL); | |
328 | } | |
329 | ||
330 | ||
331 | static int ip_vs_lblc_init_svc(struct ip_vs_service *svc) | |
332 | { | |
333 | int i; | |
334 | struct ip_vs_lblc_table *tbl; | |
335 | ||
336 | /* | |
337 | * Allocate the ip_vs_lblc_table for this service | |
338 | */ | |
339 | tbl = kmalloc(sizeof(struct ip_vs_lblc_table), GFP_ATOMIC); | |
340 | if (tbl == NULL) { | |
341 | IP_VS_ERR("ip_vs_lblc_init_svc(): no memory\n"); | |
342 | return -ENOMEM; | |
343 | } | |
344 | svc->sched_data = tbl; | |
345 | IP_VS_DBG(6, "LBLC hash table (memory=%Zdbytes) allocated for " | |
346 | "current service\n", | |
347 | sizeof(struct ip_vs_lblc_table)); | |
348 | ||
349 | /* | |
350 | * Initialize the hash buckets | |
351 | */ | |
352 | for (i=0; i<IP_VS_LBLC_TAB_SIZE; i++) { | |
353 | INIT_LIST_HEAD(&tbl->bucket[i]); | |
354 | } | |
355 | rwlock_init(&tbl->lock); | |
356 | tbl->max_size = IP_VS_LBLC_TAB_SIZE*16; | |
357 | tbl->rover = 0; | |
358 | tbl->counter = 1; | |
359 | ||
360 | /* | |
361 | * Hook periodic timer for garbage collection | |
362 | */ | |
b24b8a24 PE |
363 | setup_timer(&tbl->periodic_timer, ip_vs_lblc_check_expire, |
364 | (unsigned long)tbl); | |
1da177e4 LT |
365 | tbl->periodic_timer.expires = jiffies+CHECK_EXPIRE_INTERVAL; |
366 | add_timer(&tbl->periodic_timer); | |
367 | ||
368 | return 0; | |
369 | } | |
370 | ||
371 | ||
372 | static int ip_vs_lblc_done_svc(struct ip_vs_service *svc) | |
373 | { | |
374 | struct ip_vs_lblc_table *tbl = svc->sched_data; | |
375 | ||
376 | /* remove periodic timer */ | |
377 | del_timer_sync(&tbl->periodic_timer); | |
378 | ||
379 | /* got to clean up table entries here */ | |
380 | ip_vs_lblc_flush(tbl); | |
381 | ||
382 | /* release the table itself */ | |
383 | kfree(svc->sched_data); | |
384 | IP_VS_DBG(6, "LBLC hash table (memory=%Zdbytes) released\n", | |
385 | sizeof(struct ip_vs_lblc_table)); | |
386 | ||
387 | return 0; | |
388 | } | |
389 | ||
390 | ||
391 | static int ip_vs_lblc_update_svc(struct ip_vs_service *svc) | |
392 | { | |
393 | return 0; | |
394 | } | |
395 | ||
396 | ||
397 | static inline struct ip_vs_dest * | |
398 | __ip_vs_wlc_schedule(struct ip_vs_service *svc, struct iphdr *iph) | |
399 | { | |
400 | struct ip_vs_dest *dest, *least; | |
401 | int loh, doh; | |
402 | ||
403 | /* | |
404 | * We think the overhead of processing active connections is fifty | |
405 | * times higher than that of inactive connections in average. (This | |
406 | * fifty times might not be accurate, we will change it later.) We | |
407 | * use the following formula to estimate the overhead: | |
408 | * dest->activeconns*50 + dest->inactconns | |
409 | * and the load: | |
410 | * (dest overhead) / dest->weight | |
411 | * | |
412 | * Remember -- no floats in kernel mode!!! | |
413 | * The comparison of h1*w2 > h2*w1 is equivalent to that of | |
414 | * h1/w1 > h2/w2 | |
415 | * if every weight is larger than zero. | |
416 | * | |
417 | * The server with weight=0 is quiesced and will not receive any | |
418 | * new connection. | |
419 | */ | |
420 | list_for_each_entry(dest, &svc->destinations, n_list) { | |
421 | if (dest->flags & IP_VS_DEST_F_OVERLOAD) | |
422 | continue; | |
423 | if (atomic_read(&dest->weight) > 0) { | |
424 | least = dest; | |
425 | loh = atomic_read(&least->activeconns) * 50 | |
426 | + atomic_read(&least->inactconns); | |
427 | goto nextstage; | |
428 | } | |
429 | } | |
430 | return NULL; | |
431 | ||
432 | /* | |
433 | * Find the destination with the least load. | |
434 | */ | |
435 | nextstage: | |
436 | list_for_each_entry_continue(dest, &svc->destinations, n_list) { | |
437 | if (dest->flags & IP_VS_DEST_F_OVERLOAD) | |
438 | continue; | |
439 | ||
440 | doh = atomic_read(&dest->activeconns) * 50 | |
441 | + atomic_read(&dest->inactconns); | |
442 | if (loh * atomic_read(&dest->weight) > | |
443 | doh * atomic_read(&least->weight)) { | |
444 | least = dest; | |
445 | loh = doh; | |
446 | } | |
447 | } | |
448 | ||
449 | IP_VS_DBG(6, "LBLC: server %d.%d.%d.%d:%d " | |
450 | "activeconns %d refcnt %d weight %d overhead %d\n", | |
451 | NIPQUAD(least->addr), ntohs(least->port), | |
452 | atomic_read(&least->activeconns), | |
453 | atomic_read(&least->refcnt), | |
454 | atomic_read(&least->weight), loh); | |
455 | ||
456 | return least; | |
457 | } | |
458 | ||
459 | ||
460 | /* | |
461 | * If this destination server is overloaded and there is a less loaded | |
462 | * server, then return true. | |
463 | */ | |
464 | static inline int | |
465 | is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc) | |
466 | { | |
467 | if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) { | |
468 | struct ip_vs_dest *d; | |
469 | ||
470 | list_for_each_entry(d, &svc->destinations, n_list) { | |
471 | if (atomic_read(&d->activeconns)*2 | |
472 | < atomic_read(&d->weight)) { | |
473 | return 1; | |
474 | } | |
475 | } | |
476 | } | |
477 | return 0; | |
478 | } | |
479 | ||
480 | ||
481 | /* | |
482 | * Locality-Based (weighted) Least-Connection scheduling | |
483 | */ | |
484 | static struct ip_vs_dest * | |
485 | ip_vs_lblc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb) | |
486 | { | |
487 | struct ip_vs_dest *dest; | |
488 | struct ip_vs_lblc_table *tbl; | |
489 | struct ip_vs_lblc_entry *en; | |
eddc9ec5 | 490 | struct iphdr *iph = ip_hdr(skb); |
1da177e4 LT |
491 | |
492 | IP_VS_DBG(6, "ip_vs_lblc_schedule(): Scheduling...\n"); | |
493 | ||
494 | tbl = (struct ip_vs_lblc_table *)svc->sched_data; | |
495 | en = ip_vs_lblc_get(tbl, iph->daddr); | |
496 | if (en == NULL) { | |
497 | dest = __ip_vs_wlc_schedule(svc, iph); | |
498 | if (dest == NULL) { | |
499 | IP_VS_DBG(1, "no destination available\n"); | |
500 | return NULL; | |
501 | } | |
502 | en = ip_vs_lblc_new(iph->daddr, dest); | |
503 | if (en == NULL) { | |
504 | return NULL; | |
505 | } | |
506 | ip_vs_lblc_hash(tbl, en); | |
507 | } else { | |
508 | dest = en->dest; | |
509 | if (!(dest->flags & IP_VS_DEST_F_AVAILABLE) | |
510 | || atomic_read(&dest->weight) <= 0 | |
511 | || is_overloaded(dest, svc)) { | |
512 | dest = __ip_vs_wlc_schedule(svc, iph); | |
513 | if (dest == NULL) { | |
514 | IP_VS_DBG(1, "no destination available\n"); | |
515 | return NULL; | |
516 | } | |
517 | atomic_dec(&en->dest->refcnt); | |
518 | atomic_inc(&dest->refcnt); | |
519 | en->dest = dest; | |
520 | } | |
521 | } | |
522 | en->lastuse = jiffies; | |
523 | ||
524 | IP_VS_DBG(6, "LBLC: destination IP address %u.%u.%u.%u " | |
525 | "--> server %u.%u.%u.%u:%d\n", | |
526 | NIPQUAD(en->addr), | |
527 | NIPQUAD(dest->addr), | |
528 | ntohs(dest->port)); | |
529 | ||
530 | return dest; | |
531 | } | |
532 | ||
533 | ||
534 | /* | |
535 | * IPVS LBLC Scheduler structure | |
536 | */ | |
537 | static struct ip_vs_scheduler ip_vs_lblc_scheduler = | |
538 | { | |
539 | .name = "lblc", | |
540 | .refcnt = ATOMIC_INIT(0), | |
541 | .module = THIS_MODULE, | |
542 | .init_service = ip_vs_lblc_init_svc, | |
543 | .done_service = ip_vs_lblc_done_svc, | |
544 | .update_service = ip_vs_lblc_update_svc, | |
545 | .schedule = ip_vs_lblc_schedule, | |
546 | }; | |
547 | ||
548 | ||
549 | static int __init ip_vs_lblc_init(void) | |
550 | { | |
a014bc8f PE |
551 | int ret; |
552 | ||
1da177e4 | 553 | INIT_LIST_HEAD(&ip_vs_lblc_scheduler.n_list); |
90754f8e | 554 | sysctl_header = register_sysctl_paths(net_vs_ctl_path, vs_vars_table); |
a014bc8f PE |
555 | ret = register_ip_vs_scheduler(&ip_vs_lblc_scheduler); |
556 | if (ret) | |
557 | unregister_sysctl_table(sysctl_header); | |
558 | return ret; | |
1da177e4 LT |
559 | } |
560 | ||
561 | ||
562 | static void __exit ip_vs_lblc_cleanup(void) | |
563 | { | |
564 | unregister_sysctl_table(sysctl_header); | |
565 | unregister_ip_vs_scheduler(&ip_vs_lblc_scheduler); | |
566 | } | |
567 | ||
568 | ||
569 | module_init(ip_vs_lblc_init); | |
570 | module_exit(ip_vs_lblc_cleanup); | |
571 | MODULE_LICENSE("GPL"); |