1 /* 2 * IPVS: Locality-Based Least-Connection scheduling module 3 * 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 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 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 42 #define KMSG_COMPONENT "IPVS" 43 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt 44 45 #include <linux/ip.h> 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> 51 52 /* for sysctl */ 53 #include <linux/fs.h> 54 #include <linux/sysctl.h> 55 56 #include <net/ip_vs.h> 57 58 59 /* 60 * It is for garbage collection of stale IPVS lblc entries, 61 * when the table is full. 62 */ 63 #define CHECK_EXPIRE_INTERVAL (60*HZ) 64 #define ENTRY_TIMEOUT (6*60*HZ) 65 66 #define DEFAULT_EXPIRATION (24*60*60*HZ) 67 68 /* 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. 73 */ 74 #define COUNT_FOR_FULL_EXPIRATION 30 75 76 77 /* 78 * for IPVS lblc entry hash table 79 */ 80 #ifndef CONFIG_IP_VS_LBLC_TAB_BITS 81 #define CONFIG_IP_VS_LBLC_TAB_BITS 10 82 #endif 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) 86 87 88 /* 89 * IPVS lblc entry represents an association between destination 90 * IP address and its destination server 91 */ 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; 99 }; 100 101 102 /* 103 * IPVS lblc hash table 104 */ 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 atomic_t entries; /* number of entries */ 110 int max_size; /* maximum size of entries */ 111 int rover; /* rover for expire check */ 112 int counter; /* counter for no expire */ 113 bool dead; 114 }; 115 116 117 /* 118 * IPVS LBLC sysctl table 119 */ 120 #ifdef CONFIG_SYSCTL 121 static struct ctl_table vs_vars_table[] = { 122 { 123 .procname = "lblc_expiration", 124 .data = NULL, 125 .maxlen = sizeof(int), 126 .mode = 0644, 127 .proc_handler = proc_dointvec_jiffies, 128 }, 129 { } 130 }; 131 #endif 132 133 static void ip_vs_lblc_rcu_free(struct rcu_head *head) 134 { 135 struct ip_vs_lblc_entry *en = container_of(head, 136 struct ip_vs_lblc_entry, 137 rcu_head); 138 139 ip_vs_dest_put_and_free(en->dest); 140 kfree(en); 141 } 142 143 static inline void ip_vs_lblc_del(struct ip_vs_lblc_entry *en) 144 { 145 hlist_del_rcu(&en->list); 146 call_rcu(&en->rcu_head, ip_vs_lblc_rcu_free); 147 } 148 149 /* 150 * Returns hash value for IPVS LBLC entry 151 */ 152 static inline unsigned int 153 ip_vs_lblc_hashkey(int af, const union nf_inet_addr *addr) 154 { 155 __be32 addr_fold = addr->ip; 156 157 #ifdef CONFIG_IP_VS_IPV6 158 if (af == AF_INET6) 159 addr_fold = addr->ip6[0]^addr->ip6[1]^ 160 addr->ip6[2]^addr->ip6[3]; 161 #endif 162 return (ntohl(addr_fold)*2654435761UL) & IP_VS_LBLC_TAB_MASK; 163 } 164 165 166 /* 167 * Hash an entry in the ip_vs_lblc_table. 168 * returns bool success. 169 */ 170 static void 171 ip_vs_lblc_hash(struct ip_vs_lblc_table *tbl, struct ip_vs_lblc_entry *en) 172 { 173 unsigned int hash = ip_vs_lblc_hashkey(en->af, &en->addr); 174 175 hlist_add_head_rcu(&en->list, &tbl->bucket[hash]); 176 atomic_inc(&tbl->entries); 177 } 178 179 180 /* Get ip_vs_lblc_entry associated with supplied parameters. */ 181 static inline struct ip_vs_lblc_entry * 182 ip_vs_lblc_get(int af, struct ip_vs_lblc_table *tbl, 183 const union nf_inet_addr *addr) 184 { 185 unsigned int hash = ip_vs_lblc_hashkey(af, addr); 186 struct ip_vs_lblc_entry *en; 187 188 hlist_for_each_entry_rcu(en, &tbl->bucket[hash], list) 189 if (ip_vs_addr_equal(af, &en->addr, addr)) 190 return en; 191 192 return NULL; 193 } 194 195 196 /* 197 * Create or update an ip_vs_lblc_entry, which is a mapping of a destination IP 198 * address to a server. Called under spin lock. 199 */ 200 static inline struct ip_vs_lblc_entry * 201 ip_vs_lblc_new(struct ip_vs_lblc_table *tbl, const union nf_inet_addr *daddr, 202 struct ip_vs_dest *dest) 203 { 204 struct ip_vs_lblc_entry *en; 205 206 en = ip_vs_lblc_get(dest->af, tbl, daddr); 207 if (en) { 208 if (en->dest == dest) 209 return en; 210 ip_vs_lblc_del(en); 211 } 212 en = kmalloc(sizeof(*en), GFP_ATOMIC); 213 if (!en) 214 return NULL; 215 216 en->af = dest->af; 217 ip_vs_addr_copy(dest->af, &en->addr, daddr); 218 en->lastuse = jiffies; 219 220 ip_vs_dest_hold(dest); 221 en->dest = dest; 222 223 ip_vs_lblc_hash(tbl, en); 224 225 return en; 226 } 227 228 229 /* 230 * Flush all the entries of the specified table. 231 */ 232 static void ip_vs_lblc_flush(struct ip_vs_service *svc) 233 { 234 struct ip_vs_lblc_table *tbl = svc->sched_data; 235 struct ip_vs_lblc_entry *en; 236 struct hlist_node *next; 237 int i; 238 239 spin_lock_bh(&svc->sched_lock); 240 tbl->dead = 1; 241 for (i=0; i<IP_VS_LBLC_TAB_SIZE; i++) { 242 hlist_for_each_entry_safe(en, next, &tbl->bucket[i], list) { 243 ip_vs_lblc_del(en); 244 atomic_dec(&tbl->entries); 245 } 246 } 247 spin_unlock_bh(&svc->sched_lock); 248 } 249 250 static int sysctl_lblc_expiration(struct ip_vs_service *svc) 251 { 252 #ifdef CONFIG_SYSCTL 253 struct netns_ipvs *ipvs = net_ipvs(svc->net); 254 return ipvs->sysctl_lblc_expiration; 255 #else 256 return DEFAULT_EXPIRATION; 257 #endif 258 } 259 260 static inline void ip_vs_lblc_full_check(struct ip_vs_service *svc) 261 { 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; 266 int i, j; 267 268 for (i=0, j=tbl->rover; i<IP_VS_LBLC_TAB_SIZE; i++) { 269 j = (j + 1) & IP_VS_LBLC_TAB_MASK; 270 271 spin_lock(&svc->sched_lock); 272 hlist_for_each_entry_safe(en, next, &tbl->bucket[j], list) { 273 if (time_before(now, 274 en->lastuse + 275 sysctl_lblc_expiration(svc))) 276 continue; 277 278 ip_vs_lblc_del(en); 279 atomic_dec(&tbl->entries); 280 } 281 spin_unlock(&svc->sched_lock); 282 } 283 tbl->rover = j; 284 } 285 286 287 /* 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. 291 * 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 295 * of the table. 296 * The full expiration check is for this purpose now. 297 */ 298 static void ip_vs_lblc_check_expire(unsigned long data) 299 { 300 struct ip_vs_service *svc = (struct ip_vs_service *) data; 301 struct ip_vs_lblc_table *tbl = svc->sched_data; 302 unsigned long now = jiffies; 303 int goal; 304 int i, j; 305 struct ip_vs_lblc_entry *en; 306 struct hlist_node *next; 307 308 if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) { 309 /* do full expiration check */ 310 ip_vs_lblc_full_check(svc); 311 tbl->counter = 1; 312 goto out; 313 } 314 315 if (atomic_read(&tbl->entries) <= tbl->max_size) { 316 tbl->counter++; 317 goto out; 318 } 319 320 goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3; 321 if (goal > tbl->max_size/2) 322 goal = tbl->max_size/2; 323 324 for (i=0, j=tbl->rover; i<IP_VS_LBLC_TAB_SIZE; i++) { 325 j = (j + 1) & IP_VS_LBLC_TAB_MASK; 326 327 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)) 330 continue; 331 332 ip_vs_lblc_del(en); 333 atomic_dec(&tbl->entries); 334 goal--; 335 } 336 spin_unlock(&svc->sched_lock); 337 if (goal <= 0) 338 break; 339 } 340 tbl->rover = j; 341 342 out: 343 mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL); 344 } 345 346 347 static int ip_vs_lblc_init_svc(struct ip_vs_service *svc) 348 { 349 int i; 350 struct ip_vs_lblc_table *tbl; 351 352 /* 353 * Allocate the ip_vs_lblc_table for this service 354 */ 355 tbl = kmalloc(sizeof(*tbl), GFP_KERNEL); 356 if (tbl == NULL) 357 return -ENOMEM; 358 359 svc->sched_data = tbl; 360 IP_VS_DBG(6, "LBLC hash table (memory=%Zdbytes) allocated for " 361 "current service\n", sizeof(*tbl)); 362 363 /* 364 * Initialize the hash buckets 365 */ 366 for (i=0; i<IP_VS_LBLC_TAB_SIZE; i++) { 367 INIT_HLIST_HEAD(&tbl->bucket[i]); 368 } 369 tbl->max_size = IP_VS_LBLC_TAB_SIZE*16; 370 tbl->rover = 0; 371 tbl->counter = 1; 372 tbl->dead = 0; 373 374 /* 375 * Hook periodic timer for garbage collection 376 */ 377 setup_timer(&tbl->periodic_timer, ip_vs_lblc_check_expire, 378 (unsigned long)svc); 379 mod_timer(&tbl->periodic_timer, jiffies + CHECK_EXPIRE_INTERVAL); 380 381 return 0; 382 } 383 384 385 static void ip_vs_lblc_done_svc(struct ip_vs_service *svc) 386 { 387 struct ip_vs_lblc_table *tbl = svc->sched_data; 388 389 /* remove periodic timer */ 390 del_timer_sync(&tbl->periodic_timer); 391 392 /* got to clean up table entries here */ 393 ip_vs_lblc_flush(svc); 394 395 /* release the table itself */ 396 kfree_rcu(tbl, rcu_head); 397 IP_VS_DBG(6, "LBLC hash table (memory=%Zdbytes) released\n", 398 sizeof(*tbl)); 399 } 400 401 402 static inline struct ip_vs_dest * 403 __ip_vs_lblc_schedule(struct ip_vs_service *svc) 404 { 405 struct ip_vs_dest *dest, *least; 406 int loh, doh; 407 408 /* 409 * We use the following formula to estimate 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_rcu(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 = ip_vs_dest_conn_overhead(least); 426 goto nextstage; 427 } 428 } 429 return NULL; 430 431 /* 432 * Find the destination with the least load. 433 */ 434 nextstage: 435 list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { 436 if (dest->flags & IP_VS_DEST_F_OVERLOAD) 437 continue; 438 439 doh = ip_vs_dest_conn_overhead(dest); 440 if ((__s64)loh * atomic_read(&dest->weight) > 441 (__s64)doh * atomic_read(&least->weight)) { 442 least = dest; 443 loh = doh; 444 } 445 } 446 447 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), 450 ntohs(least->port), 451 atomic_read(&least->activeconns), 452 atomic_read(&least->refcnt), 453 atomic_read(&least->weight), loh); 454 455 return least; 456 } 457 458 459 /* 460 * If this destination server is overloaded and there is a less loaded 461 * server, then return true. 462 */ 463 static inline int 464 is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc) 465 { 466 if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) { 467 struct ip_vs_dest *d; 468 469 list_for_each_entry_rcu(d, &svc->destinations, n_list) { 470 if (atomic_read(&d->activeconns)*2 471 < atomic_read(&d->weight)) { 472 return 1; 473 } 474 } 475 } 476 return 0; 477 } 478 479 480 /* 481 * Locality-Based (weighted) Least-Connection scheduling 482 */ 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) 486 { 487 struct ip_vs_lblc_table *tbl = svc->sched_data; 488 struct ip_vs_dest *dest = NULL; 489 struct ip_vs_lblc_entry *en; 490 491 IP_VS_DBG(6, "%s(): Scheduling...\n", __func__); 492 493 /* First look in our cache */ 494 en = ip_vs_lblc_get(svc->af, tbl, &iph->daddr); 495 if (en) { 496 /* We only hold a read lock, but this is atomic */ 497 en->lastuse = jiffies; 498 499 /* 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. 506 */ 507 508 dest = en->dest; 509 if ((dest->flags & IP_VS_DEST_F_AVAILABLE) && 510 atomic_read(&dest->weight) > 0 && !is_overloaded(dest, svc)) 511 goto out; 512 } 513 514 /* No cache entry or it is invalid, time to schedule */ 515 dest = __ip_vs_lblc_schedule(svc); 516 if (!dest) { 517 ip_vs_scheduler_err(svc, "no destination available"); 518 return NULL; 519 } 520 521 /* If we fail to create a cache entry, we'll just use the valid dest */ 522 spin_lock_bh(&svc->sched_lock); 523 if (!tbl->dead) 524 ip_vs_lblc_new(tbl, &iph->daddr, dest); 525 spin_unlock_bh(&svc->sched_lock); 526 527 out: 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(svc->af, &dest->addr), ntohs(dest->port)); 531 532 return dest; 533 } 534 535 536 /* 537 * IPVS LBLC Scheduler structure 538 */ 539 static struct ip_vs_scheduler ip_vs_lblc_scheduler = 540 { 541 .name = "lblc", 542 .refcnt = ATOMIC_INIT(0), 543 .module = THIS_MODULE, 544 .n_list = LIST_HEAD_INIT(ip_vs_lblc_scheduler.n_list), 545 .init_service = ip_vs_lblc_init_svc, 546 .done_service = ip_vs_lblc_done_svc, 547 .schedule = ip_vs_lblc_schedule, 548 }; 549 550 /* 551 * per netns init. 552 */ 553 #ifdef CONFIG_SYSCTL 554 static int __net_init __ip_vs_lblc_init(struct net *net) 555 { 556 struct netns_ipvs *ipvs = net_ipvs(net); 557 558 if (!ipvs) 559 return -ENOENT; 560 561 if (!net_eq(net, &init_net)) { 562 ipvs->lblc_ctl_table = kmemdup(vs_vars_table, 563 sizeof(vs_vars_table), 564 GFP_KERNEL); 565 if (ipvs->lblc_ctl_table == NULL) 566 return -ENOMEM; 567 568 /* Don't export sysctls to unprivileged users */ 569 if (net->user_ns != &init_user_ns) 570 ipvs->lblc_ctl_table[0].procname = NULL; 571 572 } else 573 ipvs->lblc_ctl_table = vs_vars_table; 574 ipvs->sysctl_lblc_expiration = DEFAULT_EXPIRATION; 575 ipvs->lblc_ctl_table[0].data = &ipvs->sysctl_lblc_expiration; 576 577 ipvs->lblc_ctl_header = 578 register_net_sysctl(net, "net/ipv4/vs", ipvs->lblc_ctl_table); 579 if (!ipvs->lblc_ctl_header) { 580 if (!net_eq(net, &init_net)) 581 kfree(ipvs->lblc_ctl_table); 582 return -ENOMEM; 583 } 584 585 return 0; 586 } 587 588 static void __net_exit __ip_vs_lblc_exit(struct net *net) 589 { 590 struct netns_ipvs *ipvs = net_ipvs(net); 591 592 unregister_net_sysctl_table(ipvs->lblc_ctl_header); 593 594 if (!net_eq(net, &init_net)) 595 kfree(ipvs->lblc_ctl_table); 596 } 597 598 #else 599 600 static int __net_init __ip_vs_lblc_init(struct net *net) { return 0; } 601 static void __net_exit __ip_vs_lblc_exit(struct net *net) { } 602 603 #endif 604 605 static struct pernet_operations ip_vs_lblc_ops = { 606 .init = __ip_vs_lblc_init, 607 .exit = __ip_vs_lblc_exit, 608 }; 609 610 static int __init ip_vs_lblc_init(void) 611 { 612 int ret; 613 614 ret = register_pernet_subsys(&ip_vs_lblc_ops); 615 if (ret) 616 return ret; 617 618 ret = register_ip_vs_scheduler(&ip_vs_lblc_scheduler); 619 if (ret) 620 unregister_pernet_subsys(&ip_vs_lblc_ops); 621 return ret; 622 } 623 624 static void __exit ip_vs_lblc_cleanup(void) 625 { 626 unregister_ip_vs_scheduler(&ip_vs_lblc_scheduler); 627 unregister_pernet_subsys(&ip_vs_lblc_ops); 628 rcu_barrier(); 629 } 630 631 632 module_init(ip_vs_lblc_init); 633 module_exit(ip_vs_lblc_cleanup); 634 MODULE_LICENSE("GPL"); 635