1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 1991 Regents of the University of California. 5 * All rights reserved. 6 * Copyright (c) 1994 John S. Dyson 7 * All rights reserved. 8 * Copyright (c) 1994 David Greenman 9 * All rights reserved. 10 * 11 * This code is derived from software contributed to Berkeley by 12 * The Mach Operating System project at Carnegie-Mellon University. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the University of 25 * California, Berkeley and its contributors. 26 * 4. Neither the name of the University nor the names of its contributors 27 * may be used to endorse or promote products derived from this software 28 * without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 * 42 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 43 * 44 * 45 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 46 * All rights reserved. 47 * 48 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 49 * 50 * Permission to use, copy, modify and distribute this software and 51 * its documentation is hereby granted, provided that both the copyright 52 * notice and this permission notice appear in all copies of the 53 * software, derivative works or modified versions, and any portions 54 * thereof, and that both notices appear in supporting documentation. 55 * 56 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 57 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 58 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 59 * 60 * Carnegie Mellon requests users of this software to return to 61 * 62 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 63 * School of Computer Science 64 * Carnegie Mellon University 65 * Pittsburgh PA 15213-3890 66 * 67 * any improvements or extensions that they make and grant Carnegie the 68 * rights to redistribute these changes. 69 * 70 * $FreeBSD: src/sys/vm/vm_pageout.c,v 1.151.2.15 2002/12/29 18:21:04 dillon Exp $ 71 * $DragonFly: src/sys/vm/vm_pageout.c,v 1.36 2008/07/01 02:02:56 dillon Exp $ 72 */ 73 74 /* 75 * The proverbial page-out daemon. 76 */ 77 78 #include "opt_vm.h" 79 #include <sys/param.h> 80 #include <sys/systm.h> 81 #include <sys/kernel.h> 82 #include <sys/proc.h> 83 #include <sys/kthread.h> 84 #include <sys/resourcevar.h> 85 #include <sys/signalvar.h> 86 #include <sys/vnode.h> 87 #include <sys/vmmeter.h> 88 #include <sys/sysctl.h> 89 90 #include <vm/vm.h> 91 #include <vm/vm_param.h> 92 #include <sys/lock.h> 93 #include <vm/vm_object.h> 94 #include <vm/vm_page.h> 95 #include <vm/vm_map.h> 96 #include <vm/vm_pageout.h> 97 #include <vm/vm_pager.h> 98 #include <vm/swap_pager.h> 99 #include <vm/vm_extern.h> 100 101 #include <sys/thread2.h> 102 #include <vm/vm_page2.h> 103 104 /* 105 * System initialization 106 */ 107 108 /* the kernel process "vm_pageout"*/ 109 static int vm_pageout_clean (vm_page_t); 110 static int vm_pageout_scan (int pass); 111 static int vm_pageout_free_page_calc (vm_size_t count); 112 struct thread *pagethread; 113 114 #if !defined(NO_SWAPPING) 115 /* the kernel process "vm_daemon"*/ 116 static void vm_daemon (void); 117 static struct thread *vmthread; 118 119 static struct kproc_desc vm_kp = { 120 "vmdaemon", 121 vm_daemon, 122 &vmthread 123 }; 124 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) 125 #endif 126 127 128 int vm_pages_needed=0; /* Event on which pageout daemon sleeps */ 129 int vm_pageout_deficit=0; /* Estimated number of pages deficit */ 130 int vm_pageout_pages_needed=0; /* flag saying that the pageout daemon needs pages */ 131 132 #if !defined(NO_SWAPPING) 133 static int vm_pageout_req_swapout; /* XXX */ 134 static int vm_daemon_needed; 135 #endif 136 static int vm_max_launder = 32; 137 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 138 static int vm_pageout_full_stats_interval = 0; 139 static int vm_pageout_stats_free_max=0, vm_pageout_algorithm=0; 140 static int defer_swap_pageouts=0; 141 static int disable_swap_pageouts=0; 142 143 #if defined(NO_SWAPPING) 144 static int vm_swap_enabled=0; 145 static int vm_swap_idle_enabled=0; 146 #else 147 static int vm_swap_enabled=1; 148 static int vm_swap_idle_enabled=0; 149 #endif 150 151 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 152 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 153 154 SYSCTL_INT(_vm, OID_AUTO, max_launder, 155 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 156 157 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 158 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 159 160 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 161 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 162 163 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 164 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 165 166 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max, 167 CTLFLAG_RW, &vm_pageout_stats_free_max, 0, "Not implemented"); 168 169 #if defined(NO_SWAPPING) 170 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 171 CTLFLAG_RD, &vm_swap_enabled, 0, ""); 172 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 173 CTLFLAG_RD, &vm_swap_idle_enabled, 0, ""); 174 #else 175 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 176 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 177 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 178 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 179 #endif 180 181 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 182 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 183 184 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 185 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 186 187 static int pageout_lock_miss; 188 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 189 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 190 191 int vm_load; 192 SYSCTL_INT(_vm, OID_AUTO, vm_load, 193 CTLFLAG_RD, &vm_load, 0, "load on the VM system"); 194 int vm_load_enable = 1; 195 SYSCTL_INT(_vm, OID_AUTO, vm_load_enable, 196 CTLFLAG_RW, &vm_load_enable, 0, "enable vm_load rate limiting"); 197 #ifdef INVARIANTS 198 int vm_load_debug; 199 SYSCTL_INT(_vm, OID_AUTO, vm_load_debug, 200 CTLFLAG_RW, &vm_load_debug, 0, "debug vm_load"); 201 #endif 202 203 #define VM_PAGEOUT_PAGE_COUNT 16 204 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 205 206 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 207 208 #if !defined(NO_SWAPPING) 209 typedef void freeer_fcn_t (vm_map_t, vm_object_t, vm_pindex_t, int); 210 static void vm_pageout_map_deactivate_pages (vm_map_t, vm_pindex_t); 211 static freeer_fcn_t vm_pageout_object_deactivate_pages; 212 static void vm_req_vmdaemon (void); 213 #endif 214 static void vm_pageout_page_stats(void); 215 216 /* 217 * Update vm_load to slow down faulting processes. 218 * 219 * SMP races ok. 220 * No requirements. 221 */ 222 void 223 vm_fault_ratecheck(void) 224 { 225 if (vm_pages_needed) { 226 if (vm_load < 1000) 227 ++vm_load; 228 } else { 229 if (vm_load > 0) 230 --vm_load; 231 } 232 } 233 234 /* 235 * vm_pageout_clean: 236 * 237 * Clean the page and remove it from the laundry. The page must not be 238 * busy on-call. 239 * 240 * We set the busy bit to cause potential page faults on this page to 241 * block. Note the careful timing, however, the busy bit isn't set till 242 * late and we cannot do anything that will mess with the page. 243 * 244 * The caller must hold vm_token. 245 */ 246 static int 247 vm_pageout_clean(vm_page_t m) 248 { 249 vm_object_t object; 250 vm_page_t mc[2*vm_pageout_page_count]; 251 int pageout_count; 252 int ib, is, page_base; 253 vm_pindex_t pindex = m->pindex; 254 255 object = m->object; 256 257 /* 258 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 259 * with the new swapper, but we could have serious problems paging 260 * out other object types if there is insufficient memory. 261 * 262 * Unfortunately, checking free memory here is far too late, so the 263 * check has been moved up a procedural level. 264 */ 265 266 /* 267 * Don't mess with the page if it's busy, held, or special 268 */ 269 if ((m->hold_count != 0) || 270 ((m->busy != 0) || (m->flags & (PG_BUSY|PG_UNMANAGED)))) { 271 return 0; 272 } 273 274 mc[vm_pageout_page_count] = m; 275 pageout_count = 1; 276 page_base = vm_pageout_page_count; 277 ib = 1; 278 is = 1; 279 280 /* 281 * Scan object for clusterable pages. 282 * 283 * We can cluster ONLY if: ->> the page is NOT 284 * clean, wired, busy, held, or mapped into a 285 * buffer, and one of the following: 286 * 1) The page is inactive, or a seldom used 287 * active page. 288 * -or- 289 * 2) we force the issue. 290 * 291 * During heavy mmap/modification loads the pageout 292 * daemon can really fragment the underlying file 293 * due to flushing pages out of order and not trying 294 * align the clusters (which leave sporatic out-of-order 295 * holes). To solve this problem we do the reverse scan 296 * first and attempt to align our cluster, then do a 297 * forward scan if room remains. 298 */ 299 300 more: 301 while (ib && pageout_count < vm_pageout_page_count) { 302 vm_page_t p; 303 304 if (ib > pindex) { 305 ib = 0; 306 break; 307 } 308 309 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) { 310 ib = 0; 311 break; 312 } 313 if (((p->queue - p->pc) == PQ_CACHE) || 314 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 315 ib = 0; 316 break; 317 } 318 vm_page_test_dirty(p); 319 if ((p->dirty & p->valid) == 0 || 320 p->queue != PQ_INACTIVE || 321 p->wire_count != 0 || /* may be held by buf cache */ 322 p->hold_count != 0) { /* may be undergoing I/O */ 323 ib = 0; 324 break; 325 } 326 mc[--page_base] = p; 327 ++pageout_count; 328 ++ib; 329 /* 330 * alignment boundry, stop here and switch directions. Do 331 * not clear ib. 332 */ 333 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 334 break; 335 } 336 337 while (pageout_count < vm_pageout_page_count && 338 pindex + is < object->size) { 339 vm_page_t p; 340 341 if ((p = vm_page_lookup(object, pindex + is)) == NULL) 342 break; 343 if (((p->queue - p->pc) == PQ_CACHE) || 344 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 345 break; 346 } 347 vm_page_test_dirty(p); 348 if ((p->dirty & p->valid) == 0 || 349 p->queue != PQ_INACTIVE || 350 p->wire_count != 0 || /* may be held by buf cache */ 351 p->hold_count != 0) { /* may be undergoing I/O */ 352 break; 353 } 354 mc[page_base + pageout_count] = p; 355 ++pageout_count; 356 ++is; 357 } 358 359 /* 360 * If we exhausted our forward scan, continue with the reverse scan 361 * when possible, even past a page boundry. This catches boundry 362 * conditions. 363 */ 364 if (ib && pageout_count < vm_pageout_page_count) 365 goto more; 366 367 /* 368 * we allow reads during pageouts... 369 */ 370 return vm_pageout_flush(&mc[page_base], pageout_count, 0); 371 } 372 373 /* 374 * vm_pageout_flush() - launder the given pages 375 * 376 * The given pages are laundered. Note that we setup for the start of 377 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 378 * reference count all in here rather then in the parent. If we want 379 * the parent to do more sophisticated things we may have to change 380 * the ordering. 381 * 382 * The caller must hold vm_token. 383 */ 384 int 385 vm_pageout_flush(vm_page_t *mc, int count, int flags) 386 { 387 vm_object_t object; 388 int pageout_status[count]; 389 int numpagedout = 0; 390 int i; 391 392 ASSERT_LWKT_TOKEN_HELD(&vm_token); 393 394 /* 395 * Initiate I/O. Bump the vm_page_t->busy counter. 396 */ 397 for (i = 0; i < count; i++) { 398 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush page %p index %d/%d: partially invalid page", mc[i], i, count)); 399 vm_page_io_start(mc[i]); 400 } 401 402 /* 403 * We must make the pages read-only. This will also force the 404 * modified bit in the related pmaps to be cleared. The pager 405 * cannot clear the bit for us since the I/O completion code 406 * typically runs from an interrupt. The act of making the page 407 * read-only handles the case for us. 408 */ 409 for (i = 0; i < count; i++) { 410 vm_page_protect(mc[i], VM_PROT_READ); 411 } 412 413 object = mc[0]->object; 414 vm_object_pip_add(object, count); 415 416 vm_pager_put_pages(object, mc, count, 417 (flags | ((object == &kernel_object) ? VM_PAGER_PUT_SYNC : 0)), 418 pageout_status); 419 420 for (i = 0; i < count; i++) { 421 vm_page_t mt = mc[i]; 422 423 switch (pageout_status[i]) { 424 case VM_PAGER_OK: 425 numpagedout++; 426 break; 427 case VM_PAGER_PEND: 428 numpagedout++; 429 break; 430 case VM_PAGER_BAD: 431 /* 432 * Page outside of range of object. Right now we 433 * essentially lose the changes by pretending it 434 * worked. 435 */ 436 pmap_clear_modify(mt); 437 vm_page_undirty(mt); 438 break; 439 case VM_PAGER_ERROR: 440 case VM_PAGER_FAIL: 441 /* 442 * A page typically cannot be paged out when we 443 * have run out of swap. We leave the page 444 * marked inactive and will try to page it out 445 * again later. 446 * 447 * Starvation of the active page list is used to 448 * determine when the system is massively memory 449 * starved. 450 */ 451 break; 452 case VM_PAGER_AGAIN: 453 break; 454 } 455 456 /* 457 * If the operation is still going, leave the page busy to 458 * block all other accesses. Also, leave the paging in 459 * progress indicator set so that we don't attempt an object 460 * collapse. 461 * 462 * For any pages which have completed synchronously, 463 * deactivate the page if we are under a severe deficit. 464 * Do not try to enter them into the cache, though, they 465 * might still be read-heavy. 466 */ 467 if (pageout_status[i] != VM_PAGER_PEND) { 468 if (vm_page_count_severe()) 469 vm_page_deactivate(mt); 470 #if 0 471 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt)) 472 vm_page_protect(mt, VM_PROT_READ); 473 #endif 474 vm_page_io_finish(mt); 475 vm_object_pip_wakeup(object); 476 } 477 } 478 return numpagedout; 479 } 480 481 #if !defined(NO_SWAPPING) 482 /* 483 * vm_pageout_object_deactivate_pages 484 * 485 * deactivate enough pages to satisfy the inactive target 486 * requirements or if vm_page_proc_limit is set, then 487 * deactivate all of the pages in the object and its 488 * backing_objects. 489 * 490 * The map must be locked. 491 * The caller must hold vm_token. 492 */ 493 static int vm_pageout_object_deactivate_pages_callback(vm_page_t, void *); 494 495 static void 496 vm_pageout_object_deactivate_pages(vm_map_t map, vm_object_t object, 497 vm_pindex_t desired, int map_remove_only) 498 { 499 struct rb_vm_page_scan_info info; 500 int remove_mode; 501 502 if (object->type == OBJT_DEVICE || object->type == OBJT_PHYS) 503 return; 504 505 while (object) { 506 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 507 return; 508 if (object->paging_in_progress) 509 return; 510 511 remove_mode = map_remove_only; 512 if (object->shadow_count > 1) 513 remove_mode = 1; 514 515 /* 516 * scan the objects entire memory queue. spl protection is 517 * required to avoid an interrupt unbusy/free race against 518 * our busy check. 519 */ 520 crit_enter(); 521 info.limit = remove_mode; 522 info.map = map; 523 info.desired = desired; 524 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL, 525 vm_pageout_object_deactivate_pages_callback, 526 &info 527 ); 528 crit_exit(); 529 object = object->backing_object; 530 } 531 } 532 533 /* 534 * The caller must hold vm_token. 535 */ 536 static int 537 vm_pageout_object_deactivate_pages_callback(vm_page_t p, void *data) 538 { 539 struct rb_vm_page_scan_info *info = data; 540 int actcount; 541 542 if (pmap_resident_count(vm_map_pmap(info->map)) <= info->desired) { 543 return(-1); 544 } 545 mycpu->gd_cnt.v_pdpages++; 546 if (p->wire_count != 0 || p->hold_count != 0 || p->busy != 0 || 547 (p->flags & (PG_BUSY|PG_UNMANAGED)) || 548 !pmap_page_exists_quick(vm_map_pmap(info->map), p)) { 549 return(0); 550 } 551 552 actcount = pmap_ts_referenced(p); 553 if (actcount) { 554 vm_page_flag_set(p, PG_REFERENCED); 555 } else if (p->flags & PG_REFERENCED) { 556 actcount = 1; 557 } 558 559 if ((p->queue != PQ_ACTIVE) && 560 (p->flags & PG_REFERENCED)) { 561 vm_page_activate(p); 562 p->act_count += actcount; 563 vm_page_flag_clear(p, PG_REFERENCED); 564 } else if (p->queue == PQ_ACTIVE) { 565 if ((p->flags & PG_REFERENCED) == 0) { 566 p->act_count -= min(p->act_count, ACT_DECLINE); 567 if (!info->limit && (vm_pageout_algorithm || (p->act_count == 0))) { 568 vm_page_busy(p); 569 vm_page_protect(p, VM_PROT_NONE); 570 vm_page_deactivate(p); 571 vm_page_wakeup(p); 572 } else { 573 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 574 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 575 } 576 } else { 577 vm_page_activate(p); 578 vm_page_flag_clear(p, PG_REFERENCED); 579 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 580 p->act_count += ACT_ADVANCE; 581 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 582 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 583 } 584 } else if (p->queue == PQ_INACTIVE) { 585 vm_page_busy(p); 586 vm_page_protect(p, VM_PROT_NONE); 587 vm_page_wakeup(p); 588 } 589 return(0); 590 } 591 592 /* 593 * Deactivate some number of pages in a map, try to do it fairly, but 594 * that is really hard to do. 595 * 596 * The caller must hold vm_token. 597 */ 598 static void 599 vm_pageout_map_deactivate_pages(vm_map_t map, vm_pindex_t desired) 600 { 601 vm_map_entry_t tmpe; 602 vm_object_t obj, bigobj; 603 int nothingwired; 604 605 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT)) { 606 return; 607 } 608 609 bigobj = NULL; 610 nothingwired = TRUE; 611 612 /* 613 * first, search out the biggest object, and try to free pages from 614 * that. 615 */ 616 tmpe = map->header.next; 617 while (tmpe != &map->header) { 618 switch(tmpe->maptype) { 619 case VM_MAPTYPE_NORMAL: 620 case VM_MAPTYPE_VPAGETABLE: 621 obj = tmpe->object.vm_object; 622 if ((obj != NULL) && (obj->shadow_count <= 1) && 623 ((bigobj == NULL) || 624 (bigobj->resident_page_count < obj->resident_page_count))) { 625 bigobj = obj; 626 } 627 break; 628 default: 629 break; 630 } 631 if (tmpe->wired_count > 0) 632 nothingwired = FALSE; 633 tmpe = tmpe->next; 634 } 635 636 if (bigobj) 637 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 638 639 /* 640 * Next, hunt around for other pages to deactivate. We actually 641 * do this search sort of wrong -- .text first is not the best idea. 642 */ 643 tmpe = map->header.next; 644 while (tmpe != &map->header) { 645 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 646 break; 647 switch(tmpe->maptype) { 648 case VM_MAPTYPE_NORMAL: 649 case VM_MAPTYPE_VPAGETABLE: 650 obj = tmpe->object.vm_object; 651 if (obj) 652 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 653 break; 654 default: 655 break; 656 } 657 tmpe = tmpe->next; 658 }; 659 660 /* 661 * Remove all mappings if a process is swapped out, this will free page 662 * table pages. 663 */ 664 if (desired == 0 && nothingwired) 665 pmap_remove(vm_map_pmap(map), 666 VM_MIN_USER_ADDRESS, VM_MAX_USER_ADDRESS); 667 vm_map_unlock(map); 668 } 669 #endif 670 671 /* 672 * Don't try to be fancy - being fancy can lead to vnode deadlocks. We 673 * only do it for OBJT_DEFAULT and OBJT_SWAP objects which we know can 674 * be trivially freed. 675 * 676 * The caller must hold vm_token. 677 * 678 * WARNING: vm_object_reference() can block. 679 */ 680 static void 681 vm_pageout_page_free(vm_page_t m) 682 { 683 vm_object_t object = m->object; 684 int type = object->type; 685 686 vm_page_busy(m); 687 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 688 vm_object_reference(object); 689 vm_page_protect(m, VM_PROT_NONE); 690 vm_page_free(m); 691 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 692 vm_object_deallocate(object); 693 } 694 695 /* 696 * vm_pageout_scan does the dirty work for the pageout daemon. 697 */ 698 struct vm_pageout_scan_info { 699 struct proc *bigproc; 700 vm_offset_t bigsize; 701 }; 702 703 static int vm_pageout_scan_callback(struct proc *p, void *data); 704 705 /* 706 * The caller must hold vm_token. 707 */ 708 static int 709 vm_pageout_scan(int pass) 710 { 711 struct vm_pageout_scan_info info; 712 vm_page_t m, next; 713 struct vm_page marker; 714 struct vnode *vpfailed; /* warning, allowed to be stale */ 715 int maxscan, pcount; 716 int recycle_count; 717 int inactive_shortage, active_shortage; 718 int inactive_original_shortage; 719 vm_object_t object; 720 int actcount; 721 int vnodes_skipped = 0; 722 int maxlaunder; 723 724 /* 725 * Do whatever cleanup that the pmap code can. 726 */ 727 pmap_collect(); 728 729 /* 730 * Calculate our target for the number of free+cache pages we 731 * want to get to. This is higher then the number that causes 732 * allocations to stall (severe) in order to provide hysteresis, 733 * and if we don't make it all the way but get to the minimum 734 * we're happy. 735 */ 736 inactive_shortage = vm_paging_target() + vm_pageout_deficit; 737 inactive_original_shortage = inactive_shortage; 738 vm_pageout_deficit = 0; 739 740 /* 741 * Initialize our marker 742 */ 743 bzero(&marker, sizeof(marker)); 744 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 745 marker.queue = PQ_INACTIVE; 746 marker.wire_count = 1; 747 748 /* 749 * Start scanning the inactive queue for pages we can move to the 750 * cache or free. The scan will stop when the target is reached or 751 * we have scanned the entire inactive queue. Note that m->act_count 752 * is not used to form decisions for the inactive queue, only for the 753 * active queue. 754 * 755 * maxlaunder limits the number of dirty pages we flush per scan. 756 * For most systems a smaller value (16 or 32) is more robust under 757 * extreme memory and disk pressure because any unnecessary writes 758 * to disk can result in extreme performance degredation. However, 759 * systems with excessive dirty pages (especially when MAP_NOSYNC is 760 * used) will die horribly with limited laundering. If the pageout 761 * daemon cannot clean enough pages in the first pass, we let it go 762 * all out in succeeding passes. 763 */ 764 if ((maxlaunder = vm_max_launder) <= 1) 765 maxlaunder = 1; 766 if (pass) 767 maxlaunder = 10000; 768 769 /* 770 * We will generally be in a critical section throughout the 771 * scan, but we can release it temporarily when we are sitting on a 772 * non-busy page without fear. this is required to prevent an 773 * interrupt from unbusying or freeing a page prior to our busy 774 * check, leaving us on the wrong queue or checking the wrong 775 * page. 776 */ 777 crit_enter(); 778 rescan0: 779 vpfailed = NULL; 780 maxscan = vmstats.v_inactive_count; 781 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 782 m != NULL && maxscan-- > 0 && inactive_shortage > 0; 783 m = next 784 ) { 785 mycpu->gd_cnt.v_pdpages++; 786 787 /* 788 * Give interrupts a chance 789 */ 790 crit_exit(); 791 crit_enter(); 792 793 /* 794 * It's easier for some of the conditions below to just loop 795 * and catch queue changes here rather then check everywhere 796 * else. 797 */ 798 if (m->queue != PQ_INACTIVE) 799 goto rescan0; 800 next = TAILQ_NEXT(m, pageq); 801 802 /* 803 * skip marker pages 804 */ 805 if (m->flags & PG_MARKER) 806 continue; 807 808 /* 809 * A held page may be undergoing I/O, so skip it. 810 */ 811 if (m->hold_count) { 812 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 813 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 814 ++vm_swapcache_inactive_heuristic; 815 continue; 816 } 817 818 /* 819 * Dont mess with busy pages, keep in the front of the 820 * queue, most likely are being paged out. 821 */ 822 if (m->busy || (m->flags & PG_BUSY)) { 823 continue; 824 } 825 826 if (m->object->ref_count == 0) { 827 /* 828 * If the object is not being used, we ignore previous 829 * references. 830 */ 831 vm_page_flag_clear(m, PG_REFERENCED); 832 pmap_clear_reference(m); 833 834 } else if (((m->flags & PG_REFERENCED) == 0) && 835 (actcount = pmap_ts_referenced(m))) { 836 /* 837 * Otherwise, if the page has been referenced while 838 * in the inactive queue, we bump the "activation 839 * count" upwards, making it less likely that the 840 * page will be added back to the inactive queue 841 * prematurely again. Here we check the page tables 842 * (or emulated bits, if any), given the upper level 843 * VM system not knowing anything about existing 844 * references. 845 */ 846 vm_page_activate(m); 847 m->act_count += (actcount + ACT_ADVANCE); 848 continue; 849 } 850 851 /* 852 * If the upper level VM system knows about any page 853 * references, we activate the page. We also set the 854 * "activation count" higher than normal so that we will less 855 * likely place pages back onto the inactive queue again. 856 */ 857 if ((m->flags & PG_REFERENCED) != 0) { 858 vm_page_flag_clear(m, PG_REFERENCED); 859 actcount = pmap_ts_referenced(m); 860 vm_page_activate(m); 861 m->act_count += (actcount + ACT_ADVANCE + 1); 862 continue; 863 } 864 865 /* 866 * If the upper level VM system doesn't know anything about 867 * the page being dirty, we have to check for it again. As 868 * far as the VM code knows, any partially dirty pages are 869 * fully dirty. 870 * 871 * Pages marked PG_WRITEABLE may be mapped into the user 872 * address space of a process running on another cpu. A 873 * user process (without holding the MP lock) running on 874 * another cpu may be able to touch the page while we are 875 * trying to remove it. vm_page_cache() will handle this 876 * case for us. 877 */ 878 if (m->dirty == 0) { 879 vm_page_test_dirty(m); 880 } else { 881 vm_page_dirty(m); 882 } 883 884 if (m->valid == 0) { 885 /* 886 * Invalid pages can be easily freed 887 */ 888 vm_pageout_page_free(m); 889 mycpu->gd_cnt.v_dfree++; 890 --inactive_shortage; 891 } else if (m->dirty == 0) { 892 /* 893 * Clean pages can be placed onto the cache queue. 894 * This effectively frees them. 895 */ 896 vm_page_busy(m); 897 vm_page_cache(m); 898 --inactive_shortage; 899 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 900 /* 901 * Dirty pages need to be paged out, but flushing 902 * a page is extremely expensive verses freeing 903 * a clean page. Rather then artificially limiting 904 * the number of pages we can flush, we instead give 905 * dirty pages extra priority on the inactive queue 906 * by forcing them to be cycled through the queue 907 * twice before being flushed, after which the 908 * (now clean) page will cycle through once more 909 * before being freed. This significantly extends 910 * the thrash point for a heavily loaded machine. 911 */ 912 vm_page_flag_set(m, PG_WINATCFLS); 913 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 914 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 915 ++vm_swapcache_inactive_heuristic; 916 } else if (maxlaunder > 0) { 917 /* 918 * We always want to try to flush some dirty pages if 919 * we encounter them, to keep the system stable. 920 * Normally this number is small, but under extreme 921 * pressure where there are insufficient clean pages 922 * on the inactive queue, we may have to go all out. 923 */ 924 int swap_pageouts_ok; 925 struct vnode *vp = NULL; 926 927 object = m->object; 928 929 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 930 swap_pageouts_ok = 1; 931 } else { 932 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 933 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 934 vm_page_count_min(0)); 935 936 } 937 938 /* 939 * We don't bother paging objects that are "dead". 940 * Those objects are in a "rundown" state. 941 */ 942 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 943 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 944 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 945 ++vm_swapcache_inactive_heuristic; 946 continue; 947 } 948 949 /* 950 * The object is already known NOT to be dead. It 951 * is possible for the vget() to block the whole 952 * pageout daemon, but the new low-memory handling 953 * code should prevent it. 954 * 955 * The previous code skipped locked vnodes and, worse, 956 * reordered pages in the queue. This results in 957 * completely non-deterministic operation because, 958 * quite often, a vm_fault has initiated an I/O and 959 * is holding a locked vnode at just the point where 960 * the pageout daemon is woken up. 961 * 962 * We can't wait forever for the vnode lock, we might 963 * deadlock due to a vn_read() getting stuck in 964 * vm_wait while holding this vnode. We skip the 965 * vnode if we can't get it in a reasonable amount 966 * of time. 967 * 968 * vpfailed is used to (try to) avoid the case where 969 * a large number of pages are associated with a 970 * locked vnode, which could cause the pageout daemon 971 * to stall for an excessive amount of time. 972 */ 973 if (object->type == OBJT_VNODE) { 974 int flags; 975 976 vp = object->handle; 977 flags = LK_EXCLUSIVE | LK_NOOBJ; 978 if (vp == vpfailed) 979 flags |= LK_NOWAIT; 980 else 981 flags |= LK_TIMELOCK; 982 if (vget(vp, flags) != 0) { 983 vpfailed = vp; 984 ++pageout_lock_miss; 985 if (object->flags & OBJ_MIGHTBEDIRTY) 986 vnodes_skipped++; 987 continue; 988 } 989 990 /* 991 * The page might have been moved to another 992 * queue during potential blocking in vget() 993 * above. The page might have been freed and 994 * reused for another vnode. The object might 995 * have been reused for another vnode. 996 */ 997 if (m->queue != PQ_INACTIVE || 998 m->object != object || 999 object->handle != vp) { 1000 if (object->flags & OBJ_MIGHTBEDIRTY) 1001 vnodes_skipped++; 1002 vput(vp); 1003 continue; 1004 } 1005 1006 /* 1007 * The page may have been busied during the 1008 * blocking in vput(); We don't move the 1009 * page back onto the end of the queue so that 1010 * statistics are more correct if we don't. 1011 */ 1012 if (m->busy || (m->flags & PG_BUSY)) { 1013 vput(vp); 1014 continue; 1015 } 1016 1017 /* 1018 * If the page has become held it might 1019 * be undergoing I/O, so skip it 1020 */ 1021 if (m->hold_count) { 1022 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1023 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1024 ++vm_swapcache_inactive_heuristic; 1025 if (object->flags & OBJ_MIGHTBEDIRTY) 1026 vnodes_skipped++; 1027 vput(vp); 1028 continue; 1029 } 1030 } 1031 1032 /* 1033 * If a page is dirty, then it is either being washed 1034 * (but not yet cleaned) or it is still in the 1035 * laundry. If it is still in the laundry, then we 1036 * start the cleaning operation. 1037 * 1038 * This operation may cluster, invalidating the 'next' 1039 * pointer. To prevent an inordinate number of 1040 * restarts we use our marker to remember our place. 1041 * 1042 * decrement inactive_shortage on success to account 1043 * for the (future) cleaned page. Otherwise we 1044 * could wind up laundering or cleaning too many 1045 * pages. 1046 */ 1047 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq); 1048 if (vm_pageout_clean(m) != 0) { 1049 --inactive_shortage; 1050 --maxlaunder; 1051 } 1052 next = TAILQ_NEXT(&marker, pageq); 1053 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq); 1054 if (vp != NULL) 1055 vput(vp); 1056 } 1057 } 1058 1059 /* 1060 * We want to move pages from the active queue to the inactive 1061 * queue to get the inactive queue to the inactive target. If 1062 * we still have a page shortage from above we try to directly free 1063 * clean pages instead of moving them. 1064 * 1065 * If we do still have a shortage we keep track of the number of 1066 * pages we free or cache (recycle_count) as a measure of thrashing 1067 * between the active and inactive queues. 1068 * 1069 * If we were able to completely satisfy the free+cache targets 1070 * from the inactive pool we limit the number of pages we move 1071 * from the active pool to the inactive pool to 2x the pages we 1072 * had removed from the inactive pool (with a minimum of 1/5 the 1073 * inactive target). If we were not able to completely satisfy 1074 * the free+cache targets we go for the whole target aggressively. 1075 * 1076 * NOTE: Both variables can end up negative. 1077 * NOTE: We are still in a critical section. 1078 */ 1079 active_shortage = vmstats.v_inactive_target - vmstats.v_inactive_count; 1080 if (inactive_original_shortage < vmstats.v_inactive_target / 10) 1081 inactive_original_shortage = vmstats.v_inactive_target / 10; 1082 if (inactive_shortage <= 0 && 1083 active_shortage > inactive_original_shortage * 2) { 1084 active_shortage = inactive_original_shortage * 2; 1085 } 1086 1087 pcount = vmstats.v_active_count; 1088 recycle_count = 0; 1089 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1090 1091 while ((m != NULL) && (pcount-- > 0) && 1092 (inactive_shortage > 0 || active_shortage > 0) 1093 ) { 1094 /* 1095 * Give interrupts a chance. 1096 */ 1097 crit_exit(); 1098 crit_enter(); 1099 1100 /* 1101 * If the page was ripped out from under us, just stop. 1102 */ 1103 if (m->queue != PQ_ACTIVE) 1104 break; 1105 next = TAILQ_NEXT(m, pageq); 1106 1107 /* 1108 * Don't deactivate pages that are busy. 1109 */ 1110 if ((m->busy != 0) || 1111 (m->flags & PG_BUSY) || 1112 (m->hold_count != 0)) { 1113 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1114 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1115 m = next; 1116 continue; 1117 } 1118 1119 /* 1120 * The count for pagedaemon pages is done after checking the 1121 * page for eligibility... 1122 */ 1123 mycpu->gd_cnt.v_pdpages++; 1124 1125 /* 1126 * Check to see "how much" the page has been used and clear 1127 * the tracking access bits. If the object has no references 1128 * don't bother paying the expense. 1129 */ 1130 actcount = 0; 1131 if (m->object->ref_count != 0) { 1132 if (m->flags & PG_REFERENCED) 1133 ++actcount; 1134 actcount += pmap_ts_referenced(m); 1135 if (actcount) { 1136 m->act_count += ACT_ADVANCE + actcount; 1137 if (m->act_count > ACT_MAX) 1138 m->act_count = ACT_MAX; 1139 } 1140 } 1141 vm_page_flag_clear(m, PG_REFERENCED); 1142 1143 /* 1144 * actcount is only valid if the object ref_count is non-zero. 1145 */ 1146 if (actcount && m->object->ref_count != 0) { 1147 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1148 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1149 } else { 1150 m->act_count -= min(m->act_count, ACT_DECLINE); 1151 if (vm_pageout_algorithm || 1152 m->object->ref_count == 0 || 1153 m->act_count < pass + 1 1154 ) { 1155 /* 1156 * Deactivate the page. If we had a 1157 * shortage from our inactive scan try to 1158 * free (cache) the page instead. 1159 * 1160 * Don't just blindly cache the page if 1161 * we do not have a shortage from the 1162 * inactive scan, that could lead to 1163 * gigabytes being moved. 1164 */ 1165 --active_shortage; 1166 if (inactive_shortage > 0 || 1167 m->object->ref_count == 0) { 1168 if (inactive_shortage > 0) 1169 ++recycle_count; 1170 vm_page_busy(m); 1171 vm_page_protect(m, VM_PROT_NONE); 1172 if (m->dirty == 0 && 1173 inactive_shortage > 0) { 1174 --inactive_shortage; 1175 vm_page_cache(m); 1176 } else { 1177 vm_page_deactivate(m); 1178 vm_page_wakeup(m); 1179 } 1180 } else { 1181 vm_page_deactivate(m); 1182 } 1183 } else { 1184 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1185 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1186 } 1187 } 1188 m = next; 1189 } 1190 1191 /* 1192 * The number of actually free pages can drop down to v_free_reserved, 1193 * we try to build the free count back above v_free_min. Note that 1194 * vm_paging_needed() also returns TRUE if v_free_count is not at 1195 * least v_free_min so that is the minimum we must build the free 1196 * count to. 1197 * 1198 * We use a slightly higher target to improve hysteresis, 1199 * ((v_free_target + v_free_min) / 2). Since v_free_target 1200 * is usually the same as v_cache_min this maintains about 1201 * half the pages in the free queue as are in the cache queue, 1202 * providing pretty good pipelining for pageout operation. 1203 * 1204 * The system operator can manipulate vm.v_cache_min and 1205 * vm.v_free_target to tune the pageout demon. Be sure 1206 * to keep vm.v_free_min < vm.v_free_target. 1207 * 1208 * Note that the original paging target is to get at least 1209 * (free_min + cache_min) into (free + cache). The slightly 1210 * higher target will shift additional pages from cache to free 1211 * without effecting the original paging target in order to 1212 * maintain better hysteresis and not have the free count always 1213 * be dead-on v_free_min. 1214 * 1215 * NOTE: we are still in a critical section. 1216 * 1217 * Pages moved from PQ_CACHE to totally free are not counted in the 1218 * pages_freed counter. 1219 */ 1220 while (vmstats.v_free_count < 1221 (vmstats.v_free_min + vmstats.v_free_target) / 2) { 1222 /* 1223 * 1224 */ 1225 static int cache_rover = 0; 1226 m = vm_page_list_find(PQ_CACHE, cache_rover, FALSE); 1227 if (m == NULL) 1228 break; 1229 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || 1230 m->busy || 1231 m->hold_count || 1232 m->wire_count) { 1233 #ifdef INVARIANTS 1234 kprintf("Warning: busy page %p found in cache\n", m); 1235 #endif 1236 vm_page_deactivate(m); 1237 continue; 1238 } 1239 KKASSERT((m->flags & PG_MAPPED) == 0); 1240 KKASSERT(m->dirty == 0); 1241 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK; 1242 vm_pageout_page_free(m); 1243 mycpu->gd_cnt.v_dfree++; 1244 } 1245 1246 crit_exit(); 1247 1248 #if !defined(NO_SWAPPING) 1249 /* 1250 * Idle process swapout -- run once per second. 1251 */ 1252 if (vm_swap_idle_enabled) { 1253 static long lsec; 1254 if (time_second != lsec) { 1255 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1256 vm_req_vmdaemon(); 1257 lsec = time_second; 1258 } 1259 } 1260 #endif 1261 1262 /* 1263 * If we didn't get enough free pages, and we have skipped a vnode 1264 * in a writeable object, wakeup the sync daemon. And kick swapout 1265 * if we did not get enough free pages. 1266 */ 1267 if (vm_paging_target() > 0) { 1268 if (vnodes_skipped && vm_page_count_min(0)) 1269 speedup_syncer(); 1270 #if !defined(NO_SWAPPING) 1271 if (vm_swap_enabled && vm_page_count_target()) { 1272 vm_req_vmdaemon(); 1273 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1274 } 1275 #endif 1276 } 1277 1278 /* 1279 * Handle catastrophic conditions. Under good conditions we should 1280 * be at the target, well beyond our minimum. If we could not even 1281 * reach our minimum the system is under heavy stress. 1282 * 1283 * Determine whether we have run out of memory. This occurs when 1284 * swap_pager_full is TRUE and the only pages left in the page 1285 * queues are dirty. We will still likely have page shortages. 1286 * 1287 * - swap_pager_full is set if insufficient swap was 1288 * available to satisfy a requested pageout. 1289 * 1290 * - the inactive queue is bloated (4 x size of active queue), 1291 * meaning it is unable to get rid of dirty pages and. 1292 * 1293 * - vm_page_count_min() without counting pages recycled from the 1294 * active queue (recycle_count) means we could not recover 1295 * enough pages to meet bare minimum needs. This test only 1296 * works if the inactive queue is bloated. 1297 * 1298 * - due to a positive inactive_shortage we shifted the remaining 1299 * dirty pages from the active queue to the inactive queue 1300 * trying to find clean ones to free. 1301 */ 1302 if (swap_pager_full && vm_page_count_min(recycle_count)) 1303 kprintf("Warning: system low on memory+swap!\n"); 1304 if (swap_pager_full && vm_page_count_min(recycle_count) && 1305 vmstats.v_inactive_count > vmstats.v_active_count * 4 && 1306 inactive_shortage > 0) { 1307 /* 1308 * Kill something. 1309 */ 1310 info.bigproc = NULL; 1311 info.bigsize = 0; 1312 allproc_scan(vm_pageout_scan_callback, &info); 1313 if (info.bigproc != NULL) { 1314 killproc(info.bigproc, "out of swap space"); 1315 info.bigproc->p_nice = PRIO_MIN; 1316 info.bigproc->p_usched->resetpriority( 1317 FIRST_LWP_IN_PROC(info.bigproc)); 1318 wakeup(&vmstats.v_free_count); 1319 PRELE(info.bigproc); 1320 } 1321 } 1322 return(inactive_shortage); 1323 } 1324 1325 /* 1326 * The caller must hold vm_token and proc_token. 1327 */ 1328 static int 1329 vm_pageout_scan_callback(struct proc *p, void *data) 1330 { 1331 struct vm_pageout_scan_info *info = data; 1332 vm_offset_t size; 1333 1334 /* 1335 * Never kill system processes or init. If we have configured swap 1336 * then try to avoid killing low-numbered pids. 1337 */ 1338 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1339 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1340 return (0); 1341 } 1342 1343 /* 1344 * if the process is in a non-running type state, 1345 * don't touch it. 1346 */ 1347 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) 1348 return (0); 1349 1350 /* 1351 * Get the approximate process size. Note that anonymous pages 1352 * with backing swap will be counted twice, but there should not 1353 * be too many such pages due to the stress the VM system is 1354 * under at this point. 1355 */ 1356 size = vmspace_anonymous_count(p->p_vmspace) + 1357 vmspace_swap_count(p->p_vmspace); 1358 1359 /* 1360 * If the this process is bigger than the biggest one 1361 * remember it. 1362 */ 1363 if (info->bigsize < size) { 1364 if (info->bigproc) 1365 PRELE(info->bigproc); 1366 PHOLD(p); 1367 info->bigproc = p; 1368 info->bigsize = size; 1369 } 1370 return(0); 1371 } 1372 1373 /* 1374 * This routine tries to maintain the pseudo LRU active queue, 1375 * so that during long periods of time where there is no paging, 1376 * that some statistic accumulation still occurs. This code 1377 * helps the situation where paging just starts to occur. 1378 * 1379 * The caller must hold vm_token. 1380 */ 1381 static void 1382 vm_pageout_page_stats(void) 1383 { 1384 vm_page_t m,next; 1385 int pcount,tpcount; /* Number of pages to check */ 1386 static int fullintervalcount = 0; 1387 int page_shortage; 1388 1389 page_shortage = 1390 (vmstats.v_inactive_target + vmstats.v_cache_max + vmstats.v_free_min) - 1391 (vmstats.v_free_count + vmstats.v_inactive_count + vmstats.v_cache_count); 1392 1393 if (page_shortage <= 0) 1394 return; 1395 1396 crit_enter(); 1397 1398 pcount = vmstats.v_active_count; 1399 fullintervalcount += vm_pageout_stats_interval; 1400 if (fullintervalcount < vm_pageout_full_stats_interval) { 1401 tpcount = (vm_pageout_stats_max * vmstats.v_active_count) / vmstats.v_page_count; 1402 if (pcount > tpcount) 1403 pcount = tpcount; 1404 } else { 1405 fullintervalcount = 0; 1406 } 1407 1408 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1409 while ((m != NULL) && (pcount-- > 0)) { 1410 int actcount; 1411 1412 if (m->queue != PQ_ACTIVE) { 1413 break; 1414 } 1415 1416 next = TAILQ_NEXT(m, pageq); 1417 /* 1418 * Don't deactivate pages that are busy. 1419 */ 1420 if ((m->busy != 0) || 1421 (m->flags & PG_BUSY) || 1422 (m->hold_count != 0)) { 1423 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1424 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1425 m = next; 1426 continue; 1427 } 1428 1429 actcount = 0; 1430 if (m->flags & PG_REFERENCED) { 1431 vm_page_flag_clear(m, PG_REFERENCED); 1432 actcount += 1; 1433 } 1434 1435 actcount += pmap_ts_referenced(m); 1436 if (actcount) { 1437 m->act_count += ACT_ADVANCE + actcount; 1438 if (m->act_count > ACT_MAX) 1439 m->act_count = ACT_MAX; 1440 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1441 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1442 } else { 1443 if (m->act_count == 0) { 1444 /* 1445 * We turn off page access, so that we have 1446 * more accurate RSS stats. We don't do this 1447 * in the normal page deactivation when the 1448 * system is loaded VM wise, because the 1449 * cost of the large number of page protect 1450 * operations would be higher than the value 1451 * of doing the operation. 1452 */ 1453 vm_page_busy(m); 1454 vm_page_protect(m, VM_PROT_NONE); 1455 vm_page_deactivate(m); 1456 vm_page_wakeup(m); 1457 } else { 1458 m->act_count -= min(m->act_count, ACT_DECLINE); 1459 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1460 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1461 } 1462 } 1463 1464 m = next; 1465 } 1466 crit_exit(); 1467 } 1468 1469 /* 1470 * The caller must hold vm_token. 1471 */ 1472 static int 1473 vm_pageout_free_page_calc(vm_size_t count) 1474 { 1475 if (count < vmstats.v_page_count) 1476 return 0; 1477 /* 1478 * free_reserved needs to include enough for the largest swap pager 1479 * structures plus enough for any pv_entry structs when paging. 1480 */ 1481 if (vmstats.v_page_count > 1024) 1482 vmstats.v_free_min = 4 + (vmstats.v_page_count - 1024) / 200; 1483 else 1484 vmstats.v_free_min = 4; 1485 vmstats.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1486 vmstats.v_interrupt_free_min; 1487 vmstats.v_free_reserved = vm_pageout_page_count + 1488 vmstats.v_pageout_free_min + (count / 768) + PQ_L2_SIZE; 1489 vmstats.v_free_severe = vmstats.v_free_min / 2; 1490 vmstats.v_free_min += vmstats.v_free_reserved; 1491 vmstats.v_free_severe += vmstats.v_free_reserved; 1492 return 1; 1493 } 1494 1495 1496 /* 1497 * vm_pageout is the high level pageout daemon. 1498 * 1499 * No requirements. 1500 */ 1501 static void 1502 vm_pageout_thread(void) 1503 { 1504 int pass; 1505 int inactive_shortage; 1506 1507 /* 1508 * Permanently hold vm_token. 1509 */ 1510 lwkt_gettoken(&vm_token); 1511 1512 /* 1513 * Initialize some paging parameters. 1514 */ 1515 curthread->td_flags |= TDF_SYSTHREAD; 1516 1517 vmstats.v_interrupt_free_min = 2; 1518 if (vmstats.v_page_count < 2000) 1519 vm_pageout_page_count = 8; 1520 1521 vm_pageout_free_page_calc(vmstats.v_page_count); 1522 1523 /* 1524 * v_free_target and v_cache_min control pageout hysteresis. Note 1525 * that these are more a measure of the VM cache queue hysteresis 1526 * then the VM free queue. Specifically, v_free_target is the 1527 * high water mark (free+cache pages). 1528 * 1529 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1530 * low water mark, while v_free_min is the stop. v_cache_min must 1531 * be big enough to handle memory needs while the pageout daemon 1532 * is signalled and run to free more pages. 1533 */ 1534 if (vmstats.v_free_count > 6144) 1535 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved; 1536 else 1537 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved; 1538 1539 /* 1540 * NOTE: With the new buffer cache b_act_count we want the default 1541 * inactive target to be a percentage of available memory. 1542 * 1543 * The inactive target essentially determines the minimum 1544 * number of 'temporary' pages capable of caching one-time-use 1545 * files when the VM system is otherwise full of pages 1546 * belonging to multi-time-use files or active program data. 1547 * 1548 * NOTE: The inactive target is aggressively persued only if the 1549 * inactive queue becomes too small. If the inactive queue 1550 * is large enough to satisfy page movement to free+cache 1551 * then it is repopulated more slowly from the active queue. 1552 * This allows a general inactive_target default to be set. 1553 * 1554 * There is an issue here for processes which sit mostly idle 1555 * 'overnight', such as sshd, tcsh, and X. Any movement from 1556 * the active queue will eventually cause such pages to 1557 * recycle eventually causing a lot of paging in the morning. 1558 * To reduce the incidence of this pages cycled out of the 1559 * buffer cache are moved directly to the inactive queue if 1560 * they were only used once or twice. 1561 * 1562 * The vfs.vm_cycle_point sysctl can be used to adjust this. 1563 * Increasing the value (up to 64) increases the number of 1564 * buffer recyclements which go directly to the inactive queue. 1565 */ 1566 if (vmstats.v_free_count > 2048) { 1567 vmstats.v_cache_min = vmstats.v_free_target; 1568 vmstats.v_cache_max = 2 * vmstats.v_cache_min; 1569 } else { 1570 vmstats.v_cache_min = 0; 1571 vmstats.v_cache_max = 0; 1572 } 1573 vmstats.v_inactive_target = vmstats.v_free_count / 4; 1574 1575 /* XXX does not really belong here */ 1576 if (vm_page_max_wired == 0) 1577 vm_page_max_wired = vmstats.v_free_count / 3; 1578 1579 if (vm_pageout_stats_max == 0) 1580 vm_pageout_stats_max = vmstats.v_free_target; 1581 1582 /* 1583 * Set interval in seconds for stats scan. 1584 */ 1585 if (vm_pageout_stats_interval == 0) 1586 vm_pageout_stats_interval = 5; 1587 if (vm_pageout_full_stats_interval == 0) 1588 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1589 1590 1591 /* 1592 * Set maximum free per pass 1593 */ 1594 if (vm_pageout_stats_free_max == 0) 1595 vm_pageout_stats_free_max = 5; 1596 1597 swap_pager_swap_init(); 1598 pass = 0; 1599 1600 /* 1601 * The pageout daemon is never done, so loop forever. 1602 */ 1603 while (TRUE) { 1604 int error; 1605 1606 /* 1607 * Wait for an action request. If we timeout check to 1608 * see if paging is needed (in case the normal wakeup 1609 * code raced us). 1610 */ 1611 if (vm_pages_needed == 0) { 1612 error = tsleep(&vm_pages_needed, 1613 0, "psleep", 1614 vm_pageout_stats_interval * hz); 1615 if (error && 1616 vm_paging_needed() == 0 && 1617 vm_pages_needed == 0) { 1618 vm_pageout_page_stats(); 1619 continue; 1620 } 1621 vm_pages_needed = 1; 1622 } 1623 1624 mycpu->gd_cnt.v_pdwakeups++; 1625 1626 /* 1627 * Scan for pageout. Try to avoid thrashing the system 1628 * with activity. 1629 */ 1630 inactive_shortage = vm_pageout_scan(pass); 1631 if (inactive_shortage > 0) { 1632 ++pass; 1633 if (swap_pager_full) { 1634 /* 1635 * Running out of memory, catastrophic back-off 1636 * to one-second intervals. 1637 */ 1638 tsleep(&vm_pages_needed, 0, "pdelay", hz); 1639 } else if (pass < 10 && vm_pages_needed > 1) { 1640 /* 1641 * Normal operation, additional processes 1642 * have already kicked us. Retry immediately. 1643 */ 1644 } else if (pass < 10) { 1645 /* 1646 * Normal operation, fewer processes. Delay 1647 * a bit but allow wakeups. 1648 */ 1649 vm_pages_needed = 0; 1650 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10); 1651 vm_pages_needed = 1; 1652 } else { 1653 /* 1654 * We've taken too many passes, forced delay. 1655 */ 1656 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10); 1657 } 1658 } else { 1659 /* 1660 * Interlocked wakeup of waiters (non-optional) 1661 */ 1662 pass = 0; 1663 if (vm_pages_needed && !vm_page_count_min(0)) { 1664 wakeup(&vmstats.v_free_count); 1665 vm_pages_needed = 0; 1666 } 1667 } 1668 } 1669 } 1670 1671 static struct kproc_desc page_kp = { 1672 "pagedaemon", 1673 vm_pageout_thread, 1674 &pagethread 1675 }; 1676 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 1677 1678 1679 /* 1680 * Called after allocating a page out of the cache or free queue 1681 * to possibly wake the pagedaemon up to replentish our supply. 1682 * 1683 * We try to generate some hysteresis by waking the pagedaemon up 1684 * when our free+cache pages go below the free_min+cache_min level. 1685 * The pagedaemon tries to get the count back up to at least the 1686 * minimum, and through to the target level if possible. 1687 * 1688 * If the pagedaemon is already active bump vm_pages_needed as a hint 1689 * that there are even more requests pending. 1690 * 1691 * SMP races ok? 1692 * No requirements. 1693 */ 1694 void 1695 pagedaemon_wakeup(void) 1696 { 1697 if (vm_paging_needed() && curthread != pagethread) { 1698 if (vm_pages_needed == 0) { 1699 vm_pages_needed = 1; /* SMP race ok */ 1700 wakeup(&vm_pages_needed); 1701 } else if (vm_page_count_min(0)) { 1702 ++vm_pages_needed; /* SMP race ok */ 1703 } 1704 } 1705 } 1706 1707 #if !defined(NO_SWAPPING) 1708 1709 /* 1710 * SMP races ok? 1711 * No requirements. 1712 */ 1713 static void 1714 vm_req_vmdaemon(void) 1715 { 1716 static int lastrun = 0; 1717 1718 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1719 wakeup(&vm_daemon_needed); 1720 lastrun = ticks; 1721 } 1722 } 1723 1724 static int vm_daemon_callback(struct proc *p, void *data __unused); 1725 1726 /* 1727 * No requirements. 1728 */ 1729 static void 1730 vm_daemon(void) 1731 { 1732 /* 1733 * Permanently hold vm_token. 1734 */ 1735 lwkt_gettoken(&vm_token); 1736 1737 while (TRUE) { 1738 tsleep(&vm_daemon_needed, 0, "psleep", 0); 1739 if (vm_pageout_req_swapout) { 1740 swapout_procs(vm_pageout_req_swapout); 1741 vm_pageout_req_swapout = 0; 1742 } 1743 /* 1744 * scan the processes for exceeding their rlimits or if 1745 * process is swapped out -- deactivate pages 1746 */ 1747 allproc_scan(vm_daemon_callback, NULL); 1748 } 1749 } 1750 1751 /* 1752 * Caller must hold vm_token and proc_token. 1753 */ 1754 static int 1755 vm_daemon_callback(struct proc *p, void *data __unused) 1756 { 1757 vm_pindex_t limit, size; 1758 1759 /* 1760 * if this is a system process or if we have already 1761 * looked at this process, skip it. 1762 */ 1763 if (p->p_flag & (P_SYSTEM | P_WEXIT)) 1764 return (0); 1765 1766 /* 1767 * if the process is in a non-running type state, 1768 * don't touch it. 1769 */ 1770 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) 1771 return (0); 1772 1773 /* 1774 * get a limit 1775 */ 1776 limit = OFF_TO_IDX(qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 1777 p->p_rlimit[RLIMIT_RSS].rlim_max)); 1778 1779 /* 1780 * let processes that are swapped out really be 1781 * swapped out. Set the limit to nothing to get as 1782 * many pages out to swap as possible. 1783 */ 1784 if (p->p_flag & P_SWAPPEDOUT) 1785 limit = 0; 1786 1787 size = vmspace_resident_count(p->p_vmspace); 1788 if (limit >= 0 && size >= limit) { 1789 vm_pageout_map_deactivate_pages( 1790 &p->p_vmspace->vm_map, limit); 1791 } 1792 return (0); 1793 } 1794 1795 #endif 1796