1 /*- 2 * Copyright (c) 1991 Regents of the University of California. 3 * All rights reserved. 4 * Copyright (c) 1994 John S. Dyson 5 * All rights reserved. 6 * Copyright (c) 1994 David Greenman 7 * All rights reserved. 8 * Copyright (c) 2005 Yahoo! Technologies Norway AS 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 71 /* 72 * The proverbial page-out daemon. 73 */ 74 75 #include <sys/cdefs.h> 76 __FBSDID("$FreeBSD$"); 77 78 #include "opt_vm.h" 79 #include <sys/param.h> 80 #include <sys/systm.h> 81 #include <sys/kernel.h> 82 #include <sys/eventhandler.h> 83 #include <sys/lock.h> 84 #include <sys/mutex.h> 85 #include <sys/proc.h> 86 #include <sys/kthread.h> 87 #include <sys/ktr.h> 88 #include <sys/resourcevar.h> 89 #include <sys/sched.h> 90 #include <sys/signalvar.h> 91 #include <sys/vnode.h> 92 #include <sys/vmmeter.h> 93 #include <sys/sx.h> 94 #include <sys/sysctl.h> 95 96 #include <vm/vm.h> 97 #include <vm/vm_param.h> 98 #include <vm/vm_object.h> 99 #include <vm/vm_page.h> 100 #include <vm/vm_map.h> 101 #include <vm/vm_pageout.h> 102 #include <vm/vm_pager.h> 103 #include <vm/swap_pager.h> 104 #include <vm/vm_extern.h> 105 #include <vm/uma.h> 106 107 #include <machine/mutex.h> 108 109 /* 110 * System initialization 111 */ 112 113 /* the kernel process "vm_pageout"*/ 114 static void vm_pageout(void); 115 static int vm_pageout_clean(vm_page_t); 116 static void vm_pageout_scan(int pass); 117 118 struct proc *pageproc; 119 120 static struct kproc_desc page_kp = { 121 "pagedaemon", 122 vm_pageout, 123 &pageproc 124 }; 125 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 126 127 #if !defined(NO_SWAPPING) 128 /* the kernel process "vm_daemon"*/ 129 static void vm_daemon(void); 130 static struct proc *vmproc; 131 132 static struct kproc_desc vm_kp = { 133 "vmdaemon", 134 vm_daemon, 135 &vmproc 136 }; 137 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) 138 #endif 139 140 141 int vm_pages_needed; /* Event on which pageout daemon sleeps */ 142 int vm_pageout_deficit; /* Estimated number of pages deficit */ 143 int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 144 145 #if !defined(NO_SWAPPING) 146 static int vm_pageout_req_swapout; /* XXX */ 147 static int vm_daemon_needed; 148 #endif 149 static int vm_max_launder = 32; 150 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 151 static int vm_pageout_full_stats_interval = 0; 152 static int vm_pageout_algorithm=0; 153 static int defer_swap_pageouts=0; 154 static int disable_swap_pageouts=0; 155 156 #if defined(NO_SWAPPING) 157 static int vm_swap_enabled=0; 158 static int vm_swap_idle_enabled=0; 159 #else 160 static int vm_swap_enabled=1; 161 static int vm_swap_idle_enabled=0; 162 #endif 163 164 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 165 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 166 167 SYSCTL_INT(_vm, OID_AUTO, max_launder, 168 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 169 170 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 171 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 172 173 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 174 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 175 176 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 177 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 178 179 #if defined(NO_SWAPPING) 180 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 181 CTLFLAG_RD, &vm_swap_enabled, 0, ""); 182 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 183 CTLFLAG_RD, &vm_swap_idle_enabled, 0, ""); 184 #else 185 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 186 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 187 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 188 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 189 #endif 190 191 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 192 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 193 194 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 195 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 196 197 static int pageout_lock_miss; 198 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 199 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 200 201 #define VM_PAGEOUT_PAGE_COUNT 16 202 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 203 204 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 205 206 #if !defined(NO_SWAPPING) 207 static void vm_pageout_map_deactivate_pages(vm_map_t, long); 208 static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long); 209 static void vm_req_vmdaemon(void); 210 #endif 211 static void vm_pageout_page_stats(void); 212 213 /* 214 * vm_pageout_fallback_object_lock: 215 * 216 * Lock vm object currently associated with `m'. VM_OBJECT_TRYLOCK is 217 * known to have failed and page queue must be either PQ_ACTIVE or 218 * PQ_INACTIVE. To avoid lock order violation, unlock the page queues 219 * while locking the vm object. Use marker page to detect page queue 220 * changes and maintain notion of next page on page queue. Return 221 * TRUE if no changes were detected, FALSE otherwise. vm object is 222 * locked on return. 223 * 224 * This function depends on both the lock portion of struct vm_object 225 * and normal struct vm_page being type stable. 226 */ 227 static boolean_t 228 vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next) 229 { 230 struct vm_page marker; 231 boolean_t unchanged; 232 u_short queue; 233 vm_object_t object; 234 235 /* 236 * Initialize our marker 237 */ 238 bzero(&marker, sizeof(marker)); 239 marker.flags = PG_FICTITIOUS | PG_MARKER; 240 marker.oflags = VPO_BUSY; 241 marker.queue = m->queue; 242 marker.wire_count = 1; 243 244 queue = m->queue; 245 object = m->object; 246 247 TAILQ_INSERT_AFTER(&vm_page_queues[queue].pl, 248 m, &marker, pageq); 249 vm_page_unlock_queues(); 250 VM_OBJECT_LOCK(object); 251 vm_page_lock_queues(); 252 253 /* Page queue might have changed. */ 254 *next = TAILQ_NEXT(&marker, pageq); 255 unchanged = (m->queue == queue && 256 m->object == object && 257 &marker == TAILQ_NEXT(m, pageq)); 258 TAILQ_REMOVE(&vm_page_queues[queue].pl, 259 &marker, pageq); 260 return (unchanged); 261 } 262 263 /* 264 * vm_pageout_clean: 265 * 266 * Clean the page and remove it from the laundry. 267 * 268 * We set the busy bit to cause potential page faults on this page to 269 * block. Note the careful timing, however, the busy bit isn't set till 270 * late and we cannot do anything that will mess with the page. 271 */ 272 static int 273 vm_pageout_clean(m) 274 vm_page_t m; 275 { 276 vm_object_t object; 277 vm_page_t mc[2*vm_pageout_page_count]; 278 int pageout_count; 279 int ib, is, page_base; 280 vm_pindex_t pindex = m->pindex; 281 282 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 283 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 284 285 /* 286 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 287 * with the new swapper, but we could have serious problems paging 288 * out other object types if there is insufficient memory. 289 * 290 * Unfortunately, checking free memory here is far too late, so the 291 * check has been moved up a procedural level. 292 */ 293 294 /* 295 * Don't mess with the page if it's busy, held, or special 296 */ 297 if ((m->hold_count != 0) || 298 ((m->busy != 0) || (m->oflags & VPO_BUSY) || 299 (m->flags & PG_UNMANAGED))) { 300 return 0; 301 } 302 303 mc[vm_pageout_page_count] = m; 304 pageout_count = 1; 305 page_base = vm_pageout_page_count; 306 ib = 1; 307 is = 1; 308 309 /* 310 * Scan object for clusterable pages. 311 * 312 * We can cluster ONLY if: ->> the page is NOT 313 * clean, wired, busy, held, or mapped into a 314 * buffer, and one of the following: 315 * 1) The page is inactive, or a seldom used 316 * active page. 317 * -or- 318 * 2) we force the issue. 319 * 320 * During heavy mmap/modification loads the pageout 321 * daemon can really fragment the underlying file 322 * due to flushing pages out of order and not trying 323 * align the clusters (which leave sporatic out-of-order 324 * holes). To solve this problem we do the reverse scan 325 * first and attempt to align our cluster, then do a 326 * forward scan if room remains. 327 */ 328 object = m->object; 329 more: 330 while (ib && pageout_count < vm_pageout_page_count) { 331 vm_page_t p; 332 333 if (ib > pindex) { 334 ib = 0; 335 break; 336 } 337 338 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) { 339 ib = 0; 340 break; 341 } 342 if (VM_PAGE_INQUEUE1(p, PQ_CACHE) || 343 (p->oflags & VPO_BUSY) || p->busy || 344 (p->flags & PG_UNMANAGED)) { 345 ib = 0; 346 break; 347 } 348 vm_page_test_dirty(p); 349 if ((p->dirty & p->valid) == 0 || 350 p->queue != PQ_INACTIVE || 351 p->wire_count != 0 || /* may be held by buf cache */ 352 p->hold_count != 0) { /* may be undergoing I/O */ 353 ib = 0; 354 break; 355 } 356 mc[--page_base] = p; 357 ++pageout_count; 358 ++ib; 359 /* 360 * alignment boundry, stop here and switch directions. Do 361 * not clear ib. 362 */ 363 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 364 break; 365 } 366 367 while (pageout_count < vm_pageout_page_count && 368 pindex + is < object->size) { 369 vm_page_t p; 370 371 if ((p = vm_page_lookup(object, pindex + is)) == NULL) 372 break; 373 if (VM_PAGE_INQUEUE1(p, PQ_CACHE) || 374 (p->oflags & VPO_BUSY) || p->busy || 375 (p->flags & PG_UNMANAGED)) { 376 break; 377 } 378 vm_page_test_dirty(p); 379 if ((p->dirty & p->valid) == 0 || 380 p->queue != PQ_INACTIVE || 381 p->wire_count != 0 || /* may be held by buf cache */ 382 p->hold_count != 0) { /* may be undergoing I/O */ 383 break; 384 } 385 mc[page_base + pageout_count] = p; 386 ++pageout_count; 387 ++is; 388 } 389 390 /* 391 * If we exhausted our forward scan, continue with the reverse scan 392 * when possible, even past a page boundry. This catches boundry 393 * conditions. 394 */ 395 if (ib && pageout_count < vm_pageout_page_count) 396 goto more; 397 398 /* 399 * we allow reads during pageouts... 400 */ 401 return (vm_pageout_flush(&mc[page_base], pageout_count, 0)); 402 } 403 404 /* 405 * vm_pageout_flush() - launder the given pages 406 * 407 * The given pages are laundered. Note that we setup for the start of 408 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 409 * reference count all in here rather then in the parent. If we want 410 * the parent to do more sophisticated things we may have to change 411 * the ordering. 412 */ 413 int 414 vm_pageout_flush(vm_page_t *mc, int count, int flags) 415 { 416 vm_object_t object = mc[0]->object; 417 int pageout_status[count]; 418 int numpagedout = 0; 419 int i; 420 421 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 422 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 423 /* 424 * Initiate I/O. Bump the vm_page_t->busy counter and 425 * mark the pages read-only. 426 * 427 * We do not have to fixup the clean/dirty bits here... we can 428 * allow the pager to do it after the I/O completes. 429 * 430 * NOTE! mc[i]->dirty may be partial or fragmented due to an 431 * edge case with file fragments. 432 */ 433 for (i = 0; i < count; i++) { 434 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 435 ("vm_pageout_flush: partially invalid page %p index %d/%d", 436 mc[i], i, count)); 437 vm_page_io_start(mc[i]); 438 pmap_remove_write(mc[i]); 439 } 440 vm_page_unlock_queues(); 441 vm_object_pip_add(object, count); 442 443 vm_pager_put_pages(object, mc, count, 444 (flags | ((object == kernel_object) ? VM_PAGER_PUT_SYNC : 0)), 445 pageout_status); 446 447 vm_page_lock_queues(); 448 for (i = 0; i < count; i++) { 449 vm_page_t mt = mc[i]; 450 451 KASSERT((mt->flags & PG_WRITEABLE) == 0, 452 ("vm_pageout_flush: page %p is not write protected", mt)); 453 switch (pageout_status[i]) { 454 case VM_PAGER_OK: 455 case VM_PAGER_PEND: 456 numpagedout++; 457 break; 458 case VM_PAGER_BAD: 459 /* 460 * Page outside of range of object. Right now we 461 * essentially lose the changes by pretending it 462 * worked. 463 */ 464 pmap_clear_modify(mt); 465 vm_page_undirty(mt); 466 break; 467 case VM_PAGER_ERROR: 468 case VM_PAGER_FAIL: 469 /* 470 * If page couldn't be paged out, then reactivate the 471 * page so it doesn't clog the inactive list. (We 472 * will try paging out it again later). 473 */ 474 vm_page_activate(mt); 475 break; 476 case VM_PAGER_AGAIN: 477 break; 478 } 479 480 /* 481 * If the operation is still going, leave the page busy to 482 * block all other accesses. Also, leave the paging in 483 * progress indicator set so that we don't attempt an object 484 * collapse. 485 */ 486 if (pageout_status[i] != VM_PAGER_PEND) { 487 vm_object_pip_wakeup(object); 488 vm_page_io_finish(mt); 489 if (vm_page_count_severe()) 490 vm_page_try_to_cache(mt); 491 } 492 } 493 return numpagedout; 494 } 495 496 #if !defined(NO_SWAPPING) 497 /* 498 * vm_pageout_object_deactivate_pages 499 * 500 * deactivate enough pages to satisfy the inactive target 501 * requirements or if vm_page_proc_limit is set, then 502 * deactivate all of the pages in the object and its 503 * backing_objects. 504 * 505 * The object and map must be locked. 506 */ 507 static void 508 vm_pageout_object_deactivate_pages(pmap, first_object, desired) 509 pmap_t pmap; 510 vm_object_t first_object; 511 long desired; 512 { 513 vm_object_t backing_object, object; 514 vm_page_t p, next; 515 int actcount, rcount, remove_mode; 516 517 VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED); 518 if (first_object->type == OBJT_DEVICE || first_object->type == OBJT_PHYS) 519 return; 520 for (object = first_object;; object = backing_object) { 521 if (pmap_resident_count(pmap) <= desired) 522 goto unlock_return; 523 if (object->paging_in_progress) 524 goto unlock_return; 525 526 remove_mode = 0; 527 if (object->shadow_count > 1) 528 remove_mode = 1; 529 /* 530 * scan the objects entire memory queue 531 */ 532 rcount = object->resident_page_count; 533 p = TAILQ_FIRST(&object->memq); 534 vm_page_lock_queues(); 535 while (p && (rcount-- > 0)) { 536 if (pmap_resident_count(pmap) <= desired) { 537 vm_page_unlock_queues(); 538 goto unlock_return; 539 } 540 next = TAILQ_NEXT(p, listq); 541 cnt.v_pdpages++; 542 if (p->wire_count != 0 || 543 p->hold_count != 0 || 544 p->busy != 0 || 545 (p->oflags & VPO_BUSY) || 546 (p->flags & PG_UNMANAGED) || 547 !pmap_page_exists_quick(pmap, p)) { 548 p = next; 549 continue; 550 } 551 actcount = pmap_ts_referenced(p); 552 if (actcount) { 553 vm_page_flag_set(p, PG_REFERENCED); 554 } else if (p->flags & PG_REFERENCED) { 555 actcount = 1; 556 } 557 if ((p->queue != PQ_ACTIVE) && 558 (p->flags & PG_REFERENCED)) { 559 vm_page_activate(p); 560 p->act_count += actcount; 561 vm_page_flag_clear(p, PG_REFERENCED); 562 } else if (p->queue == PQ_ACTIVE) { 563 if ((p->flags & PG_REFERENCED) == 0) { 564 p->act_count -= min(p->act_count, ACT_DECLINE); 565 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) { 566 pmap_remove_all(p); 567 vm_page_deactivate(p); 568 } else { 569 vm_pageq_requeue(p); 570 } 571 } else { 572 vm_page_activate(p); 573 vm_page_flag_clear(p, PG_REFERENCED); 574 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 575 p->act_count += ACT_ADVANCE; 576 vm_pageq_requeue(p); 577 } 578 } else if (p->queue == PQ_INACTIVE) { 579 pmap_remove_all(p); 580 } 581 p = next; 582 } 583 vm_page_unlock_queues(); 584 if ((backing_object = object->backing_object) == NULL) 585 goto unlock_return; 586 VM_OBJECT_LOCK(backing_object); 587 if (object != first_object) 588 VM_OBJECT_UNLOCK(object); 589 } 590 unlock_return: 591 if (object != first_object) 592 VM_OBJECT_UNLOCK(object); 593 } 594 595 /* 596 * deactivate some number of pages in a map, try to do it fairly, but 597 * that is really hard to do. 598 */ 599 static void 600 vm_pageout_map_deactivate_pages(map, desired) 601 vm_map_t map; 602 long desired; 603 { 604 vm_map_entry_t tmpe; 605 vm_object_t obj, bigobj; 606 int nothingwired; 607 608 if (!vm_map_trylock(map)) 609 return; 610 611 bigobj = NULL; 612 nothingwired = TRUE; 613 614 /* 615 * first, search out the biggest object, and try to free pages from 616 * that. 617 */ 618 tmpe = map->header.next; 619 while (tmpe != &map->header) { 620 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 621 obj = tmpe->object.vm_object; 622 if (obj != NULL && VM_OBJECT_TRYLOCK(obj)) { 623 if (obj->shadow_count <= 1 && 624 (bigobj == NULL || 625 bigobj->resident_page_count < obj->resident_page_count)) { 626 if (bigobj != NULL) 627 VM_OBJECT_UNLOCK(bigobj); 628 bigobj = obj; 629 } else 630 VM_OBJECT_UNLOCK(obj); 631 } 632 } 633 if (tmpe->wired_count > 0) 634 nothingwired = FALSE; 635 tmpe = tmpe->next; 636 } 637 638 if (bigobj != NULL) { 639 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); 640 VM_OBJECT_UNLOCK(bigobj); 641 } 642 /* 643 * Next, hunt around for other pages to deactivate. We actually 644 * do this search sort of wrong -- .text first is not the best idea. 645 */ 646 tmpe = map->header.next; 647 while (tmpe != &map->header) { 648 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 649 break; 650 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 651 obj = tmpe->object.vm_object; 652 if (obj != NULL) { 653 VM_OBJECT_LOCK(obj); 654 vm_pageout_object_deactivate_pages(map->pmap, obj, desired); 655 VM_OBJECT_UNLOCK(obj); 656 } 657 } 658 tmpe = tmpe->next; 659 } 660 661 /* 662 * Remove all mappings if a process is swapped out, this will free page 663 * table pages. 664 */ 665 if (desired == 0 && nothingwired) { 666 pmap_remove(vm_map_pmap(map), vm_map_min(map), 667 vm_map_max(map)); 668 } 669 vm_map_unlock(map); 670 } 671 #endif /* !defined(NO_SWAPPING) */ 672 673 /* 674 * vm_pageout_scan does the dirty work for the pageout daemon. 675 */ 676 static void 677 vm_pageout_scan(int pass) 678 { 679 vm_page_t m, next; 680 struct vm_page marker; 681 int page_shortage, maxscan, pcount; 682 int addl_page_shortage, addl_page_shortage_init; 683 struct proc *p, *bigproc; 684 struct thread *td; 685 vm_offset_t size, bigsize; 686 vm_object_t object; 687 int actcount, cache_cur, cache_first_failure; 688 static int cache_last_free; 689 int vnodes_skipped = 0; 690 int maxlaunder; 691 692 mtx_lock(&Giant); 693 /* 694 * Decrease registered cache sizes. 695 */ 696 EVENTHANDLER_INVOKE(vm_lowmem, 0); 697 /* 698 * We do this explicitly after the caches have been drained above. 699 */ 700 uma_reclaim(); 701 702 addl_page_shortage_init = atomic_readandclear_int(&vm_pageout_deficit); 703 704 /* 705 * Calculate the number of pages we want to either free or move 706 * to the cache. 707 */ 708 page_shortage = vm_paging_target() + addl_page_shortage_init; 709 710 /* 711 * Initialize our marker 712 */ 713 bzero(&marker, sizeof(marker)); 714 marker.flags = PG_FICTITIOUS | PG_MARKER; 715 marker.oflags = VPO_BUSY; 716 marker.queue = PQ_INACTIVE; 717 marker.wire_count = 1; 718 719 /* 720 * Start scanning the inactive queue for pages we can move to the 721 * cache or free. The scan will stop when the target is reached or 722 * we have scanned the entire inactive queue. Note that m->act_count 723 * is not used to form decisions for the inactive queue, only for the 724 * active queue. 725 * 726 * maxlaunder limits the number of dirty pages we flush per scan. 727 * For most systems a smaller value (16 or 32) is more robust under 728 * extreme memory and disk pressure because any unnecessary writes 729 * to disk can result in extreme performance degredation. However, 730 * systems with excessive dirty pages (especially when MAP_NOSYNC is 731 * used) will die horribly with limited laundering. If the pageout 732 * daemon cannot clean enough pages in the first pass, we let it go 733 * all out in succeeding passes. 734 */ 735 if ((maxlaunder = vm_max_launder) <= 1) 736 maxlaunder = 1; 737 if (pass) 738 maxlaunder = 10000; 739 vm_page_lock_queues(); 740 rescan0: 741 addl_page_shortage = addl_page_shortage_init; 742 maxscan = cnt.v_inactive_count; 743 744 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 745 m != NULL && maxscan-- > 0 && page_shortage > 0; 746 m = next) { 747 748 cnt.v_pdpages++; 749 750 if (VM_PAGE_GETQUEUE(m) != PQ_INACTIVE) { 751 goto rescan0; 752 } 753 754 next = TAILQ_NEXT(m, pageq); 755 object = m->object; 756 757 /* 758 * skip marker pages 759 */ 760 if (m->flags & PG_MARKER) 761 continue; 762 763 /* 764 * A held page may be undergoing I/O, so skip it. 765 */ 766 if (m->hold_count) { 767 vm_pageq_requeue(m); 768 addl_page_shortage++; 769 continue; 770 } 771 /* 772 * Don't mess with busy pages, keep in the front of the 773 * queue, most likely are being paged out. 774 */ 775 if (!VM_OBJECT_TRYLOCK(object) && 776 (!vm_pageout_fallback_object_lock(m, &next) || 777 m->hold_count != 0)) { 778 VM_OBJECT_UNLOCK(object); 779 addl_page_shortage++; 780 continue; 781 } 782 if (m->busy || (m->oflags & VPO_BUSY)) { 783 VM_OBJECT_UNLOCK(object); 784 addl_page_shortage++; 785 continue; 786 } 787 788 /* 789 * If the object is not being used, we ignore previous 790 * references. 791 */ 792 if (object->ref_count == 0) { 793 vm_page_flag_clear(m, PG_REFERENCED); 794 pmap_clear_reference(m); 795 796 /* 797 * Otherwise, if the page has been referenced while in the 798 * inactive queue, we bump the "activation count" upwards, 799 * making it less likely that the page will be added back to 800 * the inactive queue prematurely again. Here we check the 801 * page tables (or emulated bits, if any), given the upper 802 * level VM system not knowing anything about existing 803 * references. 804 */ 805 } else if (((m->flags & PG_REFERENCED) == 0) && 806 (actcount = pmap_ts_referenced(m))) { 807 vm_page_activate(m); 808 VM_OBJECT_UNLOCK(object); 809 m->act_count += (actcount + ACT_ADVANCE); 810 continue; 811 } 812 813 /* 814 * If the upper level VM system knows about any page 815 * references, we activate the page. We also set the 816 * "activation count" higher than normal so that we will less 817 * likely place pages back onto the inactive queue again. 818 */ 819 if ((m->flags & PG_REFERENCED) != 0) { 820 vm_page_flag_clear(m, PG_REFERENCED); 821 actcount = pmap_ts_referenced(m); 822 vm_page_activate(m); 823 VM_OBJECT_UNLOCK(object); 824 m->act_count += (actcount + ACT_ADVANCE + 1); 825 continue; 826 } 827 828 /* 829 * If the upper level VM system doesn't know anything about 830 * the page being dirty, we have to check for it again. As 831 * far as the VM code knows, any partially dirty pages are 832 * fully dirty. 833 */ 834 if (m->dirty == 0 && !pmap_is_modified(m)) { 835 /* 836 * Avoid a race condition: Unless write access is 837 * removed from the page, another processor could 838 * modify it before all access is removed by the call 839 * to vm_page_cache() below. If vm_page_cache() finds 840 * that the page has been modified when it removes all 841 * access, it panics because it cannot cache dirty 842 * pages. In principle, we could eliminate just write 843 * access here rather than all access. In the expected 844 * case, when there are no last instant modifications 845 * to the page, removing all access will be cheaper 846 * overall. 847 */ 848 if ((m->flags & PG_WRITEABLE) != 0) 849 pmap_remove_all(m); 850 } else { 851 vm_page_dirty(m); 852 } 853 854 if (m->valid == 0) { 855 /* 856 * Invalid pages can be easily freed 857 */ 858 vm_page_free(m); 859 cnt.v_dfree++; 860 --page_shortage; 861 } else if (m->dirty == 0) { 862 /* 863 * Clean pages can be placed onto the cache queue. 864 * This effectively frees them. 865 */ 866 vm_page_cache(m); 867 --page_shortage; 868 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 869 /* 870 * Dirty pages need to be paged out, but flushing 871 * a page is extremely expensive verses freeing 872 * a clean page. Rather then artificially limiting 873 * the number of pages we can flush, we instead give 874 * dirty pages extra priority on the inactive queue 875 * by forcing them to be cycled through the queue 876 * twice before being flushed, after which the 877 * (now clean) page will cycle through once more 878 * before being freed. This significantly extends 879 * the thrash point for a heavily loaded machine. 880 */ 881 vm_page_flag_set(m, PG_WINATCFLS); 882 vm_pageq_requeue(m); 883 } else if (maxlaunder > 0) { 884 /* 885 * We always want to try to flush some dirty pages if 886 * we encounter them, to keep the system stable. 887 * Normally this number is small, but under extreme 888 * pressure where there are insufficient clean pages 889 * on the inactive queue, we may have to go all out. 890 */ 891 int swap_pageouts_ok; 892 struct vnode *vp = NULL; 893 struct mount *mp; 894 895 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 896 swap_pageouts_ok = 1; 897 } else { 898 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 899 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 900 vm_page_count_min()); 901 902 } 903 904 /* 905 * We don't bother paging objects that are "dead". 906 * Those objects are in a "rundown" state. 907 */ 908 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 909 VM_OBJECT_UNLOCK(object); 910 vm_pageq_requeue(m); 911 continue; 912 } 913 914 /* 915 * Following operations may unlock 916 * vm_page_queue_mtx, invalidating the 'next' 917 * pointer. To prevent an inordinate number 918 * of restarts we use our marker to remember 919 * our place. 920 * 921 */ 922 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, 923 m, &marker, pageq); 924 /* 925 * The object is already known NOT to be dead. It 926 * is possible for the vget() to block the whole 927 * pageout daemon, but the new low-memory handling 928 * code should prevent it. 929 * 930 * The previous code skipped locked vnodes and, worse, 931 * reordered pages in the queue. This results in 932 * completely non-deterministic operation and, on a 933 * busy system, can lead to extremely non-optimal 934 * pageouts. For example, it can cause clean pages 935 * to be freed and dirty pages to be moved to the end 936 * of the queue. Since dirty pages are also moved to 937 * the end of the queue once-cleaned, this gives 938 * way too large a weighting to defering the freeing 939 * of dirty pages. 940 * 941 * We can't wait forever for the vnode lock, we might 942 * deadlock due to a vn_read() getting stuck in 943 * vm_wait while holding this vnode. We skip the 944 * vnode if we can't get it in a reasonable amount 945 * of time. 946 */ 947 if (object->type == OBJT_VNODE) { 948 vp = object->handle; 949 mp = NULL; 950 if (vp->v_type == VREG && 951 vn_start_write(vp, &mp, V_NOWAIT) != 0) { 952 ++pageout_lock_miss; 953 if (object->flags & OBJ_MIGHTBEDIRTY) 954 vnodes_skipped++; 955 vp = NULL; 956 goto unlock_and_continue; 957 } 958 vm_page_unlock_queues(); 959 VI_LOCK(vp); 960 VM_OBJECT_UNLOCK(object); 961 if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK | 962 LK_TIMELOCK, curthread)) { 963 VM_OBJECT_LOCK(object); 964 vm_page_lock_queues(); 965 ++pageout_lock_miss; 966 vn_finished_write(mp); 967 if (object->flags & OBJ_MIGHTBEDIRTY) 968 vnodes_skipped++; 969 vp = NULL; 970 goto unlock_and_continue; 971 } 972 VM_OBJECT_LOCK(object); 973 vm_page_lock_queues(); 974 /* 975 * The page might have been moved to another 976 * queue during potential blocking in vget() 977 * above. The page might have been freed and 978 * reused for another vnode. The object might 979 * have been reused for another vnode. 980 */ 981 if (VM_PAGE_GETQUEUE(m) != PQ_INACTIVE || 982 m->object != object || 983 object->handle != vp || 984 TAILQ_NEXT(m, pageq) != &marker) { 985 if (object->flags & OBJ_MIGHTBEDIRTY) 986 vnodes_skipped++; 987 goto unlock_and_continue; 988 } 989 990 /* 991 * The page may have been busied during the 992 * blocking in vput(); We don't move the 993 * page back onto the end of the queue so that 994 * statistics are more correct if we don't. 995 */ 996 if (m->busy || (m->oflags & VPO_BUSY)) { 997 goto unlock_and_continue; 998 } 999 1000 /* 1001 * If the page has become held it might 1002 * be undergoing I/O, so skip it 1003 */ 1004 if (m->hold_count) { 1005 vm_pageq_requeue(m); 1006 if (object->flags & OBJ_MIGHTBEDIRTY) 1007 vnodes_skipped++; 1008 goto unlock_and_continue; 1009 } 1010 } 1011 1012 /* 1013 * If a page is dirty, then it is either being washed 1014 * (but not yet cleaned) or it is still in the 1015 * laundry. If it is still in the laundry, then we 1016 * start the cleaning operation. 1017 * 1018 * decrement page_shortage on success to account for 1019 * the (future) cleaned page. Otherwise we could wind 1020 * up laundering or cleaning too many pages. 1021 */ 1022 if (vm_pageout_clean(m) != 0) { 1023 --page_shortage; 1024 --maxlaunder; 1025 } 1026 unlock_and_continue: 1027 VM_OBJECT_UNLOCK(object); 1028 if (vp) { 1029 vm_page_unlock_queues(); 1030 vput(vp); 1031 vn_finished_write(mp); 1032 vm_page_lock_queues(); 1033 } 1034 next = TAILQ_NEXT(&marker, pageq); 1035 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, 1036 &marker, pageq); 1037 continue; 1038 } 1039 VM_OBJECT_UNLOCK(object); 1040 } 1041 1042 /* 1043 * Compute the number of pages we want to try to move from the 1044 * active queue to the inactive queue. 1045 */ 1046 page_shortage = vm_paging_target() + 1047 cnt.v_inactive_target - cnt.v_inactive_count; 1048 page_shortage += addl_page_shortage; 1049 1050 /* 1051 * Scan the active queue for things we can deactivate. We nominally 1052 * track the per-page activity counter and use it to locate 1053 * deactivation candidates. 1054 */ 1055 pcount = cnt.v_active_count; 1056 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1057 1058 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 1059 1060 KASSERT(VM_PAGE_INQUEUE2(m, PQ_ACTIVE), 1061 ("vm_pageout_scan: page %p isn't active", m)); 1062 1063 next = TAILQ_NEXT(m, pageq); 1064 object = m->object; 1065 if ((m->flags & PG_MARKER) != 0) { 1066 m = next; 1067 continue; 1068 } 1069 if (!VM_OBJECT_TRYLOCK(object) && 1070 !vm_pageout_fallback_object_lock(m, &next)) { 1071 VM_OBJECT_UNLOCK(object); 1072 m = next; 1073 continue; 1074 } 1075 1076 /* 1077 * Don't deactivate pages that are busy. 1078 */ 1079 if ((m->busy != 0) || 1080 (m->oflags & VPO_BUSY) || 1081 (m->hold_count != 0)) { 1082 VM_OBJECT_UNLOCK(object); 1083 vm_pageq_requeue(m); 1084 m = next; 1085 continue; 1086 } 1087 1088 /* 1089 * The count for pagedaemon pages is done after checking the 1090 * page for eligibility... 1091 */ 1092 cnt.v_pdpages++; 1093 1094 /* 1095 * Check to see "how much" the page has been used. 1096 */ 1097 actcount = 0; 1098 if (object->ref_count != 0) { 1099 if (m->flags & PG_REFERENCED) { 1100 actcount += 1; 1101 } 1102 actcount += pmap_ts_referenced(m); 1103 if (actcount) { 1104 m->act_count += ACT_ADVANCE + actcount; 1105 if (m->act_count > ACT_MAX) 1106 m->act_count = ACT_MAX; 1107 } 1108 } 1109 1110 /* 1111 * Since we have "tested" this bit, we need to clear it now. 1112 */ 1113 vm_page_flag_clear(m, PG_REFERENCED); 1114 1115 /* 1116 * Only if an object is currently being used, do we use the 1117 * page activation count stats. 1118 */ 1119 if (actcount && (object->ref_count != 0)) { 1120 vm_pageq_requeue(m); 1121 } else { 1122 m->act_count -= min(m->act_count, ACT_DECLINE); 1123 if (vm_pageout_algorithm || 1124 object->ref_count == 0 || 1125 m->act_count == 0) { 1126 page_shortage--; 1127 if (object->ref_count == 0) { 1128 pmap_remove_all(m); 1129 if (m->dirty == 0) 1130 vm_page_cache(m); 1131 else 1132 vm_page_deactivate(m); 1133 } else { 1134 vm_page_deactivate(m); 1135 } 1136 } else { 1137 vm_pageq_requeue(m); 1138 } 1139 } 1140 VM_OBJECT_UNLOCK(object); 1141 m = next; 1142 } 1143 1144 /* 1145 * We try to maintain some *really* free pages, this allows interrupt 1146 * code to be guaranteed space. Since both cache and free queues 1147 * are considered basically 'free', moving pages from cache to free 1148 * does not effect other calculations. 1149 */ 1150 cache_cur = cache_last_free; 1151 cache_first_failure = -1; 1152 while (cnt.v_free_count < cnt.v_free_reserved && (cache_cur = 1153 (cache_cur + PQ_PRIME2) & PQ_COLORMASK) != cache_first_failure) { 1154 TAILQ_FOREACH(m, &vm_page_queues[PQ_CACHE + cache_cur].pl, 1155 pageq) { 1156 KASSERT(m->dirty == 0, 1157 ("Found dirty cache page %p", m)); 1158 KASSERT(!pmap_page_is_mapped(m), 1159 ("Found mapped cache page %p", m)); 1160 KASSERT((m->flags & PG_UNMANAGED) == 0, 1161 ("Found unmanaged cache page %p", m)); 1162 KASSERT(m->wire_count == 0, 1163 ("Found wired cache page %p", m)); 1164 if (m->hold_count == 0 && VM_OBJECT_TRYLOCK(object = 1165 m->object)) { 1166 KASSERT((m->oflags & VPO_BUSY) == 0 && 1167 m->busy == 0, ("Found busy cache page %p", 1168 m)); 1169 vm_page_free(m); 1170 VM_OBJECT_UNLOCK(object); 1171 cnt.v_dfree++; 1172 cache_last_free = cache_cur; 1173 cache_first_failure = -1; 1174 break; 1175 } 1176 } 1177 if (m == NULL && cache_first_failure == -1) 1178 cache_first_failure = cache_cur; 1179 } 1180 vm_page_unlock_queues(); 1181 #if !defined(NO_SWAPPING) 1182 /* 1183 * Idle process swapout -- run once per second. 1184 */ 1185 if (vm_swap_idle_enabled) { 1186 static long lsec; 1187 if (time_second != lsec) { 1188 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1189 vm_req_vmdaemon(); 1190 lsec = time_second; 1191 } 1192 } 1193 #endif 1194 1195 /* 1196 * If we didn't get enough free pages, and we have skipped a vnode 1197 * in a writeable object, wakeup the sync daemon. And kick swapout 1198 * if we did not get enough free pages. 1199 */ 1200 if (vm_paging_target() > 0) { 1201 if (vnodes_skipped && vm_page_count_min()) 1202 (void) speedup_syncer(); 1203 #if !defined(NO_SWAPPING) 1204 if (vm_swap_enabled && vm_page_count_target()) { 1205 vm_req_vmdaemon(); 1206 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1207 } 1208 #endif 1209 } 1210 1211 /* 1212 * If we are critically low on one of RAM or swap and low on 1213 * the other, kill the largest process. However, we avoid 1214 * doing this on the first pass in order to give ourselves a 1215 * chance to flush out dirty vnode-backed pages and to allow 1216 * active pages to be moved to the inactive queue and reclaimed. 1217 * 1218 * We keep the process bigproc locked once we find it to keep anyone 1219 * from messing with it; however, there is a possibility of 1220 * deadlock if process B is bigproc and one of it's child processes 1221 * attempts to propagate a signal to B while we are waiting for A's 1222 * lock while walking this list. To avoid this, we don't block on 1223 * the process lock but just skip a process if it is already locked. 1224 */ 1225 if (pass != 0 && 1226 ((swap_pager_avail < 64 && vm_page_count_min()) || 1227 (swap_pager_full && vm_paging_target() > 0))) { 1228 bigproc = NULL; 1229 bigsize = 0; 1230 sx_slock(&allproc_lock); 1231 FOREACH_PROC_IN_SYSTEM(p) { 1232 int breakout; 1233 1234 if (PROC_TRYLOCK(p) == 0) 1235 continue; 1236 /* 1237 * If this is a system or protected process, skip it. 1238 */ 1239 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1240 (p->p_flag & P_PROTECTED) || 1241 ((p->p_pid < 48) && (swap_pager_avail != 0))) { 1242 PROC_UNLOCK(p); 1243 continue; 1244 } 1245 /* 1246 * If the process is in a non-running type state, 1247 * don't touch it. Check all the threads individually. 1248 */ 1249 PROC_SLOCK(p); 1250 breakout = 0; 1251 FOREACH_THREAD_IN_PROC(p, td) { 1252 thread_lock(td); 1253 if (!TD_ON_RUNQ(td) && 1254 !TD_IS_RUNNING(td) && 1255 !TD_IS_SLEEPING(td)) { 1256 thread_unlock(td); 1257 breakout = 1; 1258 break; 1259 } 1260 thread_unlock(td); 1261 } 1262 PROC_SUNLOCK(p); 1263 if (breakout) { 1264 PROC_UNLOCK(p); 1265 continue; 1266 } 1267 /* 1268 * get the process size 1269 */ 1270 if (!vm_map_trylock_read(&p->p_vmspace->vm_map)) { 1271 PROC_UNLOCK(p); 1272 continue; 1273 } 1274 size = vmspace_swap_count(p->p_vmspace); 1275 vm_map_unlock_read(&p->p_vmspace->vm_map); 1276 size += vmspace_resident_count(p->p_vmspace); 1277 /* 1278 * if the this process is bigger than the biggest one 1279 * remember it. 1280 */ 1281 if (size > bigsize) { 1282 if (bigproc != NULL) 1283 PROC_UNLOCK(bigproc); 1284 bigproc = p; 1285 bigsize = size; 1286 } else 1287 PROC_UNLOCK(p); 1288 } 1289 sx_sunlock(&allproc_lock); 1290 if (bigproc != NULL) { 1291 killproc(bigproc, "out of swap space"); 1292 PROC_SLOCK(bigproc); 1293 sched_nice(bigproc, PRIO_MIN); 1294 PROC_SUNLOCK(bigproc); 1295 PROC_UNLOCK(bigproc); 1296 wakeup(&cnt.v_free_count); 1297 } 1298 } 1299 mtx_unlock(&Giant); 1300 } 1301 1302 /* 1303 * This routine tries to maintain the pseudo LRU active queue, 1304 * so that during long periods of time where there is no paging, 1305 * that some statistic accumulation still occurs. This code 1306 * helps the situation where paging just starts to occur. 1307 */ 1308 static void 1309 vm_pageout_page_stats() 1310 { 1311 vm_object_t object; 1312 vm_page_t m,next; 1313 int pcount,tpcount; /* Number of pages to check */ 1314 static int fullintervalcount = 0; 1315 int page_shortage; 1316 1317 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1318 page_shortage = 1319 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1320 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1321 1322 if (page_shortage <= 0) 1323 return; 1324 1325 pcount = cnt.v_active_count; 1326 fullintervalcount += vm_pageout_stats_interval; 1327 if (fullintervalcount < vm_pageout_full_stats_interval) { 1328 tpcount = (vm_pageout_stats_max * cnt.v_active_count) / cnt.v_page_count; 1329 if (pcount > tpcount) 1330 pcount = tpcount; 1331 } else { 1332 fullintervalcount = 0; 1333 } 1334 1335 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1336 while ((m != NULL) && (pcount-- > 0)) { 1337 int actcount; 1338 1339 KASSERT(VM_PAGE_INQUEUE2(m, PQ_ACTIVE), 1340 ("vm_pageout_page_stats: page %p isn't active", m)); 1341 1342 next = TAILQ_NEXT(m, pageq); 1343 object = m->object; 1344 1345 if ((m->flags & PG_MARKER) != 0) { 1346 m = next; 1347 continue; 1348 } 1349 if (!VM_OBJECT_TRYLOCK(object) && 1350 !vm_pageout_fallback_object_lock(m, &next)) { 1351 VM_OBJECT_UNLOCK(object); 1352 m = next; 1353 continue; 1354 } 1355 1356 /* 1357 * Don't deactivate pages that are busy. 1358 */ 1359 if ((m->busy != 0) || 1360 (m->oflags & VPO_BUSY) || 1361 (m->hold_count != 0)) { 1362 VM_OBJECT_UNLOCK(object); 1363 vm_pageq_requeue(m); 1364 m = next; 1365 continue; 1366 } 1367 1368 actcount = 0; 1369 if (m->flags & PG_REFERENCED) { 1370 vm_page_flag_clear(m, PG_REFERENCED); 1371 actcount += 1; 1372 } 1373 1374 actcount += pmap_ts_referenced(m); 1375 if (actcount) { 1376 m->act_count += ACT_ADVANCE + actcount; 1377 if (m->act_count > ACT_MAX) 1378 m->act_count = ACT_MAX; 1379 vm_pageq_requeue(m); 1380 } else { 1381 if (m->act_count == 0) { 1382 /* 1383 * We turn off page access, so that we have 1384 * more accurate RSS stats. We don't do this 1385 * in the normal page deactivation when the 1386 * system is loaded VM wise, because the 1387 * cost of the large number of page protect 1388 * operations would be higher than the value 1389 * of doing the operation. 1390 */ 1391 pmap_remove_all(m); 1392 vm_page_deactivate(m); 1393 } else { 1394 m->act_count -= min(m->act_count, ACT_DECLINE); 1395 vm_pageq_requeue(m); 1396 } 1397 } 1398 VM_OBJECT_UNLOCK(object); 1399 m = next; 1400 } 1401 } 1402 1403 /* 1404 * vm_pageout is the high level pageout daemon. 1405 */ 1406 static void 1407 vm_pageout() 1408 { 1409 int error, pass; 1410 1411 /* 1412 * Initialize some paging parameters. 1413 */ 1414 cnt.v_interrupt_free_min = 2; 1415 if (cnt.v_page_count < 2000) 1416 vm_pageout_page_count = 8; 1417 1418 /* 1419 * v_free_reserved needs to include enough for the largest 1420 * swap pager structures plus enough for any pv_entry structs 1421 * when paging. 1422 */ 1423 if (cnt.v_page_count > 1024) 1424 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1425 else 1426 cnt.v_free_min = 4; 1427 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1428 cnt.v_interrupt_free_min; 1429 cnt.v_free_reserved = vm_pageout_page_count + 1430 cnt.v_pageout_free_min + (cnt.v_page_count / 768) + PQ_NUMCOLORS; 1431 cnt.v_free_severe = cnt.v_free_min / 2; 1432 cnt.v_free_min += cnt.v_free_reserved; 1433 cnt.v_free_severe += cnt.v_free_reserved; 1434 1435 /* 1436 * v_free_target and v_cache_min control pageout hysteresis. Note 1437 * that these are more a measure of the VM cache queue hysteresis 1438 * then the VM free queue. Specifically, v_free_target is the 1439 * high water mark (free+cache pages). 1440 * 1441 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1442 * low water mark, while v_free_min is the stop. v_cache_min must 1443 * be big enough to handle memory needs while the pageout daemon 1444 * is signalled and run to free more pages. 1445 */ 1446 if (cnt.v_free_count > 6144) 1447 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1448 else 1449 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1450 1451 if (cnt.v_free_count > 2048) { 1452 cnt.v_cache_min = cnt.v_free_target; 1453 cnt.v_cache_max = 2 * cnt.v_cache_min; 1454 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1455 } else { 1456 cnt.v_cache_min = 0; 1457 cnt.v_cache_max = 0; 1458 cnt.v_inactive_target = cnt.v_free_count / 4; 1459 } 1460 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1461 cnt.v_inactive_target = cnt.v_free_count / 3; 1462 1463 /* XXX does not really belong here */ 1464 if (vm_page_max_wired == 0) 1465 vm_page_max_wired = cnt.v_free_count / 3; 1466 1467 if (vm_pageout_stats_max == 0) 1468 vm_pageout_stats_max = cnt.v_free_target; 1469 1470 /* 1471 * Set interval in seconds for stats scan. 1472 */ 1473 if (vm_pageout_stats_interval == 0) 1474 vm_pageout_stats_interval = 5; 1475 if (vm_pageout_full_stats_interval == 0) 1476 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1477 1478 swap_pager_swap_init(); 1479 pass = 0; 1480 /* 1481 * The pageout daemon is never done, so loop forever. 1482 */ 1483 while (TRUE) { 1484 /* 1485 * If we have enough free memory, wakeup waiters. Do 1486 * not clear vm_pages_needed until we reach our target, 1487 * otherwise we may be woken up over and over again and 1488 * waste a lot of cpu. 1489 */ 1490 mtx_lock(&vm_page_queue_free_mtx); 1491 if (vm_pages_needed && !vm_page_count_min()) { 1492 if (!vm_paging_needed()) 1493 vm_pages_needed = 0; 1494 wakeup(&cnt.v_free_count); 1495 } 1496 if (vm_pages_needed) { 1497 /* 1498 * Still not done, take a second pass without waiting 1499 * (unlimited dirty cleaning), otherwise sleep a bit 1500 * and try again. 1501 */ 1502 ++pass; 1503 if (pass > 1) 1504 msleep(&vm_pages_needed, 1505 &vm_page_queue_free_mtx, PVM, "psleep", 1506 hz / 2); 1507 } else { 1508 /* 1509 * Good enough, sleep & handle stats. Prime the pass 1510 * for the next run. 1511 */ 1512 if (pass > 1) 1513 pass = 1; 1514 else 1515 pass = 0; 1516 error = msleep(&vm_pages_needed, 1517 &vm_page_queue_free_mtx, PVM, "psleep", 1518 vm_pageout_stats_interval * hz); 1519 if (error && !vm_pages_needed) { 1520 mtx_unlock(&vm_page_queue_free_mtx); 1521 pass = 0; 1522 vm_page_lock_queues(); 1523 vm_pageout_page_stats(); 1524 vm_page_unlock_queues(); 1525 continue; 1526 } 1527 } 1528 if (vm_pages_needed) 1529 cnt.v_pdwakeups++; 1530 mtx_unlock(&vm_page_queue_free_mtx); 1531 vm_pageout_scan(pass); 1532 } 1533 } 1534 1535 /* 1536 * Unless the free page queue lock is held by the caller, this function 1537 * should be regarded as advisory. Specifically, the caller should 1538 * not msleep() on &cnt.v_free_count following this function unless 1539 * the free page queue lock is held until the msleep() is performed. 1540 */ 1541 void 1542 pagedaemon_wakeup() 1543 { 1544 1545 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1546 vm_pages_needed = 1; 1547 wakeup(&vm_pages_needed); 1548 } 1549 } 1550 1551 #if !defined(NO_SWAPPING) 1552 static void 1553 vm_req_vmdaemon() 1554 { 1555 static int lastrun = 0; 1556 1557 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1558 wakeup(&vm_daemon_needed); 1559 lastrun = ticks; 1560 } 1561 } 1562 1563 static void 1564 vm_daemon() 1565 { 1566 struct rlimit rsslim; 1567 struct proc *p; 1568 struct thread *td; 1569 int breakout; 1570 1571 mtx_lock(&Giant); 1572 while (TRUE) { 1573 tsleep(&vm_daemon_needed, PPAUSE, "psleep", 0); 1574 if (vm_pageout_req_swapout) { 1575 swapout_procs(vm_pageout_req_swapout); 1576 vm_pageout_req_swapout = 0; 1577 } 1578 /* 1579 * scan the processes for exceeding their rlimits or if 1580 * process is swapped out -- deactivate pages 1581 */ 1582 sx_slock(&allproc_lock); 1583 FOREACH_PROC_IN_SYSTEM(p) { 1584 vm_pindex_t limit, size; 1585 1586 /* 1587 * if this is a system process or if we have already 1588 * looked at this process, skip it. 1589 */ 1590 PROC_LOCK(p); 1591 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 1592 PROC_UNLOCK(p); 1593 continue; 1594 } 1595 /* 1596 * if the process is in a non-running type state, 1597 * don't touch it. 1598 */ 1599 PROC_SLOCK(p); 1600 breakout = 0; 1601 FOREACH_THREAD_IN_PROC(p, td) { 1602 thread_lock(td); 1603 if (!TD_ON_RUNQ(td) && 1604 !TD_IS_RUNNING(td) && 1605 !TD_IS_SLEEPING(td)) { 1606 thread_unlock(td); 1607 breakout = 1; 1608 break; 1609 } 1610 thread_unlock(td); 1611 } 1612 PROC_SUNLOCK(p); 1613 if (breakout) { 1614 PROC_UNLOCK(p); 1615 continue; 1616 } 1617 /* 1618 * get a limit 1619 */ 1620 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1621 limit = OFF_TO_IDX( 1622 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1623 1624 /* 1625 * let processes that are swapped out really be 1626 * swapped out set the limit to nothing (will force a 1627 * swap-out.) 1628 */ 1629 if ((p->p_sflag & PS_INMEM) == 0) 1630 limit = 0; /* XXX */ 1631 PROC_UNLOCK(p); 1632 1633 size = vmspace_resident_count(p->p_vmspace); 1634 if (limit >= 0 && size >= limit) { 1635 vm_pageout_map_deactivate_pages( 1636 &p->p_vmspace->vm_map, limit); 1637 } 1638 } 1639 sx_sunlock(&allproc_lock); 1640 } 1641 } 1642 #endif /* !defined(NO_SWAPPING) */ 1643