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