vm_pageout.c revision 5464
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 * 9 * This code is derived from software contributed to Berkeley by 10 * The Mach Operating System project at Carnegie-Mellon University. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 41 * 42 * 43 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 44 * All rights reserved. 45 * 46 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 47 * 48 * Permission to use, copy, modify and distribute this software and 49 * its documentation is hereby granted, provided that both the copyright 50 * notice and this permission notice appear in all copies of the 51 * software, derivative works or modified versions, and any portions 52 * thereof, and that both notices appear in supporting documentation. 53 * 54 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 55 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 56 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 57 * 58 * Carnegie Mellon requests users of this software to return to 59 * 60 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 61 * School of Computer Science 62 * Carnegie Mellon University 63 * Pittsburgh PA 15213-3890 64 * 65 * any improvements or extensions that they make and grant Carnegie the 66 * rights to redistribute these changes. 67 * 68 * $Id: vm_pageout.c,v 1.29 1995/01/09 16:05:53 davidg Exp $ 69 */ 70 71/* 72 * The proverbial page-out daemon. 73 */ 74 75#include <sys/param.h> 76#include <sys/systm.h> 77#include <sys/proc.h> 78#include <sys/resourcevar.h> 79#include <sys/malloc.h> 80#include <sys/kernel.h> 81 82#include <vm/vm.h> 83#include <vm/vm_page.h> 84#include <vm/vm_pageout.h> 85#include <vm/swap_pager.h> 86 87extern vm_map_t kmem_map; 88int vm_pages_needed; /* Event on which pageout daemon sleeps */ 89int vm_pagescanner; /* Event on which pagescanner sleeps */ 90 91int vm_pageout_pages_needed = 0;/* flag saying that the pageout daemon needs pages */ 92int vm_page_pagesfreed; 93 94extern int npendingio; 95int vm_pageout_proc_limit; 96int vm_pageout_req_swapout; 97int vm_daemon_needed; 98extern int nswiodone; 99extern int swap_pager_full; 100extern int vm_swap_size; 101extern int swap_pager_ready(); 102 103#define MAXREF 32767 104 105#define MAXSCAN 512 /* maximum number of pages to scan in active queue */ 106#define ACT_DECLINE 1 107#define ACT_ADVANCE 3 108#define ACT_MAX 100 109#define MAXISCAN 256 110#define MINTOFREE 6 111#define MINFREE 2 112 113#define MAXLAUNDER (cnt.v_page_count > 1800 ? 32 : 16) 114 115#define VM_PAGEOUT_PAGE_COUNT 8 116int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 117int vm_pageout_req_do_stats; 118 119int vm_page_max_wired = 0; /* XXX max # of wired pages system-wide */ 120 121/* 122 * vm_pageout_clean: 123 * cleans a vm_page 124 */ 125int 126vm_pageout_clean(m, sync) 127 register vm_page_t m; 128 int sync; 129{ 130 /* 131 * Clean the page and remove it from the laundry. 132 * 133 * We set the busy bit to cause potential page faults on this page to 134 * block. 135 * 136 * And we set pageout-in-progress to keep the object from disappearing 137 * during pageout. This guarantees that the page won't move from the 138 * inactive queue. (However, any other page on the inactive queue may 139 * move!) 140 */ 141 142 register vm_object_t object; 143 register vm_pager_t pager; 144 int pageout_status[VM_PAGEOUT_PAGE_COUNT]; 145 vm_page_t ms[VM_PAGEOUT_PAGE_COUNT]; 146 int pageout_count; 147 int anyok = 0; 148 int i; 149 vm_offset_t offset = m->offset; 150 151 object = m->object; 152 if (!object) { 153 printf("pager: object missing\n"); 154 return 0; 155 } 156 if (!object->pager && (object->flags & OBJ_INTERNAL) == 0) { 157 printf("pager: non internal obj without pager\n"); 158 } 159 /* 160 * Try to collapse the object before making a pager for it. We must 161 * unlock the page queues first. We try to defer the creation of a 162 * pager until all shadows are not paging. This allows 163 * vm_object_collapse to work better and helps control swap space 164 * size. (J. Dyson 11 Nov 93) 165 */ 166 167 if (!object->pager && 168 (cnt.v_free_count + cnt.v_cache_count) < cnt.v_pageout_free_min) 169 return 0; 170 171 if ((!sync && m->bmapped != 0 && m->hold_count != 0) || 172 ((m->busy != 0) || (m->flags & PG_BUSY))) 173 return 0; 174 175 if (!sync && object->shadow) { 176 vm_object_collapse(object); 177 } 178 pageout_count = 1; 179 ms[0] = m; 180 181 pager = object->pager; 182 if (pager) { 183 for (i = 1; i < vm_pageout_page_count; i++) { 184 vm_page_t mt; 185 186 ms[i] = mt = vm_page_lookup(object, offset + i * NBPG); 187 if (mt) { 188 vm_page_test_dirty(mt); 189 /* 190 * we can cluster ONLY if: ->> the page is NOT 191 * busy, and is NOT clean the page is not 192 * wired, busy, held, or mapped into a buffer. 193 * and one of the following: 1) The page is 194 * inactive, or a seldom used active page. 2) 195 * or we force the issue. 196 */ 197 if ((mt->dirty & mt->valid) != 0 198 && (((mt->flags & (PG_BUSY | PG_INACTIVE)) == PG_INACTIVE) 199 || sync == VM_PAGEOUT_FORCE) 200 && (mt->wire_count == 0) 201 && (mt->busy == 0) 202 && (mt->hold_count == 0) 203 && (mt->bmapped == 0)) 204 pageout_count++; 205 else 206 break; 207 } else 208 break; 209 } 210 /* 211 * we allow reads during pageouts... 212 */ 213 for (i = 0; i < pageout_count; i++) { 214 ms[i]->flags |= PG_BUSY; 215 pmap_page_protect(VM_PAGE_TO_PHYS(ms[i]), VM_PROT_READ); 216 } 217 object->paging_in_progress += pageout_count; 218 } else { 219 220 m->flags |= PG_BUSY; 221 222 pmap_page_protect(VM_PAGE_TO_PHYS(m), VM_PROT_READ); 223 224 object->paging_in_progress++; 225 226 pager = vm_pager_allocate(PG_DFLT, (caddr_t) 0, 227 object->size, VM_PROT_ALL, 0); 228 if (pager != NULL) { 229 vm_object_setpager(object, pager, 0, FALSE); 230 } 231 } 232 233 /* 234 * If there is no pager for the page, use the default pager. If 235 * there's no place to put the page at the moment, leave it in the 236 * laundry and hope that there will be paging space later. 237 */ 238 239 if ((pager && pager->pg_type == PG_SWAP) || 240 (cnt.v_free_count + cnt.v_cache_count) >= cnt.v_pageout_free_min) { 241 if (pageout_count == 1) { 242 pageout_status[0] = pager ? 243 vm_pager_put(pager, m, 244 ((sync || (object == kernel_object)) ? TRUE : FALSE)) : 245 VM_PAGER_FAIL; 246 } else { 247 if (!pager) { 248 for (i = 0; i < pageout_count; i++) 249 pageout_status[i] = VM_PAGER_FAIL; 250 } else { 251 vm_pager_put_pages(pager, ms, pageout_count, 252 ((sync || (object == kernel_object)) ? TRUE : FALSE), 253 pageout_status); 254 } 255 } 256 } else { 257 for (i = 0; i < pageout_count; i++) 258 pageout_status[i] = VM_PAGER_FAIL; 259 } 260 261 for (i = 0; i < pageout_count; i++) { 262 switch (pageout_status[i]) { 263 case VM_PAGER_OK: 264 ++anyok; 265 break; 266 case VM_PAGER_PEND: 267 ++anyok; 268 break; 269 case VM_PAGER_BAD: 270 /* 271 * Page outside of range of object. Right now we 272 * essentially lose the changes by pretending it 273 * worked. 274 */ 275 pmap_clear_modify(VM_PAGE_TO_PHYS(ms[i])); 276 ms[i]->dirty = 0; 277 break; 278 case VM_PAGER_ERROR: 279 case VM_PAGER_FAIL: 280 /* 281 * If page couldn't be paged out, then reactivate the 282 * page so it doesn't clog the inactive list. (We 283 * will try paging out it again later). 284 */ 285 if (ms[i]->flags & PG_INACTIVE) 286 vm_page_activate(ms[i]); 287 break; 288 case VM_PAGER_AGAIN: 289 break; 290 } 291 292 293 /* 294 * If the operation is still going, leave the page busy to 295 * block all other accesses. Also, leave the paging in 296 * progress indicator set so that we don't attempt an object 297 * collapse. 298 */ 299 if (pageout_status[i] != VM_PAGER_PEND) { 300 PAGE_WAKEUP(ms[i]); 301 if (--object->paging_in_progress == 0) 302 wakeup((caddr_t) object); 303 if ((ms[i]->flags & PG_REFERENCED) || 304 pmap_is_referenced(VM_PAGE_TO_PHYS(ms[i]))) { 305 pmap_clear_reference(VM_PAGE_TO_PHYS(ms[i])); 306 ms[i]->flags &= ~PG_REFERENCED; 307 if (ms[i]->flags & PG_INACTIVE) 308 vm_page_activate(ms[i]); 309 } 310 } 311 } 312 return anyok; 313} 314 315/* 316 * vm_pageout_object_deactivate_pages 317 * 318 * deactivate enough pages to satisfy the inactive target 319 * requirements or if vm_page_proc_limit is set, then 320 * deactivate all of the pages in the object and its 321 * shadows. 322 * 323 * The object and map must be locked. 324 */ 325int 326vm_pageout_object_deactivate_pages(map, object, count, map_remove_only) 327 vm_map_t map; 328 vm_object_t object; 329 int count; 330 int map_remove_only; 331{ 332 register vm_page_t p, next; 333 int rcount; 334 int dcount; 335 336 dcount = 0; 337 if (count == 0) 338 count = 1; 339 340 if (object->shadow) { 341 if (object->shadow->ref_count == 1) 342 dcount += vm_pageout_object_deactivate_pages(map, object->shadow, count / 2 + 1, map_remove_only); 343 else 344 dcount += vm_pageout_object_deactivate_pages(map, object->shadow, count / 2 + 1, 1); 345 } 346 if (object->paging_in_progress || !vm_object_lock_try(object)) 347 return dcount; 348 349 /* 350 * scan the objects entire memory queue 351 */ 352 rcount = object->resident_page_count; 353 p = object->memq.tqh_first; 354 while (p && (rcount-- > 0)) { 355 next = p->listq.tqe_next; 356 cnt.v_pdpages++; 357 vm_page_lock_queues(); 358 if (p->wire_count != 0 || 359 p->hold_count != 0 || 360 p->bmapped != 0 || 361 p->busy != 0 || 362 !pmap_page_exists(vm_map_pmap(map), VM_PAGE_TO_PHYS(p))) { 363 p = next; 364 continue; 365 } 366 /* 367 * if a page is active, not wired and is in the processes 368 * pmap, then deactivate the page. 369 */ 370 if ((p->flags & (PG_ACTIVE | PG_BUSY)) == PG_ACTIVE) { 371 if (!pmap_is_referenced(VM_PAGE_TO_PHYS(p)) && 372 (p->flags & PG_REFERENCED) == 0) { 373 p->act_count -= min(p->act_count, ACT_DECLINE); 374 /* 375 * if the page act_count is zero -- then we 376 * deactivate 377 */ 378 if (!p->act_count) { 379 if (!map_remove_only) 380 vm_page_deactivate(p); 381 pmap_page_protect(VM_PAGE_TO_PHYS(p), 382 VM_PROT_NONE); 383 /* 384 * else if on the next go-around we 385 * will deactivate the page we need to 386 * place the page on the end of the 387 * queue to age the other pages in 388 * memory. 389 */ 390 } else { 391 TAILQ_REMOVE(&vm_page_queue_active, p, pageq); 392 TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); 393 TAILQ_REMOVE(&object->memq, p, listq); 394 TAILQ_INSERT_TAIL(&object->memq, p, listq); 395 } 396 /* 397 * see if we are done yet 398 */ 399 if (p->flags & PG_INACTIVE) { 400 --count; 401 ++dcount; 402 if (count <= 0 && 403 cnt.v_inactive_count > cnt.v_inactive_target) { 404 vm_page_unlock_queues(); 405 vm_object_unlock(object); 406 return dcount; 407 } 408 } 409 } else { 410 /* 411 * Move the page to the bottom of the queue. 412 */ 413 pmap_clear_reference(VM_PAGE_TO_PHYS(p)); 414 p->flags &= ~PG_REFERENCED; 415 if (p->act_count < ACT_MAX) 416 p->act_count += ACT_ADVANCE; 417 418 TAILQ_REMOVE(&vm_page_queue_active, p, pageq); 419 TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); 420 TAILQ_REMOVE(&object->memq, p, listq); 421 TAILQ_INSERT_TAIL(&object->memq, p, listq); 422 } 423 } else if ((p->flags & (PG_INACTIVE | PG_BUSY)) == PG_INACTIVE) { 424 pmap_page_protect(VM_PAGE_TO_PHYS(p), 425 VM_PROT_NONE); 426 } 427 vm_page_unlock_queues(); 428 p = next; 429 } 430 vm_object_unlock(object); 431 return dcount; 432} 433 434 435/* 436 * deactivate some number of pages in a map, try to do it fairly, but 437 * that is really hard to do. 438 */ 439 440void 441vm_pageout_map_deactivate_pages(map, entry, count, freeer) 442 vm_map_t map; 443 vm_map_entry_t entry; 444 int *count; 445 int (*freeer) (vm_map_t, vm_object_t, int); 446{ 447 vm_map_t tmpm; 448 vm_map_entry_t tmpe; 449 vm_object_t obj; 450 451 if (*count <= 0) 452 return; 453 vm_map_reference(map); 454 if (!lock_try_read(&map->lock)) { 455 vm_map_deallocate(map); 456 return; 457 } 458 if (entry == 0) { 459 tmpe = map->header.next; 460 while (tmpe != &map->header && *count > 0) { 461 vm_pageout_map_deactivate_pages(map, tmpe, count, freeer, 0); 462 tmpe = tmpe->next; 463 }; 464 } else if (entry->is_sub_map || entry->is_a_map) { 465 tmpm = entry->object.share_map; 466 tmpe = tmpm->header.next; 467 while (tmpe != &tmpm->header && *count > 0) { 468 vm_pageout_map_deactivate_pages(tmpm, tmpe, count, freeer, 0); 469 tmpe = tmpe->next; 470 }; 471 } else if ((obj = entry->object.vm_object) != 0) { 472 *count -= (*freeer) (map, obj, *count); 473 } 474 lock_read_done(&map->lock); 475 vm_map_deallocate(map); 476 return; 477} 478 479void 480vm_req_vmdaemon() 481{ 482 extern int ticks; 483 static int lastrun = 0; 484 485 if ((ticks > (lastrun + hz / 10)) || (ticks < lastrun)) { 486 wakeup((caddr_t) &vm_daemon_needed); 487 lastrun = ticks; 488 } 489} 490 491void 492vm_pageout_inactive_stats(int maxiscan) 493{ 494 vm_page_t m; 495 int s; 496 497 if (maxiscan > cnt.v_inactive_count) 498 maxiscan = cnt.v_inactive_count; 499 m = vm_page_queue_inactive.tqh_first; 500 while (m && (maxiscan-- > 0)) { 501 vm_page_t next; 502 503 next = m->pageq.tqe_next; 504 505 if (((m->flags & PG_REFERENCED) == 0) && 506 pmap_is_referenced(VM_PAGE_TO_PHYS(m))) { 507 m->flags |= PG_REFERENCED; 508 } 509 if (m->object->ref_count == 0) { 510 m->flags &= ~PG_REFERENCED; 511 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 512 } 513 if (m->flags & PG_REFERENCED) { 514 m->flags &= ~PG_REFERENCED; 515 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 516 vm_page_activate(m); 517 /* 518 * heuristic alert -- if a page is being re-activated, 519 * it probably will be used one more time... 520 */ 521 ++m->act_count; 522 ++m->act_count; 523 } 524 m = next; 525 } 526} 527 528 529/* 530 * vm_pageout_scan does the dirty work for the pageout daemon. 531 */ 532int 533vm_pageout_scan() 534{ 535 vm_page_t m; 536 int page_shortage, maxscan, maxlaunder; 537 int pages_freed; 538 int desired_free; 539 vm_page_t next; 540 struct proc *p, *bigproc; 541 vm_offset_t size, bigsize; 542 vm_object_t object; 543 int force_wakeup = 0; 544 int cache_size, orig_cache_size; 545 int minscan; 546 int mintofree; 547 548#ifdef LFS 549 lfs_reclaim_buffers(); 550#endif 551 552 /* calculate the total cached size */ 553 554 if ((cnt.v_inactive_count + cnt.v_free_count + cnt.v_cache_count) < 555 (cnt.v_inactive_target + cnt.v_free_min)) { 556 vm_req_vmdaemon(); 557 } 558 /* 559 * now swap processes out if we are in low memory conditions 560 */ 561 if ((cnt.v_free_count <= cnt.v_free_min) && 562 !swap_pager_full && vm_swap_size && vm_pageout_req_swapout == 0) { 563 vm_pageout_req_swapout = 1; 564 vm_req_vmdaemon(); 565 } 566 pages_freed = 0; 567 desired_free = cnt.v_free_target; 568 569 /* 570 * Start scanning the inactive queue for pages we can free. We keep 571 * scanning until we have enough free pages or we have scanned through 572 * the entire queue. If we encounter dirty pages, we start cleaning 573 * them. 574 */ 575 576 577 vm_pageout_inactive_stats(MAXISCAN); 578 maxlaunder = (cnt.v_inactive_target > MAXLAUNDER) ? 579 MAXLAUNDER : cnt.v_inactive_target; 580 581rescan1: 582 maxscan = cnt.v_inactive_count; 583 mintofree = MINTOFREE; 584 m = vm_page_queue_inactive.tqh_first; 585 while (m && 586 (maxscan-- > 0) && 587 (((cnt.v_free_count + cnt.v_cache_count) < desired_free) || 588 (--mintofree > 0))) { 589 vm_page_t next; 590 591 cnt.v_pdpages++; 592 next = m->pageq.tqe_next; 593 594#if defined(VM_DIAGNOSE) 595 if ((m->flags & PG_INACTIVE) == 0) { 596 printf("vm_pageout_scan: page not inactive?\n"); 597 break; 598 } 599#endif 600 601 /* 602 * dont mess with busy pages 603 */ 604 if (m->hold_count || m->busy || (m->flags & PG_BUSY) || 605 m->bmapped != 0) { 606 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 607 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 608 m = next; 609 continue; 610 } 611 if (((m->flags & PG_REFERENCED) == 0) && 612 pmap_is_referenced(VM_PAGE_TO_PHYS(m))) { 613 m->flags |= PG_REFERENCED; 614 } 615 if (m->object->ref_count == 0) { 616 m->flags &= ~PG_REFERENCED; 617 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 618 } 619 if ((m->flags & PG_REFERENCED) != 0) { 620 m->flags &= ~PG_REFERENCED; 621 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 622 vm_page_activate(m); 623 ++m->act_count; 624 ++m->act_count; 625 m = next; 626 continue; 627 } 628 vm_page_test_dirty(m); 629 630 if ((m->dirty & m->valid) == 0) { 631 if (((cnt.v_free_count + cnt.v_cache_count) < desired_free) || 632 (cnt.v_cache_count < cnt.v_cache_min)) 633 vm_page_cache(m); 634 } else if (maxlaunder > 0) { 635 int written; 636 637 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 638 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 639 640 object = m->object; 641 if (!vm_object_lock_try(object)) { 642 m = next; 643 continue; 644 } 645 /* 646 * If a page is dirty, then it is either being washed 647 * (but not yet cleaned) or it is still in the 648 * laundry. If it is still in the laundry, then we 649 * start the cleaning operation. 650 */ 651 written = vm_pageout_clean(m, 0); 652 vm_object_unlock(object); 653 654 if (!next) { 655 break; 656 } 657 maxlaunder -= written; 658 /* 659 * if the next page has been re-activated, start 660 * scanning again 661 */ 662 if ((next->flags & PG_INACTIVE) == 0) { 663 goto rescan1; 664 } 665 } else { 666 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 667 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 668 } 669 m = next; 670 } 671 672 /* 673 * Compute the page shortage. If we are still very low on memory be 674 * sure that we will move a minimal amount of pages from active to 675 * inactive. 676 */ 677 678 page_shortage = cnt.v_inactive_target - 679 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 680 if (page_shortage <= 0) { 681 if (pages_freed == 0) { 682 if ((cnt.v_free_count + cnt.v_cache_count) < desired_free) { 683 page_shortage = 684 desired_free - (cnt.v_free_count + cnt.v_cache_count); 685 } 686 } 687 } 688 maxscan = cnt.v_active_count; 689 minscan = cnt.v_active_count; 690 if (minscan > MAXSCAN) 691 minscan = MAXSCAN; 692 m = vm_page_queue_active.tqh_first; 693 while (m && ((maxscan > 0 && (page_shortage > 0)) || minscan > 0)) { 694 if (maxscan) 695 --maxscan; 696 if (minscan) 697 --minscan; 698 699 cnt.v_pdpages++; 700 next = m->pageq.tqe_next; 701 702 /* 703 * Don't deactivate pages that are busy. 704 */ 705 if ((m->busy != 0) || 706 (m->flags & PG_BUSY) || 707 (m->hold_count != 0) || 708 (m->bmapped != 0)) { 709 m = next; 710 continue; 711 } 712 if (m->object->ref_count && ((m->flags & PG_REFERENCED) || 713 pmap_is_referenced(VM_PAGE_TO_PHYS(m)))) { 714 int s; 715 716 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 717 m->flags &= ~PG_REFERENCED; 718 if (m->act_count < ACT_MAX) { 719 m->act_count += ACT_ADVANCE; 720 } 721 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 722 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 723 s = splhigh(); 724 TAILQ_REMOVE(&m->object->memq, m, listq); 725 TAILQ_INSERT_TAIL(&m->object->memq, m, listq); 726 splx(s); 727 } else { 728 m->act_count -= min(m->act_count, ACT_DECLINE); 729 730 /* 731 * if the page act_count is zero -- then we deactivate 732 */ 733 if (!m->act_count && (page_shortage > 0)) { 734 if (m->object->ref_count == 0) { 735 vm_page_test_dirty(m); 736 737 m->flags &= ~PG_REFERENCED; 738 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 739 740 --page_shortage; 741 if ((m->dirty & m->valid) == 0) { 742 m->act_count = 0; 743 vm_page_cache(m); 744 } else { 745 vm_page_deactivate(m); 746 } 747 } else { 748 749 m->flags &= ~PG_REFERENCED; 750 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 751 752 vm_page_deactivate(m); 753 --page_shortage; 754 } 755 } else { 756 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 757 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 758 } 759 } 760 m = next; 761 } 762 763 /* 764 * We try to maintain some *really* free pages, this allows interrupt 765 * code to be guaranteed space. 766 */ 767 while (cnt.v_free_count < MINFREE) { 768 m = vm_page_queue_cache.tqh_first; 769 if (!m) 770 break; 771 vm_page_free(m); 772 } 773 774 /* 775 * make sure that we have swap space -- if we are low on memory and 776 * swap -- then kill the biggest process. 777 */ 778 if ((vm_swap_size == 0 || swap_pager_full) && 779 ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min)) { 780 bigproc = NULL; 781 bigsize = 0; 782 for (p = (struct proc *) allproc; p != NULL; p = p->p_next) { 783 /* 784 * if this is a system process, skip it 785 */ 786 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 787 ((p->p_pid < 48) && (vm_swap_size != 0))) { 788 continue; 789 } 790 /* 791 * if the process is in a non-running type state, 792 * don't touch it. 793 */ 794 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 795 continue; 796 } 797 /* 798 * get the process size 799 */ 800 size = p->p_vmspace->vm_pmap.pm_stats.resident_count; 801 /* 802 * if the this process is bigger than the biggest one 803 * remember it. 804 */ 805 if (size > bigsize) { 806 bigproc = p; 807 bigsize = size; 808 } 809 } 810 if (bigproc != NULL) { 811 printf("Process %lu killed by vm_pageout -- out of swap\n", (u_long) bigproc->p_pid); 812 psignal(bigproc, SIGKILL); 813 bigproc->p_estcpu = 0; 814 bigproc->p_nice = PRIO_MIN; 815 resetpriority(bigproc); 816 wakeup((caddr_t) &cnt.v_free_count); 817 } 818 } 819 vm_page_pagesfreed += pages_freed; 820 return force_wakeup; 821} 822 823/* 824 * vm_pageout is the high level pageout daemon. 825 */ 826void 827vm_pageout() 828{ 829 (void) spl0(); 830 831 /* 832 * Initialize some paging parameters. 833 */ 834 835 if (cnt.v_page_count > 1024) 836 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 837 else 838 cnt.v_free_min = 4; 839 /* 840 * free_reserved needs to include enough for the largest swap pager 841 * structures plus enough for any pv_entry structs when paging. 842 */ 843 cnt.v_pageout_free_min = 5 + cnt.v_page_count / 1024; 844 cnt.v_free_reserved = cnt.v_pageout_free_min + 2; 845 cnt.v_free_target = 3 * cnt.v_free_min + cnt.v_free_reserved; 846 cnt.v_inactive_target = cnt.v_free_count / 4; 847 if (cnt.v_inactive_target > 512) 848 cnt.v_inactive_target = 512; 849 cnt.v_free_min += cnt.v_free_reserved; 850 if (cnt.v_page_count > 1024) { 851 cnt.v_cache_max = (cnt.v_free_count - 1024) / 2; 852 cnt.v_cache_min = (cnt.v_free_count - 1024) / 20; 853 } else { 854 cnt.v_cache_min = 0; 855 cnt.v_cache_max = 0; 856 } 857 858 /* XXX does not really belong here */ 859 if (vm_page_max_wired == 0) 860 vm_page_max_wired = cnt.v_free_count / 3; 861 862 863 (void) swap_pager_alloc(0, 0, 0, 0); 864 /* 865 * The pageout daemon is never done, so loop forever. 866 */ 867 while (TRUE) { 868 tsleep((caddr_t) &vm_pages_needed, PVM, "psleep", 0); 869 cnt.v_pdwakeups++; 870 vm_pager_sync(); 871 vm_pageout_scan(); 872 vm_pager_sync(); 873 wakeup((caddr_t) &cnt.v_free_count); 874 wakeup((caddr_t) kmem_map); 875 } 876} 877 878void 879vm_daemon() 880{ 881 int cache_size; 882 vm_object_t object; 883 struct proc *p; 884 885 while (TRUE) { 886 tsleep((caddr_t) &vm_daemon_needed, PUSER, "psleep", 0); 887 swapout_threads(); 888 /* 889 * scan the processes for exceeding their rlimits or if 890 * process is swapped out -- deactivate pages 891 */ 892 893 for (p = (struct proc *) allproc; p != NULL; p = p->p_next) { 894 int overage; 895 quad_t limit; 896 vm_offset_t size; 897 898 /* 899 * if this is a system process or if we have already 900 * looked at this process, skip it. 901 */ 902 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 903 continue; 904 } 905 /* 906 * if the process is in a non-running type state, 907 * don't touch it. 908 */ 909 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 910 continue; 911 } 912 /* 913 * get a limit 914 */ 915 limit = qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 916 p->p_rlimit[RLIMIT_RSS].rlim_max); 917 918 /* 919 * let processes that are swapped out really be 920 * swapped out set the limit to nothing (will force a 921 * swap-out.) 922 */ 923 if ((p->p_flag & P_INMEM) == 0) 924 limit = 0; /* XXX */ 925 926 size = p->p_vmspace->vm_pmap.pm_stats.resident_count * NBPG; 927 if (limit >= 0 && size >= limit) { 928 overage = (size - limit) / NBPG; 929 if (limit == 0) 930 overage += 20; 931 vm_pageout_map_deactivate_pages(&p->p_vmspace->vm_map, 932 (vm_map_entry_t) 0, &overage, vm_pageout_object_deactivate_pages); 933 } 934 } 935 } 936 937 /* 938 * we remove cached objects that have no RSS... 939 */ 940restart: 941 vm_object_cache_lock(); 942 object = vm_object_cached_list.tqh_first; 943 while (object) { 944 vm_object_cache_unlock(); 945 /* 946 * if there are no resident pages -- get rid of the object 947 */ 948 if (object->resident_page_count == 0) { 949 if (object != vm_object_lookup(object->pager)) 950 panic("vm_object_cache_trim: I'm sooo confused."); 951 pager_cache(object, FALSE); 952 goto restart; 953 } 954 object = object->cached_list.tqe_next; 955 vm_object_cache_lock(); 956 } 957 vm_object_cache_unlock(); 958} 959