vm_pageout.c revision 3612
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 1.17 1994/10/13 21:01:39 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 81#include <vm/vm.h> 82#include <vm/vm_page.h> 83#include <vm/vm_pageout.h> 84#include <vm/swap_pager.h> 85 86extern vm_map_t kmem_map; 87int vm_pages_needed; /* Event on which pageout daemon sleeps */ 88int vm_pagescanner; /* Event on which pagescanner sleeps */ 89int vm_pageout_free_min = 0; /* Stop pageout to wait for pagers at this free level */ 90 91int vm_pageout_pages_needed = 0; /* flag saying that the pageout daemon needs pages */ 92int vm_page_pagesfreed; 93int vm_desired_cache_size; 94 95extern int npendingio; 96extern int hz; 97int vm_pageout_proc_limit; 98extern int nswiodone; 99extern int swap_pager_full; 100extern int swap_pager_ready(); 101 102#define MAXREF 32767 103 104#define MAXSCAN 512 /* maximum number of pages to scan in active queue */ 105 /* set the "clock" hands to be (MAXSCAN * 4096) Bytes */ 106#define ACT_DECLINE 1 107#define ACT_ADVANCE 3 108#define ACT_MAX 100 109 110#define LOWATER ((2048*1024)/NBPG) 111 112#define VM_PAGEOUT_PAGE_COUNT 8 113int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 114int vm_pageout_req_do_stats; 115 116int vm_page_max_wired = 0; /* XXX max # of wired pages system-wide */ 117 118 119/* 120 * vm_pageout_clean: 121 * cleans a vm_page 122 */ 123int 124vm_pageout_clean(m, sync) 125 register vm_page_t m; 126 int sync; 127{ 128 /* 129 * Clean the page and remove it from the 130 * laundry. 131 * 132 * We set the busy bit to cause 133 * potential page faults on this page to 134 * block. 135 * 136 * And we set pageout-in-progress to keep 137 * the object from disappearing during 138 * pageout. This guarantees that the 139 * page won't move from the inactive 140 * queue. (However, any other page on 141 * the inactive queue may move!) 142 */ 143 144 register vm_object_t object; 145 register vm_pager_t pager; 146 int pageout_status[VM_PAGEOUT_PAGE_COUNT]; 147 vm_page_t ms[VM_PAGEOUT_PAGE_COUNT]; 148 int pageout_count; 149 int anyok=0; 150 int i; 151 vm_offset_t offset = m->offset; 152 153 object = m->object; 154 if (!object) { 155 printf("pager: object missing\n"); 156 return 0; 157 } 158 159 /* 160 * Try to collapse the object before 161 * making a pager for it. We must 162 * unlock the page queues first. 163 * We try to defer the creation of a pager 164 * until all shadows are not paging. This 165 * allows vm_object_collapse to work better and 166 * helps control swap space size. 167 * (J. Dyson 11 Nov 93) 168 */ 169 170 if (!object->pager && 171 cnt.v_free_count < vm_pageout_free_min) 172 return 0; 173 174 if (!object->pager && 175 object->shadow && 176 object->shadow->paging_in_progress) 177 return 0; 178 179 if( !sync) { 180 if (object->shadow) { 181 vm_object_collapse(object); 182 if (!vm_page_lookup(object, offset)) 183 return 0; 184 } 185 186 if ((m->busy != 0) || 187 (m->flags & PG_BUSY) || (m->hold_count != 0)) { 188 return 0; 189 } 190 } 191 192 pageout_count = 1; 193 ms[0] = m; 194 195 pager = object->pager; 196 if (pager) { 197 for (i = 1; i < vm_pageout_page_count; i++) { 198 ms[i] = vm_page_lookup(object, offset+i*NBPG); 199 if (ms[i]) { 200 if (( ((ms[i]->flags & (PG_CLEAN|PG_INACTIVE|PG_BUSY)) == PG_INACTIVE) 201 || ( (ms[i]->flags & (PG_CLEAN|PG_BUSY)) == 0 && sync == VM_PAGEOUT_FORCE)) 202 && (ms[i]->wire_count == 0) 203 && (ms[i]->busy == 0) 204 && (ms[i]->hold_count == 0)) 205 pageout_count++; 206 else 207 break; 208 } else 209 break; 210 } 211 for(i=0;i<pageout_count;i++) { 212 ms[i]->flags |= PG_BUSY; 213 pmap_page_protect(VM_PAGE_TO_PHYS(ms[i]), VM_PROT_READ); 214 } 215 object->paging_in_progress += pageout_count; 216 } else { 217 218 m->flags |= PG_BUSY; 219 220 pmap_page_protect(VM_PAGE_TO_PHYS(m), VM_PROT_READ); 221 222 object->paging_in_progress++; 223 224 pager = vm_pager_allocate(PG_DFLT, (caddr_t)0, 225 object->size, VM_PROT_ALL, 0); 226 if (pager != NULL) { 227 vm_object_setpager(object, pager, 0, FALSE); 228 } 229 } 230 231 /* 232 * If there is no pager for the page, 233 * use the default pager. If there's 234 * no place to put the page at the 235 * moment, leave it in the laundry and 236 * hope that there will be paging space 237 * later. 238 */ 239 240 if ((pager && pager->pg_type == PG_SWAP) || 241 cnt.v_free_count >= vm_pageout_free_min) { 242 if( pageout_count == 1) { 243 pageout_status[0] = pager ? 244 vm_pager_put(pager, m, 245 ((sync || (object == kernel_object)) ? TRUE: FALSE)) : 246 VM_PAGER_FAIL; 247 } else { 248 if( !pager) { 249 for(i=0;i<pageout_count;i++) 250 pageout_status[i] = VM_PAGER_FAIL; 251 } else { 252 vm_pager_put_pages(pager, ms, pageout_count, 253 ((sync || (object == kernel_object)) ? TRUE : FALSE), 254 pageout_status); 255 } 256 } 257 258 } else { 259 for(i=0;i<pageout_count;i++) 260 pageout_status[i] = VM_PAGER_FAIL; 261 } 262 263 for(i=0;i<pageout_count;i++) { 264 switch (pageout_status[i]) { 265 case VM_PAGER_OK: 266 ms[i]->flags &= ~PG_LAUNDRY; 267 ++anyok; 268 break; 269 case VM_PAGER_PEND: 270 ms[i]->flags &= ~PG_LAUNDRY; 271 ++anyok; 272 break; 273 case VM_PAGER_BAD: 274 /* 275 * Page outside of range of object. 276 * Right now we essentially lose the 277 * changes by pretending it worked. 278 */ 279 ms[i]->flags &= ~PG_LAUNDRY; 280 ms[i]->flags |= PG_CLEAN; 281 pmap_clear_modify(VM_PAGE_TO_PHYS(ms[i])); 282 break; 283 case VM_PAGER_ERROR: 284 case VM_PAGER_FAIL: 285 /* 286 * If page couldn't be paged out, then 287 * reactivate the page so it doesn't 288 * clog the inactive list. (We will 289 * try paging out it again later). 290 */ 291 if (ms[i]->flags & PG_INACTIVE) 292 vm_page_activate(ms[i]); 293 break; 294 case VM_PAGER_AGAIN: 295 break; 296 } 297 298 299 /* 300 * If the operation is still going, leave 301 * the page busy to block all other accesses. 302 * Also, leave the paging in progress 303 * indicator set so that we don't attempt an 304 * object collapse. 305 */ 306 if (pageout_status[i] != VM_PAGER_PEND) { 307 PAGE_WAKEUP(ms[i]); 308 if (--object->paging_in_progress == 0) 309 wakeup((caddr_t) object); 310 if ((ms[i]->flags & PG_REFERENCED) || 311 pmap_is_referenced(VM_PAGE_TO_PHYS(ms[i]))) { 312 pmap_clear_reference(VM_PAGE_TO_PHYS(ms[i])); 313 ms[i]->flags &= ~PG_REFERENCED; 314 if( ms[i]->flags & PG_INACTIVE) 315 vm_page_activate(ms[i]); 316 } 317 } 318 } 319 return anyok; 320} 321 322/* 323 * vm_pageout_object_deactivate_pages 324 * 325 * deactivate enough pages to satisfy the inactive target 326 * requirements or if vm_page_proc_limit is set, then 327 * deactivate all of the pages in the object and its 328 * shadows. 329 * 330 * The object and map must be locked. 331 */ 332int 333vm_pageout_object_deactivate_pages(map, object, count) 334 vm_map_t map; 335 vm_object_t object; 336 int count; 337{ 338 register vm_page_t p, next; 339 int rcount; 340 int dcount; 341 342 dcount = 0; 343 if (count == 0) 344 count = 1; 345 346 if (object->shadow) { 347 int scount = count; 348 if( object->shadow->ref_count > 1) 349 scount /= object->shadow->ref_count; 350 if( scount) 351 dcount += vm_pageout_object_deactivate_pages(map, object->shadow, scount); 352 } 353 354 if (object->paging_in_progress) 355 return dcount; 356 357 /* 358 * scan the objects entire memory queue 359 */ 360 rcount = object->resident_page_count; 361 p = object->memq.tqh_first; 362 while (p && (rcount-- > 0)) { 363 next = p->listq.tqe_next; 364 vm_page_lock_queues(); 365 /* 366 * if a page is active, not wired and is in the processes pmap, 367 * then deactivate the page. 368 */ 369 if ((p->flags & (PG_ACTIVE|PG_BUSY)) == PG_ACTIVE && 370 p->wire_count == 0 && 371 p->hold_count == 0 && 372 p->busy == 0 && 373 pmap_page_exists(vm_map_pmap(map), VM_PAGE_TO_PHYS(p))) { 374 if (!pmap_is_referenced(VM_PAGE_TO_PHYS(p)) && 375 (p->flags & PG_REFERENCED) == 0) { 376 p->act_count -= min(p->act_count, ACT_DECLINE); 377 /* 378 * if the page act_count is zero -- then we deactivate 379 */ 380 if (!p->act_count) { 381 vm_page_deactivate(p); 382 pmap_page_protect(VM_PAGE_TO_PHYS(p), 383 VM_PROT_NONE); 384 /* 385 * else if on the next go-around we will deactivate the page 386 * we need to place the page on the end of the queue to age 387 * the other pages in memory. 388 */ 389 } else { 390 TAILQ_REMOVE(&vm_page_queue_active, p, pageq); 391 TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); 392 TAILQ_REMOVE(&object->memq, p, listq); 393 TAILQ_INSERT_TAIL(&object->memq, p, listq); 394 } 395 /* 396 * see if we are done yet 397 */ 398 if (p->flags & PG_INACTIVE) { 399 --count; 400 ++dcount; 401 if (count <= 0 && 402 cnt.v_inactive_count > cnt.v_inactive_target) { 403 vm_page_unlock_queues(); 404 return dcount; 405 } 406 } 407 408 } else { 409 /* 410 * Move the page to the bottom of the queue. 411 */ 412 pmap_clear_reference(VM_PAGE_TO_PHYS(p)); 413 p->flags &= ~PG_REFERENCED; 414 if (p->act_count < ACT_MAX) 415 p->act_count += ACT_ADVANCE; 416 417 TAILQ_REMOVE(&vm_page_queue_active, p, pageq); 418 TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); 419 TAILQ_REMOVE(&object->memq, p, listq); 420 TAILQ_INSERT_TAIL(&object->memq, p, listq); 421 } 422 } 423 424 vm_page_unlock_queues(); 425 p = next; 426 } 427 return dcount; 428} 429 430 431/* 432 * deactivate some number of pages in a map, try to do it fairly, but 433 * that is really hard to do. 434 */ 435 436void 437vm_pageout_map_deactivate_pages(map, entry, count, freeer) 438 vm_map_t map; 439 vm_map_entry_t entry; 440 int *count; 441 int (*freeer)(vm_map_t, vm_object_t, int); 442{ 443 vm_map_t tmpm; 444 vm_map_entry_t tmpe; 445 vm_object_t obj; 446 if (*count <= 0) 447 return; 448 vm_map_reference(map); 449 if (!lock_try_read(&map->lock)) { 450 vm_map_deallocate(map); 451 return; 452 } 453 if (entry == 0) { 454 tmpe = map->header.next; 455 while (tmpe != &map->header && *count > 0) { 456 vm_pageout_map_deactivate_pages(map, tmpe, count, freeer); 457 tmpe = tmpe->next; 458 }; 459 } else if (entry->is_sub_map || entry->is_a_map) { 460 tmpm = entry->object.share_map; 461 tmpe = tmpm->header.next; 462 while (tmpe != &tmpm->header && *count > 0) { 463 vm_pageout_map_deactivate_pages(tmpm, tmpe, count, freeer); 464 tmpe = tmpe->next; 465 }; 466 } else if ((obj = entry->object.vm_object) != 0) { 467 *count -= (*freeer)(map, obj, *count); 468 } 469 lock_read_done(&map->lock); 470 vm_map_deallocate(map); 471 return; 472} 473 474/* 475 * vm_pageout_scan does the dirty work for the pageout daemon. 476 */ 477int 478vm_pageout_scan() 479{ 480 vm_page_t m; 481 int page_shortage, maxscan, maxlaunder; 482 int pages_freed; 483 int desired_free; 484 vm_page_t next; 485 struct proc *p; 486 vm_object_t object; 487 int force_wakeup = 0; 488 int cache_size, orig_cache_size; 489 490 /* 491 * We manage the cached memory by attempting to keep it 492 * at about the desired level. 493 * We deactivate the pages for the oldest cached objects 494 * first. This keeps pages that are "cached" from hogging 495 * physical memory. 496 */ 497 orig_cache_size = 0; 498 object = vm_object_cached_list.tqh_first; 499 500 /* calculate the total cached size */ 501 502 while( object) { 503 orig_cache_size += object->resident_page_count; 504 object = object->cached_list.tqe_next; 505 } 506 507redeact: 508 cache_size = orig_cache_size; 509 object = vm_object_cached_list.tqh_first; 510 vm_object_cache_lock(); 511 while ( object && (cnt.v_inactive_count < cnt.v_inactive_target) && 512 (cache_size >= vm_desired_cache_size)) { 513 vm_object_cache_unlock(); 514 515 /* 516 * if there are no resident pages -- get rid of the object 517 */ 518 if( object->resident_page_count == 0) { 519 if (object != vm_object_lookup(object->pager)) 520 panic("vm_object_deactivate: I'm sooo confused."); 521 pager_cache(object, FALSE); 522 goto redeact; 523 } else { 524 /* 525 * if there are resident pages -- deactivate them 526 */ 527 vm_object_deactivate_pages(object); 528 cache_size -= object->resident_page_count; 529 object = object->cached_list.tqe_next; 530 } 531 532 vm_object_cache_lock(); 533 } 534 vm_object_cache_unlock(); 535 536morefree: 537 /* 538 * now swap processes out if we are in low memory conditions 539 */ 540 if (cnt.v_free_count <= cnt.v_free_min) { 541 /* 542 * swap out inactive processes 543 */ 544 swapout_threads(); 545 } 546 547 /* 548 * scan the processes for exceeding their rlimits or if process 549 * is swapped out -- deactivate pages 550 */ 551 552 for (p = (struct proc *)allproc; p != NULL; p = p->p_next) { 553 vm_offset_t size; 554 int overage; 555 quad_t limit; 556 557 /* 558 * if this is a system process or if we have already 559 * looked at this process, skip it. 560 */ 561 if (p->p_flag & (P_SYSTEM|P_WEXIT)) { 562 continue; 563 } 564 565 /* 566 * if the process is in a non-running type state, 567 * don't touch it. 568 */ 569 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 570 continue; 571 } 572 573 /* 574 * get a limit 575 */ 576 limit = qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 577 p->p_rlimit[RLIMIT_RSS].rlim_max); 578 579 /* 580 * let processes that are swapped out really be swapped out 581 * set the limit to nothing (will force a swap-out.) 582 */ 583 if ((p->p_flag & P_INMEM) == 0) 584 limit = 0; 585 586 size = p->p_vmspace->vm_pmap.pm_stats.resident_count * NBPG; 587 if (limit >= 0 && size >= limit) { 588 overage = (size - limit) / NBPG; 589 vm_pageout_map_deactivate_pages(&p->p_vmspace->vm_map, 590 (vm_map_entry_t) 0, &overage, vm_pageout_object_deactivate_pages); 591 } 592 } 593 594 if (((cnt.v_free_count + cnt.v_inactive_count) >= 595 (cnt.v_inactive_target + cnt.v_free_target)) && 596 (cnt.v_free_count >= cnt.v_free_target)) 597 return force_wakeup; 598 599 pages_freed = 0; 600 desired_free = cnt.v_free_target; 601 602 /* 603 * Start scanning the inactive queue for pages we can free. 604 * We keep scanning until we have enough free pages or 605 * we have scanned through the entire queue. If we 606 * encounter dirty pages, we start cleaning them. 607 */ 608 609 maxlaunder = (cnt.v_free_target - cnt.v_free_count); 610 maxscan = cnt.v_inactive_count; 611rescan1: 612 m = vm_page_queue_inactive.tqh_first; 613 while (m && (maxscan-- > 0) && 614 (cnt.v_free_count < desired_free) ) { 615 vm_page_t next; 616 617 next = m->pageq.tqe_next; 618 619 if( (m->flags & PG_INACTIVE) == 0) { 620 printf("vm_pageout_scan: page not inactive?"); 621 continue; 622 } 623 624 /* 625 * activate held pages 626 */ 627 if (m->hold_count != 0) { 628 vm_page_activate(m); 629 m = next; 630 continue; 631 } 632 633 /* 634 * dont mess with busy pages 635 */ 636 if (m->busy || (m->flags & PG_BUSY)) { 637 m = next; 638 continue; 639 } 640 641 /* 642 * NOTE: PG_CLEAN doesn't guarantee that the page is clean. 643 */ 644 if (m->flags & PG_CLEAN) { 645 /* 646 * If we're not low on memory and the page has been reference, 647 * or if the page has been modified, then reactivate the page. 648 */ 649 if (((cnt.v_free_count > vm_pageout_free_min) && 650 (pmap_is_referenced(VM_PAGE_TO_PHYS(m)) || ((m->flags & PG_REFERENCED) != 0))) || 651 pmap_is_modified(VM_PAGE_TO_PHYS(m))) { 652 m->flags &= ~PG_REFERENCED; 653 vm_page_activate(m); 654 } else if (!m->act_count) { 655 pmap_page_protect(VM_PAGE_TO_PHYS(m), 656 VM_PROT_NONE); 657 vm_page_free(m); 658 ++cnt.v_dfree; 659 ++pages_freed; 660 } else { 661 m->act_count -= min(m->act_count, ACT_DECLINE); 662 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 663 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 664 } 665 } else if ((m->flags & PG_LAUNDRY) && maxlaunder > 0) { 666 int written; 667 if (pmap_is_referenced(VM_PAGE_TO_PHYS(m)) || 668 ((m->flags & PG_REFERENCED) != 0)) { 669 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 670 vm_page_activate(m); 671 m->flags &= ~PG_REFERENCED; 672 m = next; 673 continue; 674 } 675 /* 676 * If a page is dirty, then it is either 677 * being washed (but not yet cleaned) 678 * or it is still in the laundry. If it is 679 * still in the laundry, then we start the 680 * cleaning operation. 681 */ 682 683 written = vm_pageout_clean(m,0); 684 if (written) 685 maxlaunder -= written; 686 687 if (!next) 688 break; 689 /* 690 * if the next page has been re-activated, start scanning again 691 */ 692 if ((next->flags & PG_INACTIVE) == 0) 693 goto rescan1; 694 } else if ((m->flags & PG_REFERENCED) || 695 pmap_is_referenced(VM_PAGE_TO_PHYS(m))) { 696 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 697 m->flags &= ~PG_REFERENCED; 698 vm_page_activate(m); 699 } 700 m = next; 701 } 702 703 /* 704 * Compute the page shortage. If we are still very low on memory 705 * be sure that we will move a minimal amount of pages from active 706 * to inactive. 707 */ 708 709 page_shortage = cnt.v_inactive_target - 710 (cnt.v_free_count + cnt.v_inactive_count); 711 712 if (page_shortage <= 0) { 713 if (pages_freed == 0) { 714 if( cnt.v_free_count < cnt.v_free_min) { 715 page_shortage = cnt.v_free_min - cnt.v_free_count; 716 } else if(((cnt.v_free_count + cnt.v_inactive_count) < 717 (cnt.v_free_min + cnt.v_inactive_target))) { 718 page_shortage = 1; 719 } else { 720 page_shortage = 0; 721 } 722 } 723 724 } 725 726 maxscan = cnt.v_active_count; 727 m = vm_page_queue_active.tqh_first; 728 while (m && maxscan-- && (page_shortage > 0)) { 729 730 next = m->pageq.tqe_next; 731 732 /* 733 * Don't deactivate pages that are busy. 734 */ 735 if ((m->busy != 0) || 736 (m->flags & PG_BUSY) || (m->hold_count != 0)) { 737 m = next; 738 continue; 739 } 740 741 if ((m->flags & PG_REFERENCED) || 742 pmap_is_referenced(VM_PAGE_TO_PHYS(m))) { 743 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 744 m->flags &= ~PG_REFERENCED; 745 if (m->act_count < ACT_MAX) 746 m->act_count += ACT_ADVANCE; 747 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 748 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 749 TAILQ_REMOVE(&m->object->memq, m, listq); 750 TAILQ_INSERT_TAIL(&m->object->memq, m, listq); 751 } else { 752 m->act_count -= min(m->act_count, ACT_DECLINE); 753 754 /* 755 * if the page act_count is zero -- then we deactivate 756 */ 757 if (!m->act_count) { 758 vm_page_deactivate(m); 759 --page_shortage; 760 /* 761 * else if on the next go-around we will deactivate the page 762 * we need to place the page on the end of the queue to age 763 * the other pages in memory. 764 */ 765 } else { 766 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 767 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 768 TAILQ_REMOVE(&m->object->memq, m, listq); 769 TAILQ_INSERT_TAIL(&m->object->memq, m, listq); 770 } 771 } 772 m = next; 773 } 774 775 /* 776 * if we have not freed any pages and we are desparate for memory 777 * then we keep trying until we get some (any) memory. 778 */ 779 780 if( !force_wakeup && (swap_pager_full || !force_wakeup || 781 (pages_freed == 0 && (cnt.v_free_count < cnt.v_free_min)))){ 782 vm_pager_sync(); 783 force_wakeup = 1; 784 goto morefree; 785 } 786 vm_page_pagesfreed += pages_freed; 787 return force_wakeup; 788} 789 790/* 791 * vm_pageout is the high level pageout daemon. 792 */ 793void 794vm_pageout() 795{ 796 (void) spl0(); 797 798 /* 799 * Initialize some paging parameters. 800 */ 801 802 cnt.v_free_min = 12; 803 /* 804 * free_reserved needs to include enough for the largest 805 * swap pager structures plus enough for any pv_entry 806 * structs when paging. 807 */ 808 cnt.v_free_reserved = 4 + cnt.v_page_count / 1024; 809 if (cnt.v_free_min < 8) 810 cnt.v_free_min = 8; 811 if (cnt.v_free_min > 32) 812 cnt.v_free_min = 32; 813 vm_pageout_free_min = cnt.v_free_reserved; 814 cnt.v_free_target = 2*cnt.v_free_min + cnt.v_free_reserved; 815 cnt.v_inactive_target = cnt.v_free_count / 12; 816 cnt.v_free_min += cnt.v_free_reserved; 817 vm_desired_cache_size = cnt.v_page_count / 3; 818 819 /* XXX does not really belong here */ 820 if (vm_page_max_wired == 0) 821 vm_page_max_wired = cnt.v_free_count / 3; 822 823 824 (void) swap_pager_alloc(0, 0, 0, 0); 825 826 /* 827 * The pageout daemon is never done, so loop 828 * forever. 829 */ 830 while (TRUE) { 831 int force_wakeup; 832/* 833 cnt.v_free_min = 12 + averunnable.ldavg[0] / 1024; 834 cnt.v_free_target = 2*cnt.v_free_min + cnt.v_free_reserved; 835 cnt.v_inactive_target = cnt.v_free_target*2; 836*/ 837 838 tsleep((caddr_t) &vm_pages_needed, PVM, "psleep", 0); 839 840 vm_pager_sync(); 841 /* 842 * The force wakeup hack added to eliminate delays and potiential 843 * deadlock. It was possible for the page daemon to indefintely 844 * postpone waking up a process that it might be waiting for memory 845 * on. The putmulti stuff seems to have aggravated the situation. 846 */ 847 force_wakeup = vm_pageout_scan(); 848 vm_pager_sync(); 849 if( force_wakeup) 850 wakeup( (caddr_t) &cnt.v_free_count); 851 cnt.v_scan++; 852 wakeup((caddr_t) kmem_map); 853 } 854} 855 856