vm_pageout.c revision 12110
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 1.58 1995/10/23 05:35:48 dyson 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/kernel.h> 78#include <sys/proc.h> 79#include <sys/resourcevar.h> 80#include <sys/malloc.h> 81#include <sys/kernel.h> 82#include <sys/signalvar.h> 83#include <sys/vnode.h> 84 85#include <vm/vm.h> 86#include <vm/vm_page.h> 87#include <vm/vm_pageout.h> 88#include <vm/vm_kern.h> 89#include <vm/vm_pager.h> 90#include <vm/swap_pager.h> 91 92/* 93 * System initialization 94 */ 95 96/* the kernel process "vm_pageout"*/ 97static void vm_pageout __P((void)); 98struct proc *pageproc; 99 100static struct kproc_desc page_kp = { 101 "pagedaemon", 102 vm_pageout, 103 &pageproc 104}; 105SYSINIT_KT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 106 107/* the kernel process "vm_daemon"*/ 108static void vm_daemon __P((void)); 109struct proc *vmproc; 110 111static struct kproc_desc vm_kp = { 112 "vmdaemon", 113 vm_daemon, 114 &vmproc 115}; 116SYSINIT_KT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) 117 118 119int vm_pages_needed; /* Event on which pageout daemon sleeps */ 120 121int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 122 123extern int npendingio; 124int vm_pageout_req_swapout; /* XXX */ 125int vm_daemon_needed; 126extern int nswiodone; 127extern int vm_swap_size; 128extern int vfs_update_wakeup; 129 130#define MAXSCAN 1024 /* maximum number of pages to scan in queues */ 131 132#define MAXLAUNDER (cnt.v_page_count > 1800 ? 32 : 16) 133 134#define VM_PAGEOUT_PAGE_COUNT 8 135int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 136 137int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 138 139typedef int freeer_fcn_t __P((vm_map_t, vm_object_t, int, int)); 140static void vm_pageout_map_deactivate_pages __P((vm_map_t, vm_map_entry_t, 141 int *, freeer_fcn_t *)); 142static freeer_fcn_t vm_pageout_object_deactivate_pages; 143static void vm_req_vmdaemon __P((void)); 144 145/* 146 * vm_pageout_clean: 147 * 148 * Clean the page and remove it from the laundry. 149 * 150 * We set the busy bit to cause potential page faults on this page to 151 * block. 152 * 153 * And we set pageout-in-progress to keep the object from disappearing 154 * during pageout. This guarantees that the page won't move from the 155 * inactive queue. (However, any other page on the inactive queue may 156 * move!) 157 */ 158int 159vm_pageout_clean(m, sync) 160 vm_page_t m; 161 int sync; 162{ 163 register vm_object_t object; 164 int pageout_status[VM_PAGEOUT_PAGE_COUNT]; 165 vm_page_t mc[2*VM_PAGEOUT_PAGE_COUNT]; 166 int pageout_count; 167 int i, forward_okay, backward_okay, page_base; 168 vm_offset_t offset = m->offset; 169 170 object = m->object; 171 172 /* 173 * If not OBJT_SWAP, additional memory may be needed to do the pageout. 174 * Try to avoid the deadlock. 175 */ 176 if ((sync != VM_PAGEOUT_FORCE) && 177 (object->type != OBJT_SWAP) && 178 ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_pageout_free_min)) 179 return 0; 180 181 /* 182 * Don't mess with the page if it's busy. 183 */ 184 if ((!sync && m->hold_count != 0) || 185 ((m->busy != 0) || (m->flags & PG_BUSY))) 186 return 0; 187 188 /* 189 * Try collapsing before it's too late. 190 */ 191 if (!sync && object->backing_object) { 192 vm_object_collapse(object); 193 } 194 mc[VM_PAGEOUT_PAGE_COUNT] = m; 195 pageout_count = 1; 196 page_base = VM_PAGEOUT_PAGE_COUNT; 197 forward_okay = TRUE; 198 if (offset != 0) 199 backward_okay = TRUE; 200 else 201 backward_okay = FALSE; 202 /* 203 * Scan object for clusterable pages. 204 * 205 * We can cluster ONLY if: ->> the page is NOT 206 * clean, wired, busy, held, or mapped into a 207 * buffer, and one of the following: 208 * 1) The page is inactive, or a seldom used 209 * active page. 210 * -or- 211 * 2) we force the issue. 212 */ 213 for (i = 1; (i < vm_pageout_page_count) && (forward_okay || backward_okay); i++) { 214 vm_page_t p; 215 216 /* 217 * See if forward page is clusterable. 218 */ 219 if (forward_okay) { 220 /* 221 * Stop forward scan at end of object. 222 */ 223 if ((offset + i * PAGE_SIZE) > object->size) { 224 forward_okay = FALSE; 225 goto do_backward; 226 } 227 p = vm_page_lookup(object, offset + i * PAGE_SIZE); 228 if (p) { 229 if ((p->flags & (PG_BUSY|PG_CACHE)) || p->busy) { 230 forward_okay = FALSE; 231 goto do_backward; 232 } 233 vm_page_test_dirty(p); 234 if ((p->dirty & p->valid) != 0 && 235 ((p->flags & PG_INACTIVE) || 236 (sync == VM_PAGEOUT_FORCE)) && 237 (p->wire_count == 0) && 238 (p->hold_count == 0)) { 239 mc[VM_PAGEOUT_PAGE_COUNT + i] = p; 240 pageout_count++; 241 if (pageout_count == vm_pageout_page_count) 242 break; 243 } else { 244 forward_okay = FALSE; 245 } 246 } else { 247 forward_okay = FALSE; 248 } 249 } 250do_backward: 251 /* 252 * See if backward page is clusterable. 253 */ 254 if (backward_okay) { 255 /* 256 * Stop backward scan at beginning of object. 257 */ 258 if ((offset - i * PAGE_SIZE) == 0) { 259 backward_okay = FALSE; 260 } 261 p = vm_page_lookup(object, offset - i * PAGE_SIZE); 262 if (p) { 263 if ((p->flags & (PG_BUSY|PG_CACHE)) || p->busy) { 264 backward_okay = FALSE; 265 continue; 266 } 267 vm_page_test_dirty(p); 268 if ((p->dirty & p->valid) != 0 && 269 ((p->flags & PG_INACTIVE) || 270 (sync == VM_PAGEOUT_FORCE)) && 271 (p->wire_count == 0) && 272 (p->hold_count == 0)) { 273 mc[VM_PAGEOUT_PAGE_COUNT - i] = p; 274 pageout_count++; 275 page_base--; 276 if (pageout_count == vm_pageout_page_count) 277 break; 278 } else { 279 backward_okay = FALSE; 280 } 281 } else { 282 backward_okay = FALSE; 283 } 284 } 285 } 286 287 /* 288 * we allow reads during pageouts... 289 */ 290 for (i = page_base; i < (page_base + pageout_count); i++) { 291 mc[i]->flags |= PG_BUSY; 292 vm_page_protect(mc[i], VM_PROT_READ); 293 } 294 295 return vm_pageout_flush(&mc[page_base], pageout_count, sync); 296} 297 298int 299vm_pageout_flush(mc, count, sync) 300 vm_page_t *mc; 301 int count; 302 int sync; 303{ 304 register vm_object_t object; 305 int pageout_status[count]; 306 int anyok = 0; 307 int i; 308 309 object = mc[0]->object; 310 object->paging_in_progress += count; 311 312 vm_pager_put_pages(object, mc, count, 313 ((sync || (object == kernel_object)) ? TRUE : FALSE), 314 pageout_status); 315 316 317 for (i = 0; i < count; i++) { 318 vm_page_t mt = mc[i]; 319 320 switch (pageout_status[i]) { 321 case VM_PAGER_OK: 322 ++anyok; 323 break; 324 case VM_PAGER_PEND: 325 ++anyok; 326 break; 327 case VM_PAGER_BAD: 328 /* 329 * Page outside of range of object. Right now we 330 * essentially lose the changes by pretending it 331 * worked. 332 */ 333 pmap_clear_modify(VM_PAGE_TO_PHYS(mt)); 334 mt->dirty = 0; 335 break; 336 case VM_PAGER_ERROR: 337 case VM_PAGER_FAIL: 338 /* 339 * If page couldn't be paged out, then reactivate the 340 * page so it doesn't clog the inactive list. (We 341 * will try paging out it again later). 342 */ 343 if (mt->flags & PG_INACTIVE) 344 vm_page_activate(mt); 345 break; 346 case VM_PAGER_AGAIN: 347 break; 348 } 349 350 351 /* 352 * If the operation is still going, leave the page busy to 353 * block all other accesses. Also, leave the paging in 354 * progress indicator set so that we don't attempt an object 355 * collapse. 356 */ 357 if (pageout_status[i] != VM_PAGER_PEND) { 358 vm_object_pip_wakeup(object); 359 if ((mt->flags & (PG_REFERENCED|PG_WANTED)) || 360 pmap_is_referenced(VM_PAGE_TO_PHYS(mt))) { 361 pmap_clear_reference(VM_PAGE_TO_PHYS(mt)); 362 mt->flags &= ~PG_REFERENCED; 363 if (mt->flags & PG_INACTIVE) 364 vm_page_activate(mt); 365 } 366 PAGE_WAKEUP(mt); 367 } 368 } 369 return anyok; 370} 371 372/* 373 * vm_pageout_object_deactivate_pages 374 * 375 * deactivate enough pages to satisfy the inactive target 376 * requirements or if vm_page_proc_limit is set, then 377 * deactivate all of the pages in the object and its 378 * backing_objects. 379 * 380 * The object and map must be locked. 381 */ 382static int 383vm_pageout_object_deactivate_pages(map, object, count, map_remove_only) 384 vm_map_t map; 385 vm_object_t object; 386 int count; 387 int map_remove_only; 388{ 389 register vm_page_t p, next; 390 int rcount; 391 int dcount; 392 393 dcount = 0; 394 if (count == 0) 395 count = 1; 396 397 if (object->type == OBJT_DEVICE) 398 return 0; 399 400 if (object->backing_object) { 401 if (object->backing_object->ref_count == 1) 402 dcount += vm_pageout_object_deactivate_pages(map, 403 object->backing_object, count / 2 + 1, map_remove_only); 404 else 405 vm_pageout_object_deactivate_pages(map, 406 object->backing_object, count, 1); 407 } 408 if (object->paging_in_progress) 409 return dcount; 410 411 /* 412 * scan the objects entire memory queue 413 */ 414 rcount = object->resident_page_count; 415 p = object->memq.tqh_first; 416 while (p && (rcount-- > 0)) { 417 next = p->listq.tqe_next; 418 cnt.v_pdpages++; 419 if (p->wire_count != 0 || 420 p->hold_count != 0 || 421 p->busy != 0 || 422 !pmap_page_exists(vm_map_pmap(map), VM_PAGE_TO_PHYS(p))) { 423 p = next; 424 continue; 425 } 426 /* 427 * if a page is active, not wired and is in the processes 428 * pmap, then deactivate the page. 429 */ 430 if ((p->flags & (PG_ACTIVE | PG_BUSY)) == PG_ACTIVE) { 431 if (!pmap_is_referenced(VM_PAGE_TO_PHYS(p)) && 432 (p->flags & (PG_REFERENCED|PG_WANTED)) == 0) { 433 p->act_count -= min(p->act_count, ACT_DECLINE); 434 /* 435 * if the page act_count is zero -- then we 436 * deactivate 437 */ 438 if (!p->act_count) { 439 if (!map_remove_only) 440 vm_page_deactivate(p); 441 vm_page_protect(p, VM_PROT_NONE); 442 /* 443 * else if on the next go-around we 444 * will deactivate the page we need to 445 * place the page on the end of the 446 * queue to age the other pages in 447 * memory. 448 */ 449 } else { 450 TAILQ_REMOVE(&vm_page_queue_active, p, pageq); 451 TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); 452 } 453 /* 454 * see if we are done yet 455 */ 456 if (p->flags & PG_INACTIVE) { 457 --count; 458 ++dcount; 459 if (count <= 0 && 460 cnt.v_inactive_count > cnt.v_inactive_target) { 461 return dcount; 462 } 463 } 464 } else { 465 /* 466 * Move the page to the bottom of the queue. 467 */ 468 pmap_clear_reference(VM_PAGE_TO_PHYS(p)); 469 p->flags &= ~PG_REFERENCED; 470 if (p->act_count < ACT_MAX) 471 p->act_count += ACT_ADVANCE; 472 473 TAILQ_REMOVE(&vm_page_queue_active, p, pageq); 474 TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); 475 } 476 } else if ((p->flags & (PG_INACTIVE | PG_BUSY)) == PG_INACTIVE) { 477 vm_page_protect(p, VM_PROT_NONE); 478 } 479 p = next; 480 } 481 return dcount; 482} 483 484 485/* 486 * deactivate some number of pages in a map, try to do it fairly, but 487 * that is really hard to do. 488 */ 489 490static void 491vm_pageout_map_deactivate_pages(map, entry, count, freeer) 492 vm_map_t map; 493 vm_map_entry_t entry; 494 int *count; 495 freeer_fcn_t *freeer; 496{ 497 vm_map_t tmpm; 498 vm_map_entry_t tmpe; 499 vm_object_t obj; 500 501 if (*count <= 0) 502 return; 503 vm_map_reference(map); 504 if (!lock_try_read(&map->lock)) { 505 vm_map_deallocate(map); 506 return; 507 } 508 if (entry == 0) { 509 tmpe = map->header.next; 510 while (tmpe != &map->header && *count > 0) { 511 vm_pageout_map_deactivate_pages(map, tmpe, count, freeer); 512 tmpe = tmpe->next; 513 }; 514 } else if (entry->is_sub_map || entry->is_a_map) { 515 tmpm = entry->object.share_map; 516 tmpe = tmpm->header.next; 517 while (tmpe != &tmpm->header && *count > 0) { 518 vm_pageout_map_deactivate_pages(tmpm, tmpe, count, freeer); 519 tmpe = tmpe->next; 520 }; 521 } else if ((obj = entry->object.vm_object) != 0) { 522 *count -= (*freeer) (map, obj, *count, TRUE); 523 } 524 lock_read_done(&map->lock); 525 vm_map_deallocate(map); 526 return; 527} 528 529static void 530vm_req_vmdaemon() 531{ 532 static int lastrun = 0; 533 534 if ((ticks > (lastrun + hz / 10)) || (ticks < lastrun)) { 535 wakeup(&vm_daemon_needed); 536 lastrun = ticks; 537 } 538} 539 540/* 541 * vm_pageout_scan does the dirty work for the pageout daemon. 542 */ 543int 544vm_pageout_scan() 545{ 546 vm_page_t m; 547 int page_shortage, maxscan, maxlaunder, pcount; 548 int pages_freed; 549 vm_page_t next; 550 struct proc *p, *bigproc; 551 vm_offset_t size, bigsize; 552 vm_object_t object; 553 int force_wakeup = 0; 554 int vnodes_skipped = 0; 555 556 pages_freed = 0; 557 558 /* 559 * Start scanning the inactive queue for pages we can free. We keep 560 * scanning until we have enough free pages or we have scanned through 561 * the entire queue. If we encounter dirty pages, we start cleaning 562 * them. 563 */ 564 565 maxlaunder = (cnt.v_inactive_target > MAXLAUNDER) ? 566 MAXLAUNDER : cnt.v_inactive_target; 567 568rescan1: 569 maxscan = cnt.v_inactive_count; 570 m = vm_page_queue_inactive.tqh_first; 571 while ((m != NULL) && (maxscan-- > 0) && 572 ((cnt.v_cache_count + cnt.v_free_count) < (cnt.v_cache_min + cnt.v_free_target))) { 573 vm_page_t next; 574 575 cnt.v_pdpages++; 576 next = m->pageq.tqe_next; 577 578#if defined(VM_DIAGNOSE) 579 if ((m->flags & PG_INACTIVE) == 0) { 580 printf("vm_pageout_scan: page not inactive?\n"); 581 break; 582 } 583#endif 584 585 /* 586 * dont mess with busy pages 587 */ 588 if (m->hold_count || m->busy || (m->flags & PG_BUSY)) { 589 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 590 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 591 m = next; 592 continue; 593 } 594 if (((m->flags & PG_REFERENCED) == 0) && 595 pmap_is_referenced(VM_PAGE_TO_PHYS(m))) { 596 m->flags |= PG_REFERENCED; 597 } 598 if (m->object->ref_count == 0) { 599 m->flags &= ~PG_REFERENCED; 600 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 601 } 602 if ((m->flags & (PG_REFERENCED|PG_WANTED)) != 0) { 603 m->flags &= ~PG_REFERENCED; 604 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 605 vm_page_activate(m); 606 if (m->act_count < ACT_MAX) 607 m->act_count += ACT_ADVANCE; 608 m = next; 609 continue; 610 } 611 612 vm_page_test_dirty(m); 613 if (m->dirty == 0) { 614 if (m->bmapped == 0) { 615 if (m->valid == 0) { 616 pmap_page_protect(VM_PAGE_TO_PHYS(m), VM_PROT_NONE); 617 vm_page_free(m); 618 cnt.v_dfree++; 619 } else { 620 vm_page_cache(m); 621 } 622 ++pages_freed; 623 } else { 624 m = next; 625 continue; 626 } 627 } else if (maxlaunder > 0) { 628 int written; 629 struct vnode *vp = NULL; 630 631 object = m->object; 632 if (object->flags & OBJ_DEAD) { 633 m = next; 634 continue; 635 } 636 637 if (object->type == OBJT_VNODE) { 638 vp = object->handle; 639 if (VOP_ISLOCKED(vp) || vget(vp, 1)) { 640 if (object->flags & OBJ_MIGHTBEDIRTY) 641 ++vnodes_skipped; 642 m = next; 643 continue; 644 } 645 } 646 647 /* 648 * If a page is dirty, then it is either being washed 649 * (but not yet cleaned) or it is still in the 650 * laundry. If it is still in the laundry, then we 651 * start the cleaning operation. 652 */ 653 written = vm_pageout_clean(m, 0); 654 655 if (vp) 656 vput(vp); 657 658 if (!next) { 659 break; 660 } 661 maxlaunder -= written; 662 /* 663 * if the next page has been re-activated, start 664 * scanning again 665 */ 666 if ((next->flags & PG_INACTIVE) == 0) { 667 goto rescan1; 668 } 669 } 670 m = next; 671 } 672 673 /* 674 * Compute the page shortage. If we are still very low on memory be 675 * sure that we will move a minimal amount of pages from active to 676 * inactive. 677 */ 678 679 page_shortage = cnt.v_inactive_target - 680 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 681 if (page_shortage <= 0) { 682 if (pages_freed == 0) { 683 page_shortage = cnt.v_free_min - cnt.v_free_count; 684 } else { 685 page_shortage = 1; 686 } 687 } 688 maxscan = MAXSCAN; 689 pcount = cnt.v_active_count; 690 m = vm_page_queue_active.tqh_first; 691 while ((m != NULL) && (maxscan > 0) && (pcount-- > 0) && (page_shortage > 0)) { 692 693 cnt.v_pdpages++; 694 next = m->pageq.tqe_next; 695 696 /* 697 * Don't deactivate pages that are busy. 698 */ 699 if ((m->busy != 0) || 700 (m->flags & PG_BUSY) || 701 (m->hold_count != 0)) { 702 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 703 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 704 m = next; 705 continue; 706 } 707 if (m->object->ref_count && ((m->flags & (PG_REFERENCED|PG_WANTED)) || 708 pmap_is_referenced(VM_PAGE_TO_PHYS(m)))) { 709 int s; 710 711 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 712 m->flags &= ~PG_REFERENCED; 713 if (m->act_count < ACT_MAX) { 714 m->act_count += ACT_ADVANCE; 715 } 716 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 717 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 718 } else { 719 m->flags &= ~PG_REFERENCED; 720 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 721 m->act_count -= min(m->act_count, ACT_DECLINE); 722 723 /* 724 * if the page act_count is zero -- then we deactivate 725 */ 726 if (!m->act_count && (page_shortage > 0)) { 727 if (m->object->ref_count == 0) { 728 --page_shortage; 729 vm_page_test_dirty(m); 730 if ((m->bmapped == 0) && (m->dirty == 0) ) { 731 m->act_count = 0; 732 vm_page_cache(m); 733 } else { 734 vm_page_deactivate(m); 735 } 736 } else { 737 vm_page_deactivate(m); 738 --page_shortage; 739 } 740 } else if (m->act_count) { 741 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 742 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 743 } 744 } 745 maxscan--; 746 m = next; 747 } 748 749 /* 750 * We try to maintain some *really* free pages, this allows interrupt 751 * code to be guaranteed space. 752 */ 753 while (cnt.v_free_count < cnt.v_free_reserved) { 754 m = vm_page_queue_cache.tqh_first; 755 if (!m) 756 break; 757 vm_page_free(m); 758 cnt.v_dfree++; 759 } 760 761 /* 762 * If we didn't get enough free pages, and we have skipped a vnode 763 * in a writeable object, wakeup the sync daemon. And kick swapout 764 * if we did not get enough free pages. 765 */ 766 if ((cnt.v_cache_count + cnt.v_free_count) < cnt.v_free_target) { 767 if (vnodes_skipped && 768 (cnt.v_cache_count + cnt.v_free_count) < cnt.v_free_min) { 769 if (!vfs_update_wakeup) { 770 vfs_update_wakeup = 1; 771 wakeup(&vfs_update_wakeup); 772 } 773 } 774 /* 775 * now swap processes out if we are in low memory conditions 776 */ 777 if (!swap_pager_full && vm_swap_size && 778 vm_pageout_req_swapout == 0) { 779 vm_pageout_req_swapout = 1; 780 vm_req_vmdaemon(); 781 } 782 } 783 784 if ((cnt.v_inactive_count + cnt.v_free_count + cnt.v_cache_count) < 785 (cnt.v_inactive_target + cnt.v_free_min)) { 786 vm_req_vmdaemon(); 787 } 788 789 /* 790 * make sure that we have swap space -- if we are low on memory and 791 * swap -- then kill the biggest process. 792 */ 793 if ((vm_swap_size == 0 || swap_pager_full) && 794 ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min)) { 795 bigproc = NULL; 796 bigsize = 0; 797 for (p = (struct proc *) allproc; p != NULL; p = p->p_next) { 798 /* 799 * if this is a system process, skip it 800 */ 801 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 802 ((p->p_pid < 48) && (vm_swap_size != 0))) { 803 continue; 804 } 805 /* 806 * if the process is in a non-running type state, 807 * don't touch it. 808 */ 809 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 810 continue; 811 } 812 /* 813 * get the process size 814 */ 815 size = p->p_vmspace->vm_pmap.pm_stats.resident_count; 816 /* 817 * if the this process is bigger than the biggest one 818 * remember it. 819 */ 820 if (size > bigsize) { 821 bigproc = p; 822 bigsize = size; 823 } 824 } 825 if (bigproc != NULL) { 826 printf("Process %lu killed by vm_pageout -- out of swap\n", (u_long) bigproc->p_pid); 827 psignal(bigproc, SIGKILL); 828 bigproc->p_estcpu = 0; 829 bigproc->p_nice = PRIO_MIN; 830 resetpriority(bigproc); 831 wakeup(&cnt.v_free_count); 832 } 833 } 834 return force_wakeup; 835} 836 837/* 838 * vm_pageout is the high level pageout daemon. 839 */ 840static void 841vm_pageout() 842{ 843 (void) spl0(); 844 845 /* 846 * Initialize some paging parameters. 847 */ 848 849 cnt.v_interrupt_free_min = 2; 850 851 if (cnt.v_page_count > 1024) 852 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 853 else 854 cnt.v_free_min = 4; 855 /* 856 * free_reserved needs to include enough for the largest swap pager 857 * structures plus enough for any pv_entry structs when paging. 858 */ 859 cnt.v_pageout_free_min = 6 + cnt.v_page_count / 1024 + 860 cnt.v_interrupt_free_min; 861 cnt.v_free_reserved = cnt.v_pageout_free_min + 6; 862 cnt.v_free_target = 3 * cnt.v_free_min + cnt.v_free_reserved; 863 cnt.v_free_min += cnt.v_free_reserved; 864 865 if (cnt.v_page_count > 1024) { 866 cnt.v_cache_max = (cnt.v_free_count - 1024) / 2; 867 cnt.v_cache_min = (cnt.v_free_count - 1024) / 8; 868 cnt.v_inactive_target = 2*cnt.v_cache_min + 192; 869 } else { 870 cnt.v_cache_min = 0; 871 cnt.v_cache_max = 0; 872 cnt.v_inactive_target = cnt.v_free_count / 4; 873 } 874 875 /* XXX does not really belong here */ 876 if (vm_page_max_wired == 0) 877 vm_page_max_wired = cnt.v_free_count / 3; 878 879 880 swap_pager_swap_init(); 881 /* 882 * The pageout daemon is never done, so loop forever. 883 */ 884 while (TRUE) { 885 int s = splhigh(); 886 887 if (!vm_pages_needed || 888 ((cnt.v_free_count >= cnt.v_free_reserved) && 889 (cnt.v_free_count + cnt.v_cache_count >= cnt.v_free_min))) { 890 vm_pages_needed = 0; 891 tsleep(&vm_pages_needed, PVM, "psleep", 0); 892 } 893 vm_pages_needed = 0; 894 splx(s); 895 cnt.v_pdwakeups++; 896 vm_pager_sync(); 897 vm_pageout_scan(); 898 vm_pager_sync(); 899 wakeup(&cnt.v_free_count); 900 wakeup(kmem_map); 901 } 902} 903 904static void 905vm_daemon() 906{ 907 vm_object_t object; 908 struct proc *p; 909 910 while (TRUE) { 911 tsleep(&vm_daemon_needed, PUSER, "psleep", 0); 912 if (vm_pageout_req_swapout) { 913 swapout_procs(); 914 vm_pageout_req_swapout = 0; 915 } 916 /* 917 * scan the processes for exceeding their rlimits or if 918 * process is swapped out -- deactivate pages 919 */ 920 921 for (p = (struct proc *) allproc; p != NULL; p = p->p_next) { 922 int overage; 923 quad_t limit; 924 vm_offset_t size; 925 926 /* 927 * if this is a system process or if we have already 928 * looked at this process, skip it. 929 */ 930 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 931 continue; 932 } 933 /* 934 * if the process is in a non-running type state, 935 * don't touch it. 936 */ 937 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 938 continue; 939 } 940 /* 941 * get a limit 942 */ 943 limit = qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 944 p->p_rlimit[RLIMIT_RSS].rlim_max); 945 946 /* 947 * let processes that are swapped out really be 948 * swapped out set the limit to nothing (will force a 949 * swap-out.) 950 */ 951 if ((p->p_flag & P_INMEM) == 0) 952 limit = 0; /* XXX */ 953 954 size = p->p_vmspace->vm_pmap.pm_stats.resident_count * PAGE_SIZE; 955 if (limit >= 0 && size >= limit) { 956 overage = (size - limit) >> PAGE_SHIFT; 957 vm_pageout_map_deactivate_pages(&p->p_vmspace->vm_map, 958 (vm_map_entry_t) 0, &overage, vm_pageout_object_deactivate_pages); 959 } 960 } 961 962 /* 963 * we remove cached objects that have no RSS... 964 */ 965restart: 966 object = vm_object_cached_list.tqh_first; 967 while (object) { 968 /* 969 * if there are no resident pages -- get rid of the object 970 */ 971 if (object->resident_page_count == 0) { 972 vm_object_reference(object); 973 pager_cache(object, FALSE); 974 goto restart; 975 } 976 object = object->cached_list.tqe_next; 977 } 978 } 979} 980