vm_pageout.c revision 11709
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 1.57 1995/10/07 19:02:55 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/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 anyok = 0; 168 int i, forward_okay, backward_okay, page_base; 169 vm_offset_t offset = m->offset; 170 171 object = m->object; 172 173 /* 174 * If not OBJT_SWAP, additional memory may be needed to do the pageout. 175 * Try to avoid the deadlock. 176 */ 177 if ((sync != VM_PAGEOUT_FORCE) && 178 (object->type != OBJT_SWAP) && 179 ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_pageout_free_min)) 180 return 0; 181 182 /* 183 * Don't mess with the page if it's busy. 184 */ 185 if ((!sync && m->hold_count != 0) || 186 ((m->busy != 0) || (m->flags & PG_BUSY))) 187 return 0; 188 189 /* 190 * Try collapsing before it's too late. 191 */ 192 if (!sync && object->backing_object) { 193 vm_object_collapse(object); 194 } 195 mc[VM_PAGEOUT_PAGE_COUNT] = m; 196 pageout_count = 1; 197 page_base = VM_PAGEOUT_PAGE_COUNT; 198 forward_okay = TRUE; 199 if (offset != 0) 200 backward_okay = TRUE; 201 else 202 backward_okay = FALSE; 203 /* 204 * Scan object for clusterable pages. 205 * 206 * We can cluster ONLY if: ->> the page is NOT 207 * clean, wired, busy, held, or mapped into a 208 * buffer, and one of the following: 209 * 1) The page is inactive, or a seldom used 210 * active page. 211 * -or- 212 * 2) we force the issue. 213 */ 214 for (i = 1; (i < vm_pageout_page_count) && (forward_okay || backward_okay); i++) { 215 vm_page_t p; 216 217 /* 218 * See if forward page is clusterable. 219 */ 220 if (forward_okay) { 221 /* 222 * Stop forward scan at end of object. 223 */ 224 if ((offset + i * PAGE_SIZE) > object->size) { 225 forward_okay = FALSE; 226 goto do_backward; 227 } 228 p = vm_page_lookup(object, offset + i * PAGE_SIZE); 229 if (p) { 230 if ((p->flags & (PG_BUSY|PG_CACHE)) || p->busy) { 231 forward_okay = FALSE; 232 goto do_backward; 233 } 234 vm_page_test_dirty(p); 235 if ((p->dirty & p->valid) != 0 && 236 ((p->flags & PG_INACTIVE) || 237 (sync == VM_PAGEOUT_FORCE)) && 238 (p->wire_count == 0) && 239 (p->hold_count == 0)) { 240 mc[VM_PAGEOUT_PAGE_COUNT + i] = p; 241 pageout_count++; 242 if (pageout_count == vm_pageout_page_count) 243 break; 244 } else { 245 forward_okay = FALSE; 246 } 247 } else { 248 forward_okay = FALSE; 249 } 250 } 251do_backward: 252 /* 253 * See if backward page is clusterable. 254 */ 255 if (backward_okay) { 256 /* 257 * Stop backward scan at beginning of object. 258 */ 259 if ((offset - i * PAGE_SIZE) == 0) { 260 backward_okay = FALSE; 261 } 262 p = vm_page_lookup(object, offset - i * PAGE_SIZE); 263 if (p) { 264 if ((p->flags & (PG_BUSY|PG_CACHE)) || p->busy) { 265 backward_okay = FALSE; 266 continue; 267 } 268 vm_page_test_dirty(p); 269 if ((p->dirty & p->valid) != 0 && 270 ((p->flags & PG_INACTIVE) || 271 (sync == VM_PAGEOUT_FORCE)) && 272 (p->wire_count == 0) && 273 (p->hold_count == 0)) { 274 mc[VM_PAGEOUT_PAGE_COUNT - i] = p; 275 pageout_count++; 276 page_base--; 277 if (pageout_count == vm_pageout_page_count) 278 break; 279 } else { 280 backward_okay = FALSE; 281 } 282 } else { 283 backward_okay = FALSE; 284 } 285 } 286 } 287 288 /* 289 * we allow reads during pageouts... 290 */ 291 for (i = page_base; i < (page_base + pageout_count); i++) { 292 mc[i]->flags |= PG_BUSY; 293 vm_page_protect(mc[i], VM_PROT_READ); 294 } 295 object->paging_in_progress += pageout_count; 296 297 vm_pager_put_pages(object, &mc[page_base], pageout_count, 298 ((sync || (object == kernel_object)) ? TRUE : FALSE), 299 pageout_status); 300 301 for (i = 0; i < pageout_count; i++) { 302 vm_page_t mt = mc[page_base + i]; 303 304 switch (pageout_status[i]) { 305 case VM_PAGER_OK: 306 ++anyok; 307 break; 308 case VM_PAGER_PEND: 309 ++anyok; 310 break; 311 case VM_PAGER_BAD: 312 /* 313 * Page outside of range of object. Right now we 314 * essentially lose the changes by pretending it 315 * worked. 316 */ 317 pmap_clear_modify(VM_PAGE_TO_PHYS(mt)); 318 mt->dirty = 0; 319 break; 320 case VM_PAGER_ERROR: 321 case VM_PAGER_FAIL: 322 /* 323 * If page couldn't be paged out, then reactivate the 324 * page so it doesn't clog the inactive list. (We 325 * will try paging out it again later). 326 */ 327 if (mt->flags & PG_INACTIVE) 328 vm_page_activate(mt); 329 break; 330 case VM_PAGER_AGAIN: 331 break; 332 } 333 334 335 /* 336 * If the operation is still going, leave the page busy to 337 * block all other accesses. Also, leave the paging in 338 * progress indicator set so that we don't attempt an object 339 * collapse. 340 */ 341 if (pageout_status[i] != VM_PAGER_PEND) { 342 vm_object_pip_wakeup(object); 343 if ((mt->flags & (PG_REFERENCED|PG_WANTED)) || 344 pmap_is_referenced(VM_PAGE_TO_PHYS(mt))) { 345 pmap_clear_reference(VM_PAGE_TO_PHYS(mt)); 346 mt->flags &= ~PG_REFERENCED; 347 if (mt->flags & PG_INACTIVE) 348 vm_page_activate(mt); 349 } 350 PAGE_WAKEUP(mt); 351 } 352 } 353 return anyok; 354} 355 356/* 357 * vm_pageout_object_deactivate_pages 358 * 359 * deactivate enough pages to satisfy the inactive target 360 * requirements or if vm_page_proc_limit is set, then 361 * deactivate all of the pages in the object and its 362 * backing_objects. 363 * 364 * The object and map must be locked. 365 */ 366static int 367vm_pageout_object_deactivate_pages(map, object, count, map_remove_only) 368 vm_map_t map; 369 vm_object_t object; 370 int count; 371 int map_remove_only; 372{ 373 register vm_page_t p, next; 374 int rcount; 375 int dcount; 376 377 dcount = 0; 378 if (count == 0) 379 count = 1; 380 381 if (object->type == OBJT_DEVICE) 382 return 0; 383 384 if (object->backing_object) { 385 if (object->backing_object->ref_count == 1) 386 dcount += vm_pageout_object_deactivate_pages(map, 387 object->backing_object, count / 2 + 1, map_remove_only); 388 else 389 vm_pageout_object_deactivate_pages(map, 390 object->backing_object, count, 1); 391 } 392 if (object->paging_in_progress) 393 return dcount; 394 395 /* 396 * scan the objects entire memory queue 397 */ 398 rcount = object->resident_page_count; 399 p = object->memq.tqh_first; 400 while (p && (rcount-- > 0)) { 401 next = p->listq.tqe_next; 402 cnt.v_pdpages++; 403 if (p->wire_count != 0 || 404 p->hold_count != 0 || 405 p->busy != 0 || 406 !pmap_page_exists(vm_map_pmap(map), VM_PAGE_TO_PHYS(p))) { 407 p = next; 408 continue; 409 } 410 /* 411 * if a page is active, not wired and is in the processes 412 * pmap, then deactivate the page. 413 */ 414 if ((p->flags & (PG_ACTIVE | PG_BUSY)) == PG_ACTIVE) { 415 if (!pmap_is_referenced(VM_PAGE_TO_PHYS(p)) && 416 (p->flags & (PG_REFERENCED|PG_WANTED)) == 0) { 417 p->act_count -= min(p->act_count, ACT_DECLINE); 418 /* 419 * if the page act_count is zero -- then we 420 * deactivate 421 */ 422 if (!p->act_count) { 423 if (!map_remove_only) 424 vm_page_deactivate(p); 425 vm_page_protect(p, VM_PROT_NONE); 426 /* 427 * else if on the next go-around we 428 * will deactivate the page we need to 429 * place the page on the end of the 430 * queue to age the other pages in 431 * memory. 432 */ 433 } else { 434 TAILQ_REMOVE(&vm_page_queue_active, p, pageq); 435 TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); 436 } 437 /* 438 * see if we are done yet 439 */ 440 if (p->flags & PG_INACTIVE) { 441 --count; 442 ++dcount; 443 if (count <= 0 && 444 cnt.v_inactive_count > cnt.v_inactive_target) { 445 return dcount; 446 } 447 } 448 } else { 449 /* 450 * Move the page to the bottom of the queue. 451 */ 452 pmap_clear_reference(VM_PAGE_TO_PHYS(p)); 453 p->flags &= ~PG_REFERENCED; 454 if (p->act_count < ACT_MAX) 455 p->act_count += ACT_ADVANCE; 456 457 TAILQ_REMOVE(&vm_page_queue_active, p, pageq); 458 TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); 459 } 460 } else if ((p->flags & (PG_INACTIVE | PG_BUSY)) == PG_INACTIVE) { 461 vm_page_protect(p, VM_PROT_NONE); 462 } 463 p = next; 464 } 465 return dcount; 466} 467 468 469/* 470 * deactivate some number of pages in a map, try to do it fairly, but 471 * that is really hard to do. 472 */ 473 474static void 475vm_pageout_map_deactivate_pages(map, entry, count, freeer) 476 vm_map_t map; 477 vm_map_entry_t entry; 478 int *count; 479 freeer_fcn_t *freeer; 480{ 481 vm_map_t tmpm; 482 vm_map_entry_t tmpe; 483 vm_object_t obj; 484 485 if (*count <= 0) 486 return; 487 vm_map_reference(map); 488 if (!lock_try_read(&map->lock)) { 489 vm_map_deallocate(map); 490 return; 491 } 492 if (entry == 0) { 493 tmpe = map->header.next; 494 while (tmpe != &map->header && *count > 0) { 495 vm_pageout_map_deactivate_pages(map, tmpe, count, freeer); 496 tmpe = tmpe->next; 497 }; 498 } else if (entry->is_sub_map || entry->is_a_map) { 499 tmpm = entry->object.share_map; 500 tmpe = tmpm->header.next; 501 while (tmpe != &tmpm->header && *count > 0) { 502 vm_pageout_map_deactivate_pages(tmpm, tmpe, count, freeer); 503 tmpe = tmpe->next; 504 }; 505 } else if ((obj = entry->object.vm_object) != 0) { 506 *count -= (*freeer) (map, obj, *count, TRUE); 507 } 508 lock_read_done(&map->lock); 509 vm_map_deallocate(map); 510 return; 511} 512 513static void 514vm_req_vmdaemon() 515{ 516 static int lastrun = 0; 517 518 if ((ticks > (lastrun + hz / 10)) || (ticks < lastrun)) { 519 wakeup(&vm_daemon_needed); 520 lastrun = ticks; 521 } 522} 523 524/* 525 * vm_pageout_scan does the dirty work for the pageout daemon. 526 */ 527int 528vm_pageout_scan() 529{ 530 vm_page_t m; 531 int page_shortage, maxscan, maxlaunder, pcount; 532 int pages_freed; 533 vm_page_t next; 534 struct proc *p, *bigproc; 535 vm_offset_t size, bigsize; 536 vm_object_t object; 537 int force_wakeup = 0; 538 int vnodes_skipped = 0; 539 540 pages_freed = 0; 541 542 /* 543 * Start scanning the inactive queue for pages we can free. We keep 544 * scanning until we have enough free pages or we have scanned through 545 * the entire queue. If we encounter dirty pages, we start cleaning 546 * them. 547 */ 548 549 maxlaunder = (cnt.v_inactive_target > MAXLAUNDER) ? 550 MAXLAUNDER : cnt.v_inactive_target; 551 552rescan1: 553 maxscan = cnt.v_inactive_count; 554 m = vm_page_queue_inactive.tqh_first; 555 while ((m != NULL) && (maxscan-- > 0) && 556 ((cnt.v_cache_count + cnt.v_free_count) < (cnt.v_cache_min + cnt.v_free_target))) { 557 vm_page_t next; 558 559 cnt.v_pdpages++; 560 next = m->pageq.tqe_next; 561 562#if defined(VM_DIAGNOSE) 563 if ((m->flags & PG_INACTIVE) == 0) { 564 printf("vm_pageout_scan: page not inactive?\n"); 565 break; 566 } 567#endif 568 569 /* 570 * dont mess with busy pages 571 */ 572 if (m->hold_count || m->busy || (m->flags & PG_BUSY)) { 573 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 574 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 575 m = next; 576 continue; 577 } 578 if (((m->flags & PG_REFERENCED) == 0) && 579 pmap_is_referenced(VM_PAGE_TO_PHYS(m))) { 580 m->flags |= PG_REFERENCED; 581 } 582 if (m->object->ref_count == 0) { 583 m->flags &= ~PG_REFERENCED; 584 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 585 } 586 if ((m->flags & (PG_REFERENCED|PG_WANTED)) != 0) { 587 m->flags &= ~PG_REFERENCED; 588 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 589 vm_page_activate(m); 590 if (m->act_count < ACT_MAX) 591 m->act_count += ACT_ADVANCE; 592 m = next; 593 continue; 594 } 595 596 vm_page_test_dirty(m); 597 if (m->dirty == 0) { 598 if (m->bmapped == 0) { 599 if (m->valid == 0) { 600 pmap_page_protect(VM_PAGE_TO_PHYS(m), VM_PROT_NONE); 601 vm_page_free(m); 602 cnt.v_dfree++; 603 } else { 604 vm_page_cache(m); 605 } 606 ++pages_freed; 607 } else { 608 m = next; 609 continue; 610 } 611 } else if (maxlaunder > 0) { 612 int written; 613 struct vnode *vp = NULL; 614 615 object = m->object; 616 if (object->flags & OBJ_DEAD) { 617 m = next; 618 continue; 619 } 620 621 if (object->type == OBJT_VNODE) { 622 vp = object->handle; 623 if (VOP_ISLOCKED(vp) || vget(vp, 1)) { 624 if (object->flags & OBJ_WRITEABLE) 625 ++vnodes_skipped; 626 m = next; 627 continue; 628 } 629 } 630 631 /* 632 * If a page is dirty, then it is either being washed 633 * (but not yet cleaned) or it is still in the 634 * laundry. If it is still in the laundry, then we 635 * start the cleaning operation. 636 */ 637 written = vm_pageout_clean(m, 0); 638 639 if (vp) 640 vput(vp); 641 642 if (!next) { 643 break; 644 } 645 maxlaunder -= written; 646 /* 647 * if the next page has been re-activated, start 648 * scanning again 649 */ 650 if ((next->flags & PG_INACTIVE) == 0) { 651 goto rescan1; 652 } 653 } 654 m = next; 655 } 656 657 /* 658 * Compute the page shortage. If we are still very low on memory be 659 * sure that we will move a minimal amount of pages from active to 660 * inactive. 661 */ 662 663 page_shortage = cnt.v_inactive_target - 664 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 665 if (page_shortage <= 0) { 666 if (pages_freed == 0) { 667 page_shortage = cnt.v_free_min - cnt.v_free_count; 668 } else { 669 page_shortage = 1; 670 } 671 } 672 maxscan = MAXSCAN; 673 pcount = cnt.v_active_count; 674 m = vm_page_queue_active.tqh_first; 675 while ((m != NULL) && (maxscan > 0) && (pcount-- > 0) && (page_shortage > 0)) { 676 677 cnt.v_pdpages++; 678 next = m->pageq.tqe_next; 679 680 /* 681 * Don't deactivate pages that are busy. 682 */ 683 if ((m->busy != 0) || 684 (m->flags & PG_BUSY) || 685 (m->hold_count != 0)) { 686 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 687 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 688 m = next; 689 continue; 690 } 691 if (m->object->ref_count && ((m->flags & (PG_REFERENCED|PG_WANTED)) || 692 pmap_is_referenced(VM_PAGE_TO_PHYS(m)))) { 693 int s; 694 695 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 696 m->flags &= ~PG_REFERENCED; 697 if (m->act_count < ACT_MAX) { 698 m->act_count += ACT_ADVANCE; 699 } 700 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 701 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 702 } else { 703 m->flags &= ~PG_REFERENCED; 704 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 705 m->act_count -= min(m->act_count, ACT_DECLINE); 706 707 /* 708 * if the page act_count is zero -- then we deactivate 709 */ 710 if (!m->act_count && (page_shortage > 0)) { 711 if (m->object->ref_count == 0) { 712 --page_shortage; 713 vm_page_test_dirty(m); 714 if ((m->bmapped == 0) && (m->dirty == 0) ) { 715 m->act_count = 0; 716 vm_page_cache(m); 717 } else { 718 vm_page_deactivate(m); 719 } 720 } else { 721 vm_page_deactivate(m); 722 --page_shortage; 723 } 724 } else if (m->act_count) { 725 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 726 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 727 } 728 } 729 maxscan--; 730 m = next; 731 } 732 733 /* 734 * We try to maintain some *really* free pages, this allows interrupt 735 * code to be guaranteed space. 736 */ 737 while (cnt.v_free_count < cnt.v_free_reserved) { 738 m = vm_page_queue_cache.tqh_first; 739 if (!m) 740 break; 741 vm_page_free(m); 742 cnt.v_dfree++; 743 } 744 745 /* 746 * If we didn't get enough free pages, and we have skipped a vnode 747 * in a writeable object, wakeup the sync daemon. And kick swapout 748 * if we did not get enough free pages. 749 */ 750 if ((cnt.v_cache_count + cnt.v_free_count) < cnt.v_free_target) { 751 if (vnodes_skipped && 752 (cnt.v_cache_count + cnt.v_free_count) < cnt.v_free_min) { 753 if (!vfs_update_wakeup) { 754 vfs_update_wakeup = 1; 755 wakeup(&vfs_update_wakeup); 756 } 757 } 758 /* 759 * now swap processes out if we are in low memory conditions 760 */ 761 if (!swap_pager_full && vm_swap_size && 762 vm_pageout_req_swapout == 0) { 763 vm_pageout_req_swapout = 1; 764 vm_req_vmdaemon(); 765 } 766 } 767 768 if ((cnt.v_inactive_count + cnt.v_free_count + cnt.v_cache_count) < 769 (cnt.v_inactive_target + cnt.v_free_min)) { 770 vm_req_vmdaemon(); 771 } 772 773 /* 774 * make sure that we have swap space -- if we are low on memory and 775 * swap -- then kill the biggest process. 776 */ 777 if ((vm_swap_size == 0 || swap_pager_full) && 778 ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min)) { 779 bigproc = NULL; 780 bigsize = 0; 781 for (p = (struct proc *) allproc; p != NULL; p = p->p_next) { 782 /* 783 * if this is a system process, skip it 784 */ 785 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 786 ((p->p_pid < 48) && (vm_swap_size != 0))) { 787 continue; 788 } 789 /* 790 * if the process is in a non-running type state, 791 * don't touch it. 792 */ 793 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 794 continue; 795 } 796 /* 797 * get the process size 798 */ 799 size = p->p_vmspace->vm_pmap.pm_stats.resident_count; 800 /* 801 * if the this process is bigger than the biggest one 802 * remember it. 803 */ 804 if (size > bigsize) { 805 bigproc = p; 806 bigsize = size; 807 } 808 } 809 if (bigproc != NULL) { 810 printf("Process %lu killed by vm_pageout -- out of swap\n", (u_long) bigproc->p_pid); 811 psignal(bigproc, SIGKILL); 812 bigproc->p_estcpu = 0; 813 bigproc->p_nice = PRIO_MIN; 814 resetpriority(bigproc); 815 wakeup(&cnt.v_free_count); 816 } 817 } 818 return force_wakeup; 819} 820 821/* 822 * vm_pageout is the high level pageout daemon. 823 */ 824static void 825vm_pageout() 826{ 827 (void) spl0(); 828 829 /* 830 * Initialize some paging parameters. 831 */ 832 833 cnt.v_interrupt_free_min = 2; 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 = 6 + cnt.v_page_count / 1024 + 844 cnt.v_interrupt_free_min; 845 cnt.v_free_reserved = cnt.v_pageout_free_min + 6; 846 cnt.v_free_target = 3 * cnt.v_free_min + cnt.v_free_reserved; 847 cnt.v_free_min += cnt.v_free_reserved; 848 849 if (cnt.v_page_count > 1024) { 850 cnt.v_cache_max = (cnt.v_free_count - 1024) / 2; 851 cnt.v_cache_min = (cnt.v_free_count - 1024) / 8; 852 cnt.v_inactive_target = 2*cnt.v_cache_min + 192; 853 } else { 854 cnt.v_cache_min = 0; 855 cnt.v_cache_max = 0; 856 cnt.v_inactive_target = cnt.v_free_count / 4; 857 } 858 859 /* XXX does not really belong here */ 860 if (vm_page_max_wired == 0) 861 vm_page_max_wired = cnt.v_free_count / 3; 862 863 864 swap_pager_swap_init(); 865 /* 866 * The pageout daemon is never done, so loop forever. 867 */ 868 while (TRUE) { 869 int s = splhigh(); 870 871 if (!vm_pages_needed || 872 ((cnt.v_free_count >= cnt.v_free_reserved) && 873 (cnt.v_free_count + cnt.v_cache_count >= cnt.v_free_min))) { 874 vm_pages_needed = 0; 875 tsleep(&vm_pages_needed, PVM, "psleep", 0); 876 } 877 vm_pages_needed = 0; 878 splx(s); 879 cnt.v_pdwakeups++; 880 vm_pager_sync(); 881 vm_pageout_scan(); 882 vm_pager_sync(); 883 wakeup(&cnt.v_free_count); 884 wakeup(kmem_map); 885 } 886} 887 888static void 889vm_daemon() 890{ 891 vm_object_t object; 892 struct proc *p; 893 894 while (TRUE) { 895 tsleep(&vm_daemon_needed, PUSER, "psleep", 0); 896 if (vm_pageout_req_swapout) { 897 swapout_procs(); 898 vm_pageout_req_swapout = 0; 899 } 900 /* 901 * scan the processes for exceeding their rlimits or if 902 * process is swapped out -- deactivate pages 903 */ 904 905 for (p = (struct proc *) allproc; p != NULL; p = p->p_next) { 906 int overage; 907 quad_t limit; 908 vm_offset_t size; 909 910 /* 911 * if this is a system process or if we have already 912 * looked at this process, skip it. 913 */ 914 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 915 continue; 916 } 917 /* 918 * if the process is in a non-running type state, 919 * don't touch it. 920 */ 921 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 922 continue; 923 } 924 /* 925 * get a limit 926 */ 927 limit = qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 928 p->p_rlimit[RLIMIT_RSS].rlim_max); 929 930 /* 931 * let processes that are swapped out really be 932 * swapped out set the limit to nothing (will force a 933 * swap-out.) 934 */ 935 if ((p->p_flag & P_INMEM) == 0) 936 limit = 0; /* XXX */ 937 938 size = p->p_vmspace->vm_pmap.pm_stats.resident_count * PAGE_SIZE; 939 if (limit >= 0 && size >= limit) { 940 overage = (size - limit) >> PAGE_SHIFT; 941 vm_pageout_map_deactivate_pages(&p->p_vmspace->vm_map, 942 (vm_map_entry_t) 0, &overage, vm_pageout_object_deactivate_pages); 943 } 944 } 945 946 /* 947 * we remove cached objects that have no RSS... 948 */ 949restart: 950 object = vm_object_cached_list.tqh_first; 951 while (object) { 952 /* 953 * if there are no resident pages -- get rid of the object 954 */ 955 if (object->resident_page_count == 0) { 956 vm_object_reference(object); 957 pager_cache(object, FALSE); 958 goto restart; 959 } 960 object = object->cached_list.tqe_next; 961 } 962 } 963} 964