vm_pageout.c revision 18526
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 1.85 1996/09/08 20:44:48 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#include <sys/vmmeter.h> 85#include <sys/sysctl.h> 86 87#include <vm/vm.h> 88#include <vm/vm_param.h> 89#include <vm/vm_prot.h> 90#include <vm/lock.h> 91#include <vm/vm_object.h> 92#include <vm/vm_page.h> 93#include <vm/vm_map.h> 94#include <vm/vm_pageout.h> 95#include <vm/vm_kern.h> 96#include <vm/vm_pager.h> 97#include <vm/swap_pager.h> 98#include <vm/vm_extern.h> 99 100/* 101 * System initialization 102 */ 103 104/* the kernel process "vm_pageout"*/ 105static void vm_pageout __P((void)); 106static int vm_pageout_clean __P((vm_page_t, int)); 107static int vm_pageout_scan __P((void)); 108static int vm_pageout_free_page_calc __P((vm_size_t count)); 109struct proc *pageproc; 110 111static struct kproc_desc page_kp = { 112 "pagedaemon", 113 vm_pageout, 114 &pageproc 115}; 116SYSINIT_KT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 117 118#if !defined(NO_SWAPPING) 119/* the kernel process "vm_daemon"*/ 120static void vm_daemon __P((void)); 121static struct proc *vmproc; 122 123static struct kproc_desc vm_kp = { 124 "vmdaemon", 125 vm_daemon, 126 &vmproc 127}; 128SYSINIT_KT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) 129#endif 130 131 132int vm_pages_needed; /* Event on which pageout daemon sleeps */ 133 134int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 135 136extern int npendingio; 137#if !defined(NO_SWAPPING) 138static int vm_pageout_req_swapout; /* XXX */ 139static int vm_daemon_needed; 140#endif 141extern int nswiodone; 142extern int vm_swap_size; 143extern int vfs_update_wakeup; 144int vm_pageout_algorithm_lru=0; 145#if defined(NO_SWAPPING) 146int vm_swapping_enabled=0; 147#else 148int vm_swapping_enabled=1; 149#endif 150 151SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 152 CTLFLAG_RW, &vm_pageout_algorithm_lru, 0, ""); 153 154#if defined(NO_SWAPPING) 155SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swapping_enabled, 156 CTLFLAG_RD, &vm_swapping_enabled, 0, ""); 157#else 158SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swapping_enabled, 159 CTLFLAG_RW, &vm_swapping_enabled, 0, ""); 160#endif 161 162#define MAXLAUNDER (cnt.v_page_count > 1800 ? 32 : 16) 163 164#define VM_PAGEOUT_PAGE_COUNT 16 165int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 166 167int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 168 169#if !defined(NO_SWAPPING) 170typedef void freeer_fcn_t __P((vm_map_t, vm_object_t, vm_pindex_t, int)); 171static void vm_pageout_map_deactivate_pages __P((vm_map_t, vm_pindex_t)); 172static freeer_fcn_t vm_pageout_object_deactivate_pages; 173static void vm_req_vmdaemon __P((void)); 174#endif 175 176/* 177 * vm_pageout_clean: 178 * 179 * Clean the page and remove it from the laundry. 180 * 181 * We set the busy bit to cause potential page faults on this page to 182 * block. 183 * 184 * And we set pageout-in-progress to keep the object from disappearing 185 * during pageout. This guarantees that the page won't move from the 186 * inactive queue. (However, any other page on the inactive queue may 187 * move!) 188 */ 189static int 190vm_pageout_clean(m, sync) 191 vm_page_t m; 192 int sync; 193{ 194 register vm_object_t object; 195 vm_page_t mc[2*vm_pageout_page_count]; 196 int pageout_count; 197 int i, forward_okay, backward_okay, page_base; 198 vm_pindex_t pindex = m->pindex; 199 200 object = m->object; 201 202 /* 203 * If not OBJT_SWAP, additional memory may be needed to do the pageout. 204 * Try to avoid the deadlock. 205 */ 206 if ((sync != VM_PAGEOUT_FORCE) && 207 (object->type == OBJT_DEFAULT) && 208 ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_pageout_free_min)) 209 return 0; 210 211 /* 212 * Don't mess with the page if it's busy. 213 */ 214 if ((!sync && m->hold_count != 0) || 215 ((m->busy != 0) || (m->flags & PG_BUSY))) 216 return 0; 217 218 /* 219 * Try collapsing before it's too late. 220 */ 221 if (!sync && object->backing_object) { 222 vm_object_collapse(object); 223 } 224 mc[vm_pageout_page_count] = m; 225 pageout_count = 1; 226 page_base = vm_pageout_page_count; 227 forward_okay = TRUE; 228 if (pindex != 0) 229 backward_okay = TRUE; 230 else 231 backward_okay = FALSE; 232 /* 233 * Scan object for clusterable pages. 234 * 235 * We can cluster ONLY if: ->> the page is NOT 236 * clean, wired, busy, held, or mapped into a 237 * buffer, and one of the following: 238 * 1) The page is inactive, or a seldom used 239 * active page. 240 * -or- 241 * 2) we force the issue. 242 */ 243 for (i = 1; (i < vm_pageout_page_count) && (forward_okay || backward_okay); i++) { 244 vm_page_t p; 245 246 /* 247 * See if forward page is clusterable. 248 */ 249 if (forward_okay) { 250 /* 251 * Stop forward scan at end of object. 252 */ 253 if ((pindex + i) > object->size) { 254 forward_okay = FALSE; 255 goto do_backward; 256 } 257 p = vm_page_lookup(object, pindex + i); 258 if (p) { 259 if (((p->queue - p->pc) == PQ_CACHE) || 260 (p->flags & PG_BUSY) || p->busy) { 261 forward_okay = FALSE; 262 goto do_backward; 263 } 264 vm_page_test_dirty(p); 265 if ((p->dirty & p->valid) != 0 && 266 ((p->queue == PQ_INACTIVE) || 267 (sync == VM_PAGEOUT_FORCE)) && 268 (p->wire_count == 0) && 269 (p->hold_count == 0)) { 270 mc[vm_pageout_page_count + i] = p; 271 pageout_count++; 272 if (pageout_count == vm_pageout_page_count) 273 break; 274 } else { 275 forward_okay = FALSE; 276 } 277 } else { 278 forward_okay = FALSE; 279 } 280 } 281do_backward: 282 /* 283 * See if backward page is clusterable. 284 */ 285 if (backward_okay) { 286 /* 287 * Stop backward scan at beginning of object. 288 */ 289 if ((pindex - i) == 0) { 290 backward_okay = FALSE; 291 } 292 p = vm_page_lookup(object, pindex - i); 293 if (p) { 294 if (((p->queue - p->pc) == PQ_CACHE) || 295 (p->flags & PG_BUSY) || p->busy) { 296 backward_okay = FALSE; 297 continue; 298 } 299 vm_page_test_dirty(p); 300 if ((p->dirty & p->valid) != 0 && 301 ((p->queue == PQ_INACTIVE) || 302 (sync == VM_PAGEOUT_FORCE)) && 303 (p->wire_count == 0) && 304 (p->hold_count == 0)) { 305 mc[vm_pageout_page_count - i] = p; 306 pageout_count++; 307 page_base--; 308 if (pageout_count == vm_pageout_page_count) 309 break; 310 } else { 311 backward_okay = FALSE; 312 } 313 } else { 314 backward_okay = FALSE; 315 } 316 } 317 } 318 319 /* 320 * we allow reads during pageouts... 321 */ 322 for (i = page_base; i < (page_base + pageout_count); i++) { 323 mc[i]->flags |= PG_BUSY; 324 vm_page_protect(mc[i], VM_PROT_READ); 325 } 326 327 return vm_pageout_flush(&mc[page_base], pageout_count, sync); 328} 329 330int 331vm_pageout_flush(mc, count, sync) 332 vm_page_t *mc; 333 int count; 334 int sync; 335{ 336 register vm_object_t object; 337 int pageout_status[count]; 338 int anyok = 0; 339 int i; 340 341 object = mc[0]->object; 342 object->paging_in_progress += count; 343 344 vm_pager_put_pages(object, mc, count, 345 ((sync || (object == kernel_object)) ? TRUE : FALSE), 346 pageout_status); 347 348 for (i = 0; i < count; i++) { 349 vm_page_t mt = mc[i]; 350 351 switch (pageout_status[i]) { 352 case VM_PAGER_OK: 353 ++anyok; 354 break; 355 case VM_PAGER_PEND: 356 ++anyok; 357 break; 358 case VM_PAGER_BAD: 359 /* 360 * Page outside of range of object. Right now we 361 * essentially lose the changes by pretending it 362 * worked. 363 */ 364 pmap_clear_modify(VM_PAGE_TO_PHYS(mt)); 365 mt->dirty = 0; 366 break; 367 case VM_PAGER_ERROR: 368 case VM_PAGER_FAIL: 369 /* 370 * If page couldn't be paged out, then reactivate the 371 * page so it doesn't clog the inactive list. (We 372 * will try paging out it again later). 373 */ 374 if (mt->queue == PQ_INACTIVE) 375 vm_page_activate(mt); 376 break; 377 case VM_PAGER_AGAIN: 378 break; 379 } 380 381 382 /* 383 * If the operation is still going, leave the page busy to 384 * block all other accesses. Also, leave the paging in 385 * progress indicator set so that we don't attempt an object 386 * collapse. 387 */ 388 if (pageout_status[i] != VM_PAGER_PEND) { 389 vm_object_pip_wakeup(object); 390 PAGE_WAKEUP(mt); 391 } 392 } 393 return anyok; 394} 395 396#if !defined(NO_SWAPPING) 397/* 398 * vm_pageout_object_deactivate_pages 399 * 400 * deactivate enough pages to satisfy the inactive target 401 * requirements or if vm_page_proc_limit is set, then 402 * deactivate all of the pages in the object and its 403 * backing_objects. 404 * 405 * The object and map must be locked. 406 */ 407static void 408vm_pageout_object_deactivate_pages(map, object, desired, map_remove_only) 409 vm_map_t map; 410 vm_object_t object; 411 vm_pindex_t desired; 412 int map_remove_only; 413{ 414 register vm_page_t p, next; 415 int rcount; 416 int remove_mode; 417 int s; 418 419 if (object->type == OBJT_DEVICE) 420 return; 421 422 while (object) { 423 if (vm_map_pmap(map)->pm_stats.resident_count <= desired) 424 return; 425 if (object->paging_in_progress) 426 return; 427 428 remove_mode = map_remove_only; 429 if (object->shadow_count > 1) 430 remove_mode = 1; 431 /* 432 * scan the objects entire memory queue 433 */ 434 rcount = object->resident_page_count; 435 p = TAILQ_FIRST(&object->memq); 436 while (p && (rcount-- > 0)) { 437 int refcount; 438 if (vm_map_pmap(map)->pm_stats.resident_count <= desired) 439 return; 440 next = TAILQ_NEXT(p, listq); 441 cnt.v_pdpages++; 442 if (p->wire_count != 0 || 443 p->hold_count != 0 || 444 p->busy != 0 || 445 (p->flags & PG_BUSY) || 446 !pmap_page_exists(vm_map_pmap(map), VM_PAGE_TO_PHYS(p))) { 447 p = next; 448 continue; 449 } 450 451 refcount = pmap_ts_referenced(VM_PAGE_TO_PHYS(p)); 452 if (refcount) { 453 p->flags |= PG_REFERENCED; 454 } else if (p->flags & PG_REFERENCED) { 455 refcount = 1; 456 } 457 458 if ((p->queue != PQ_ACTIVE) && 459 (p->flags & PG_REFERENCED)) { 460 vm_page_activate(p); 461 p->act_count += refcount; 462 p->flags &= ~PG_REFERENCED; 463 } else if (p->queue == PQ_ACTIVE) { 464 if ((p->flags & PG_REFERENCED) == 0) { 465 p->act_count -= min(p->act_count, ACT_DECLINE); 466 if (!remove_mode && (vm_pageout_algorithm_lru || (p->act_count == 0))) { 467 vm_page_protect(p, VM_PROT_NONE); 468 vm_page_deactivate(p); 469 } else { 470 s = splvm(); 471 TAILQ_REMOVE(&vm_page_queue_active, p, pageq); 472 TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); 473 splx(s); 474 } 475 } else { 476 p->flags &= ~PG_REFERENCED; 477 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 478 p->act_count += ACT_ADVANCE; 479 s = splvm(); 480 TAILQ_REMOVE(&vm_page_queue_active, p, pageq); 481 TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); 482 splx(s); 483 } 484 } else if (p->queue == PQ_INACTIVE) { 485 vm_page_protect(p, VM_PROT_NONE); 486 } 487 p = next; 488 } 489 object = object->backing_object; 490 } 491 return; 492} 493 494/* 495 * deactivate some number of pages in a map, try to do it fairly, but 496 * that is really hard to do. 497 */ 498static void 499vm_pageout_map_deactivate_pages(map, desired) 500 vm_map_t map; 501 vm_pindex_t desired; 502{ 503 vm_map_entry_t tmpe; 504 vm_object_t obj, bigobj; 505 506 vm_map_reference(map); 507 if (!lock_try_write(&map->lock)) { 508 vm_map_deallocate(map); 509 return; 510 } 511 512 bigobj = NULL; 513 514 /* 515 * first, search out the biggest object, and try to free pages from 516 * that. 517 */ 518 tmpe = map->header.next; 519 while (tmpe != &map->header) { 520 if ((tmpe->is_sub_map == 0) && (tmpe->is_a_map == 0)) { 521 obj = tmpe->object.vm_object; 522 if ((obj != NULL) && (obj->shadow_count <= 1) && 523 ((bigobj == NULL) || 524 (bigobj->resident_page_count < obj->resident_page_count))) { 525 bigobj = obj; 526 } 527 } 528 tmpe = tmpe->next; 529 } 530 531 if (bigobj) 532 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 533 534 /* 535 * Next, hunt around for other pages to deactivate. We actually 536 * do this search sort of wrong -- .text first is not the best idea. 537 */ 538 tmpe = map->header.next; 539 while (tmpe != &map->header) { 540 if (vm_map_pmap(map)->pm_stats.resident_count <= desired) 541 break; 542 if ((tmpe->is_sub_map == 0) && (tmpe->is_a_map == 0)) { 543 obj = tmpe->object.vm_object; 544 if (obj) 545 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 546 } 547 tmpe = tmpe->next; 548 }; 549 550 /* 551 * Remove all mappings if a process is swapped out, this will free page 552 * table pages. 553 */ 554 if (desired == 0) 555 pmap_remove(vm_map_pmap(map), 556 VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS); 557 vm_map_unlock(map); 558 vm_map_deallocate(map); 559 return; 560} 561#endif 562 563/* 564 * vm_pageout_scan does the dirty work for the pageout daemon. 565 */ 566static int 567vm_pageout_scan() 568{ 569 vm_page_t m, next; 570 int page_shortage, addl_page_shortage, maxscan, maxlaunder, pcount; 571 int pages_freed; 572 struct proc *p, *bigproc; 573 vm_offset_t size, bigsize; 574 vm_object_t object; 575 int force_wakeup = 0; 576 int vnodes_skipped = 0; 577 int s; 578 579 /* 580 * Start scanning the inactive queue for pages we can free. We keep 581 * scanning until we have enough free pages or we have scanned through 582 * the entire queue. If we encounter dirty pages, we start cleaning 583 * them. 584 */ 585 586 pages_freed = 0; 587 addl_page_shortage = 0; 588 589 maxlaunder = (cnt.v_inactive_target > MAXLAUNDER) ? 590 MAXLAUNDER : cnt.v_inactive_target; 591rescan0: 592 maxscan = cnt.v_inactive_count; 593 for( m = TAILQ_FIRST(&vm_page_queue_inactive); 594 595 (m != NULL) && (maxscan-- > 0) && 596 ((cnt.v_cache_count + cnt.v_free_count) < 597 (cnt.v_cache_min + cnt.v_free_target)); 598 599 m = next) { 600 601 cnt.v_pdpages++; 602 603 if (m->queue != PQ_INACTIVE) { 604 goto rescan0; 605 } 606 607 next = TAILQ_NEXT(m, pageq); 608 609 if (m->hold_count) { 610 s = splvm(); 611 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 612 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 613 splx(s); 614 addl_page_shortage++; 615 continue; 616 } 617 /* 618 * Dont mess with busy pages, keep in the front of the 619 * queue, most likely are being paged out. 620 */ 621 if (m->busy || (m->flags & PG_BUSY)) { 622 addl_page_shortage++; 623 continue; 624 } 625 626 if (m->object->ref_count == 0) { 627 m->flags &= ~PG_REFERENCED; 628 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 629 } else if (((m->flags & PG_REFERENCED) == 0) && 630 pmap_ts_referenced(VM_PAGE_TO_PHYS(m))) { 631 vm_page_activate(m); 632 continue; 633 } 634 635 if ((m->flags & PG_REFERENCED) != 0) { 636 m->flags &= ~PG_REFERENCED; 637 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 638 vm_page_activate(m); 639 continue; 640 } 641 642 if (m->dirty == 0) { 643 vm_page_test_dirty(m); 644 } else if (m->dirty != 0) { 645 m->dirty = VM_PAGE_BITS_ALL; 646 } 647 648 if (m->valid == 0) { 649 vm_page_protect(m, VM_PROT_NONE); 650 vm_page_free(m); 651 cnt.v_dfree++; 652 ++pages_freed; 653 } else if (m->dirty == 0) { 654 vm_page_cache(m); 655 ++pages_freed; 656 } else if (maxlaunder > 0) { 657 int written; 658 struct vnode *vp = NULL; 659 660 object = m->object; 661 if (object->flags & OBJ_DEAD) { 662 s = splvm(); 663 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 664 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 665 splx(s); 666 continue; 667 } 668 669 if (object->type == OBJT_VNODE) { 670 vp = object->handle; 671 if (VOP_ISLOCKED(vp) || vget(vp, 1)) { 672 if ((m->queue == PQ_INACTIVE) && 673 (m->hold_count == 0) && 674 (m->busy == 0) && 675 (m->flags & PG_BUSY) == 0) { 676 s = splvm(); 677 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 678 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 679 splx(s); 680 } 681 if (object->flags & OBJ_MIGHTBEDIRTY) 682 ++vnodes_skipped; 683 continue; 684 } 685 686 /* 687 * The page might have been moved to another queue 688 * during potential blocking in vget() above. 689 */ 690 if (m->queue != PQ_INACTIVE) { 691 if (object->flags & OBJ_MIGHTBEDIRTY) 692 ++vnodes_skipped; 693 vput(vp); 694 continue; 695 } 696 697 /* 698 * The page may have been busied during the blocking in 699 * vput(); We don't move the page back onto the end of 700 * the queue so that statistics are more correct if we don't. 701 */ 702 if (m->busy || (m->flags & PG_BUSY)) { 703 vput(vp); 704 continue; 705 } 706 707 /* 708 * If the page has become held, then skip it 709 */ 710 if (m->hold_count) { 711 s = splvm(); 712 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 713 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 714 splx(s); 715 if (object->flags & OBJ_MIGHTBEDIRTY) 716 ++vnodes_skipped; 717 vput(vp); 718 continue; 719 } 720 } 721 722 /* 723 * If a page is dirty, then it is either being washed 724 * (but not yet cleaned) or it is still in the 725 * laundry. If it is still in the laundry, then we 726 * start the cleaning operation. 727 */ 728 written = vm_pageout_clean(m, 0); 729 730 if (vp) 731 vput(vp); 732 733 maxlaunder -= written; 734 } 735 } 736 737 /* 738 * Compute the page shortage. If we are still very low on memory be 739 * sure that we will move a minimal amount of pages from active to 740 * inactive. 741 */ 742 743 page_shortage = (cnt.v_inactive_target + cnt.v_cache_min) - 744 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 745 if (page_shortage <= 0) { 746 if (pages_freed == 0) { 747 page_shortage = cnt.v_free_min - cnt.v_free_count; 748 } else { 749 page_shortage = 1; 750 } 751 } 752 if (addl_page_shortage) { 753 if (page_shortage < 0) 754 page_shortage = 0; 755 page_shortage += addl_page_shortage; 756 } 757 758 pcount = cnt.v_active_count; 759 m = TAILQ_FIRST(&vm_page_queue_active); 760 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 761 int refcount; 762 763 if (m->queue != PQ_ACTIVE) { 764 break; 765 } 766 767 next = TAILQ_NEXT(m, pageq); 768 /* 769 * Don't deactivate pages that are busy. 770 */ 771 if ((m->busy != 0) || 772 (m->flags & PG_BUSY) || 773 (m->hold_count != 0)) { 774 s = splvm(); 775 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 776 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 777 splx(s); 778 m = next; 779 continue; 780 } 781 782 /* 783 * The count for pagedaemon pages is done after checking the 784 * page for eligbility... 785 */ 786 cnt.v_pdpages++; 787 788 refcount = 0; 789 if (m->object->ref_count != 0) { 790 if (m->flags & PG_REFERENCED) { 791 refcount += 1; 792 } 793 refcount += pmap_ts_referenced(VM_PAGE_TO_PHYS(m)); 794 if (refcount) { 795 m->act_count += ACT_ADVANCE + refcount; 796 if (m->act_count > ACT_MAX) 797 m->act_count = ACT_MAX; 798 } 799 } 800 801 m->flags &= ~PG_REFERENCED; 802 803 if (refcount && (m->object->ref_count != 0)) { 804 s = splvm(); 805 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 806 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 807 splx(s); 808 } else { 809 m->act_count -= min(m->act_count, ACT_DECLINE); 810 if (vm_pageout_algorithm_lru || 811 (m->object->ref_count == 0) || (m->act_count == 0)) { 812 --page_shortage; 813 vm_page_protect(m, VM_PROT_NONE); 814 if ((m->dirty == 0) && 815 (m->object->ref_count == 0)) { 816 vm_page_cache(m); 817 } else { 818 vm_page_deactivate(m); 819 } 820 } else { 821 s = splvm(); 822 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 823 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 824 splx(s); 825 } 826 } 827 m = next; 828 } 829 830 s = splvm(); 831 /* 832 * We try to maintain some *really* free pages, this allows interrupt 833 * code to be guaranteed space. 834 */ 835 while (cnt.v_free_count < cnt.v_free_reserved) { 836 static int cache_rover = 0; 837 m = vm_page_list_find(PQ_CACHE, cache_rover); 838 if (!m) 839 break; 840 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK; 841 vm_page_free(m); 842 cnt.v_dfree++; 843 } 844 splx(s); 845 846 /* 847 * If we didn't get enough free pages, and we have skipped a vnode 848 * in a writeable object, wakeup the sync daemon. And kick swapout 849 * if we did not get enough free pages. 850 */ 851 if ((cnt.v_cache_count + cnt.v_free_count) < 852 (cnt.v_free_target + cnt.v_cache_min) ) { 853 if (vnodes_skipped && 854 (cnt.v_cache_count + cnt.v_free_count) < cnt.v_free_min) { 855 if (!vfs_update_wakeup) { 856 vfs_update_wakeup = 1; 857 wakeup(&vfs_update_wakeup); 858 } 859 } 860#if !defined(NO_SWAPPING) 861 if (vm_swapping_enabled && 862 (cnt.v_free_count + cnt.v_cache_count < cnt.v_free_target)) { 863 vm_req_vmdaemon(); 864 vm_pageout_req_swapout = 1; 865 } 866#endif 867 } 868 869 870 /* 871 * make sure that we have swap space -- if we are low on memory and 872 * swap -- then kill the biggest process. 873 */ 874 if ((vm_swap_size == 0 || swap_pager_full) && 875 ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min)) { 876 bigproc = NULL; 877 bigsize = 0; 878 for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) { 879 /* 880 * if this is a system process, skip it 881 */ 882 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 883 ((p->p_pid < 48) && (vm_swap_size != 0))) { 884 continue; 885 } 886 /* 887 * if the process is in a non-running type state, 888 * don't touch it. 889 */ 890 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 891 continue; 892 } 893 /* 894 * get the process size 895 */ 896 size = p->p_vmspace->vm_pmap.pm_stats.resident_count; 897 /* 898 * if the this process is bigger than the biggest one 899 * remember it. 900 */ 901 if (size > bigsize) { 902 bigproc = p; 903 bigsize = size; 904 } 905 } 906 if (bigproc != NULL) { 907 killproc(bigproc, "out of swap space"); 908 bigproc->p_estcpu = 0; 909 bigproc->p_nice = PRIO_MIN; 910 resetpriority(bigproc); 911 wakeup(&cnt.v_free_count); 912 } 913 } 914 return force_wakeup; 915} 916 917static int 918vm_pageout_free_page_calc(count) 919vm_size_t count; 920{ 921 if (count < cnt.v_page_count) 922 return 0; 923 /* 924 * free_reserved needs to include enough for the largest swap pager 925 * structures plus enough for any pv_entry structs when paging. 926 */ 927 if (cnt.v_page_count > 1024) 928 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 929 else 930 cnt.v_free_min = 4; 931 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 932 cnt.v_interrupt_free_min; 933 cnt.v_free_reserved = vm_pageout_page_count + 934 cnt.v_pageout_free_min + (count / 768) + PQ_L2_SIZE; 935 cnt.v_free_min += cnt.v_free_reserved; 936 return 1; 937} 938 939 940#ifdef unused 941int 942vm_pageout_free_pages(object, add) 943vm_object_t object; 944int add; 945{ 946 return vm_pageout_free_page_calc(object->size); 947} 948#endif 949 950/* 951 * vm_pageout is the high level pageout daemon. 952 */ 953static void 954vm_pageout() 955{ 956 (void) spl0(); 957 958 /* 959 * Initialize some paging parameters. 960 */ 961 962 cnt.v_interrupt_free_min = 2; 963 if (cnt.v_page_count < 2000) 964 vm_pageout_page_count = 8; 965 966 vm_pageout_free_page_calc(cnt.v_page_count); 967 /* 968 * free_reserved needs to include enough for the largest swap pager 969 * structures plus enough for any pv_entry structs when paging. 970 */ 971 cnt.v_free_target = 3 * cnt.v_free_min + cnt.v_free_reserved; 972 973 if (cnt.v_free_count > 1024) { 974 cnt.v_cache_max = (cnt.v_free_count - 1024) / 2; 975 cnt.v_cache_min = (cnt.v_free_count - 1024) / 8; 976 cnt.v_inactive_target = 2*cnt.v_cache_min + 192; 977 } else { 978 cnt.v_cache_min = 0; 979 cnt.v_cache_max = 0; 980 cnt.v_inactive_target = cnt.v_free_count / 4; 981 } 982 983 /* XXX does not really belong here */ 984 if (vm_page_max_wired == 0) 985 vm_page_max_wired = cnt.v_free_count / 3; 986 987 988 swap_pager_swap_init(); 989 /* 990 * The pageout daemon is never done, so loop forever. 991 */ 992 while (TRUE) { 993 int inactive_target; 994 int s = splvm(); 995 if (!vm_pages_needed || 996 ((cnt.v_free_count + cnt.v_cache_count) > cnt.v_free_min)) { 997 vm_pages_needed = 0; 998 tsleep(&vm_pages_needed, PVM, "psleep", 0); 999 } else if (!vm_pages_needed) { 1000 tsleep(&vm_pages_needed, PVM, "psleep", hz/10); 1001 } 1002 inactive_target = 1003 (cnt.v_page_count - cnt.v_wire_count) / 4; 1004 if (inactive_target < 2*cnt.v_free_min) 1005 inactive_target = 2*cnt.v_free_min; 1006 cnt.v_inactive_target = inactive_target; 1007 if (vm_pages_needed) 1008 cnt.v_pdwakeups++; 1009 vm_pages_needed = 0; 1010 splx(s); 1011 vm_pager_sync(); 1012 vm_pageout_scan(); 1013 vm_pager_sync(); 1014 wakeup(&cnt.v_free_count); 1015 } 1016} 1017 1018#if !defined(NO_SWAPPING) 1019static void 1020vm_req_vmdaemon() 1021{ 1022 static int lastrun = 0; 1023 1024 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1025 wakeup(&vm_daemon_needed); 1026 lastrun = ticks; 1027 } 1028} 1029 1030static void 1031vm_daemon() 1032{ 1033 vm_object_t object; 1034 struct proc *p; 1035 1036 (void) spl0(); 1037 1038 while (TRUE) { 1039 tsleep(&vm_daemon_needed, PUSER, "psleep", 0); 1040 if (vm_pageout_req_swapout) { 1041 swapout_procs(); 1042 vm_pageout_req_swapout = 0; 1043 } 1044 /* 1045 * scan the processes for exceeding their rlimits or if 1046 * process is swapped out -- deactivate pages 1047 */ 1048 1049 for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) { 1050 quad_t limit; 1051 vm_offset_t size; 1052 1053 /* 1054 * if this is a system process or if we have already 1055 * looked at this process, skip it. 1056 */ 1057 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 1058 continue; 1059 } 1060 /* 1061 * if the process is in a non-running type state, 1062 * don't touch it. 1063 */ 1064 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 1065 continue; 1066 } 1067 /* 1068 * get a limit 1069 */ 1070 limit = qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 1071 p->p_rlimit[RLIMIT_RSS].rlim_max); 1072 1073 /* 1074 * let processes that are swapped out really be 1075 * swapped out set the limit to nothing (will force a 1076 * swap-out.) 1077 */ 1078 if ((p->p_flag & P_INMEM) == 0) 1079 limit = 0; /* XXX */ 1080 1081 size = p->p_vmspace->vm_pmap.pm_stats.resident_count * PAGE_SIZE; 1082 if (limit >= 0 && size >= limit) { 1083 vm_pageout_map_deactivate_pages(&p->p_vmspace->vm_map, 1084 (vm_pindex_t)(limit >> PAGE_SHIFT) ); 1085 } 1086 } 1087 1088 /* 1089 * we remove cached objects that have no RSS... 1090 */ 1091restart: 1092 object = TAILQ_FIRST(&vm_object_cached_list); 1093 while (object) { 1094 /* 1095 * if there are no resident pages -- get rid of the object 1096 */ 1097 if (object->resident_page_count == 0) { 1098 vm_object_reference(object); 1099 pager_cache(object, FALSE); 1100 goto restart; 1101 } 1102 object = TAILQ_NEXT(object, cached_list); 1103 } 1104 } 1105} 1106#endif 1107