vm_pageout.c revision 8692
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 1.49 1995/05/10 18:56:06 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/swap_pager.h> 90#include <vm/vnode_pager.h> 91 92int vm_pages_needed; /* Event on which pageout daemon sleeps */ 93 94int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 95 96extern int npendingio; 97int vm_pageout_req_swapout; /* XXX */ 98int vm_daemon_needed; 99extern int nswiodone; 100extern int swap_pager_full; 101extern int vm_swap_size; 102extern int vfs_update_wakeup; 103 104#define MAXSCAN 1024 /* maximum number of pages to scan in queues */ 105 106#define MAXLAUNDER (cnt.v_page_count > 1800 ? 32 : 16) 107 108#define VM_PAGEOUT_PAGE_COUNT 8 109int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 110 111int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 112 113/* 114 * vm_pageout_clean: 115 * cleans a vm_page 116 */ 117int 118vm_pageout_clean(m, sync) 119 register vm_page_t m; 120 int sync; 121{ 122 /* 123 * Clean the page and remove it from the laundry. 124 * 125 * We set the busy bit to cause potential page faults on this page to 126 * block. 127 * 128 * And we set pageout-in-progress to keep the object from disappearing 129 * during pageout. This guarantees that the page won't move from the 130 * inactive queue. (However, any other page on the inactive queue may 131 * move!) 132 */ 133 134 register vm_object_t object; 135 register vm_pager_t pager; 136 int pageout_status[VM_PAGEOUT_PAGE_COUNT]; 137 vm_page_t ms[VM_PAGEOUT_PAGE_COUNT], mb[VM_PAGEOUT_PAGE_COUNT]; 138 int pageout_count, b_pageout_count; 139 int anyok = 0; 140 int i; 141 vm_offset_t offset = m->offset; 142 143 object = m->object; 144 if (!object) { 145 printf("pager: object missing\n"); 146 return 0; 147 } 148 if (!object->pager && (object->flags & OBJ_INTERNAL) == 0) { 149 printf("pager: non internal obj without pager\n"); 150 } 151 /* 152 * Try to collapse the object before making a pager for it. We must 153 * unlock the page queues first. We try to defer the creation of a 154 * pager until all shadows are not paging. This allows 155 * vm_object_collapse to work better and helps control swap space 156 * size. (J. Dyson 11 Nov 93) 157 */ 158 159 if (!object->pager && 160 (cnt.v_free_count + cnt.v_cache_count) < cnt.v_pageout_free_min) 161 return 0; 162 163 if ((!sync && m->hold_count != 0) || 164 ((m->busy != 0) || (m->flags & PG_BUSY))) 165 return 0; 166 167 if (!sync && object->shadow) { 168 vm_object_collapse(object); 169 } 170 pageout_count = 1; 171 ms[0] = m; 172 173 pager = object->pager; 174 if (pager) { 175 for (i = 1; i < vm_pageout_page_count; i++) { 176 vm_page_t mt; 177 178 ms[i] = mt = vm_page_lookup(object, offset + i * NBPG); 179 if (mt) { 180 if (mt->flags & (PG_BUSY|PG_CACHE) || mt->busy) 181 break; 182 /* 183 * we can cluster ONLY if: ->> the page is NOT 184 * busy, and is NOT clean the page is not 185 * wired, busy, held, or mapped into a buffer. 186 * and one of the following: 1) The page is 187 * inactive, or a seldom used active page. 2) 188 * or we force the issue. 189 */ 190 vm_page_test_dirty(mt); 191 if ((mt->dirty & mt->valid) != 0 192 && ((mt->flags & PG_INACTIVE) || 193 (sync == VM_PAGEOUT_FORCE)) 194 && (mt->wire_count == 0) 195 && (mt->hold_count == 0)) 196 pageout_count++; 197 else 198 break; 199 } else 200 break; 201 } 202 203 if ((pageout_count < vm_pageout_page_count) && (offset != 0)) { 204 b_pageout_count = 0; 205 for (i = 0; i < vm_pageout_page_count-pageout_count; i++) { 206 vm_page_t mt; 207 208 mt = vm_page_lookup(object, offset - (i + 1) * NBPG); 209 if (mt) { 210 if (mt->flags & (PG_BUSY|PG_CACHE) || mt->busy) 211 break; 212 vm_page_test_dirty(mt); 213 if ((mt->dirty & mt->valid) != 0 214 && ((mt->flags & PG_INACTIVE) || 215 (sync == VM_PAGEOUT_FORCE)) 216 && (mt->wire_count == 0) 217 && (mt->hold_count == 0)) { 218 mb[b_pageout_count] = mt; 219 b_pageout_count++; 220 if ((offset - (i + 1) * NBPG) == 0) 221 break; 222 } else 223 break; 224 } else 225 break; 226 } 227 if (b_pageout_count > 0) { 228 for(i=pageout_count - 1;i>=0;--i) { 229 ms[i+b_pageout_count] = ms[i]; 230 } 231 for(i=0;i<b_pageout_count;i++) { 232 ms[i] = mb[b_pageout_count - (i + 1)]; 233 } 234 pageout_count += b_pageout_count; 235 } 236 } 237 238 /* 239 * we allow reads during pageouts... 240 */ 241 for (i = 0; i < pageout_count; i++) { 242 ms[i]->flags |= PG_BUSY; 243 vm_page_protect(ms[i], VM_PROT_READ); 244 } 245 object->paging_in_progress += pageout_count; 246 } else { 247 248 m->flags |= PG_BUSY; 249 250 vm_page_protect(m, VM_PROT_READ); 251 252 object->paging_in_progress++; 253 254 pager = vm_pager_allocate(PG_DFLT, 0, 255 object->size, VM_PROT_ALL, 0); 256 if (pager != NULL) { 257 object->pager = pager; 258 } 259 } 260 261 /* 262 * If there is no pager for the page, use the default pager. If 263 * there's no place to put the page at the moment, leave it in the 264 * laundry and hope that there will be paging space later. 265 */ 266 267 if ((pager && pager->pg_type == PG_SWAP) || 268 (cnt.v_free_count + cnt.v_cache_count) >= cnt.v_pageout_free_min) { 269 if (pageout_count == 1) { 270 pageout_status[0] = pager ? 271 vm_pager_put(pager, m, 272 ((sync || (object == kernel_object)) ? TRUE : FALSE)) : 273 VM_PAGER_FAIL; 274 } else { 275 if (!pager) { 276 for (i = 0; i < pageout_count; i++) 277 pageout_status[i] = VM_PAGER_FAIL; 278 } else { 279 vm_pager_put_pages(pager, ms, pageout_count, 280 ((sync || (object == kernel_object)) ? TRUE : FALSE), 281 pageout_status); 282 } 283 } 284 } else { 285 for (i = 0; i < pageout_count; i++) 286 pageout_status[i] = VM_PAGER_FAIL; 287 } 288 289 for (i = 0; i < pageout_count; i++) { 290 switch (pageout_status[i]) { 291 case VM_PAGER_OK: 292 ++anyok; 293 break; 294 case VM_PAGER_PEND: 295 ++anyok; 296 break; 297 case VM_PAGER_BAD: 298 /* 299 * Page outside of range of object. Right now we 300 * essentially lose the changes by pretending it 301 * worked. 302 */ 303 pmap_clear_modify(VM_PAGE_TO_PHYS(ms[i])); 304 ms[i]->dirty = 0; 305 break; 306 case VM_PAGER_ERROR: 307 case VM_PAGER_FAIL: 308 /* 309 * If page couldn't be paged out, then reactivate the 310 * page so it doesn't clog the inactive list. (We 311 * will try paging out it again later). 312 */ 313 if (ms[i]->flags & PG_INACTIVE) 314 vm_page_activate(ms[i]); 315 break; 316 case VM_PAGER_AGAIN: 317 break; 318 } 319 320 321 /* 322 * If the operation is still going, leave the page busy to 323 * block all other accesses. Also, leave the paging in 324 * progress indicator set so that we don't attempt an object 325 * collapse. 326 */ 327 if (pageout_status[i] != VM_PAGER_PEND) { 328 vm_object_pip_wakeup(object); 329 if ((ms[i]->flags & (PG_REFERENCED|PG_WANTED)) || 330 pmap_is_referenced(VM_PAGE_TO_PHYS(ms[i]))) { 331 pmap_clear_reference(VM_PAGE_TO_PHYS(ms[i])); 332 ms[i]->flags &= ~PG_REFERENCED; 333 if (ms[i]->flags & PG_INACTIVE) 334 vm_page_activate(ms[i]); 335 } 336 PAGE_WAKEUP(ms[i]); 337 } 338 } 339 return anyok; 340} 341 342/* 343 * vm_pageout_object_deactivate_pages 344 * 345 * deactivate enough pages to satisfy the inactive target 346 * requirements or if vm_page_proc_limit is set, then 347 * deactivate all of the pages in the object and its 348 * shadows. 349 * 350 * The object and map must be locked. 351 */ 352int 353vm_pageout_object_deactivate_pages(map, object, count, map_remove_only) 354 vm_map_t map; 355 vm_object_t object; 356 int count; 357 int map_remove_only; 358{ 359 register vm_page_t p, next; 360 int rcount; 361 int dcount; 362 363 dcount = 0; 364 if (count == 0) 365 count = 1; 366 367 if (object->pager && (object->pager->pg_type == PG_DEVICE)) 368 return 0; 369 370 if (object->shadow) { 371 if (object->shadow->ref_count == 1) 372 dcount += vm_pageout_object_deactivate_pages(map, object->shadow, count / 2 + 1, map_remove_only); 373 else 374 vm_pageout_object_deactivate_pages(map, object->shadow, count, 1); 375 } 376 if (object->paging_in_progress || !vm_object_lock_try(object)) 377 return dcount; 378 379 /* 380 * scan the objects entire memory queue 381 */ 382 rcount = object->resident_page_count; 383 p = object->memq.tqh_first; 384 while (p && (rcount-- > 0)) { 385 next = p->listq.tqe_next; 386 cnt.v_pdpages++; 387 vm_page_lock_queues(); 388 if (p->wire_count != 0 || 389 p->hold_count != 0 || 390 p->busy != 0 || 391 !pmap_page_exists(vm_map_pmap(map), VM_PAGE_TO_PHYS(p))) { 392 p = next; 393 continue; 394 } 395 /* 396 * if a page is active, not wired and is in the processes 397 * pmap, then deactivate the page. 398 */ 399 if ((p->flags & (PG_ACTIVE | PG_BUSY)) == PG_ACTIVE) { 400 if (!pmap_is_referenced(VM_PAGE_TO_PHYS(p)) && 401 (p->flags & (PG_REFERENCED|PG_WANTED)) == 0) { 402 p->act_count -= min(p->act_count, ACT_DECLINE); 403 /* 404 * if the page act_count is zero -- then we 405 * deactivate 406 */ 407 if (!p->act_count) { 408 if (!map_remove_only) 409 vm_page_deactivate(p); 410 vm_page_protect(p, VM_PROT_NONE); 411 /* 412 * else if on the next go-around we 413 * will deactivate the page we need to 414 * place the page on the end of the 415 * queue to age the other pages in 416 * memory. 417 */ 418 } else { 419 TAILQ_REMOVE(&vm_page_queue_active, p, pageq); 420 TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); 421 } 422 /* 423 * see if we are done yet 424 */ 425 if (p->flags & PG_INACTIVE) { 426 --count; 427 ++dcount; 428 if (count <= 0 && 429 cnt.v_inactive_count > cnt.v_inactive_target) { 430 vm_page_unlock_queues(); 431 vm_object_unlock(object); 432 return dcount; 433 } 434 } 435 } else { 436 /* 437 * Move the page to the bottom of the queue. 438 */ 439 pmap_clear_reference(VM_PAGE_TO_PHYS(p)); 440 p->flags &= ~PG_REFERENCED; 441 if (p->act_count < ACT_MAX) 442 p->act_count += ACT_ADVANCE; 443 444 TAILQ_REMOVE(&vm_page_queue_active, p, pageq); 445 TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); 446 } 447 } else if ((p->flags & (PG_INACTIVE | PG_BUSY)) == PG_INACTIVE) { 448 vm_page_protect(p, VM_PROT_NONE); 449 } 450 vm_page_unlock_queues(); 451 p = next; 452 } 453 vm_object_unlock(object); 454 return dcount; 455} 456 457 458/* 459 * deactivate some number of pages in a map, try to do it fairly, but 460 * that is really hard to do. 461 */ 462 463void 464vm_pageout_map_deactivate_pages(map, entry, count, freeer) 465 vm_map_t map; 466 vm_map_entry_t entry; 467 int *count; 468 int (*freeer) (vm_map_t, vm_object_t, int); 469{ 470 vm_map_t tmpm; 471 vm_map_entry_t tmpe; 472 vm_object_t obj; 473 474 if (*count <= 0) 475 return; 476 vm_map_reference(map); 477 if (!lock_try_read(&map->lock)) { 478 vm_map_deallocate(map); 479 return; 480 } 481 if (entry == 0) { 482 tmpe = map->header.next; 483 while (tmpe != &map->header && *count > 0) { 484 vm_pageout_map_deactivate_pages(map, tmpe, count, freeer, 0); 485 tmpe = tmpe->next; 486 }; 487 } else if (entry->is_sub_map || entry->is_a_map) { 488 tmpm = entry->object.share_map; 489 tmpe = tmpm->header.next; 490 while (tmpe != &tmpm->header && *count > 0) { 491 vm_pageout_map_deactivate_pages(tmpm, tmpe, count, freeer, 0); 492 tmpe = tmpe->next; 493 }; 494 } else if ((obj = entry->object.vm_object) != 0) { 495 *count -= (*freeer) (map, obj, *count); 496 } 497 lock_read_done(&map->lock); 498 vm_map_deallocate(map); 499 return; 500} 501 502void 503vm_req_vmdaemon() 504{ 505 static int lastrun = 0; 506 507 if ((ticks > (lastrun + hz / 10)) || (ticks < lastrun)) { 508 wakeup((caddr_t) &vm_daemon_needed); 509 lastrun = ticks; 510 } 511} 512 513/* 514 * vm_pageout_scan does the dirty work for the pageout daemon. 515 */ 516int 517vm_pageout_scan() 518{ 519 vm_page_t m; 520 int page_shortage, maxscan, maxlaunder, pcount; 521 int pages_freed; 522 vm_page_t next; 523 struct proc *p, *bigproc; 524 vm_offset_t size, bigsize; 525 vm_object_t object; 526 int force_wakeup = 0; 527 int vnodes_skipped = 0; 528 529 pages_freed = 0; 530 531 /* 532 * Start scanning the inactive queue for pages we can free. We keep 533 * scanning until we have enough free pages or we have scanned through 534 * the entire queue. If we encounter dirty pages, we start cleaning 535 * them. 536 */ 537 538 maxlaunder = (cnt.v_inactive_target > MAXLAUNDER) ? 539 MAXLAUNDER : cnt.v_inactive_target; 540 541rescan1: 542 maxscan = cnt.v_inactive_count; 543 m = vm_page_queue_inactive.tqh_first; 544 while ((m != NULL) && (maxscan-- > 0) && 545 ((cnt.v_cache_count + cnt.v_free_count) < (cnt.v_cache_min + cnt.v_free_target))) { 546 vm_page_t next; 547 548 cnt.v_pdpages++; 549 next = m->pageq.tqe_next; 550 551#if defined(VM_DIAGNOSE) 552 if ((m->flags & PG_INACTIVE) == 0) { 553 printf("vm_pageout_scan: page not inactive?\n"); 554 break; 555 } 556#endif 557 558 /* 559 * dont mess with busy pages 560 */ 561 if (m->hold_count || m->busy || (m->flags & PG_BUSY)) { 562 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 563 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 564 m = next; 565 continue; 566 } 567 if (((m->flags & PG_REFERENCED) == 0) && 568 pmap_is_referenced(VM_PAGE_TO_PHYS(m))) { 569 m->flags |= PG_REFERENCED; 570 } 571 if (m->object->ref_count == 0) { 572 m->flags &= ~PG_REFERENCED; 573 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 574 } 575 if ((m->flags & (PG_REFERENCED|PG_WANTED)) != 0) { 576 m->flags &= ~PG_REFERENCED; 577 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 578 vm_page_activate(m); 579 if (m->act_count < ACT_MAX) 580 m->act_count += ACT_ADVANCE; 581 m = next; 582 continue; 583 } 584 585 vm_page_test_dirty(m); 586 if (m->dirty == 0) { 587 if (m->bmapped == 0) { 588 if (m->valid == 0) { 589 pmap_page_protect(VM_PAGE_TO_PHYS(m), VM_PROT_NONE); 590 vm_page_free(m); 591 cnt.v_dfree++; 592 } else { 593 vm_page_cache(m); 594 } 595 ++pages_freed; 596 } else { 597 m = next; 598 continue; 599 } 600 } else if (maxlaunder > 0) { 601 int written; 602 struct vnode *vp = NULL; 603 604 object = m->object; 605 if ((object->flags & OBJ_DEAD) || !vm_object_lock_try(object)) { 606 m = next; 607 continue; 608 } 609 610 if (object->pager && object->pager->pg_type == PG_VNODE) { 611 vp = ((vn_pager_t) object->pager->pg_data)->vnp_vp; 612 if (VOP_ISLOCKED(vp) || vget(vp, 1)) { 613 vm_object_unlock(object); 614 if (object->flags & OBJ_WRITEABLE) 615 ++vnodes_skipped; 616 m = next; 617 continue; 618 } 619 } 620 621 /* 622 * If a page is dirty, then it is either being washed 623 * (but not yet cleaned) or it is still in the 624 * laundry. If it is still in the laundry, then we 625 * start the cleaning operation. 626 */ 627 written = vm_pageout_clean(m, 0); 628 629 if (vp) 630 vput(vp); 631 632 vm_object_unlock(object); 633 634 if (!next) { 635 break; 636 } 637 maxlaunder -= written; 638 /* 639 * if the next page has been re-activated, start 640 * scanning again 641 */ 642 if ((next->flags & PG_INACTIVE) == 0) { 643 goto rescan1; 644 } 645 } 646 m = next; 647 } 648 649 /* 650 * Compute the page shortage. If we are still very low on memory be 651 * sure that we will move a minimal amount of pages from active to 652 * inactive. 653 */ 654 655 page_shortage = cnt.v_inactive_target - 656 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 657 if (page_shortage <= 0) { 658 if (pages_freed == 0) { 659 page_shortage = cnt.v_free_min - cnt.v_free_count; 660 } else { 661 page_shortage = 1; 662 } 663 } 664 maxscan = MAXSCAN; 665 pcount = cnt.v_active_count; 666 m = vm_page_queue_active.tqh_first; 667 while ((m != NULL) && (maxscan > 0) && (pcount-- > 0) && (page_shortage > 0)) { 668 669 cnt.v_pdpages++; 670 next = m->pageq.tqe_next; 671 672 /* 673 * Don't deactivate pages that are busy. 674 */ 675 if ((m->busy != 0) || 676 (m->flags & PG_BUSY) || 677 (m->hold_count != 0)) { 678 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 679 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 680 m = next; 681 continue; 682 } 683 if (m->object->ref_count && ((m->flags & (PG_REFERENCED|PG_WANTED)) || 684 pmap_is_referenced(VM_PAGE_TO_PHYS(m)))) { 685 int s; 686 687 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 688 m->flags &= ~PG_REFERENCED; 689 if (m->act_count < ACT_MAX) { 690 m->act_count += ACT_ADVANCE; 691 } 692 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 693 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 694 } else { 695 m->flags &= ~PG_REFERENCED; 696 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 697 m->act_count -= min(m->act_count, ACT_DECLINE); 698 699 /* 700 * if the page act_count is zero -- then we deactivate 701 */ 702 if (!m->act_count && (page_shortage > 0)) { 703 if (m->object->ref_count == 0) { 704 --page_shortage; 705 vm_page_test_dirty(m); 706 if ((m->bmapped == 0) && (m->dirty == 0) ) { 707 m->act_count = 0; 708 vm_page_cache(m); 709 } else { 710 vm_page_deactivate(m); 711 } 712 } else { 713 vm_page_deactivate(m); 714 --page_shortage; 715 } 716 } else if (m->act_count) { 717 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 718 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 719 } 720 } 721 maxscan--; 722 m = next; 723 } 724 725 /* 726 * We try to maintain some *really* free pages, this allows interrupt 727 * code to be guaranteed space. 728 */ 729 while (cnt.v_free_count < cnt.v_free_reserved) { 730 m = vm_page_queue_cache.tqh_first; 731 if (!m) 732 break; 733 vm_page_free(m); 734 cnt.v_dfree++; 735 } 736 737 /* 738 * If we didn't get enough free pages, and we have skipped a vnode 739 * in a writeable object, wakeup the sync daemon. And kick swapout 740 * if we did not get enough free pages. 741 */ 742 if ((cnt.v_cache_count + cnt.v_free_count) < cnt.v_free_target) { 743 if (vnodes_skipped && 744 (cnt.v_cache_count + cnt.v_free_count) < cnt.v_free_min) { 745 if (!vfs_update_wakeup) { 746 vfs_update_wakeup = 1; 747 wakeup((caddr_t) &vfs_update_wakeup); 748 } 749 } 750 /* 751 * now swap processes out if we are in low memory conditions 752 */ 753 if (!swap_pager_full && vm_swap_size && 754 vm_pageout_req_swapout == 0) { 755 vm_pageout_req_swapout = 1; 756 vm_req_vmdaemon(); 757 } 758 } 759 760 if ((cnt.v_inactive_count + cnt.v_free_count + cnt.v_cache_count) < 761 (cnt.v_inactive_target + cnt.v_free_min)) { 762 vm_req_vmdaemon(); 763 } 764 765 /* 766 * make sure that we have swap space -- if we are low on memory and 767 * swap -- then kill the biggest process. 768 */ 769 if ((vm_swap_size == 0 || swap_pager_full) && 770 ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min)) { 771 bigproc = NULL; 772 bigsize = 0; 773 for (p = (struct proc *) allproc; p != NULL; p = p->p_next) { 774 /* 775 * if this is a system process, skip it 776 */ 777 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 778 ((p->p_pid < 48) && (vm_swap_size != 0))) { 779 continue; 780 } 781 /* 782 * if the process is in a non-running type state, 783 * don't touch it. 784 */ 785 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 786 continue; 787 } 788 /* 789 * get the process size 790 */ 791 size = p->p_vmspace->vm_pmap.pm_stats.resident_count; 792 /* 793 * if the this process is bigger than the biggest one 794 * remember it. 795 */ 796 if (size > bigsize) { 797 bigproc = p; 798 bigsize = size; 799 } 800 } 801 if (bigproc != NULL) { 802 printf("Process %lu killed by vm_pageout -- out of swap\n", (u_long) bigproc->p_pid); 803 psignal(bigproc, SIGKILL); 804 bigproc->p_estcpu = 0; 805 bigproc->p_nice = PRIO_MIN; 806 resetpriority(bigproc); 807 wakeup((caddr_t) &cnt.v_free_count); 808 } 809 } 810 return force_wakeup; 811} 812 813/* 814 * vm_pageout is the high level pageout daemon. 815 */ 816void 817vm_pageout() 818{ 819 (void) spl0(); 820 821 /* 822 * Initialize some paging parameters. 823 */ 824 825 cnt.v_interrupt_free_min = 2; 826 827 if (cnt.v_page_count > 1024) 828 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 829 else 830 cnt.v_free_min = 4; 831 /* 832 * free_reserved needs to include enough for the largest swap pager 833 * structures plus enough for any pv_entry structs when paging. 834 */ 835 cnt.v_pageout_free_min = 6 + cnt.v_page_count / 1024 + 836 cnt.v_interrupt_free_min; 837 cnt.v_free_reserved = cnt.v_pageout_free_min + 6; 838 cnt.v_free_target = 3 * cnt.v_free_min + cnt.v_free_reserved; 839 cnt.v_free_min += cnt.v_free_reserved; 840 841 if (cnt.v_page_count > 1024) { 842 cnt.v_cache_max = (cnt.v_free_count - 1024) / 2; 843 cnt.v_cache_min = (cnt.v_free_count - 1024) / 8; 844 cnt.v_inactive_target = 2*cnt.v_cache_min + 192; 845 } else { 846 cnt.v_cache_min = 0; 847 cnt.v_cache_max = 0; 848 cnt.v_inactive_target = cnt.v_free_count / 4; 849 } 850 851 /* XXX does not really belong here */ 852 if (vm_page_max_wired == 0) 853 vm_page_max_wired = cnt.v_free_count / 3; 854 855 856 (void) swap_pager_alloc(0, 0, 0, 0); 857 /* 858 * The pageout daemon is never done, so loop forever. 859 */ 860 while (TRUE) { 861 int s = splhigh(); 862 863 if (!vm_pages_needed || 864 ((cnt.v_free_count >= cnt.v_free_reserved) && 865 (cnt.v_free_count + cnt.v_cache_count >= cnt.v_free_min))) { 866 vm_pages_needed = 0; 867 tsleep((caddr_t) &vm_pages_needed, PVM, "psleep", 0); 868 } 869 vm_pages_needed = 0; 870 splx(s); 871 cnt.v_pdwakeups++; 872 vm_pager_sync(); 873 vm_pageout_scan(); 874 vm_pager_sync(); 875 wakeup((caddr_t) &cnt.v_free_count); 876 wakeup((caddr_t) kmem_map); 877 } 878} 879 880void 881vm_daemon() 882{ 883 vm_object_t object; 884 struct proc *p; 885 886 while (TRUE) { 887 tsleep((caddr_t) &vm_daemon_needed, PUSER, "psleep", 0); 888 if( vm_pageout_req_swapout) { 889 swapout_threads(); 890 vm_pageout_req_swapout = 0; 891 } 892 /* 893 * scan the processes for exceeding their rlimits or if 894 * process is swapped out -- deactivate pages 895 */ 896 897 for (p = (struct proc *) allproc; p != NULL; p = p->p_next) { 898 int overage; 899 quad_t limit; 900 vm_offset_t size; 901 902 /* 903 * if this is a system process or if we have already 904 * looked at this process, skip it. 905 */ 906 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 907 continue; 908 } 909 /* 910 * if the process is in a non-running type state, 911 * don't touch it. 912 */ 913 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 914 continue; 915 } 916 /* 917 * get a limit 918 */ 919 limit = qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 920 p->p_rlimit[RLIMIT_RSS].rlim_max); 921 922 /* 923 * let processes that are swapped out really be 924 * swapped out set the limit to nothing (will force a 925 * swap-out.) 926 */ 927 if ((p->p_flag & P_INMEM) == 0) 928 limit = 0; /* XXX */ 929 930 size = p->p_vmspace->vm_pmap.pm_stats.resident_count * NBPG; 931 if (limit >= 0 && size >= limit) { 932 overage = (size - limit) / NBPG; 933 vm_pageout_map_deactivate_pages(&p->p_vmspace->vm_map, 934 (vm_map_entry_t) 0, &overage, vm_pageout_object_deactivate_pages); 935 } 936 } 937 } 938 939 /* 940 * we remove cached objects that have no RSS... 941 */ 942restart: 943 vm_object_cache_lock(); 944 object = vm_object_cached_list.tqh_first; 945 while (object) { 946 vm_object_cache_unlock(); 947 /* 948 * if there are no resident pages -- get rid of the object 949 */ 950 if (object->resident_page_count == 0) { 951 if (object != vm_object_lookup(object->pager)) 952 panic("vm_object_cache_trim: I'm sooo confused."); 953 pager_cache(object, FALSE); 954 goto restart; 955 } 956 object = object->cached_list.tqe_next; 957 vm_object_cache_lock(); 958 } 959 vm_object_cache_unlock(); 960} 961