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 1.97 1997/07/27 04:49:19 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/signalvar.h> 81 #include <sys/vnode.h> 82 #include <sys/vmmeter.h> 83 #include <sys/sysctl.h> 84 85 #include <vm/vm.h> 86 #include <vm/vm_param.h> 87 #include <vm/vm_prot.h> 88 #include <sys/lock.h> 89 #include <vm/vm_object.h> 90 #include <vm/vm_page.h> 91 #include <vm/vm_map.h> 92 #include <vm/vm_pageout.h> 93 #include <vm/vm_pager.h> 94 #include <vm/swap_pager.h> 95 #include <vm/vm_extern.h> 96 97 /* 98 * System initialization 99 */ 100 101 /* the kernel process "vm_pageout"*/ 102 static void vm_pageout __P((void)); 103 static int vm_pageout_clean __P((vm_page_t, int)); 104 static int vm_pageout_scan __P((void)); 105 static int vm_pageout_free_page_calc __P((vm_size_t count)); 106 struct proc *pageproc; 107 108 static struct kproc_desc page_kp = { 109 "pagedaemon", 110 vm_pageout, 111 &pageproc 112 }; 113 SYSINIT_KT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 114 115 #if !defined(NO_SWAPPING) 116 /* the kernel process "vm_daemon"*/ 117 static void vm_daemon __P((void)); 118 static struct proc *vmproc; 119 120 static struct kproc_desc vm_kp = { 121 "vmdaemon", 122 vm_daemon, 123 &vmproc 124 }; 125 SYSINIT_KT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) 126 #endif 127 128 129 int vm_pages_needed; /* Event on which pageout daemon sleeps */ 130 131 int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 132 133 extern int npendingio; 134 #if !defined(NO_SWAPPING) 135 static int vm_pageout_req_swapout; /* XXX */ 136 static int vm_daemon_needed; 137 #endif 138 extern int nswiodone; 139 extern int vm_swap_size; 140 extern int vfs_update_wakeup; 141 int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 142 int vm_pageout_full_stats_interval = 0; 143 int vm_pageout_stats_free_max=0, vm_pageout_algorithm_lru=0; 144 #if defined(NO_SWAPPING) 145 int vm_swapping_enabled=0; 146 #else 147 int vm_swapping_enabled=1; 148 #endif 149 150 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 151 CTLFLAG_RW, &vm_pageout_algorithm_lru, 0, ""); 152 153 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 154 CTLFLAG_RW, &vm_pageout_stats_max, 0, ""); 155 156 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 157 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, ""); 158 159 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 160 CTLFLAG_RW, &vm_pageout_stats_interval, 0, ""); 161 162 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max, 163 CTLFLAG_RW, &vm_pageout_stats_free_max, 0, ""); 164 165 #if defined(NO_SWAPPING) 166 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swapping_enabled, 167 CTLFLAG_RD, &vm_swapping_enabled, 0, ""); 168 #else 169 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swapping_enabled, 170 CTLFLAG_RW, &vm_swapping_enabled, 0, ""); 171 #endif 172 173 #define MAXLAUNDER (cnt.v_page_count > 1800 ? 32 : 16) 174 175 #define VM_PAGEOUT_PAGE_COUNT 16 176 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 177 178 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 179 180 #if !defined(NO_SWAPPING) 181 typedef void freeer_fcn_t __P((vm_map_t, vm_object_t, vm_pindex_t, int)); 182 static void vm_pageout_map_deactivate_pages __P((vm_map_t, vm_pindex_t)); 183 static freeer_fcn_t vm_pageout_object_deactivate_pages; 184 static void vm_req_vmdaemon __P((void)); 185 #endif 186 static void vm_pageout_page_stats(void); 187 188 /* 189 * vm_pageout_clean: 190 * 191 * Clean the page and remove it from the laundry. 192 * 193 * We set the busy bit to cause potential page faults on this page to 194 * block. 195 * 196 * And we set pageout-in-progress to keep the object from disappearing 197 * during pageout. This guarantees that the page won't move from the 198 * inactive queue. (However, any other page on the inactive queue may 199 * move!) 200 */ 201 static int 202 vm_pageout_clean(m, sync) 203 vm_page_t m; 204 int sync; 205 { 206 register vm_object_t object; 207 vm_page_t mc[2*vm_pageout_page_count]; 208 int pageout_count; 209 int i, forward_okay, backward_okay, page_base; 210 vm_pindex_t pindex = m->pindex; 211 212 object = m->object; 213 214 /* 215 * If not OBJT_SWAP, additional memory may be needed to do the pageout. 216 * Try to avoid the deadlock. 217 */ 218 if ((sync != VM_PAGEOUT_FORCE) && 219 (object->type == OBJT_DEFAULT) && 220 ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_pageout_free_min)) 221 return 0; 222 223 /* 224 * Don't mess with the page if it's busy. 225 */ 226 if ((!sync && m->hold_count != 0) || 227 ((m->busy != 0) || (m->flags & PG_BUSY))) 228 return 0; 229 230 /* 231 * Try collapsing before it's too late. 232 */ 233 if (!sync && object->backing_object) { 234 vm_object_collapse(object); 235 } 236 237 mc[vm_pageout_page_count] = m; 238 pageout_count = 1; 239 page_base = vm_pageout_page_count; 240 forward_okay = TRUE; 241 if (pindex != 0) 242 backward_okay = TRUE; 243 else 244 backward_okay = FALSE; 245 /* 246 * Scan object for clusterable pages. 247 * 248 * We can cluster ONLY if: ->> the page is NOT 249 * clean, wired, busy, held, or mapped into a 250 * buffer, and one of the following: 251 * 1) The page is inactive, or a seldom used 252 * active page. 253 * -or- 254 * 2) we force the issue. 255 */ 256 for (i = 1; (i < vm_pageout_page_count) && (forward_okay || backward_okay); i++) { 257 vm_page_t p; 258 259 /* 260 * See if forward page is clusterable. 261 */ 262 if (forward_okay) { 263 /* 264 * Stop forward scan at end of object. 265 */ 266 if ((pindex + i) > object->size) { 267 forward_okay = FALSE; 268 goto do_backward; 269 } 270 p = vm_page_lookup(object, pindex + i); 271 if (p) { 272 if (((p->queue - p->pc) == PQ_CACHE) || 273 (p->flags & PG_BUSY) || p->busy) { 274 forward_okay = FALSE; 275 goto do_backward; 276 } 277 vm_page_test_dirty(p); 278 if ((p->dirty & p->valid) != 0 && 279 ((p->queue == PQ_INACTIVE) || 280 (sync == VM_PAGEOUT_FORCE)) && 281 (p->wire_count == 0) && 282 (p->hold_count == 0)) { 283 mc[vm_pageout_page_count + i] = p; 284 pageout_count++; 285 if (pageout_count == vm_pageout_page_count) 286 break; 287 } else { 288 forward_okay = FALSE; 289 } 290 } else { 291 forward_okay = FALSE; 292 } 293 } 294 do_backward: 295 /* 296 * See if backward page is clusterable. 297 */ 298 if (backward_okay) { 299 /* 300 * Stop backward scan at beginning of object. 301 */ 302 if ((pindex - i) == 0) { 303 backward_okay = FALSE; 304 } 305 p = vm_page_lookup(object, pindex - i); 306 if (p) { 307 if (((p->queue - p->pc) == PQ_CACHE) || 308 (p->flags & PG_BUSY) || p->busy) { 309 backward_okay = FALSE; 310 continue; 311 } 312 vm_page_test_dirty(p); 313 if ((p->dirty & p->valid) != 0 && 314 ((p->queue == PQ_INACTIVE) || 315 (sync == VM_PAGEOUT_FORCE)) && 316 (p->wire_count == 0) && 317 (p->hold_count == 0)) { 318 mc[vm_pageout_page_count - i] = p; 319 pageout_count++; 320 page_base--; 321 if (pageout_count == vm_pageout_page_count) 322 break; 323 } else { 324 backward_okay = FALSE; 325 } 326 } else { 327 backward_okay = FALSE; 328 } 329 } 330 } 331 332 /* 333 * we allow reads during pageouts... 334 */ 335 for (i = page_base; i < (page_base + pageout_count); i++) { 336 mc[i]->flags |= PG_BUSY; 337 vm_page_protect(mc[i], VM_PROT_READ); 338 } 339 340 return vm_pageout_flush(&mc[page_base], pageout_count, sync); 341 } 342 343 int 344 vm_pageout_flush(mc, count, sync) 345 vm_page_t *mc; 346 int count; 347 int sync; 348 { 349 register vm_object_t object; 350 int pageout_status[count]; 351 int anyok = 0; 352 int i; 353 354 object = mc[0]->object; 355 object->paging_in_progress += count; 356 357 vm_pager_put_pages(object, mc, count, 358 ((sync || (object == kernel_object)) ? TRUE : FALSE), 359 pageout_status); 360 361 for (i = 0; i < count; i++) { 362 vm_page_t mt = mc[i]; 363 364 switch (pageout_status[i]) { 365 case VM_PAGER_OK: 366 ++anyok; 367 break; 368 case VM_PAGER_PEND: 369 ++anyok; 370 break; 371 case VM_PAGER_BAD: 372 /* 373 * Page outside of range of object. Right now we 374 * essentially lose the changes by pretending it 375 * worked. 376 */ 377 pmap_clear_modify(VM_PAGE_TO_PHYS(mt)); 378 mt->dirty = 0; 379 break; 380 case VM_PAGER_ERROR: 381 case VM_PAGER_FAIL: 382 /* 383 * If page couldn't be paged out, then reactivate the 384 * page so it doesn't clog the inactive list. (We 385 * will try paging out it again later). 386 */ 387 if (mt->queue == PQ_INACTIVE) 388 vm_page_activate(mt); 389 break; 390 case VM_PAGER_AGAIN: 391 break; 392 } 393 394 395 /* 396 * If the operation is still going, leave the page busy to 397 * block all other accesses. Also, leave the paging in 398 * progress indicator set so that we don't attempt an object 399 * collapse. 400 */ 401 if (pageout_status[i] != VM_PAGER_PEND) { 402 vm_object_pip_wakeup(object); 403 PAGE_WAKEUP(mt); 404 } 405 } 406 return anyok; 407 } 408 409 #if !defined(NO_SWAPPING) 410 /* 411 * vm_pageout_object_deactivate_pages 412 * 413 * deactivate enough pages to satisfy the inactive target 414 * requirements or if vm_page_proc_limit is set, then 415 * deactivate all of the pages in the object and its 416 * backing_objects. 417 * 418 * The object and map must be locked. 419 */ 420 static void 421 vm_pageout_object_deactivate_pages(map, object, desired, map_remove_only) 422 vm_map_t map; 423 vm_object_t object; 424 vm_pindex_t desired; 425 int map_remove_only; 426 { 427 register vm_page_t p, next; 428 int rcount; 429 int remove_mode; 430 int s; 431 432 if (object->type == OBJT_DEVICE) 433 return; 434 435 while (object) { 436 if (vm_map_pmap(map)->pm_stats.resident_count <= desired) 437 return; 438 if (object->paging_in_progress) 439 return; 440 441 remove_mode = map_remove_only; 442 if (object->shadow_count > 1) 443 remove_mode = 1; 444 /* 445 * scan the objects entire memory queue 446 */ 447 rcount = object->resident_page_count; 448 p = TAILQ_FIRST(&object->memq); 449 while (p && (rcount-- > 0)) { 450 int refcount; 451 if (vm_map_pmap(map)->pm_stats.resident_count <= desired) 452 return; 453 next = TAILQ_NEXT(p, listq); 454 cnt.v_pdpages++; 455 if (p->wire_count != 0 || 456 p->hold_count != 0 || 457 p->busy != 0 || 458 (p->flags & PG_BUSY) || 459 !pmap_page_exists(vm_map_pmap(map), VM_PAGE_TO_PHYS(p))) { 460 p = next; 461 continue; 462 } 463 464 refcount = pmap_ts_referenced(VM_PAGE_TO_PHYS(p)); 465 if (refcount) { 466 p->flags |= PG_REFERENCED; 467 } else if (p->flags & PG_REFERENCED) { 468 refcount = 1; 469 } 470 471 if ((p->queue != PQ_ACTIVE) && 472 (p->flags & PG_REFERENCED)) { 473 vm_page_activate(p); 474 p->act_count += refcount; 475 p->flags &= ~PG_REFERENCED; 476 } else if (p->queue == PQ_ACTIVE) { 477 if ((p->flags & PG_REFERENCED) == 0) { 478 p->act_count -= min(p->act_count, ACT_DECLINE); 479 if (!remove_mode && (vm_pageout_algorithm_lru || (p->act_count == 0))) { 480 vm_page_protect(p, VM_PROT_NONE); 481 vm_page_deactivate(p); 482 } else { 483 s = splvm(); 484 TAILQ_REMOVE(&vm_page_queue_active, p, pageq); 485 TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); 486 splx(s); 487 } 488 } else { 489 p->flags &= ~PG_REFERENCED; 490 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 491 p->act_count += ACT_ADVANCE; 492 s = splvm(); 493 TAILQ_REMOVE(&vm_page_queue_active, p, pageq); 494 TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); 495 splx(s); 496 } 497 } else if (p->queue == PQ_INACTIVE) { 498 vm_page_protect(p, VM_PROT_NONE); 499 } 500 p = next; 501 } 502 object = object->backing_object; 503 } 504 return; 505 } 506 507 /* 508 * deactivate some number of pages in a map, try to do it fairly, but 509 * that is really hard to do. 510 */ 511 static void 512 vm_pageout_map_deactivate_pages(map, desired) 513 vm_map_t map; 514 vm_pindex_t desired; 515 { 516 vm_map_entry_t tmpe; 517 vm_object_t obj, bigobj; 518 519 vm_map_reference(map); 520 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT, (void *)0, curproc)) { 521 vm_map_deallocate(map); 522 return; 523 } 524 525 bigobj = NULL; 526 527 /* 528 * first, search out the biggest object, and try to free pages from 529 * that. 530 */ 531 tmpe = map->header.next; 532 while (tmpe != &map->header) { 533 if ((tmpe->eflags & (MAP_ENTRY_IS_A_MAP|MAP_ENTRY_IS_SUB_MAP)) == 0) { 534 obj = tmpe->object.vm_object; 535 if ((obj != NULL) && (obj->shadow_count <= 1) && 536 ((bigobj == NULL) || 537 (bigobj->resident_page_count < obj->resident_page_count))) { 538 bigobj = obj; 539 } 540 } 541 tmpe = tmpe->next; 542 } 543 544 if (bigobj) 545 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 546 547 /* 548 * Next, hunt around for other pages to deactivate. We actually 549 * do this search sort of wrong -- .text first is not the best idea. 550 */ 551 tmpe = map->header.next; 552 while (tmpe != &map->header) { 553 if (vm_map_pmap(map)->pm_stats.resident_count <= desired) 554 break; 555 if ((tmpe->eflags & (MAP_ENTRY_IS_A_MAP|MAP_ENTRY_IS_SUB_MAP)) == 0) { 556 obj = tmpe->object.vm_object; 557 if (obj) 558 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 559 } 560 tmpe = tmpe->next; 561 }; 562 563 /* 564 * Remove all mappings if a process is swapped out, this will free page 565 * table pages. 566 */ 567 if (desired == 0) 568 pmap_remove(vm_map_pmap(map), 569 VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS); 570 vm_map_unlock(map); 571 vm_map_deallocate(map); 572 return; 573 } 574 #endif 575 576 /* 577 * vm_pageout_scan does the dirty work for the pageout daemon. 578 */ 579 static int 580 vm_pageout_scan() 581 { 582 vm_page_t m, next; 583 int page_shortage, addl_page_shortage, maxscan, maxlaunder, pcount; 584 int pages_freed; 585 struct proc *p, *bigproc; 586 vm_offset_t size, bigsize; 587 vm_object_t object; 588 int force_wakeup = 0; 589 int vnodes_skipped = 0; 590 int s; 591 592 /* 593 * Start scanning the inactive queue for pages we can free. We keep 594 * scanning until we have enough free pages or we have scanned through 595 * the entire queue. If we encounter dirty pages, we start cleaning 596 * them. 597 */ 598 599 pages_freed = 0; 600 addl_page_shortage = 0; 601 602 maxlaunder = (cnt.v_inactive_target > MAXLAUNDER) ? 603 MAXLAUNDER : cnt.v_inactive_target; 604 rescan0: 605 maxscan = cnt.v_inactive_count; 606 for( m = TAILQ_FIRST(&vm_page_queue_inactive); 607 608 (m != NULL) && (maxscan-- > 0) && 609 ((cnt.v_cache_count + cnt.v_free_count) < 610 (cnt.v_cache_min + cnt.v_free_target)); 611 612 m = next) { 613 614 cnt.v_pdpages++; 615 616 if (m->queue != PQ_INACTIVE) { 617 goto rescan0; 618 } 619 620 next = TAILQ_NEXT(m, pageq); 621 622 if (m->hold_count) { 623 s = splvm(); 624 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 625 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 626 splx(s); 627 addl_page_shortage++; 628 continue; 629 } 630 /* 631 * Dont mess with busy pages, keep in the front of the 632 * queue, most likely are being paged out. 633 */ 634 if (m->busy || (m->flags & PG_BUSY)) { 635 addl_page_shortage++; 636 continue; 637 } 638 639 if (m->object->ref_count == 0) { 640 m->flags &= ~PG_REFERENCED; 641 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 642 } else if (((m->flags & PG_REFERENCED) == 0) && 643 pmap_ts_referenced(VM_PAGE_TO_PHYS(m))) { 644 vm_page_activate(m); 645 continue; 646 } 647 648 if ((m->flags & PG_REFERENCED) != 0) { 649 m->flags &= ~PG_REFERENCED; 650 pmap_clear_reference(VM_PAGE_TO_PHYS(m)); 651 vm_page_activate(m); 652 continue; 653 } 654 655 if (m->dirty == 0) { 656 vm_page_test_dirty(m); 657 } else if (m->dirty != 0) { 658 m->dirty = VM_PAGE_BITS_ALL; 659 } 660 661 if (m->valid == 0) { 662 vm_page_protect(m, VM_PROT_NONE); 663 vm_page_free(m); 664 cnt.v_dfree++; 665 ++pages_freed; 666 } else if (m->dirty == 0) { 667 vm_page_cache(m); 668 ++pages_freed; 669 } else if (maxlaunder > 0) { 670 int written; 671 struct vnode *vp = NULL; 672 673 object = m->object; 674 if (object->flags & OBJ_DEAD) { 675 s = splvm(); 676 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 677 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 678 splx(s); 679 continue; 680 } 681 682 if (object->type == OBJT_VNODE) { 683 vp = object->handle; 684 if (VOP_ISLOCKED(vp) || 685 vget(vp, LK_EXCLUSIVE, curproc)) { 686 if ((m->queue == PQ_INACTIVE) && 687 (m->hold_count == 0) && 688 (m->busy == 0) && 689 (m->flags & PG_BUSY) == 0) { 690 s = splvm(); 691 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 692 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 693 splx(s); 694 } 695 if (object->flags & OBJ_MIGHTBEDIRTY) 696 ++vnodes_skipped; 697 continue; 698 } 699 700 /* 701 * The page might have been moved to another queue 702 * during potential blocking in vget() above. 703 */ 704 if (m->queue != PQ_INACTIVE) { 705 if (object->flags & OBJ_MIGHTBEDIRTY) 706 ++vnodes_skipped; 707 vput(vp); 708 continue; 709 } 710 711 /* 712 * The page may have been busied during the blocking in 713 * vput(); We don't move the page back onto the end of 714 * the queue so that statistics are more correct if we don't. 715 */ 716 if (m->busy || (m->flags & PG_BUSY)) { 717 vput(vp); 718 continue; 719 } 720 721 /* 722 * If the page has become held, then skip it 723 */ 724 if (m->hold_count) { 725 s = splvm(); 726 TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); 727 TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); 728 splx(s); 729 if (object->flags & OBJ_MIGHTBEDIRTY) 730 ++vnodes_skipped; 731 vput(vp); 732 continue; 733 } 734 } 735 736 /* 737 * If a page is dirty, then it is either being washed 738 * (but not yet cleaned) or it is still in the 739 * laundry. If it is still in the laundry, then we 740 * start the cleaning operation. 741 */ 742 written = vm_pageout_clean(m, 0); 743 744 if (vp) 745 vput(vp); 746 747 maxlaunder -= written; 748 } 749 } 750 751 /* 752 * Compute the page shortage. If we are still very low on memory be 753 * sure that we will move a minimal amount of pages from active to 754 * inactive. 755 */ 756 757 page_shortage = (cnt.v_inactive_target + cnt.v_cache_min) - 758 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 759 if (page_shortage <= 0) { 760 if (pages_freed == 0) { 761 page_shortage = cnt.v_free_min - cnt.v_free_count; 762 } else { 763 page_shortage = 1; 764 } 765 } 766 if (addl_page_shortage) { 767 if (page_shortage < 0) 768 page_shortage = 0; 769 page_shortage += addl_page_shortage; 770 } 771 772 pcount = cnt.v_active_count; 773 m = TAILQ_FIRST(&vm_page_queue_active); 774 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 775 int refcount; 776 777 if (m->queue != PQ_ACTIVE) { 778 break; 779 } 780 781 next = TAILQ_NEXT(m, pageq); 782 /* 783 * Don't deactivate pages that are busy. 784 */ 785 if ((m->busy != 0) || 786 (m->flags & PG_BUSY) || 787 (m->hold_count != 0)) { 788 s = splvm(); 789 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 790 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 791 splx(s); 792 m = next; 793 continue; 794 } 795 796 /* 797 * The count for pagedaemon pages is done after checking the 798 * page for eligbility... 799 */ 800 cnt.v_pdpages++; 801 802 refcount = 0; 803 if (m->object->ref_count != 0) { 804 if (m->flags & PG_REFERENCED) { 805 refcount += 1; 806 } 807 refcount += pmap_ts_referenced(VM_PAGE_TO_PHYS(m)); 808 if (refcount) { 809 m->act_count += ACT_ADVANCE + refcount; 810 if (m->act_count > ACT_MAX) 811 m->act_count = ACT_MAX; 812 } 813 } 814 815 m->flags &= ~PG_REFERENCED; 816 817 if (refcount && (m->object->ref_count != 0)) { 818 s = splvm(); 819 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 820 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 821 splx(s); 822 } else { 823 m->act_count -= min(m->act_count, ACT_DECLINE); 824 if (vm_pageout_algorithm_lru || 825 (m->object->ref_count == 0) || (m->act_count == 0)) { 826 --page_shortage; 827 if (m->object->ref_count == 0) { 828 vm_page_protect(m, VM_PROT_NONE); 829 if (m->dirty == 0) 830 vm_page_cache(m); 831 else 832 vm_page_deactivate(m); 833 } else { 834 vm_page_deactivate(m); 835 } 836 } else { 837 s = splvm(); 838 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 839 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 840 splx(s); 841 } 842 } 843 m = next; 844 } 845 846 s = splvm(); 847 /* 848 * We try to maintain some *really* free pages, this allows interrupt 849 * code to be guaranteed space. 850 */ 851 while (cnt.v_free_count < cnt.v_free_reserved) { 852 static int cache_rover = 0; 853 m = vm_page_list_find(PQ_CACHE, cache_rover); 854 if (!m) 855 break; 856 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK; 857 vm_page_free(m); 858 cnt.v_dfree++; 859 } 860 splx(s); 861 862 /* 863 * If we didn't get enough free pages, and we have skipped a vnode 864 * in a writeable object, wakeup the sync daemon. And kick swapout 865 * if we did not get enough free pages. 866 */ 867 if ((cnt.v_cache_count + cnt.v_free_count) < 868 (cnt.v_free_target + cnt.v_cache_min) ) { 869 if (vnodes_skipped && 870 (cnt.v_cache_count + cnt.v_free_count) < cnt.v_free_min) { 871 if (!vfs_update_wakeup) { 872 vfs_update_wakeup = 1; 873 wakeup(&vfs_update_wakeup); 874 } 875 } 876 #if !defined(NO_SWAPPING) 877 if (vm_swapping_enabled && 878 (cnt.v_free_count + cnt.v_cache_count < cnt.v_free_target)) { 879 vm_req_vmdaemon(); 880 vm_pageout_req_swapout = 1; 881 } 882 #endif 883 } 884 885 886 /* 887 * make sure that we have swap space -- if we are low on memory and 888 * swap -- then kill the biggest process. 889 */ 890 if ((vm_swap_size == 0 || swap_pager_full) && 891 ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min)) { 892 bigproc = NULL; 893 bigsize = 0; 894 for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) { 895 /* 896 * if this is a system process, skip it 897 */ 898 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 899 ((p->p_pid < 48) && (vm_swap_size != 0))) { 900 continue; 901 } 902 /* 903 * if the process is in a non-running type state, 904 * don't touch it. 905 */ 906 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 907 continue; 908 } 909 /* 910 * get the process size 911 */ 912 size = p->p_vmspace->vm_pmap.pm_stats.resident_count; 913 /* 914 * if the this process is bigger than the biggest one 915 * remember it. 916 */ 917 if (size > bigsize) { 918 bigproc = p; 919 bigsize = size; 920 } 921 } 922 if (bigproc != NULL) { 923 killproc(bigproc, "out of swap space"); 924 bigproc->p_estcpu = 0; 925 bigproc->p_nice = PRIO_MIN; 926 resetpriority(bigproc); 927 wakeup(&cnt.v_free_count); 928 } 929 } 930 return force_wakeup; 931 } 932 933 /* 934 * This routine tries to maintain the pseudo LRU active queue, 935 * so that during long periods of time where there is no paging, 936 * that some statistic accumlation still occurs. This code 937 * helps the situation where paging just starts to occur. 938 */ 939 static void 940 vm_pageout_page_stats() 941 { 942 int s; 943 vm_page_t m,next; 944 int pcount,tpcount; /* Number of pages to check */ 945 static int fullintervalcount = 0; 946 947 pcount = cnt.v_active_count; 948 fullintervalcount += vm_pageout_stats_interval; 949 if (fullintervalcount < vm_pageout_full_stats_interval) { 950 tpcount = (vm_pageout_stats_max * cnt.v_active_count) / cnt.v_page_count; 951 if (pcount > tpcount) 952 pcount = tpcount; 953 } 954 955 m = TAILQ_FIRST(&vm_page_queue_active); 956 while ((m != NULL) && (pcount-- > 0)) { 957 int refcount; 958 959 if (m->queue != PQ_ACTIVE) { 960 break; 961 } 962 963 next = TAILQ_NEXT(m, pageq); 964 /* 965 * Don't deactivate pages that are busy. 966 */ 967 if ((m->busy != 0) || 968 (m->flags & PG_BUSY) || 969 (m->hold_count != 0)) { 970 s = splvm(); 971 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 972 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 973 splx(s); 974 m = next; 975 continue; 976 } 977 978 refcount = 0; 979 if (m->flags & PG_REFERENCED) { 980 m->flags &= ~PG_REFERENCED; 981 refcount += 1; 982 } 983 984 refcount += pmap_ts_referenced(VM_PAGE_TO_PHYS(m)); 985 if (refcount) { 986 m->act_count += ACT_ADVANCE + refcount; 987 if (m->act_count > ACT_MAX) 988 m->act_count = ACT_MAX; 989 s = splvm(); 990 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 991 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 992 splx(s); 993 } else { 994 if (m->act_count == 0) { 995 vm_page_protect(m, VM_PROT_NONE); 996 vm_page_deactivate(m); 997 } else { 998 m->act_count -= min(m->act_count, ACT_DECLINE); 999 s = splvm(); 1000 TAILQ_REMOVE(&vm_page_queue_active, m, pageq); 1001 TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); 1002 splx(s); 1003 } 1004 } 1005 1006 m = next; 1007 } 1008 } 1009 1010 1011 static int 1012 vm_pageout_free_page_calc(count) 1013 vm_size_t count; 1014 { 1015 if (count < cnt.v_page_count) 1016 return 0; 1017 /* 1018 * free_reserved needs to include enough for the largest swap pager 1019 * structures plus enough for any pv_entry structs when paging. 1020 */ 1021 if (cnt.v_page_count > 1024) 1022 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1023 else 1024 cnt.v_free_min = 4; 1025 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1026 cnt.v_interrupt_free_min; 1027 cnt.v_free_reserved = vm_pageout_page_count + 1028 cnt.v_pageout_free_min + (count / 768) + PQ_L2_SIZE; 1029 cnt.v_free_min += cnt.v_free_reserved; 1030 return 1; 1031 } 1032 1033 1034 /* 1035 * vm_pageout is the high level pageout daemon. 1036 */ 1037 static void 1038 vm_pageout() 1039 { 1040 /* 1041 * Initialize some paging parameters. 1042 */ 1043 1044 cnt.v_interrupt_free_min = 2; 1045 if (cnt.v_page_count < 2000) 1046 vm_pageout_page_count = 8; 1047 1048 vm_pageout_free_page_calc(cnt.v_page_count); 1049 /* 1050 * free_reserved needs to include enough for the largest swap pager 1051 * structures plus enough for any pv_entry structs when paging. 1052 */ 1053 cnt.v_free_target = 3 * cnt.v_free_min + cnt.v_free_reserved; 1054 1055 if (cnt.v_free_count > 1024) { 1056 cnt.v_cache_max = (cnt.v_free_count - 1024) / 2; 1057 cnt.v_cache_min = (cnt.v_free_count - 1024) / 8; 1058 cnt.v_inactive_target = 2*cnt.v_cache_min + 192; 1059 } else { 1060 cnt.v_cache_min = 0; 1061 cnt.v_cache_max = 0; 1062 cnt.v_inactive_target = cnt.v_free_count / 4; 1063 } 1064 1065 /* XXX does not really belong here */ 1066 if (vm_page_max_wired == 0) 1067 vm_page_max_wired = cnt.v_free_count / 3; 1068 1069 if (vm_pageout_stats_max == 0) 1070 vm_pageout_stats_max = cnt.v_free_target; 1071 1072 /* 1073 * Set interval in seconds for stats scan. 1074 */ 1075 if (vm_pageout_stats_interval == 0) 1076 vm_pageout_stats_interval = 4; 1077 if (vm_pageout_full_stats_interval == 0) 1078 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1079 1080 1081 /* 1082 * Set maximum free per pass 1083 */ 1084 if (vm_pageout_stats_free_max == 0) 1085 vm_pageout_stats_free_max = 25; 1086 1087 1088 swap_pager_swap_init(); 1089 /* 1090 * The pageout daemon is never done, so loop forever. 1091 */ 1092 while (TRUE) { 1093 int inactive_target; 1094 int error; 1095 int s = splvm(); 1096 if (!vm_pages_needed || 1097 ((cnt.v_free_count + cnt.v_cache_count) > cnt.v_free_min)) { 1098 vm_pages_needed = 0; 1099 error = tsleep(&vm_pages_needed, 1100 PVM, "psleep", vm_pageout_stats_interval * hz); 1101 if (error && !vm_pages_needed) { 1102 splx(s); 1103 vm_pageout_page_stats(); 1104 continue; 1105 } 1106 } else if (vm_pages_needed) { 1107 tsleep(&vm_pages_needed, PVM, "psleep", hz/10); 1108 } 1109 inactive_target = 1110 (cnt.v_page_count - cnt.v_wire_count) / 4; 1111 if (inactive_target < 2*cnt.v_free_min) 1112 inactive_target = 2*cnt.v_free_min; 1113 cnt.v_inactive_target = inactive_target; 1114 if (vm_pages_needed) 1115 cnt.v_pdwakeups++; 1116 vm_pages_needed = 0; 1117 splx(s); 1118 vm_pager_sync(); 1119 vm_pageout_scan(); 1120 vm_pager_sync(); 1121 wakeup(&cnt.v_free_count); 1122 } 1123 } 1124 1125 void 1126 pagedaemon_wakeup() 1127 { 1128 if (!vm_pages_needed && curproc != pageproc) { 1129 vm_pages_needed++; 1130 wakeup(&vm_pages_needed); 1131 } 1132 } 1133 1134 #if !defined(NO_SWAPPING) 1135 static void 1136 vm_req_vmdaemon() 1137 { 1138 static int lastrun = 0; 1139 1140 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1141 wakeup(&vm_daemon_needed); 1142 lastrun = ticks; 1143 } 1144 } 1145 1146 static void 1147 vm_daemon() 1148 { 1149 vm_object_t object; 1150 struct proc *p; 1151 1152 while (TRUE) { 1153 tsleep(&vm_daemon_needed, PUSER, "psleep", 0); 1154 if (vm_pageout_req_swapout) { 1155 swapout_procs(); 1156 vm_pageout_req_swapout = 0; 1157 } 1158 /* 1159 * scan the processes for exceeding their rlimits or if 1160 * process is swapped out -- deactivate pages 1161 */ 1162 1163 for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) { 1164 quad_t limit; 1165 vm_offset_t size; 1166 1167 /* 1168 * if this is a system process or if we have already 1169 * looked at this process, skip it. 1170 */ 1171 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 1172 continue; 1173 } 1174 /* 1175 * if the process is in a non-running type state, 1176 * don't touch it. 1177 */ 1178 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 1179 continue; 1180 } 1181 /* 1182 * get a limit 1183 */ 1184 limit = qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 1185 p->p_rlimit[RLIMIT_RSS].rlim_max); 1186 1187 /* 1188 * let processes that are swapped out really be 1189 * swapped out set the limit to nothing (will force a 1190 * swap-out.) 1191 */ 1192 if ((p->p_flag & P_INMEM) == 0) 1193 limit = 0; /* XXX */ 1194 1195 size = p->p_vmspace->vm_pmap.pm_stats.resident_count * PAGE_SIZE; 1196 if (limit >= 0 && size >= limit) { 1197 vm_pageout_map_deactivate_pages(&p->p_vmspace->vm_map, 1198 (vm_pindex_t)(limit >> PAGE_SHIFT) ); 1199 } 1200 } 1201 1202 /* 1203 * we remove cached objects that have no RSS... 1204 */ 1205 restart: 1206 object = TAILQ_FIRST(&vm_object_cached_list); 1207 while (object) { 1208 /* 1209 * if there are no resident pages -- get rid of the object 1210 */ 1211 if (object->resident_page_count == 0) { 1212 vm_object_reference(object); 1213 pager_cache(object, FALSE); 1214 goto restart; 1215 } 1216 object = TAILQ_NEXT(object, cached_list); 1217 } 1218 } 1219 } 1220 #endif 1221