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 * $FreeBSD: src/sys/vm/vm_pageout.c,v 1.151.2.15 2002/12/29 18:21:04 dillon Exp $ 69 * $DragonFly: src/sys/vm/vm_pageout.c,v 1.9 2004/03/01 06:33:24 dillon Exp $ 70 */ 71 72 /* 73 * The proverbial page-out daemon. 74 */ 75 76 #include "opt_vm.h" 77 #include <sys/param.h> 78 #include <sys/systm.h> 79 #include <sys/kernel.h> 80 #include <sys/proc.h> 81 #include <sys/kthread.h> 82 #include <sys/resourcevar.h> 83 #include <sys/signalvar.h> 84 #include <sys/vnode.h> 85 #include <sys/vmmeter.h> 86 #include <sys/sysctl.h> 87 88 #include <vm/vm.h> 89 #include <vm/vm_param.h> 90 #include <sys/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_pager.h> 96 #include <vm/swap_pager.h> 97 #include <vm/vm_extern.h> 98 #include <vm/vm_page2.h> 99 100 /* 101 * System initialization 102 */ 103 104 /* the kernel process "vm_pageout"*/ 105 static void vm_pageout (void); 106 static int vm_pageout_clean (vm_page_t); 107 static void vm_pageout_scan (int pass); 108 static int vm_pageout_free_page_calc (vm_size_t count); 109 struct thread *pagethread; 110 111 static struct kproc_desc page_kp = { 112 "pagedaemon", 113 vm_pageout, 114 &pagethread 115 }; 116 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 117 118 #if !defined(NO_SWAPPING) 119 /* the kernel process "vm_daemon"*/ 120 static void vm_daemon (void); 121 static struct thread *vmthread; 122 123 static struct kproc_desc vm_kp = { 124 "vmdaemon", 125 vm_daemon, 126 &vmthread 127 }; 128 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) 129 #endif 130 131 132 int vm_pages_needed=0; /* Event on which pageout daemon sleeps */ 133 int vm_pageout_deficit=0; /* Estimated number of pages deficit */ 134 int vm_pageout_pages_needed=0; /* flag saying that the pageout daemon needs pages */ 135 136 #if !defined(NO_SWAPPING) 137 static int vm_pageout_req_swapout; /* XXX */ 138 static int vm_daemon_needed; 139 #endif 140 extern int vm_swap_size; 141 static int vm_max_launder = 32; 142 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 143 static int vm_pageout_full_stats_interval = 0; 144 static int vm_pageout_stats_free_max=0, vm_pageout_algorithm=0; 145 static int defer_swap_pageouts=0; 146 static int disable_swap_pageouts=0; 147 148 #if defined(NO_SWAPPING) 149 static int vm_swap_enabled=0; 150 static int vm_swap_idle_enabled=0; 151 #else 152 static int vm_swap_enabled=1; 153 static int vm_swap_idle_enabled=0; 154 #endif 155 156 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 157 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 158 159 SYSCTL_INT(_vm, OID_AUTO, max_launder, 160 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 161 162 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 163 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 164 165 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 166 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 167 168 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 169 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 170 171 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max, 172 CTLFLAG_RW, &vm_pageout_stats_free_max, 0, "Not implemented"); 173 174 #if defined(NO_SWAPPING) 175 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 176 CTLFLAG_RD, &vm_swap_enabled, 0, ""); 177 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 178 CTLFLAG_RD, &vm_swap_idle_enabled, 0, ""); 179 #else 180 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 181 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 182 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 183 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 184 #endif 185 186 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 187 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 188 189 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 190 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 191 192 static int pageout_lock_miss; 193 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 194 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 195 196 #define VM_PAGEOUT_PAGE_COUNT 16 197 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 198 199 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 200 201 #if !defined(NO_SWAPPING) 202 typedef void freeer_fcn_t (vm_map_t, vm_object_t, vm_pindex_t, int); 203 static void vm_pageout_map_deactivate_pages (vm_map_t, vm_pindex_t); 204 static freeer_fcn_t vm_pageout_object_deactivate_pages; 205 static void vm_req_vmdaemon (void); 206 #endif 207 static void vm_pageout_page_stats(void); 208 209 /* 210 * vm_pageout_clean: 211 * 212 * Clean the page and remove it from the laundry. 213 * 214 * We set the busy bit to cause potential page faults on this page to 215 * block. Note the careful timing, however, the busy bit isn't set till 216 * late and we cannot do anything that will mess with the page. 217 */ 218 219 static int 220 vm_pageout_clean(m) 221 vm_page_t m; 222 { 223 vm_object_t object; 224 vm_page_t mc[2*vm_pageout_page_count]; 225 int pageout_count; 226 int ib, is, page_base; 227 vm_pindex_t pindex = m->pindex; 228 229 object = m->object; 230 231 /* 232 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 233 * with the new swapper, but we could have serious problems paging 234 * out other object types if there is insufficient memory. 235 * 236 * Unfortunately, checking free memory here is far too late, so the 237 * check has been moved up a procedural level. 238 */ 239 240 /* 241 * Don't mess with the page if it's busy, held, or special 242 */ 243 if ((m->hold_count != 0) || 244 ((m->busy != 0) || (m->flags & (PG_BUSY|PG_UNMANAGED)))) { 245 return 0; 246 } 247 248 mc[vm_pageout_page_count] = m; 249 pageout_count = 1; 250 page_base = vm_pageout_page_count; 251 ib = 1; 252 is = 1; 253 254 /* 255 * Scan object for clusterable pages. 256 * 257 * We can cluster ONLY if: ->> the page is NOT 258 * clean, wired, busy, held, or mapped into a 259 * buffer, and one of the following: 260 * 1) The page is inactive, or a seldom used 261 * active page. 262 * -or- 263 * 2) we force the issue. 264 * 265 * During heavy mmap/modification loads the pageout 266 * daemon can really fragment the underlying file 267 * due to flushing pages out of order and not trying 268 * align the clusters (which leave sporatic out-of-order 269 * holes). To solve this problem we do the reverse scan 270 * first and attempt to align our cluster, then do a 271 * forward scan if room remains. 272 */ 273 274 more: 275 while (ib && pageout_count < vm_pageout_page_count) { 276 vm_page_t p; 277 278 if (ib > pindex) { 279 ib = 0; 280 break; 281 } 282 283 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) { 284 ib = 0; 285 break; 286 } 287 if (((p->queue - p->pc) == PQ_CACHE) || 288 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 289 ib = 0; 290 break; 291 } 292 vm_page_test_dirty(p); 293 if ((p->dirty & p->valid) == 0 || 294 p->queue != PQ_INACTIVE || 295 p->wire_count != 0 || /* may be held by buf cache */ 296 p->hold_count != 0) { /* may be undergoing I/O */ 297 ib = 0; 298 break; 299 } 300 mc[--page_base] = p; 301 ++pageout_count; 302 ++ib; 303 /* 304 * alignment boundry, stop here and switch directions. Do 305 * not clear ib. 306 */ 307 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 308 break; 309 } 310 311 while (pageout_count < vm_pageout_page_count && 312 pindex + is < object->size) { 313 vm_page_t p; 314 315 if ((p = vm_page_lookup(object, pindex + is)) == NULL) 316 break; 317 if (((p->queue - p->pc) == PQ_CACHE) || 318 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 319 break; 320 } 321 vm_page_test_dirty(p); 322 if ((p->dirty & p->valid) == 0 || 323 p->queue != PQ_INACTIVE || 324 p->wire_count != 0 || /* may be held by buf cache */ 325 p->hold_count != 0) { /* may be undergoing I/O */ 326 break; 327 } 328 mc[page_base + pageout_count] = p; 329 ++pageout_count; 330 ++is; 331 } 332 333 /* 334 * If we exhausted our forward scan, continue with the reverse scan 335 * when possible, even past a page boundry. This catches boundry 336 * conditions. 337 */ 338 if (ib && pageout_count < vm_pageout_page_count) 339 goto more; 340 341 /* 342 * we allow reads during pageouts... 343 */ 344 return vm_pageout_flush(&mc[page_base], pageout_count, 0); 345 } 346 347 /* 348 * vm_pageout_flush() - launder the given pages 349 * 350 * The given pages are laundered. Note that we setup for the start of 351 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 352 * reference count all in here rather then in the parent. If we want 353 * the parent to do more sophisticated things we may have to change 354 * the ordering. 355 */ 356 357 int 358 vm_pageout_flush(mc, count, flags) 359 vm_page_t *mc; 360 int count; 361 int flags; 362 { 363 vm_object_t object; 364 int pageout_status[count]; 365 int numpagedout = 0; 366 int i; 367 368 /* 369 * Initiate I/O. Bump the vm_page_t->busy counter and 370 * mark the pages read-only. 371 * 372 * We do not have to fixup the clean/dirty bits here... we can 373 * allow the pager to do it after the I/O completes. 374 */ 375 376 for (i = 0; i < count; i++) { 377 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush page %p index %d/%d: partially invalid page", mc[i], i, count)); 378 vm_page_io_start(mc[i]); 379 vm_page_protect(mc[i], VM_PROT_READ); 380 } 381 382 object = mc[0]->object; 383 vm_object_pip_add(object, count); 384 385 vm_pager_put_pages(object, mc, count, 386 (flags | ((object == kernel_object) ? VM_PAGER_PUT_SYNC : 0)), 387 pageout_status); 388 389 for (i = 0; i < count; i++) { 390 vm_page_t mt = mc[i]; 391 392 switch (pageout_status[i]) { 393 case VM_PAGER_OK: 394 numpagedout++; 395 break; 396 case VM_PAGER_PEND: 397 numpagedout++; 398 break; 399 case VM_PAGER_BAD: 400 /* 401 * Page outside of range of object. Right now we 402 * essentially lose the changes by pretending it 403 * worked. 404 */ 405 pmap_clear_modify(mt); 406 vm_page_undirty(mt); 407 break; 408 case VM_PAGER_ERROR: 409 case VM_PAGER_FAIL: 410 /* 411 * If page couldn't be paged out, then reactivate the 412 * page so it doesn't clog the inactive list. (We 413 * will try paging out it again later). 414 */ 415 vm_page_activate(mt); 416 break; 417 case VM_PAGER_AGAIN: 418 break; 419 } 420 421 /* 422 * If the operation is still going, leave the page busy to 423 * block all other accesses. Also, leave the paging in 424 * progress indicator set so that we don't attempt an object 425 * collapse. 426 */ 427 if (pageout_status[i] != VM_PAGER_PEND) { 428 vm_object_pip_wakeup(object); 429 vm_page_io_finish(mt); 430 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt)) 431 vm_page_protect(mt, VM_PROT_READ); 432 } 433 } 434 return numpagedout; 435 } 436 437 #if !defined(NO_SWAPPING) 438 /* 439 * vm_pageout_object_deactivate_pages 440 * 441 * deactivate enough pages to satisfy the inactive target 442 * requirements or if vm_page_proc_limit is set, then 443 * deactivate all of the pages in the object and its 444 * backing_objects. 445 * 446 * The object and map must be locked. 447 */ 448 static void 449 vm_pageout_object_deactivate_pages(map, object, desired, map_remove_only) 450 vm_map_t map; 451 vm_object_t object; 452 vm_pindex_t desired; 453 int map_remove_only; 454 { 455 vm_page_t p, next; 456 int rcount; 457 int remove_mode; 458 int s; 459 460 if (object->type == OBJT_DEVICE || object->type == OBJT_PHYS) 461 return; 462 463 while (object) { 464 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 465 return; 466 if (object->paging_in_progress) 467 return; 468 469 remove_mode = map_remove_only; 470 if (object->shadow_count > 1) 471 remove_mode = 1; 472 /* 473 * scan the objects entire memory queue 474 */ 475 rcount = object->resident_page_count; 476 p = TAILQ_FIRST(&object->memq); 477 while (p && (rcount-- > 0)) { 478 int actcount; 479 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 480 return; 481 next = TAILQ_NEXT(p, listq); 482 mycpu->gd_cnt.v_pdpages++; 483 if (p->wire_count != 0 || 484 p->hold_count != 0 || 485 p->busy != 0 || 486 (p->flags & (PG_BUSY|PG_UNMANAGED)) || 487 !pmap_page_exists_quick(vm_map_pmap(map), p)) { 488 p = next; 489 continue; 490 } 491 492 actcount = pmap_ts_referenced(p); 493 if (actcount) { 494 vm_page_flag_set(p, PG_REFERENCED); 495 } else if (p->flags & PG_REFERENCED) { 496 actcount = 1; 497 } 498 499 if ((p->queue != PQ_ACTIVE) && 500 (p->flags & PG_REFERENCED)) { 501 vm_page_activate(p); 502 p->act_count += actcount; 503 vm_page_flag_clear(p, PG_REFERENCED); 504 } else if (p->queue == PQ_ACTIVE) { 505 if ((p->flags & PG_REFERENCED) == 0) { 506 p->act_count -= min(p->act_count, ACT_DECLINE); 507 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) { 508 vm_page_protect(p, VM_PROT_NONE); 509 vm_page_deactivate(p); 510 } else { 511 s = splvm(); 512 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 513 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 514 splx(s); 515 } 516 } else { 517 vm_page_activate(p); 518 vm_page_flag_clear(p, PG_REFERENCED); 519 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 520 p->act_count += ACT_ADVANCE; 521 s = splvm(); 522 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 523 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 524 splx(s); 525 } 526 } else if (p->queue == PQ_INACTIVE) { 527 vm_page_protect(p, VM_PROT_NONE); 528 } 529 p = next; 530 } 531 object = object->backing_object; 532 } 533 return; 534 } 535 536 /* 537 * deactivate some number of pages in a map, try to do it fairly, but 538 * that is really hard to do. 539 */ 540 static void 541 vm_pageout_map_deactivate_pages(map, desired) 542 vm_map_t map; 543 vm_pindex_t desired; 544 { 545 vm_map_entry_t tmpe; 546 vm_object_t obj, bigobj; 547 int nothingwired; 548 549 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT, NULL, curthread)) { 550 return; 551 } 552 553 bigobj = NULL; 554 nothingwired = TRUE; 555 556 /* 557 * first, search out the biggest object, and try to free pages from 558 * that. 559 */ 560 tmpe = map->header.next; 561 while (tmpe != &map->header) { 562 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 563 obj = tmpe->object.vm_object; 564 if ((obj != NULL) && (obj->shadow_count <= 1) && 565 ((bigobj == NULL) || 566 (bigobj->resident_page_count < obj->resident_page_count))) { 567 bigobj = obj; 568 } 569 } 570 if (tmpe->wired_count > 0) 571 nothingwired = FALSE; 572 tmpe = tmpe->next; 573 } 574 575 if (bigobj) 576 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 577 578 /* 579 * Next, hunt around for other pages to deactivate. We actually 580 * do this search sort of wrong -- .text first is not the best idea. 581 */ 582 tmpe = map->header.next; 583 while (tmpe != &map->header) { 584 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 585 break; 586 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 587 obj = tmpe->object.vm_object; 588 if (obj) 589 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 590 } 591 tmpe = tmpe->next; 592 }; 593 594 /* 595 * Remove all mappings if a process is swapped out, this will free page 596 * table pages. 597 */ 598 if (desired == 0 && nothingwired) 599 pmap_remove(vm_map_pmap(map), 600 VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS); 601 vm_map_unlock(map); 602 return; 603 } 604 #endif 605 606 /* 607 * Don't try to be fancy - being fancy can lead to VOP_LOCK's and therefore 608 * to vnode deadlocks. We only do it for OBJT_DEFAULT and OBJT_SWAP objects 609 * which we know can be trivially freed. 610 */ 611 612 void 613 vm_pageout_page_free(vm_page_t m) { 614 vm_object_t object = m->object; 615 int type = object->type; 616 617 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 618 vm_object_reference(object); 619 vm_page_busy(m); 620 vm_page_protect(m, VM_PROT_NONE); 621 vm_page_free(m); 622 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 623 vm_object_deallocate(object); 624 } 625 626 /* 627 * vm_pageout_scan does the dirty work for the pageout daemon. 628 */ 629 static void 630 vm_pageout_scan(int pass) 631 { 632 vm_page_t m, next; 633 struct vm_page marker; 634 int page_shortage, maxscan, pcount; 635 int addl_page_shortage, addl_page_shortage_init; 636 struct proc *p, *bigproc; 637 vm_offset_t size, bigsize; 638 vm_object_t object; 639 int actcount; 640 int vnodes_skipped = 0; 641 int maxlaunder; 642 int s; 643 644 /* 645 * Do whatever cleanup that the pmap code can. 646 */ 647 pmap_collect(); 648 649 addl_page_shortage_init = vm_pageout_deficit; 650 vm_pageout_deficit = 0; 651 652 /* 653 * Calculate the number of pages we want to either free or move 654 * to the cache. 655 */ 656 page_shortage = vm_paging_target() + addl_page_shortage_init; 657 658 /* 659 * Initialize our marker 660 */ 661 bzero(&marker, sizeof(marker)); 662 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 663 marker.queue = PQ_INACTIVE; 664 marker.wire_count = 1; 665 666 /* 667 * Start scanning the inactive queue for pages we can move to the 668 * cache or free. The scan will stop when the target is reached or 669 * we have scanned the entire inactive queue. Note that m->act_count 670 * is not used to form decisions for the inactive queue, only for the 671 * active queue. 672 * 673 * maxlaunder limits the number of dirty pages we flush per scan. 674 * For most systems a smaller value (16 or 32) is more robust under 675 * extreme memory and disk pressure because any unnecessary writes 676 * to disk can result in extreme performance degredation. However, 677 * systems with excessive dirty pages (especially when MAP_NOSYNC is 678 * used) will die horribly with limited laundering. If the pageout 679 * daemon cannot clean enough pages in the first pass, we let it go 680 * all out in succeeding passes. 681 */ 682 if ((maxlaunder = vm_max_launder) <= 1) 683 maxlaunder = 1; 684 if (pass) 685 maxlaunder = 10000; 686 687 rescan0: 688 addl_page_shortage = addl_page_shortage_init; 689 maxscan = vmstats.v_inactive_count; 690 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 691 m != NULL && maxscan-- > 0 && page_shortage > 0; 692 m = next) { 693 694 mycpu->gd_cnt.v_pdpages++; 695 696 if (m->queue != PQ_INACTIVE) { 697 goto rescan0; 698 } 699 700 next = TAILQ_NEXT(m, pageq); 701 702 /* 703 * skip marker pages 704 */ 705 if (m->flags & PG_MARKER) 706 continue; 707 708 /* 709 * A held page may be undergoing I/O, so skip it. 710 */ 711 if (m->hold_count) { 712 s = splvm(); 713 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 714 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 715 splx(s); 716 addl_page_shortage++; 717 continue; 718 } 719 /* 720 * Dont mess with busy pages, keep in the front of the 721 * queue, most likely are being paged out. 722 */ 723 if (m->busy || (m->flags & PG_BUSY)) { 724 addl_page_shortage++; 725 continue; 726 } 727 728 /* 729 * If the object is not being used, we ignore previous 730 * references. 731 */ 732 if (m->object->ref_count == 0) { 733 vm_page_flag_clear(m, PG_REFERENCED); 734 pmap_clear_reference(m); 735 736 /* 737 * Otherwise, if the page has been referenced while in the 738 * inactive queue, we bump the "activation count" upwards, 739 * making it less likely that the page will be added back to 740 * the inactive queue prematurely again. Here we check the 741 * page tables (or emulated bits, if any), given the upper 742 * level VM system not knowing anything about existing 743 * references. 744 */ 745 } else if (((m->flags & PG_REFERENCED) == 0) && 746 (actcount = pmap_ts_referenced(m))) { 747 vm_page_activate(m); 748 m->act_count += (actcount + ACT_ADVANCE); 749 continue; 750 } 751 752 /* 753 * If the upper level VM system knows about any page 754 * references, we activate the page. We also set the 755 * "activation count" higher than normal so that we will less 756 * likely place pages back onto the inactive queue again. 757 */ 758 if ((m->flags & PG_REFERENCED) != 0) { 759 vm_page_flag_clear(m, PG_REFERENCED); 760 actcount = pmap_ts_referenced(m); 761 vm_page_activate(m); 762 m->act_count += (actcount + ACT_ADVANCE + 1); 763 continue; 764 } 765 766 /* 767 * If the upper level VM system doesn't know anything about 768 * the page being dirty, we have to check for it again. As 769 * far as the VM code knows, any partially dirty pages are 770 * fully dirty. 771 * 772 * Pages marked PG_WRITEABLE may be mapped into the user 773 * address space of a process running on another cpu. A 774 * user process (without holding the MP lock) running on 775 * another cpu may be able to touch the page while we are 776 * trying to remove it. To prevent this from occuring we 777 * must call pmap_remove_all() or otherwise make the page 778 * read-only. If the race occured pmap_remove_all() is 779 * responsible for setting m->dirty. 780 */ 781 if (m->dirty == 0) { 782 vm_page_test_dirty(m); 783 #if 0 784 if (m->dirty == 0 && (m->flags & PG_WRITEABLE) != 0) 785 pmap_remove_all(m); 786 #endif 787 } else { 788 vm_page_dirty(m); 789 } 790 791 if (m->valid == 0) { 792 /* 793 * Invalid pages can be easily freed 794 */ 795 vm_pageout_page_free(m); 796 mycpu->gd_cnt.v_dfree++; 797 --page_shortage; 798 } else if (m->dirty == 0) { 799 /* 800 * Clean pages can be placed onto the cache queue. 801 * This effectively frees them. 802 */ 803 vm_page_cache(m); 804 --page_shortage; 805 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 806 /* 807 * Dirty pages need to be paged out, but flushing 808 * a page is extremely expensive verses freeing 809 * a clean page. Rather then artificially limiting 810 * the number of pages we can flush, we instead give 811 * dirty pages extra priority on the inactive queue 812 * by forcing them to be cycled through the queue 813 * twice before being flushed, after which the 814 * (now clean) page will cycle through once more 815 * before being freed. This significantly extends 816 * the thrash point for a heavily loaded machine. 817 */ 818 s = splvm(); 819 vm_page_flag_set(m, PG_WINATCFLS); 820 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 821 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 822 splx(s); 823 } else if (maxlaunder > 0) { 824 /* 825 * We always want to try to flush some dirty pages if 826 * we encounter them, to keep the system stable. 827 * Normally this number is small, but under extreme 828 * pressure where there are insufficient clean pages 829 * on the inactive queue, we may have to go all out. 830 */ 831 int swap_pageouts_ok; 832 struct vnode *vp = NULL; 833 834 object = m->object; 835 836 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 837 swap_pageouts_ok = 1; 838 } else { 839 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 840 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 841 vm_page_count_min()); 842 843 } 844 845 /* 846 * We don't bother paging objects that are "dead". 847 * Those objects are in a "rundown" state. 848 */ 849 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 850 s = splvm(); 851 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 852 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 853 splx(s); 854 continue; 855 } 856 857 /* 858 * The object is already known NOT to be dead. It 859 * is possible for the vget() to block the whole 860 * pageout daemon, but the new low-memory handling 861 * code should prevent it. 862 * 863 * The previous code skipped locked vnodes and, worse, 864 * reordered pages in the queue. This results in 865 * completely non-deterministic operation because, 866 * quite often, a vm_fault has initiated an I/O and 867 * is holding a locked vnode at just the point where 868 * the pageout daemon is woken up. 869 * 870 * We can't wait forever for the vnode lock, we might 871 * deadlock due to a vn_read() getting stuck in 872 * vm_wait while holding this vnode. We skip the 873 * vnode if we can't get it in a reasonable amount 874 * of time. 875 */ 876 877 if (object->type == OBJT_VNODE) { 878 vp = object->handle; 879 880 if (vget(vp, NULL, LK_EXCLUSIVE|LK_NOOBJ|LK_TIMELOCK, curthread)) { 881 ++pageout_lock_miss; 882 if (object->flags & OBJ_MIGHTBEDIRTY) 883 vnodes_skipped++; 884 continue; 885 } 886 887 /* 888 * The page might have been moved to another 889 * queue during potential blocking in vget() 890 * above. The page might have been freed and 891 * reused for another vnode. The object might 892 * have been reused for another vnode. 893 */ 894 if (m->queue != PQ_INACTIVE || 895 m->object != object || 896 object->handle != vp) { 897 if (object->flags & OBJ_MIGHTBEDIRTY) 898 vnodes_skipped++; 899 vput(vp); 900 continue; 901 } 902 903 /* 904 * The page may have been busied during the 905 * blocking in vput(); We don't move the 906 * page back onto the end of the queue so that 907 * statistics are more correct if we don't. 908 */ 909 if (m->busy || (m->flags & PG_BUSY)) { 910 vput(vp); 911 continue; 912 } 913 914 /* 915 * If the page has become held it might 916 * be undergoing I/O, so skip it 917 */ 918 if (m->hold_count) { 919 s = splvm(); 920 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 921 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 922 splx(s); 923 if (object->flags & OBJ_MIGHTBEDIRTY) 924 vnodes_skipped++; 925 vput(vp); 926 continue; 927 } 928 } 929 930 /* 931 * If a page is dirty, then it is either being washed 932 * (but not yet cleaned) or it is still in the 933 * laundry. If it is still in the laundry, then we 934 * start the cleaning operation. 935 * 936 * This operation may cluster, invalidating the 'next' 937 * pointer. To prevent an inordinate number of 938 * restarts we use our marker to remember our place. 939 * 940 * decrement page_shortage on success to account for 941 * the (future) cleaned page. Otherwise we could wind 942 * up laundering or cleaning too many pages. 943 */ 944 s = splvm(); 945 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq); 946 splx(s); 947 if (vm_pageout_clean(m) != 0) { 948 --page_shortage; 949 --maxlaunder; 950 } 951 s = splvm(); 952 next = TAILQ_NEXT(&marker, pageq); 953 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq); 954 splx(s); 955 if (vp != NULL) 956 vput(vp); 957 } 958 } 959 960 /* 961 * Compute the number of pages we want to try to move from the 962 * active queue to the inactive queue. 963 */ 964 page_shortage = vm_paging_target() + 965 vmstats.v_inactive_target - vmstats.v_inactive_count; 966 page_shortage += addl_page_shortage; 967 968 /* 969 * Scan the active queue for things we can deactivate. We nominally 970 * track the per-page activity counter and use it to locate 971 * deactivation candidates. 972 */ 973 974 pcount = vmstats.v_active_count; 975 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 976 977 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 978 979 /* 980 * This is a consistency check, and should likely be a panic 981 * or warning. 982 */ 983 if (m->queue != PQ_ACTIVE) { 984 break; 985 } 986 987 next = TAILQ_NEXT(m, pageq); 988 /* 989 * Don't deactivate pages that are busy. 990 */ 991 if ((m->busy != 0) || 992 (m->flags & PG_BUSY) || 993 (m->hold_count != 0)) { 994 s = splvm(); 995 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 996 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 997 splx(s); 998 m = next; 999 continue; 1000 } 1001 1002 /* 1003 * The count for pagedaemon pages is done after checking the 1004 * page for eligibility... 1005 */ 1006 mycpu->gd_cnt.v_pdpages++; 1007 1008 /* 1009 * Check to see "how much" the page has been used. 1010 */ 1011 actcount = 0; 1012 if (m->object->ref_count != 0) { 1013 if (m->flags & PG_REFERENCED) { 1014 actcount += 1; 1015 } 1016 actcount += pmap_ts_referenced(m); 1017 if (actcount) { 1018 m->act_count += ACT_ADVANCE + actcount; 1019 if (m->act_count > ACT_MAX) 1020 m->act_count = ACT_MAX; 1021 } 1022 } 1023 1024 /* 1025 * Since we have "tested" this bit, we need to clear it now. 1026 */ 1027 vm_page_flag_clear(m, PG_REFERENCED); 1028 1029 /* 1030 * Only if an object is currently being used, do we use the 1031 * page activation count stats. 1032 */ 1033 if (actcount && (m->object->ref_count != 0)) { 1034 s = splvm(); 1035 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1036 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1037 splx(s); 1038 } else { 1039 m->act_count -= min(m->act_count, ACT_DECLINE); 1040 if (vm_pageout_algorithm || 1041 m->object->ref_count == 0 || 1042 m->act_count == 0) { 1043 page_shortage--; 1044 if (m->object->ref_count == 0) { 1045 vm_page_protect(m, VM_PROT_NONE); 1046 if (m->dirty == 0) 1047 vm_page_cache(m); 1048 else 1049 vm_page_deactivate(m); 1050 } else { 1051 vm_page_deactivate(m); 1052 } 1053 } else { 1054 s = splvm(); 1055 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1056 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1057 splx(s); 1058 } 1059 } 1060 m = next; 1061 } 1062 1063 s = splvm(); 1064 1065 /* 1066 * We try to maintain some *really* free pages, this allows interrupt 1067 * code to be guaranteed space. Since both cache and free queues 1068 * are considered basically 'free', moving pages from cache to free 1069 * does not effect other calculations. 1070 */ 1071 1072 while (vmstats.v_free_count < vmstats.v_free_reserved) { 1073 static int cache_rover = 0; 1074 m = vm_page_list_find(PQ_CACHE, cache_rover, FALSE); 1075 if (!m) 1076 break; 1077 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || 1078 m->busy || 1079 m->hold_count || 1080 m->wire_count) { 1081 #ifdef INVARIANTS 1082 printf("Warning: busy page %p found in cache\n", m); 1083 #endif 1084 vm_page_deactivate(m); 1085 continue; 1086 } 1087 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK; 1088 vm_pageout_page_free(m); 1089 mycpu->gd_cnt.v_dfree++; 1090 } 1091 splx(s); 1092 1093 #if !defined(NO_SWAPPING) 1094 /* 1095 * Idle process swapout -- run once per second. 1096 */ 1097 if (vm_swap_idle_enabled) { 1098 static long lsec; 1099 if (time_second != lsec) { 1100 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1101 vm_req_vmdaemon(); 1102 lsec = time_second; 1103 } 1104 } 1105 #endif 1106 1107 /* 1108 * If we didn't get enough free pages, and we have skipped a vnode 1109 * in a writeable object, wakeup the sync daemon. And kick swapout 1110 * if we did not get enough free pages. 1111 */ 1112 if (vm_paging_target() > 0) { 1113 if (vnodes_skipped && vm_page_count_min()) 1114 (void) speedup_syncer(); 1115 #if !defined(NO_SWAPPING) 1116 if (vm_swap_enabled && vm_page_count_target()) { 1117 vm_req_vmdaemon(); 1118 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1119 } 1120 #endif 1121 } 1122 1123 /* 1124 * If we are out of swap and were not able to reach our paging 1125 * target, kill the largest process. 1126 */ 1127 if ((vm_swap_size < 64 && vm_page_count_min()) || 1128 (swap_pager_full && vm_paging_target() > 0)) { 1129 #if 0 1130 if ((vm_swap_size < 64 || swap_pager_full) && vm_page_count_min()) { 1131 #endif 1132 bigproc = NULL; 1133 bigsize = 0; 1134 for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) { 1135 /* 1136 * if this is a system process, skip it 1137 */ 1138 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1139 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1140 continue; 1141 } 1142 /* 1143 * if the process is in a non-running type state, 1144 * don't touch it. 1145 */ 1146 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 1147 continue; 1148 } 1149 /* 1150 * get the process size 1151 */ 1152 size = vmspace_resident_count(p->p_vmspace) + 1153 vmspace_swap_count(p->p_vmspace); 1154 /* 1155 * if the this process is bigger than the biggest one 1156 * remember it. 1157 */ 1158 if (size > bigsize) { 1159 bigproc = p; 1160 bigsize = size; 1161 } 1162 } 1163 if (bigproc != NULL) { 1164 killproc(bigproc, "out of swap space"); 1165 bigproc->p_estcpu = 0; 1166 bigproc->p_nice = PRIO_MIN; 1167 resetpriority(bigproc); 1168 wakeup(&vmstats.v_free_count); 1169 } 1170 } 1171 } 1172 1173 /* 1174 * This routine tries to maintain the pseudo LRU active queue, 1175 * so that during long periods of time where there is no paging, 1176 * that some statistic accumulation still occurs. This code 1177 * helps the situation where paging just starts to occur. 1178 */ 1179 static void 1180 vm_pageout_page_stats() 1181 { 1182 int s; 1183 vm_page_t m,next; 1184 int pcount,tpcount; /* Number of pages to check */ 1185 static int fullintervalcount = 0; 1186 int page_shortage; 1187 int s0; 1188 1189 page_shortage = 1190 (vmstats.v_inactive_target + vmstats.v_cache_max + vmstats.v_free_min) - 1191 (vmstats.v_free_count + vmstats.v_inactive_count + vmstats.v_cache_count); 1192 1193 if (page_shortage <= 0) 1194 return; 1195 1196 s0 = splvm(); 1197 1198 pcount = vmstats.v_active_count; 1199 fullintervalcount += vm_pageout_stats_interval; 1200 if (fullintervalcount < vm_pageout_full_stats_interval) { 1201 tpcount = (vm_pageout_stats_max * vmstats.v_active_count) / vmstats.v_page_count; 1202 if (pcount > tpcount) 1203 pcount = tpcount; 1204 } else { 1205 fullintervalcount = 0; 1206 } 1207 1208 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1209 while ((m != NULL) && (pcount-- > 0)) { 1210 int actcount; 1211 1212 if (m->queue != PQ_ACTIVE) { 1213 break; 1214 } 1215 1216 next = TAILQ_NEXT(m, pageq); 1217 /* 1218 * Don't deactivate pages that are busy. 1219 */ 1220 if ((m->busy != 0) || 1221 (m->flags & PG_BUSY) || 1222 (m->hold_count != 0)) { 1223 s = splvm(); 1224 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1225 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1226 splx(s); 1227 m = next; 1228 continue; 1229 } 1230 1231 actcount = 0; 1232 if (m->flags & PG_REFERENCED) { 1233 vm_page_flag_clear(m, PG_REFERENCED); 1234 actcount += 1; 1235 } 1236 1237 actcount += pmap_ts_referenced(m); 1238 if (actcount) { 1239 m->act_count += ACT_ADVANCE + actcount; 1240 if (m->act_count > ACT_MAX) 1241 m->act_count = ACT_MAX; 1242 s = splvm(); 1243 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1244 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1245 splx(s); 1246 } else { 1247 if (m->act_count == 0) { 1248 /* 1249 * We turn off page access, so that we have 1250 * more accurate RSS stats. We don't do this 1251 * in the normal page deactivation when the 1252 * system is loaded VM wise, because the 1253 * cost of the large number of page protect 1254 * operations would be higher than the value 1255 * of doing the operation. 1256 */ 1257 vm_page_protect(m, VM_PROT_NONE); 1258 vm_page_deactivate(m); 1259 } else { 1260 m->act_count -= min(m->act_count, ACT_DECLINE); 1261 s = splvm(); 1262 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1263 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1264 splx(s); 1265 } 1266 } 1267 1268 m = next; 1269 } 1270 splx(s0); 1271 } 1272 1273 static int 1274 vm_pageout_free_page_calc(count) 1275 vm_size_t count; 1276 { 1277 if (count < vmstats.v_page_count) 1278 return 0; 1279 /* 1280 * free_reserved needs to include enough for the largest swap pager 1281 * structures plus enough for any pv_entry structs when paging. 1282 */ 1283 if (vmstats.v_page_count > 1024) 1284 vmstats.v_free_min = 4 + (vmstats.v_page_count - 1024) / 200; 1285 else 1286 vmstats.v_free_min = 4; 1287 vmstats.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1288 vmstats.v_interrupt_free_min; 1289 vmstats.v_free_reserved = vm_pageout_page_count + 1290 vmstats.v_pageout_free_min + (count / 768) + PQ_L2_SIZE; 1291 vmstats.v_free_severe = vmstats.v_free_min / 2; 1292 vmstats.v_free_min += vmstats.v_free_reserved; 1293 vmstats.v_free_severe += vmstats.v_free_reserved; 1294 return 1; 1295 } 1296 1297 1298 /* 1299 * vm_pageout is the high level pageout daemon. 1300 */ 1301 static void 1302 vm_pageout() 1303 { 1304 int pass; 1305 1306 /* 1307 * Initialize some paging parameters. 1308 */ 1309 1310 vmstats.v_interrupt_free_min = 2; 1311 if (vmstats.v_page_count < 2000) 1312 vm_pageout_page_count = 8; 1313 1314 vm_pageout_free_page_calc(vmstats.v_page_count); 1315 /* 1316 * v_free_target and v_cache_min control pageout hysteresis. Note 1317 * that these are more a measure of the VM cache queue hysteresis 1318 * then the VM free queue. Specifically, v_free_target is the 1319 * high water mark (free+cache pages). 1320 * 1321 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1322 * low water mark, while v_free_min is the stop. v_cache_min must 1323 * be big enough to handle memory needs while the pageout daemon 1324 * is signalled and run to free more pages. 1325 */ 1326 if (vmstats.v_free_count > 6144) 1327 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved; 1328 else 1329 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved; 1330 1331 if (vmstats.v_free_count > 2048) { 1332 vmstats.v_cache_min = vmstats.v_free_target; 1333 vmstats.v_cache_max = 2 * vmstats.v_cache_min; 1334 vmstats.v_inactive_target = (3 * vmstats.v_free_target) / 2; 1335 } else { 1336 vmstats.v_cache_min = 0; 1337 vmstats.v_cache_max = 0; 1338 vmstats.v_inactive_target = vmstats.v_free_count / 4; 1339 } 1340 if (vmstats.v_inactive_target > vmstats.v_free_count / 3) 1341 vmstats.v_inactive_target = vmstats.v_free_count / 3; 1342 1343 /* XXX does not really belong here */ 1344 if (vm_page_max_wired == 0) 1345 vm_page_max_wired = vmstats.v_free_count / 3; 1346 1347 if (vm_pageout_stats_max == 0) 1348 vm_pageout_stats_max = vmstats.v_free_target; 1349 1350 /* 1351 * Set interval in seconds for stats scan. 1352 */ 1353 if (vm_pageout_stats_interval == 0) 1354 vm_pageout_stats_interval = 5; 1355 if (vm_pageout_full_stats_interval == 0) 1356 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1357 1358 1359 /* 1360 * Set maximum free per pass 1361 */ 1362 if (vm_pageout_stats_free_max == 0) 1363 vm_pageout_stats_free_max = 5; 1364 1365 swap_pager_swap_init(); 1366 pass = 0; 1367 /* 1368 * The pageout daemon is never done, so loop forever. 1369 */ 1370 while (TRUE) { 1371 int error; 1372 int s = splvm(); 1373 1374 /* 1375 * If we have enough free memory, wakeup waiters. Do 1376 * not clear vm_pages_needed until we reach our target, 1377 * otherwise we may be woken up over and over again and 1378 * waste a lot of cpu. 1379 */ 1380 if (vm_pages_needed && !vm_page_count_min()) { 1381 if (vm_paging_needed() <= 0) 1382 vm_pages_needed = 0; 1383 wakeup(&vmstats.v_free_count); 1384 } 1385 if (vm_pages_needed) { 1386 /* 1387 * Still not done, take a second pass without waiting 1388 * (unlimited dirty cleaning), otherwise sleep a bit 1389 * and try again. 1390 */ 1391 ++pass; 1392 if (pass > 1) 1393 tsleep(&vm_pages_needed, 0, "psleep", hz/2); 1394 } else { 1395 /* 1396 * Good enough, sleep & handle stats. Prime the pass 1397 * for the next run. 1398 */ 1399 if (pass > 1) 1400 pass = 1; 1401 else 1402 pass = 0; 1403 error = tsleep(&vm_pages_needed, 1404 0, "psleep", vm_pageout_stats_interval * hz); 1405 if (error && !vm_pages_needed) { 1406 splx(s); 1407 pass = 0; 1408 vm_pageout_page_stats(); 1409 continue; 1410 } 1411 } 1412 1413 if (vm_pages_needed) 1414 mycpu->gd_cnt.v_pdwakeups++; 1415 splx(s); 1416 vm_pageout_scan(pass); 1417 vm_pageout_deficit = 0; 1418 } 1419 } 1420 1421 void 1422 pagedaemon_wakeup() 1423 { 1424 if (!vm_pages_needed && curthread != pagethread) { 1425 vm_pages_needed++; 1426 wakeup(&vm_pages_needed); 1427 } 1428 } 1429 1430 #if !defined(NO_SWAPPING) 1431 static void 1432 vm_req_vmdaemon() 1433 { 1434 static int lastrun = 0; 1435 1436 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1437 wakeup(&vm_daemon_needed); 1438 lastrun = ticks; 1439 } 1440 } 1441 1442 static void 1443 vm_daemon() 1444 { 1445 struct proc *p; 1446 1447 while (TRUE) { 1448 tsleep(&vm_daemon_needed, 0, "psleep", 0); 1449 if (vm_pageout_req_swapout) { 1450 swapout_procs(vm_pageout_req_swapout); 1451 vm_pageout_req_swapout = 0; 1452 } 1453 /* 1454 * scan the processes for exceeding their rlimits or if 1455 * process is swapped out -- deactivate pages 1456 */ 1457 1458 for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) { 1459 vm_pindex_t limit, size; 1460 1461 /* 1462 * if this is a system process or if we have already 1463 * looked at this process, skip it. 1464 */ 1465 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 1466 continue; 1467 } 1468 /* 1469 * if the process is in a non-running type state, 1470 * don't touch it. 1471 */ 1472 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 1473 continue; 1474 } 1475 /* 1476 * get a limit 1477 */ 1478 limit = OFF_TO_IDX( 1479 qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 1480 p->p_rlimit[RLIMIT_RSS].rlim_max)); 1481 1482 /* 1483 * let processes that are swapped out really be 1484 * swapped out set the limit to nothing (will force a 1485 * swap-out.) 1486 */ 1487 if ((p->p_flag & P_INMEM) == 0) 1488 limit = 0; /* XXX */ 1489 1490 size = vmspace_resident_count(p->p_vmspace); 1491 if (limit >= 0 && size >= limit) { 1492 vm_pageout_map_deactivate_pages( 1493 &p->p_vmspace->vm_map, limit); 1494 } 1495 } 1496 } 1497 } 1498 #endif 1499