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 1.11 2004/05/13 17:40:19 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. The page must not be 213 * busy on-call. 214 * 215 * We set the busy bit to cause potential page faults on this page to 216 * block. Note the careful timing, however, the busy bit isn't set till 217 * late and we cannot do anything that will mess with the page. 218 */ 219 220 static int 221 vm_pageout_clean(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(vm_page_t *mc, int count, int flags) 359 { 360 vm_object_t object; 361 int pageout_status[count]; 362 int numpagedout = 0; 363 int i; 364 365 /* 366 * Initiate I/O. Bump the vm_page_t->busy counter and 367 * mark the pages read-only. 368 * 369 * We do not have to fixup the clean/dirty bits here... we can 370 * allow the pager to do it after the I/O completes. 371 */ 372 373 for (i = 0; i < count; i++) { 374 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush page %p index %d/%d: partially invalid page", mc[i], i, count)); 375 vm_page_io_start(mc[i]); 376 vm_page_protect(mc[i], VM_PROT_READ); 377 } 378 379 object = mc[0]->object; 380 vm_object_pip_add(object, count); 381 382 vm_pager_put_pages(object, mc, count, 383 (flags | ((object == kernel_object) ? VM_PAGER_PUT_SYNC : 0)), 384 pageout_status); 385 386 for (i = 0; i < count; i++) { 387 vm_page_t mt = mc[i]; 388 389 switch (pageout_status[i]) { 390 case VM_PAGER_OK: 391 numpagedout++; 392 break; 393 case VM_PAGER_PEND: 394 numpagedout++; 395 break; 396 case VM_PAGER_BAD: 397 /* 398 * Page outside of range of object. Right now we 399 * essentially lose the changes by pretending it 400 * worked. 401 */ 402 pmap_clear_modify(mt); 403 vm_page_undirty(mt); 404 break; 405 case VM_PAGER_ERROR: 406 case VM_PAGER_FAIL: 407 /* 408 * If page couldn't be paged out, then reactivate the 409 * page so it doesn't clog the inactive list. (We 410 * will try paging out it again later). 411 */ 412 vm_page_activate(mt); 413 break; 414 case VM_PAGER_AGAIN: 415 break; 416 } 417 418 /* 419 * If the operation is still going, leave the page busy to 420 * block all other accesses. Also, leave the paging in 421 * progress indicator set so that we don't attempt an object 422 * collapse. 423 */ 424 if (pageout_status[i] != VM_PAGER_PEND) { 425 vm_object_pip_wakeup(object); 426 vm_page_io_finish(mt); 427 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt)) 428 vm_page_protect(mt, VM_PROT_READ); 429 } 430 } 431 return numpagedout; 432 } 433 434 #if !defined(NO_SWAPPING) 435 /* 436 * vm_pageout_object_deactivate_pages 437 * 438 * deactivate enough pages to satisfy the inactive target 439 * requirements or if vm_page_proc_limit is set, then 440 * deactivate all of the pages in the object and its 441 * backing_objects. 442 * 443 * The object and map must be locked. 444 */ 445 static void 446 vm_pageout_object_deactivate_pages(vm_map_t map, vm_object_t object, 447 vm_pindex_t desired, int map_remove_only) 448 { 449 vm_page_t p, next; 450 int rcount; 451 int remove_mode; 452 int s; 453 454 if (object->type == OBJT_DEVICE || object->type == OBJT_PHYS) 455 return; 456 457 while (object) { 458 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 459 return; 460 if (object->paging_in_progress) 461 return; 462 463 remove_mode = map_remove_only; 464 if (object->shadow_count > 1) 465 remove_mode = 1; 466 467 /* 468 * scan the objects entire memory queue. spl protection is 469 * required to avoid an interrupt unbusy/free race against 470 * our busy check. 471 */ 472 s = splvm(); 473 rcount = object->resident_page_count; 474 p = TAILQ_FIRST(&object->memq); 475 476 while (p && (rcount-- > 0)) { 477 int actcount; 478 if (pmap_resident_count(vm_map_pmap(map)) <= desired) { 479 splx(s); 480 return; 481 } 482 next = TAILQ_NEXT(p, listq); 483 mycpu->gd_cnt.v_pdpages++; 484 if (p->wire_count != 0 || 485 p->hold_count != 0 || 486 p->busy != 0 || 487 (p->flags & (PG_BUSY|PG_UNMANAGED)) || 488 !pmap_page_exists_quick(vm_map_pmap(map), p)) { 489 p = next; 490 continue; 491 } 492 493 actcount = pmap_ts_referenced(p); 494 if (actcount) { 495 vm_page_flag_set(p, PG_REFERENCED); 496 } else if (p->flags & PG_REFERENCED) { 497 actcount = 1; 498 } 499 500 if ((p->queue != PQ_ACTIVE) && 501 (p->flags & PG_REFERENCED)) { 502 vm_page_activate(p); 503 p->act_count += actcount; 504 vm_page_flag_clear(p, PG_REFERENCED); 505 } else if (p->queue == PQ_ACTIVE) { 506 if ((p->flags & PG_REFERENCED) == 0) { 507 p->act_count -= min(p->act_count, ACT_DECLINE); 508 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) { 509 vm_page_protect(p, VM_PROT_NONE); 510 vm_page_deactivate(p); 511 } else { 512 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 513 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 514 } 515 } else { 516 vm_page_activate(p); 517 vm_page_flag_clear(p, PG_REFERENCED); 518 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 519 p->act_count += ACT_ADVANCE; 520 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 521 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 522 } 523 } else if (p->queue == PQ_INACTIVE) { 524 vm_page_protect(p, VM_PROT_NONE); 525 } 526 p = next; 527 } 528 splx(s); 529 object = object->backing_object; 530 } 531 } 532 533 /* 534 * deactivate some number of pages in a map, try to do it fairly, but 535 * that is really hard to do. 536 */ 537 static void 538 vm_pageout_map_deactivate_pages(vm_map_t map, vm_pindex_t desired) 539 { 540 vm_map_entry_t tmpe; 541 vm_object_t obj, bigobj; 542 int nothingwired; 543 544 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT, NULL, curthread)) { 545 return; 546 } 547 548 bigobj = NULL; 549 nothingwired = TRUE; 550 551 /* 552 * first, search out the biggest object, and try to free pages from 553 * that. 554 */ 555 tmpe = map->header.next; 556 while (tmpe != &map->header) { 557 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 558 obj = tmpe->object.vm_object; 559 if ((obj != NULL) && (obj->shadow_count <= 1) && 560 ((bigobj == NULL) || 561 (bigobj->resident_page_count < obj->resident_page_count))) { 562 bigobj = obj; 563 } 564 } 565 if (tmpe->wired_count > 0) 566 nothingwired = FALSE; 567 tmpe = tmpe->next; 568 } 569 570 if (bigobj) 571 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 572 573 /* 574 * Next, hunt around for other pages to deactivate. We actually 575 * do this search sort of wrong -- .text first is not the best idea. 576 */ 577 tmpe = map->header.next; 578 while (tmpe != &map->header) { 579 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 580 break; 581 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 582 obj = tmpe->object.vm_object; 583 if (obj) 584 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 585 } 586 tmpe = tmpe->next; 587 }; 588 589 /* 590 * Remove all mappings if a process is swapped out, this will free page 591 * table pages. 592 */ 593 if (desired == 0 && nothingwired) 594 pmap_remove(vm_map_pmap(map), 595 VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS); 596 vm_map_unlock(map); 597 return; 598 } 599 #endif 600 601 /* 602 * Don't try to be fancy - being fancy can lead to VOP_LOCK's and therefore 603 * to vnode deadlocks. We only do it for OBJT_DEFAULT and OBJT_SWAP objects 604 * which we know can be trivially freed. 605 */ 606 607 void 608 vm_pageout_page_free(vm_page_t m) { 609 vm_object_t object = m->object; 610 int type = object->type; 611 612 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 613 vm_object_reference(object); 614 vm_page_busy(m); 615 vm_page_protect(m, VM_PROT_NONE); 616 vm_page_free(m); 617 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 618 vm_object_deallocate(object); 619 } 620 621 /* 622 * vm_pageout_scan does the dirty work for the pageout daemon. 623 */ 624 static void 625 vm_pageout_scan(int pass) 626 { 627 vm_page_t m, next; 628 struct vm_page marker; 629 int page_shortage, maxscan, pcount; 630 int addl_page_shortage, addl_page_shortage_init; 631 struct proc *p, *bigproc; 632 vm_offset_t size, bigsize; 633 vm_object_t object; 634 int actcount; 635 int vnodes_skipped = 0; 636 int maxlaunder; 637 int s; 638 639 /* 640 * Do whatever cleanup that the pmap code can. 641 */ 642 pmap_collect(); 643 644 addl_page_shortage_init = vm_pageout_deficit; 645 vm_pageout_deficit = 0; 646 647 /* 648 * Calculate the number of pages we want to either free or move 649 * to the cache. 650 */ 651 page_shortage = vm_paging_target() + addl_page_shortage_init; 652 653 /* 654 * Initialize our marker 655 */ 656 bzero(&marker, sizeof(marker)); 657 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 658 marker.queue = PQ_INACTIVE; 659 marker.wire_count = 1; 660 661 /* 662 * Start scanning the inactive queue for pages we can move to the 663 * cache or free. The scan will stop when the target is reached or 664 * we have scanned the entire inactive queue. Note that m->act_count 665 * is not used to form decisions for the inactive queue, only for the 666 * active queue. 667 * 668 * maxlaunder limits the number of dirty pages we flush per scan. 669 * For most systems a smaller value (16 or 32) is more robust under 670 * extreme memory and disk pressure because any unnecessary writes 671 * to disk can result in extreme performance degredation. However, 672 * systems with excessive dirty pages (especially when MAP_NOSYNC is 673 * used) will die horribly with limited laundering. If the pageout 674 * daemon cannot clean enough pages in the first pass, we let it go 675 * all out in succeeding passes. 676 */ 677 if ((maxlaunder = vm_max_launder) <= 1) 678 maxlaunder = 1; 679 if (pass) 680 maxlaunder = 10000; 681 682 /* 683 * We will generally be at splvm() throughout the scan, but we 684 * can release it temporarily when we are sitting on a non-busy 685 * page without fear. The spl protection is required because an 686 * an interrupt can come along and unbusy/free a busy page prior 687 * to our busy check, leaving us on the wrong queue or checking 688 * the wrong page. 689 */ 690 s = splvm(); 691 rescan0: 692 addl_page_shortage = addl_page_shortage_init; 693 maxscan = vmstats.v_inactive_count; 694 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 695 m != NULL && maxscan-- > 0 && page_shortage > 0; 696 m = next 697 ) { 698 mycpu->gd_cnt.v_pdpages++; 699 700 /* 701 * Give interrupts a chance 702 */ 703 splx(s); 704 s = splvm(); 705 706 /* 707 * It's easier for some of the conditions below to just loop 708 * and catch queue changes here rather then check everywhere 709 * else. 710 */ 711 if (m->queue != PQ_INACTIVE) 712 goto rescan0; 713 next = TAILQ_NEXT(m, pageq); 714 715 /* 716 * skip marker pages 717 */ 718 if (m->flags & PG_MARKER) 719 continue; 720 721 /* 722 * A held page may be undergoing I/O, so skip it. 723 */ 724 if (m->hold_count) { 725 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 726 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 727 addl_page_shortage++; 728 continue; 729 } 730 731 /* 732 * Dont mess with busy pages, keep in the front of the 733 * queue, most likely are being paged out. 734 */ 735 if (m->busy || (m->flags & PG_BUSY)) { 736 addl_page_shortage++; 737 continue; 738 } 739 740 if (m->object->ref_count == 0) { 741 /* 742 * If the object is not being used, we ignore previous 743 * references. 744 */ 745 vm_page_flag_clear(m, PG_REFERENCED); 746 pmap_clear_reference(m); 747 748 } else if (((m->flags & PG_REFERENCED) == 0) && 749 (actcount = pmap_ts_referenced(m))) { 750 /* 751 * Otherwise, if the page has been referenced while 752 * in the inactive queue, we bump the "activation 753 * count" upwards, making it less likely that the 754 * page will be added back to the inactive queue 755 * prematurely again. Here we check the page tables 756 * (or emulated bits, if any), given the upper level 757 * VM system not knowing anything about existing 758 * references. 759 */ 760 vm_page_activate(m); 761 m->act_count += (actcount + ACT_ADVANCE); 762 continue; 763 } 764 765 /* 766 * If the upper level VM system knows about any page 767 * references, we activate the page. We also set the 768 * "activation count" higher than normal so that we will less 769 * likely place pages back onto the inactive queue again. 770 */ 771 if ((m->flags & PG_REFERENCED) != 0) { 772 vm_page_flag_clear(m, PG_REFERENCED); 773 actcount = pmap_ts_referenced(m); 774 vm_page_activate(m); 775 m->act_count += (actcount + ACT_ADVANCE + 1); 776 continue; 777 } 778 779 /* 780 * If the upper level VM system doesn't know anything about 781 * the page being dirty, we have to check for it again. As 782 * far as the VM code knows, any partially dirty pages are 783 * fully dirty. 784 * 785 * Pages marked PG_WRITEABLE may be mapped into the user 786 * address space of a process running on another cpu. A 787 * user process (without holding the MP lock) running on 788 * another cpu may be able to touch the page while we are 789 * trying to remove it. To prevent this from occuring we 790 * must call pmap_remove_all() or otherwise make the page 791 * read-only. If the race occured pmap_remove_all() is 792 * responsible for setting m->dirty. 793 */ 794 if (m->dirty == 0) { 795 vm_page_test_dirty(m); 796 #if 0 797 if (m->dirty == 0 && (m->flags & PG_WRITEABLE) != 0) 798 pmap_remove_all(m); 799 #endif 800 } else { 801 vm_page_dirty(m); 802 } 803 804 if (m->valid == 0) { 805 /* 806 * Invalid pages can be easily freed 807 */ 808 vm_pageout_page_free(m); 809 mycpu->gd_cnt.v_dfree++; 810 --page_shortage; 811 } else if (m->dirty == 0) { 812 /* 813 * Clean pages can be placed onto the cache queue. 814 * This effectively frees them. 815 */ 816 vm_page_cache(m); 817 --page_shortage; 818 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 819 /* 820 * Dirty pages need to be paged out, but flushing 821 * a page is extremely expensive verses freeing 822 * a clean page. Rather then artificially limiting 823 * the number of pages we can flush, we instead give 824 * dirty pages extra priority on the inactive queue 825 * by forcing them to be cycled through the queue 826 * twice before being flushed, after which the 827 * (now clean) page will cycle through once more 828 * before being freed. This significantly extends 829 * the thrash point for a heavily loaded machine. 830 */ 831 vm_page_flag_set(m, PG_WINATCFLS); 832 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 833 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 834 } else if (maxlaunder > 0) { 835 /* 836 * We always want to try to flush some dirty pages if 837 * we encounter them, to keep the system stable. 838 * Normally this number is small, but under extreme 839 * pressure where there are insufficient clean pages 840 * on the inactive queue, we may have to go all out. 841 */ 842 int swap_pageouts_ok; 843 struct vnode *vp = NULL; 844 845 object = m->object; 846 847 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 848 swap_pageouts_ok = 1; 849 } else { 850 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 851 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 852 vm_page_count_min()); 853 854 } 855 856 /* 857 * We don't bother paging objects that are "dead". 858 * Those objects are in a "rundown" state. 859 */ 860 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 861 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 862 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 863 continue; 864 } 865 866 /* 867 * The object is already known NOT to be dead. It 868 * is possible for the vget() to block the whole 869 * pageout daemon, but the new low-memory handling 870 * code should prevent it. 871 * 872 * The previous code skipped locked vnodes and, worse, 873 * reordered pages in the queue. This results in 874 * completely non-deterministic operation because, 875 * quite often, a vm_fault has initiated an I/O and 876 * is holding a locked vnode at just the point where 877 * the pageout daemon is woken up. 878 * 879 * We can't wait forever for the vnode lock, we might 880 * deadlock due to a vn_read() getting stuck in 881 * vm_wait while holding this vnode. We skip the 882 * vnode if we can't get it in a reasonable amount 883 * of time. 884 */ 885 886 if (object->type == OBJT_VNODE) { 887 vp = object->handle; 888 889 if (vget(vp, NULL, LK_EXCLUSIVE|LK_NOOBJ|LK_TIMELOCK, curthread)) { 890 ++pageout_lock_miss; 891 if (object->flags & OBJ_MIGHTBEDIRTY) 892 vnodes_skipped++; 893 continue; 894 } 895 896 /* 897 * The page might have been moved to another 898 * queue during potential blocking in vget() 899 * above. The page might have been freed and 900 * reused for another vnode. The object might 901 * have been reused for another vnode. 902 */ 903 if (m->queue != PQ_INACTIVE || 904 m->object != object || 905 object->handle != vp) { 906 if (object->flags & OBJ_MIGHTBEDIRTY) 907 vnodes_skipped++; 908 vput(vp); 909 continue; 910 } 911 912 /* 913 * The page may have been busied during the 914 * blocking in vput(); We don't move the 915 * page back onto the end of the queue so that 916 * statistics are more correct if we don't. 917 */ 918 if (m->busy || (m->flags & PG_BUSY)) { 919 vput(vp); 920 continue; 921 } 922 923 /* 924 * If the page has become held it might 925 * be undergoing I/O, so skip it 926 */ 927 if (m->hold_count) { 928 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 929 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 930 if (object->flags & OBJ_MIGHTBEDIRTY) 931 vnodes_skipped++; 932 vput(vp); 933 continue; 934 } 935 } 936 937 /* 938 * If a page is dirty, then it is either being washed 939 * (but not yet cleaned) or it is still in the 940 * laundry. If it is still in the laundry, then we 941 * start the cleaning operation. 942 * 943 * This operation may cluster, invalidating the 'next' 944 * pointer. To prevent an inordinate number of 945 * restarts we use our marker to remember our place. 946 * 947 * decrement page_shortage on success to account for 948 * the (future) cleaned page. Otherwise we could wind 949 * up laundering or cleaning too many pages. 950 */ 951 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq); 952 if (vm_pageout_clean(m) != 0) { 953 --page_shortage; 954 --maxlaunder; 955 } 956 next = TAILQ_NEXT(&marker, pageq); 957 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq); 958 if (vp != NULL) 959 vput(vp); 960 } 961 } 962 963 /* 964 * Compute the number of pages we want to try to move from the 965 * active queue to the inactive queue. 966 */ 967 page_shortage = vm_paging_target() + 968 vmstats.v_inactive_target - vmstats.v_inactive_count; 969 page_shortage += addl_page_shortage; 970 971 /* 972 * Scan the active queue for things we can deactivate. We nominally 973 * track the per-page activity counter and use it to locate 974 * deactivation candidates. 975 * 976 * NOTE: we are still at splvm(). 977 */ 978 pcount = vmstats.v_active_count; 979 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 980 981 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 982 /* 983 * Give interrupts a chance. 984 */ 985 splx(s); 986 s = splvm(); 987 988 /* 989 * If the page was ripped out from under us, just stop. 990 */ 991 if (m->queue != PQ_ACTIVE) 992 break; 993 next = TAILQ_NEXT(m, pageq); 994 995 /* 996 * Don't deactivate pages that are busy. 997 */ 998 if ((m->busy != 0) || 999 (m->flags & PG_BUSY) || 1000 (m->hold_count != 0)) { 1001 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1002 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1003 m = next; 1004 continue; 1005 } 1006 1007 /* 1008 * The count for pagedaemon pages is done after checking the 1009 * page for eligibility... 1010 */ 1011 mycpu->gd_cnt.v_pdpages++; 1012 1013 /* 1014 * Check to see "how much" the page has been used. 1015 */ 1016 actcount = 0; 1017 if (m->object->ref_count != 0) { 1018 if (m->flags & PG_REFERENCED) { 1019 actcount += 1; 1020 } 1021 actcount += pmap_ts_referenced(m); 1022 if (actcount) { 1023 m->act_count += ACT_ADVANCE + actcount; 1024 if (m->act_count > ACT_MAX) 1025 m->act_count = ACT_MAX; 1026 } 1027 } 1028 1029 /* 1030 * Since we have "tested" this bit, we need to clear it now. 1031 */ 1032 vm_page_flag_clear(m, PG_REFERENCED); 1033 1034 /* 1035 * Only if an object is currently being used, do we use the 1036 * page activation count stats. 1037 */ 1038 if (actcount && (m->object->ref_count != 0)) { 1039 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1040 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1041 } else { 1042 m->act_count -= min(m->act_count, ACT_DECLINE); 1043 if (vm_pageout_algorithm || 1044 m->object->ref_count == 0 || 1045 m->act_count == 0) { 1046 page_shortage--; 1047 if (m->object->ref_count == 0) { 1048 vm_page_protect(m, VM_PROT_NONE); 1049 if (m->dirty == 0) 1050 vm_page_cache(m); 1051 else 1052 vm_page_deactivate(m); 1053 } else { 1054 vm_page_deactivate(m); 1055 } 1056 } else { 1057 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1058 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1059 } 1060 } 1061 m = next; 1062 } 1063 1064 /* 1065 * We try to maintain some *really* free pages, this allows interrupt 1066 * code to be guaranteed space. Since both cache and free queues 1067 * are considered basically 'free', moving pages from cache to free 1068 * does not effect other calculations. 1069 * 1070 * NOTE: we are still at splvm(). 1071 */ 1072 1073 while (vmstats.v_free_count < vmstats.v_free_reserved) { 1074 static int cache_rover = 0; 1075 m = vm_page_list_find(PQ_CACHE, cache_rover, FALSE); 1076 if (!m) 1077 break; 1078 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || 1079 m->busy || 1080 m->hold_count || 1081 m->wire_count) { 1082 #ifdef INVARIANTS 1083 printf("Warning: busy page %p found in cache\n", m); 1084 #endif 1085 vm_page_deactivate(m); 1086 continue; 1087 } 1088 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK; 1089 vm_pageout_page_free(m); 1090 mycpu->gd_cnt.v_dfree++; 1091 } 1092 1093 splx(s); 1094 1095 #if !defined(NO_SWAPPING) 1096 /* 1097 * Idle process swapout -- run once per second. 1098 */ 1099 if (vm_swap_idle_enabled) { 1100 static long lsec; 1101 if (time_second != lsec) { 1102 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1103 vm_req_vmdaemon(); 1104 lsec = time_second; 1105 } 1106 } 1107 #endif 1108 1109 /* 1110 * If we didn't get enough free pages, and we have skipped a vnode 1111 * in a writeable object, wakeup the sync daemon. And kick swapout 1112 * if we did not get enough free pages. 1113 */ 1114 if (vm_paging_target() > 0) { 1115 if (vnodes_skipped && vm_page_count_min()) 1116 (void) speedup_syncer(); 1117 #if !defined(NO_SWAPPING) 1118 if (vm_swap_enabled && vm_page_count_target()) { 1119 vm_req_vmdaemon(); 1120 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1121 } 1122 #endif 1123 } 1124 1125 /* 1126 * If we are out of swap and were not able to reach our paging 1127 * target, kill the largest process. 1128 */ 1129 if ((vm_swap_size < 64 && vm_page_count_min()) || 1130 (swap_pager_full && vm_paging_target() > 0)) { 1131 #if 0 1132 if ((vm_swap_size < 64 || swap_pager_full) && vm_page_count_min()) { 1133 #endif 1134 bigproc = NULL; 1135 bigsize = 0; 1136 for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) { 1137 /* 1138 * if this is a system process, skip it 1139 */ 1140 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1141 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1142 continue; 1143 } 1144 /* 1145 * if the process is in a non-running type state, 1146 * don't touch it. 1147 */ 1148 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 1149 continue; 1150 } 1151 /* 1152 * get the process size 1153 */ 1154 size = vmspace_resident_count(p->p_vmspace) + 1155 vmspace_swap_count(p->p_vmspace); 1156 /* 1157 * if the this process is bigger than the biggest one 1158 * remember it. 1159 */ 1160 if (size > bigsize) { 1161 bigproc = p; 1162 bigsize = size; 1163 } 1164 } 1165 if (bigproc != NULL) { 1166 killproc(bigproc, "out of swap space"); 1167 bigproc->p_estcpu = 0; 1168 bigproc->p_nice = PRIO_MIN; 1169 resetpriority(bigproc); 1170 wakeup(&vmstats.v_free_count); 1171 } 1172 } 1173 } 1174 1175 /* 1176 * This routine tries to maintain the pseudo LRU active queue, 1177 * so that during long periods of time where there is no paging, 1178 * that some statistic accumulation still occurs. This code 1179 * helps the situation where paging just starts to occur. 1180 */ 1181 static void 1182 vm_pageout_page_stats(void) 1183 { 1184 int s; 1185 vm_page_t m,next; 1186 int pcount,tpcount; /* Number of pages to check */ 1187 static int fullintervalcount = 0; 1188 int page_shortage; 1189 int s0; 1190 1191 page_shortage = 1192 (vmstats.v_inactive_target + vmstats.v_cache_max + vmstats.v_free_min) - 1193 (vmstats.v_free_count + vmstats.v_inactive_count + vmstats.v_cache_count); 1194 1195 if (page_shortage <= 0) 1196 return; 1197 1198 s0 = splvm(); 1199 1200 pcount = vmstats.v_active_count; 1201 fullintervalcount += vm_pageout_stats_interval; 1202 if (fullintervalcount < vm_pageout_full_stats_interval) { 1203 tpcount = (vm_pageout_stats_max * vmstats.v_active_count) / vmstats.v_page_count; 1204 if (pcount > tpcount) 1205 pcount = tpcount; 1206 } else { 1207 fullintervalcount = 0; 1208 } 1209 1210 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1211 while ((m != NULL) && (pcount-- > 0)) { 1212 int actcount; 1213 1214 if (m->queue != PQ_ACTIVE) { 1215 break; 1216 } 1217 1218 next = TAILQ_NEXT(m, pageq); 1219 /* 1220 * Don't deactivate pages that are busy. 1221 */ 1222 if ((m->busy != 0) || 1223 (m->flags & PG_BUSY) || 1224 (m->hold_count != 0)) { 1225 s = splvm(); 1226 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1227 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1228 splx(s); 1229 m = next; 1230 continue; 1231 } 1232 1233 actcount = 0; 1234 if (m->flags & PG_REFERENCED) { 1235 vm_page_flag_clear(m, PG_REFERENCED); 1236 actcount += 1; 1237 } 1238 1239 actcount += pmap_ts_referenced(m); 1240 if (actcount) { 1241 m->act_count += ACT_ADVANCE + actcount; 1242 if (m->act_count > ACT_MAX) 1243 m->act_count = ACT_MAX; 1244 s = splvm(); 1245 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1246 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1247 splx(s); 1248 } else { 1249 if (m->act_count == 0) { 1250 /* 1251 * We turn off page access, so that we have 1252 * more accurate RSS stats. We don't do this 1253 * in the normal page deactivation when the 1254 * system is loaded VM wise, because the 1255 * cost of the large number of page protect 1256 * operations would be higher than the value 1257 * of doing the operation. 1258 */ 1259 vm_page_protect(m, VM_PROT_NONE); 1260 vm_page_deactivate(m); 1261 } else { 1262 m->act_count -= min(m->act_count, ACT_DECLINE); 1263 s = splvm(); 1264 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1265 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1266 splx(s); 1267 } 1268 } 1269 1270 m = next; 1271 } 1272 splx(s0); 1273 } 1274 1275 static int 1276 vm_pageout_free_page_calc(vm_size_t count) 1277 { 1278 if (count < vmstats.v_page_count) 1279 return 0; 1280 /* 1281 * free_reserved needs to include enough for the largest swap pager 1282 * structures plus enough for any pv_entry structs when paging. 1283 */ 1284 if (vmstats.v_page_count > 1024) 1285 vmstats.v_free_min = 4 + (vmstats.v_page_count - 1024) / 200; 1286 else 1287 vmstats.v_free_min = 4; 1288 vmstats.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1289 vmstats.v_interrupt_free_min; 1290 vmstats.v_free_reserved = vm_pageout_page_count + 1291 vmstats.v_pageout_free_min + (count / 768) + PQ_L2_SIZE; 1292 vmstats.v_free_severe = vmstats.v_free_min / 2; 1293 vmstats.v_free_min += vmstats.v_free_reserved; 1294 vmstats.v_free_severe += vmstats.v_free_reserved; 1295 return 1; 1296 } 1297 1298 1299 /* 1300 * vm_pageout is the high level pageout daemon. 1301 */ 1302 static void 1303 vm_pageout(void) 1304 { 1305 int pass; 1306 1307 /* 1308 * Initialize some paging parameters. 1309 */ 1310 1311 vmstats.v_interrupt_free_min = 2; 1312 if (vmstats.v_page_count < 2000) 1313 vm_pageout_page_count = 8; 1314 1315 vm_pageout_free_page_calc(vmstats.v_page_count); 1316 /* 1317 * v_free_target and v_cache_min control pageout hysteresis. Note 1318 * that these are more a measure of the VM cache queue hysteresis 1319 * then the VM free queue. Specifically, v_free_target is the 1320 * high water mark (free+cache pages). 1321 * 1322 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1323 * low water mark, while v_free_min is the stop. v_cache_min must 1324 * be big enough to handle memory needs while the pageout daemon 1325 * is signalled and run to free more pages. 1326 */ 1327 if (vmstats.v_free_count > 6144) 1328 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved; 1329 else 1330 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved; 1331 1332 if (vmstats.v_free_count > 2048) { 1333 vmstats.v_cache_min = vmstats.v_free_target; 1334 vmstats.v_cache_max = 2 * vmstats.v_cache_min; 1335 vmstats.v_inactive_target = (3 * vmstats.v_free_target) / 2; 1336 } else { 1337 vmstats.v_cache_min = 0; 1338 vmstats.v_cache_max = 0; 1339 vmstats.v_inactive_target = vmstats.v_free_count / 4; 1340 } 1341 if (vmstats.v_inactive_target > vmstats.v_free_count / 3) 1342 vmstats.v_inactive_target = vmstats.v_free_count / 3; 1343 1344 /* XXX does not really belong here */ 1345 if (vm_page_max_wired == 0) 1346 vm_page_max_wired = vmstats.v_free_count / 3; 1347 1348 if (vm_pageout_stats_max == 0) 1349 vm_pageout_stats_max = vmstats.v_free_target; 1350 1351 /* 1352 * Set interval in seconds for stats scan. 1353 */ 1354 if (vm_pageout_stats_interval == 0) 1355 vm_pageout_stats_interval = 5; 1356 if (vm_pageout_full_stats_interval == 0) 1357 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1358 1359 1360 /* 1361 * Set maximum free per pass 1362 */ 1363 if (vm_pageout_stats_free_max == 0) 1364 vm_pageout_stats_free_max = 5; 1365 1366 swap_pager_swap_init(); 1367 pass = 0; 1368 /* 1369 * The pageout daemon is never done, so loop forever. 1370 */ 1371 while (TRUE) { 1372 int error; 1373 int s = splvm(); 1374 1375 /* 1376 * If we have enough free memory, wakeup waiters. Do 1377 * not clear vm_pages_needed until we reach our target, 1378 * otherwise we may be woken up over and over again and 1379 * waste a lot of cpu. 1380 */ 1381 if (vm_pages_needed && !vm_page_count_min()) { 1382 if (vm_paging_needed() <= 0) 1383 vm_pages_needed = 0; 1384 wakeup(&vmstats.v_free_count); 1385 } 1386 if (vm_pages_needed) { 1387 /* 1388 * Still not done, take a second pass without waiting 1389 * (unlimited dirty cleaning), otherwise sleep a bit 1390 * and try again. 1391 */ 1392 ++pass; 1393 if (pass > 1) 1394 tsleep(&vm_pages_needed, 0, "psleep", hz/2); 1395 } else { 1396 /* 1397 * Good enough, sleep & handle stats. Prime the pass 1398 * for the next run. 1399 */ 1400 if (pass > 1) 1401 pass = 1; 1402 else 1403 pass = 0; 1404 error = tsleep(&vm_pages_needed, 1405 0, "psleep", vm_pageout_stats_interval * hz); 1406 if (error && !vm_pages_needed) { 1407 splx(s); 1408 pass = 0; 1409 vm_pageout_page_stats(); 1410 continue; 1411 } 1412 } 1413 1414 if (vm_pages_needed) 1415 mycpu->gd_cnt.v_pdwakeups++; 1416 splx(s); 1417 vm_pageout_scan(pass); 1418 vm_pageout_deficit = 0; 1419 } 1420 } 1421 1422 void 1423 pagedaemon_wakeup(void) 1424 { 1425 if (!vm_pages_needed && curthread != pagethread) { 1426 vm_pages_needed++; 1427 wakeup(&vm_pages_needed); 1428 } 1429 } 1430 1431 #if !defined(NO_SWAPPING) 1432 static void 1433 vm_req_vmdaemon(void) 1434 { 1435 static int lastrun = 0; 1436 1437 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1438 wakeup(&vm_daemon_needed); 1439 lastrun = ticks; 1440 } 1441 } 1442 1443 static void 1444 vm_daemon(void) 1445 { 1446 struct proc *p; 1447 1448 while (TRUE) { 1449 tsleep(&vm_daemon_needed, 0, "psleep", 0); 1450 if (vm_pageout_req_swapout) { 1451 swapout_procs(vm_pageout_req_swapout); 1452 vm_pageout_req_swapout = 0; 1453 } 1454 /* 1455 * scan the processes for exceeding their rlimits or if 1456 * process is swapped out -- deactivate pages 1457 */ 1458 1459 for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) { 1460 vm_pindex_t limit, size; 1461 1462 /* 1463 * if this is a system process or if we have already 1464 * looked at this process, skip it. 1465 */ 1466 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 1467 continue; 1468 } 1469 /* 1470 * if the process is in a non-running type state, 1471 * don't touch it. 1472 */ 1473 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 1474 continue; 1475 } 1476 /* 1477 * get a limit 1478 */ 1479 limit = OFF_TO_IDX( 1480 qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 1481 p->p_rlimit[RLIMIT_RSS].rlim_max)); 1482 1483 /* 1484 * let processes that are swapped out really be 1485 * swapped out set the limit to nothing (will force a 1486 * swap-out.) 1487 */ 1488 if ((p->p_flag & P_INMEM) == 0) 1489 limit = 0; /* XXX */ 1490 1491 size = vmspace_resident_count(p->p_vmspace); 1492 if (limit >= 0 && size >= limit) { 1493 vm_pageout_map_deactivate_pages( 1494 &p->p_vmspace->vm_map, limit); 1495 } 1496 } 1497 } 1498 } 1499 #endif 1500