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 1.17 2006/01/13 20:45:30 swildner 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 99 #include <sys/thread2.h> 100 #include <vm/vm_page2.h> 101 102 /* 103 * System initialization 104 */ 105 106 /* the kernel process "vm_pageout"*/ 107 static void vm_pageout (void); 108 static int vm_pageout_clean (vm_page_t); 109 static void vm_pageout_scan (int pass); 110 static int vm_pageout_free_page_calc (vm_size_t count); 111 struct thread *pagethread; 112 113 static struct kproc_desc page_kp = { 114 "pagedaemon", 115 vm_pageout, 116 &pagethread 117 }; 118 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 119 120 #if !defined(NO_SWAPPING) 121 /* the kernel process "vm_daemon"*/ 122 static void vm_daemon (void); 123 static struct thread *vmthread; 124 125 static struct kproc_desc vm_kp = { 126 "vmdaemon", 127 vm_daemon, 128 &vmthread 129 }; 130 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) 131 #endif 132 133 134 int vm_pages_needed=0; /* Event on which pageout daemon sleeps */ 135 int vm_pageout_deficit=0; /* Estimated number of pages deficit */ 136 int vm_pageout_pages_needed=0; /* flag saying that the pageout daemon needs pages */ 137 138 #if !defined(NO_SWAPPING) 139 static int vm_pageout_req_swapout; /* XXX */ 140 static int vm_daemon_needed; 141 #endif 142 extern int vm_swap_size; 143 static int vm_max_launder = 32; 144 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 145 static int vm_pageout_full_stats_interval = 0; 146 static int vm_pageout_stats_free_max=0, vm_pageout_algorithm=0; 147 static int defer_swap_pageouts=0; 148 static int disable_swap_pageouts=0; 149 150 #if defined(NO_SWAPPING) 151 static int vm_swap_enabled=0; 152 static int vm_swap_idle_enabled=0; 153 #else 154 static int vm_swap_enabled=1; 155 static int vm_swap_idle_enabled=0; 156 #endif 157 158 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 159 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 160 161 SYSCTL_INT(_vm, OID_AUTO, max_launder, 162 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 163 164 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 165 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 166 167 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 168 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 169 170 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 171 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 172 173 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max, 174 CTLFLAG_RW, &vm_pageout_stats_free_max, 0, "Not implemented"); 175 176 #if defined(NO_SWAPPING) 177 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 178 CTLFLAG_RD, &vm_swap_enabled, 0, ""); 179 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 180 CTLFLAG_RD, &vm_swap_idle_enabled, 0, ""); 181 #else 182 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 183 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 184 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 185 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 186 #endif 187 188 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 189 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 190 191 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 192 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 193 194 static int pageout_lock_miss; 195 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 196 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 197 198 #define VM_PAGEOUT_PAGE_COUNT 16 199 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 200 201 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 202 203 #if !defined(NO_SWAPPING) 204 typedef void freeer_fcn_t (vm_map_t, vm_object_t, vm_pindex_t, int); 205 static void vm_pageout_map_deactivate_pages (vm_map_t, vm_pindex_t); 206 static freeer_fcn_t vm_pageout_object_deactivate_pages; 207 static void vm_req_vmdaemon (void); 208 #endif 209 static void vm_pageout_page_stats(void); 210 211 /* 212 * vm_pageout_clean: 213 * 214 * Clean the page and remove it from the laundry. The page must not be 215 * busy on-call. 216 * 217 * We set the busy bit to cause potential page faults on this page to 218 * block. Note the careful timing, however, the busy bit isn't set till 219 * late and we cannot do anything that will mess with the page. 220 */ 221 222 static int 223 vm_pageout_clean(vm_page_t m) 224 { 225 vm_object_t object; 226 vm_page_t mc[2*vm_pageout_page_count]; 227 int pageout_count; 228 int ib, is, page_base; 229 vm_pindex_t pindex = m->pindex; 230 231 object = m->object; 232 233 /* 234 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 235 * with the new swapper, but we could have serious problems paging 236 * out other object types if there is insufficient memory. 237 * 238 * Unfortunately, checking free memory here is far too late, so the 239 * check has been moved up a procedural level. 240 */ 241 242 /* 243 * Don't mess with the page if it's busy, held, or special 244 */ 245 if ((m->hold_count != 0) || 246 ((m->busy != 0) || (m->flags & (PG_BUSY|PG_UNMANAGED)))) { 247 return 0; 248 } 249 250 mc[vm_pageout_page_count] = m; 251 pageout_count = 1; 252 page_base = vm_pageout_page_count; 253 ib = 1; 254 is = 1; 255 256 /* 257 * Scan object for clusterable pages. 258 * 259 * We can cluster ONLY if: ->> the page is NOT 260 * clean, wired, busy, held, or mapped into a 261 * buffer, and one of the following: 262 * 1) The page is inactive, or a seldom used 263 * active page. 264 * -or- 265 * 2) we force the issue. 266 * 267 * During heavy mmap/modification loads the pageout 268 * daemon can really fragment the underlying file 269 * due to flushing pages out of order and not trying 270 * align the clusters (which leave sporatic out-of-order 271 * holes). To solve this problem we do the reverse scan 272 * first and attempt to align our cluster, then do a 273 * forward scan if room remains. 274 */ 275 276 more: 277 while (ib && pageout_count < vm_pageout_page_count) { 278 vm_page_t p; 279 280 if (ib > pindex) { 281 ib = 0; 282 break; 283 } 284 285 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) { 286 ib = 0; 287 break; 288 } 289 if (((p->queue - p->pc) == PQ_CACHE) || 290 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 291 ib = 0; 292 break; 293 } 294 vm_page_test_dirty(p); 295 if ((p->dirty & p->valid) == 0 || 296 p->queue != PQ_INACTIVE || 297 p->wire_count != 0 || /* may be held by buf cache */ 298 p->hold_count != 0) { /* may be undergoing I/O */ 299 ib = 0; 300 break; 301 } 302 mc[--page_base] = p; 303 ++pageout_count; 304 ++ib; 305 /* 306 * alignment boundry, stop here and switch directions. Do 307 * not clear ib. 308 */ 309 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 310 break; 311 } 312 313 while (pageout_count < vm_pageout_page_count && 314 pindex + is < object->size) { 315 vm_page_t p; 316 317 if ((p = vm_page_lookup(object, pindex + is)) == NULL) 318 break; 319 if (((p->queue - p->pc) == PQ_CACHE) || 320 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 321 break; 322 } 323 vm_page_test_dirty(p); 324 if ((p->dirty & p->valid) == 0 || 325 p->queue != PQ_INACTIVE || 326 p->wire_count != 0 || /* may be held by buf cache */ 327 p->hold_count != 0) { /* may be undergoing I/O */ 328 break; 329 } 330 mc[page_base + pageout_count] = p; 331 ++pageout_count; 332 ++is; 333 } 334 335 /* 336 * If we exhausted our forward scan, continue with the reverse scan 337 * when possible, even past a page boundry. This catches boundry 338 * conditions. 339 */ 340 if (ib && pageout_count < vm_pageout_page_count) 341 goto more; 342 343 /* 344 * we allow reads during pageouts... 345 */ 346 return vm_pageout_flush(&mc[page_base], pageout_count, 0); 347 } 348 349 /* 350 * vm_pageout_flush() - launder the given pages 351 * 352 * The given pages are laundered. Note that we setup for the start of 353 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 354 * reference count all in here rather then in the parent. If we want 355 * the parent to do more sophisticated things we may have to change 356 * the ordering. 357 */ 358 359 int 360 vm_pageout_flush(vm_page_t *mc, int count, int flags) 361 { 362 vm_object_t object; 363 int pageout_status[count]; 364 int numpagedout = 0; 365 int i; 366 367 /* 368 * Initiate I/O. Bump the vm_page_t->busy counter and 369 * mark the pages read-only. 370 * 371 * We do not have to fixup the clean/dirty bits here... we can 372 * allow the pager to do it after the I/O completes. 373 */ 374 375 for (i = 0; i < count; i++) { 376 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush page %p index %d/%d: partially invalid page", mc[i], i, count)); 377 vm_page_io_start(mc[i]); 378 vm_page_protect(mc[i], VM_PROT_READ); 379 } 380 381 object = mc[0]->object; 382 vm_object_pip_add(object, count); 383 384 vm_pager_put_pages(object, mc, count, 385 (flags | ((object == kernel_object) ? VM_PAGER_PUT_SYNC : 0)), 386 pageout_status); 387 388 for (i = 0; i < count; i++) { 389 vm_page_t mt = mc[i]; 390 391 switch (pageout_status[i]) { 392 case VM_PAGER_OK: 393 numpagedout++; 394 break; 395 case VM_PAGER_PEND: 396 numpagedout++; 397 break; 398 case VM_PAGER_BAD: 399 /* 400 * Page outside of range of object. Right now we 401 * essentially lose the changes by pretending it 402 * worked. 403 */ 404 pmap_clear_modify(mt); 405 vm_page_undirty(mt); 406 break; 407 case VM_PAGER_ERROR: 408 case VM_PAGER_FAIL: 409 /* 410 * If page couldn't be paged out, then reactivate the 411 * page so it doesn't clog the inactive list. (We 412 * will try paging out it again later). 413 */ 414 vm_page_activate(mt); 415 break; 416 case VM_PAGER_AGAIN: 417 break; 418 } 419 420 /* 421 * If the operation is still going, leave the page busy to 422 * block all other accesses. Also, leave the paging in 423 * progress indicator set so that we don't attempt an object 424 * collapse. 425 */ 426 if (pageout_status[i] != VM_PAGER_PEND) { 427 vm_object_pip_wakeup(object); 428 vm_page_io_finish(mt); 429 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt)) 430 vm_page_protect(mt, VM_PROT_READ); 431 } 432 } 433 return numpagedout; 434 } 435 436 #if !defined(NO_SWAPPING) 437 /* 438 * vm_pageout_object_deactivate_pages 439 * 440 * deactivate enough pages to satisfy the inactive target 441 * requirements or if vm_page_proc_limit is set, then 442 * deactivate all of the pages in the object and its 443 * backing_objects. 444 * 445 * The object and map must be locked. 446 */ 447 static void 448 vm_pageout_object_deactivate_pages(vm_map_t map, vm_object_t object, 449 vm_pindex_t desired, int map_remove_only) 450 { 451 vm_page_t p, next; 452 int rcount; 453 int remove_mode; 454 455 if (object->type == OBJT_DEVICE || object->type == OBJT_PHYS) 456 return; 457 458 while (object) { 459 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 460 return; 461 if (object->paging_in_progress) 462 return; 463 464 remove_mode = map_remove_only; 465 if (object->shadow_count > 1) 466 remove_mode = 1; 467 468 /* 469 * scan the objects entire memory queue. spl protection is 470 * required to avoid an interrupt unbusy/free race against 471 * our busy check. 472 */ 473 crit_enter(); 474 rcount = object->resident_page_count; 475 p = TAILQ_FIRST(&object->memq); 476 477 while (p && (rcount-- > 0)) { 478 int actcount; 479 if (pmap_resident_count(vm_map_pmap(map)) <= desired) { 480 crit_exit(); 481 return; 482 } 483 next = TAILQ_NEXT(p, listq); 484 mycpu->gd_cnt.v_pdpages++; 485 if (p->wire_count != 0 || 486 p->hold_count != 0 || 487 p->busy != 0 || 488 (p->flags & (PG_BUSY|PG_UNMANAGED)) || 489 !pmap_page_exists_quick(vm_map_pmap(map), p)) { 490 p = next; 491 continue; 492 } 493 494 actcount = pmap_ts_referenced(p); 495 if (actcount) { 496 vm_page_flag_set(p, PG_REFERENCED); 497 } else if (p->flags & PG_REFERENCED) { 498 actcount = 1; 499 } 500 501 if ((p->queue != PQ_ACTIVE) && 502 (p->flags & PG_REFERENCED)) { 503 vm_page_activate(p); 504 p->act_count += actcount; 505 vm_page_flag_clear(p, PG_REFERENCED); 506 } else if (p->queue == PQ_ACTIVE) { 507 if ((p->flags & PG_REFERENCED) == 0) { 508 p->act_count -= min(p->act_count, ACT_DECLINE); 509 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) { 510 vm_page_protect(p, VM_PROT_NONE); 511 vm_page_deactivate(p); 512 } else { 513 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 514 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 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 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 522 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 523 } 524 } else if (p->queue == PQ_INACTIVE) { 525 vm_page_protect(p, VM_PROT_NONE); 526 } 527 p = next; 528 } 529 crit_exit(); 530 object = object->backing_object; 531 } 532 } 533 534 /* 535 * deactivate some number of pages in a map, try to do it fairly, but 536 * that is really hard to do. 537 */ 538 static void 539 vm_pageout_map_deactivate_pages(vm_map_t map, vm_pindex_t desired) 540 { 541 vm_map_entry_t tmpe; 542 vm_object_t obj, bigobj; 543 int nothingwired; 544 545 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT, NULL, curthread)) { 546 return; 547 } 548 549 bigobj = NULL; 550 nothingwired = TRUE; 551 552 /* 553 * first, search out the biggest object, and try to free pages from 554 * that. 555 */ 556 tmpe = map->header.next; 557 while (tmpe != &map->header) { 558 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 559 obj = tmpe->object.vm_object; 560 if ((obj != NULL) && (obj->shadow_count <= 1) && 561 ((bigobj == NULL) || 562 (bigobj->resident_page_count < obj->resident_page_count))) { 563 bigobj = obj; 564 } 565 } 566 if (tmpe->wired_count > 0) 567 nothingwired = FALSE; 568 tmpe = tmpe->next; 569 } 570 571 if (bigobj) 572 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 573 574 /* 575 * Next, hunt around for other pages to deactivate. We actually 576 * do this search sort of wrong -- .text first is not the best idea. 577 */ 578 tmpe = map->header.next; 579 while (tmpe != &map->header) { 580 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 581 break; 582 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 583 obj = tmpe->object.vm_object; 584 if (obj) 585 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 586 } 587 tmpe = tmpe->next; 588 }; 589 590 /* 591 * Remove all mappings if a process is swapped out, this will free page 592 * table pages. 593 */ 594 if (desired == 0 && nothingwired) 595 pmap_remove(vm_map_pmap(map), 596 VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS); 597 vm_map_unlock(map); 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; 637 638 /* 639 * Do whatever cleanup that the pmap code can. 640 */ 641 pmap_collect(); 642 643 addl_page_shortage_init = vm_pageout_deficit; 644 vm_pageout_deficit = 0; 645 646 /* 647 * Calculate the number of pages we want to either free or move 648 * to the cache. 649 */ 650 page_shortage = vm_paging_target() + addl_page_shortage_init; 651 652 /* 653 * Initialize our marker 654 */ 655 bzero(&marker, sizeof(marker)); 656 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 657 marker.queue = PQ_INACTIVE; 658 marker.wire_count = 1; 659 660 /* 661 * Start scanning the inactive queue for pages we can move to the 662 * cache or free. The scan will stop when the target is reached or 663 * we have scanned the entire inactive queue. Note that m->act_count 664 * is not used to form decisions for the inactive queue, only for the 665 * active queue. 666 * 667 * maxlaunder limits the number of dirty pages we flush per scan. 668 * For most systems a smaller value (16 or 32) is more robust under 669 * extreme memory and disk pressure because any unnecessary writes 670 * to disk can result in extreme performance degredation. However, 671 * systems with excessive dirty pages (especially when MAP_NOSYNC is 672 * used) will die horribly with limited laundering. If the pageout 673 * daemon cannot clean enough pages in the first pass, we let it go 674 * all out in succeeding passes. 675 */ 676 if ((maxlaunder = vm_max_launder) <= 1) 677 maxlaunder = 1; 678 if (pass) 679 maxlaunder = 10000; 680 681 /* 682 * We will generally be in a critical section throughout the 683 * scan, but we can release it temporarily when we are sitting on a 684 * non-busy page without fear. this is required to prevent an 685 * interrupt from unbusying or freeing a page prior to our busy 686 * check, leaving us on the wrong queue or checking the wrong 687 * page. 688 */ 689 crit_enter(); 690 rescan0: 691 addl_page_shortage = addl_page_shortage_init; 692 maxscan = vmstats.v_inactive_count; 693 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 694 m != NULL && maxscan-- > 0 && page_shortage > 0; 695 m = next 696 ) { 697 mycpu->gd_cnt.v_pdpages++; 698 699 /* 700 * Give interrupts a chance 701 */ 702 crit_exit(); 703 crit_enter(); 704 705 /* 706 * It's easier for some of the conditions below to just loop 707 * and catch queue changes here rather then check everywhere 708 * else. 709 */ 710 if (m->queue != PQ_INACTIVE) 711 goto rescan0; 712 next = TAILQ_NEXT(m, pageq); 713 714 /* 715 * skip marker pages 716 */ 717 if (m->flags & PG_MARKER) 718 continue; 719 720 /* 721 * A held page may be undergoing I/O, so skip it. 722 */ 723 if (m->hold_count) { 724 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 725 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 726 addl_page_shortage++; 727 continue; 728 } 729 730 /* 731 * Dont mess with busy pages, keep in the front of the 732 * queue, most likely are being paged out. 733 */ 734 if (m->busy || (m->flags & PG_BUSY)) { 735 addl_page_shortage++; 736 continue; 737 } 738 739 if (m->object->ref_count == 0) { 740 /* 741 * If the object is not being used, we ignore previous 742 * references. 743 */ 744 vm_page_flag_clear(m, PG_REFERENCED); 745 pmap_clear_reference(m); 746 747 } else if (((m->flags & PG_REFERENCED) == 0) && 748 (actcount = pmap_ts_referenced(m))) { 749 /* 750 * Otherwise, if the page has been referenced while 751 * in the inactive queue, we bump the "activation 752 * count" upwards, making it less likely that the 753 * page will be added back to the inactive queue 754 * prematurely again. Here we check the page tables 755 * (or emulated bits, if any), given the upper level 756 * VM system not knowing anything about existing 757 * references. 758 */ 759 vm_page_activate(m); 760 m->act_count += (actcount + ACT_ADVANCE); 761 continue; 762 } 763 764 /* 765 * If the upper level VM system knows about any page 766 * references, we activate the page. We also set the 767 * "activation count" higher than normal so that we will less 768 * likely place pages back onto the inactive queue again. 769 */ 770 if ((m->flags & PG_REFERENCED) != 0) { 771 vm_page_flag_clear(m, PG_REFERENCED); 772 actcount = pmap_ts_referenced(m); 773 vm_page_activate(m); 774 m->act_count += (actcount + ACT_ADVANCE + 1); 775 continue; 776 } 777 778 /* 779 * If the upper level VM system doesn't know anything about 780 * the page being dirty, we have to check for it again. As 781 * far as the VM code knows, any partially dirty pages are 782 * fully dirty. 783 * 784 * Pages marked PG_WRITEABLE may be mapped into the user 785 * address space of a process running on another cpu. A 786 * user process (without holding the MP lock) running on 787 * another cpu may be able to touch the page while we are 788 * trying to remove it. To prevent this from occuring we 789 * must call pmap_remove_all() or otherwise make the page 790 * read-only. If the race occured pmap_remove_all() is 791 * responsible for setting m->dirty. 792 */ 793 if (m->dirty == 0) { 794 vm_page_test_dirty(m); 795 #if 0 796 if (m->dirty == 0 && (m->flags & PG_WRITEABLE) != 0) 797 pmap_remove_all(m); 798 #endif 799 } else { 800 vm_page_dirty(m); 801 } 802 803 if (m->valid == 0) { 804 /* 805 * Invalid pages can be easily freed 806 */ 807 vm_pageout_page_free(m); 808 mycpu->gd_cnt.v_dfree++; 809 --page_shortage; 810 } else if (m->dirty == 0) { 811 /* 812 * Clean pages can be placed onto the cache queue. 813 * This effectively frees them. 814 */ 815 vm_page_cache(m); 816 --page_shortage; 817 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 818 /* 819 * Dirty pages need to be paged out, but flushing 820 * a page is extremely expensive verses freeing 821 * a clean page. Rather then artificially limiting 822 * the number of pages we can flush, we instead give 823 * dirty pages extra priority on the inactive queue 824 * by forcing them to be cycled through the queue 825 * twice before being flushed, after which the 826 * (now clean) page will cycle through once more 827 * before being freed. This significantly extends 828 * the thrash point for a heavily loaded machine. 829 */ 830 vm_page_flag_set(m, PG_WINATCFLS); 831 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 832 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 833 } else if (maxlaunder > 0) { 834 /* 835 * We always want to try to flush some dirty pages if 836 * we encounter them, to keep the system stable. 837 * Normally this number is small, but under extreme 838 * pressure where there are insufficient clean pages 839 * on the inactive queue, we may have to go all out. 840 */ 841 int swap_pageouts_ok; 842 struct vnode *vp = NULL; 843 844 object = m->object; 845 846 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 847 swap_pageouts_ok = 1; 848 } else { 849 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 850 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 851 vm_page_count_min()); 852 853 } 854 855 /* 856 * We don't bother paging objects that are "dead". 857 * Those objects are in a "rundown" state. 858 */ 859 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 860 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 861 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 862 continue; 863 } 864 865 /* 866 * The object is already known NOT to be dead. It 867 * is possible for the vget() to block the whole 868 * pageout daemon, but the new low-memory handling 869 * code should prevent it. 870 * 871 * The previous code skipped locked vnodes and, worse, 872 * reordered pages in the queue. This results in 873 * completely non-deterministic operation because, 874 * quite often, a vm_fault has initiated an I/O and 875 * is holding a locked vnode at just the point where 876 * the pageout daemon is woken up. 877 * 878 * We can't wait forever for the vnode lock, we might 879 * deadlock due to a vn_read() getting stuck in 880 * vm_wait while holding this vnode. We skip the 881 * vnode if we can't get it in a reasonable amount 882 * of time. 883 */ 884 885 if (object->type == OBJT_VNODE) { 886 vp = object->handle; 887 888 if (vget(vp, LK_EXCLUSIVE|LK_NOOBJ|LK_TIMELOCK, curthread)) { 889 ++pageout_lock_miss; 890 if (object->flags & OBJ_MIGHTBEDIRTY) 891 vnodes_skipped++; 892 continue; 893 } 894 895 /* 896 * The page might have been moved to another 897 * queue during potential blocking in vget() 898 * above. The page might have been freed and 899 * reused for another vnode. The object might 900 * have been reused for another vnode. 901 */ 902 if (m->queue != PQ_INACTIVE || 903 m->object != object || 904 object->handle != vp) { 905 if (object->flags & OBJ_MIGHTBEDIRTY) 906 vnodes_skipped++; 907 vput(vp); 908 continue; 909 } 910 911 /* 912 * The page may have been busied during the 913 * blocking in vput(); We don't move the 914 * page back onto the end of the queue so that 915 * statistics are more correct if we don't. 916 */ 917 if (m->busy || (m->flags & PG_BUSY)) { 918 vput(vp); 919 continue; 920 } 921 922 /* 923 * If the page has become held it might 924 * be undergoing I/O, so skip it 925 */ 926 if (m->hold_count) { 927 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 928 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 929 if (object->flags & OBJ_MIGHTBEDIRTY) 930 vnodes_skipped++; 931 vput(vp); 932 continue; 933 } 934 } 935 936 /* 937 * If a page is dirty, then it is either being washed 938 * (but not yet cleaned) or it is still in the 939 * laundry. If it is still in the laundry, then we 940 * start the cleaning operation. 941 * 942 * This operation may cluster, invalidating the 'next' 943 * pointer. To prevent an inordinate number of 944 * restarts we use our marker to remember our place. 945 * 946 * decrement page_shortage on success to account for 947 * the (future) cleaned page. Otherwise we could wind 948 * up laundering or cleaning too many pages. 949 */ 950 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq); 951 if (vm_pageout_clean(m) != 0) { 952 --page_shortage; 953 --maxlaunder; 954 } 955 next = TAILQ_NEXT(&marker, pageq); 956 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq); 957 if (vp != NULL) 958 vput(vp); 959 } 960 } 961 962 /* 963 * Compute the number of pages we want to try to move from the 964 * active queue to the inactive queue. 965 */ 966 page_shortage = vm_paging_target() + 967 vmstats.v_inactive_target - vmstats.v_inactive_count; 968 page_shortage += addl_page_shortage; 969 970 /* 971 * Scan the active queue for things we can deactivate. We nominally 972 * track the per-page activity counter and use it to locate 973 * deactivation candidates. 974 * 975 * NOTE: we are still in a critical section. 976 */ 977 pcount = vmstats.v_active_count; 978 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 979 980 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 981 /* 982 * Give interrupts a chance. 983 */ 984 crit_exit(); 985 crit_enter(); 986 987 /* 988 * If the page was ripped out from under us, just stop. 989 */ 990 if (m->queue != PQ_ACTIVE) 991 break; 992 next = TAILQ_NEXT(m, pageq); 993 994 /* 995 * Don't deactivate pages that are busy. 996 */ 997 if ((m->busy != 0) || 998 (m->flags & PG_BUSY) || 999 (m->hold_count != 0)) { 1000 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1001 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1002 m = next; 1003 continue; 1004 } 1005 1006 /* 1007 * The count for pagedaemon pages is done after checking the 1008 * page for eligibility... 1009 */ 1010 mycpu->gd_cnt.v_pdpages++; 1011 1012 /* 1013 * Check to see "how much" the page has been used. 1014 */ 1015 actcount = 0; 1016 if (m->object->ref_count != 0) { 1017 if (m->flags & PG_REFERENCED) { 1018 actcount += 1; 1019 } 1020 actcount += pmap_ts_referenced(m); 1021 if (actcount) { 1022 m->act_count += ACT_ADVANCE + actcount; 1023 if (m->act_count > ACT_MAX) 1024 m->act_count = ACT_MAX; 1025 } 1026 } 1027 1028 /* 1029 * Since we have "tested" this bit, we need to clear it now. 1030 */ 1031 vm_page_flag_clear(m, PG_REFERENCED); 1032 1033 /* 1034 * Only if an object is currently being used, do we use the 1035 * page activation count stats. 1036 */ 1037 if (actcount && (m->object->ref_count != 0)) { 1038 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1039 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1040 } else { 1041 m->act_count -= min(m->act_count, ACT_DECLINE); 1042 if (vm_pageout_algorithm || 1043 m->object->ref_count == 0 || 1044 m->act_count == 0) { 1045 page_shortage--; 1046 if (m->object->ref_count == 0) { 1047 vm_page_protect(m, VM_PROT_NONE); 1048 if (m->dirty == 0) 1049 vm_page_cache(m); 1050 else 1051 vm_page_deactivate(m); 1052 } else { 1053 vm_page_deactivate(m); 1054 } 1055 } else { 1056 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1057 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1058 } 1059 } 1060 m = next; 1061 } 1062 1063 /* 1064 * We try to maintain some *really* free pages, this allows interrupt 1065 * code to be guaranteed space. Since both cache and free queues 1066 * are considered basically 'free', moving pages from cache to free 1067 * does not effect other calculations. 1068 * 1069 * NOTE: we are still in a critical section. 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 1092 crit_exit(); 1093 1094 #if !defined(NO_SWAPPING) 1095 /* 1096 * Idle process swapout -- run once per second. 1097 */ 1098 if (vm_swap_idle_enabled) { 1099 static long lsec; 1100 if (time_second != lsec) { 1101 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1102 vm_req_vmdaemon(); 1103 lsec = time_second; 1104 } 1105 } 1106 #endif 1107 1108 /* 1109 * If we didn't get enough free pages, and we have skipped a vnode 1110 * in a writeable object, wakeup the sync daemon. And kick swapout 1111 * if we did not get enough free pages. 1112 */ 1113 if (vm_paging_target() > 0) { 1114 if (vnodes_skipped && vm_page_count_min()) 1115 speedup_syncer(); 1116 #if !defined(NO_SWAPPING) 1117 if (vm_swap_enabled && vm_page_count_target()) { 1118 vm_req_vmdaemon(); 1119 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1120 } 1121 #endif 1122 } 1123 1124 /* 1125 * If we are out of swap and were not able to reach our paging 1126 * target, kill the largest process. 1127 */ 1128 if ((vm_swap_size < 64 && vm_page_count_min()) || 1129 (swap_pager_full && vm_paging_target() > 0)) { 1130 #if 0 1131 if ((vm_swap_size < 64 || swap_pager_full) && vm_page_count_min()) { 1132 #endif 1133 bigproc = NULL; 1134 bigsize = 0; 1135 for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) { 1136 /* 1137 * if this is a system process, skip it 1138 */ 1139 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1140 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1141 continue; 1142 } 1143 /* 1144 * if the process is in a non-running type state, 1145 * don't touch it. 1146 */ 1147 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 1148 continue; 1149 } 1150 /* 1151 * get the process size 1152 */ 1153 size = vmspace_resident_count(p->p_vmspace) + 1154 vmspace_swap_count(p->p_vmspace); 1155 /* 1156 * if the this process is bigger than the biggest one 1157 * remember it. 1158 */ 1159 if (size > bigsize) { 1160 bigproc = p; 1161 bigsize = size; 1162 } 1163 } 1164 if (bigproc != NULL) { 1165 killproc(bigproc, "out of swap space"); 1166 bigproc->p_nice = PRIO_MIN; 1167 bigproc->p_usched->resetpriority(&bigproc->p_lwp); 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(void) 1181 { 1182 vm_page_t m,next; 1183 int pcount,tpcount; /* Number of pages to check */ 1184 static int fullintervalcount = 0; 1185 int page_shortage; 1186 1187 page_shortage = 1188 (vmstats.v_inactive_target + vmstats.v_cache_max + vmstats.v_free_min) - 1189 (vmstats.v_free_count + vmstats.v_inactive_count + vmstats.v_cache_count); 1190 1191 if (page_shortage <= 0) 1192 return; 1193 1194 crit_enter(); 1195 1196 pcount = vmstats.v_active_count; 1197 fullintervalcount += vm_pageout_stats_interval; 1198 if (fullintervalcount < vm_pageout_full_stats_interval) { 1199 tpcount = (vm_pageout_stats_max * vmstats.v_active_count) / vmstats.v_page_count; 1200 if (pcount > tpcount) 1201 pcount = tpcount; 1202 } else { 1203 fullintervalcount = 0; 1204 } 1205 1206 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1207 while ((m != NULL) && (pcount-- > 0)) { 1208 int actcount; 1209 1210 if (m->queue != PQ_ACTIVE) { 1211 break; 1212 } 1213 1214 next = TAILQ_NEXT(m, pageq); 1215 /* 1216 * Don't deactivate pages that are busy. 1217 */ 1218 if ((m->busy != 0) || 1219 (m->flags & PG_BUSY) || 1220 (m->hold_count != 0)) { 1221 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1222 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1223 m = next; 1224 continue; 1225 } 1226 1227 actcount = 0; 1228 if (m->flags & PG_REFERENCED) { 1229 vm_page_flag_clear(m, PG_REFERENCED); 1230 actcount += 1; 1231 } 1232 1233 actcount += pmap_ts_referenced(m); 1234 if (actcount) { 1235 m->act_count += ACT_ADVANCE + actcount; 1236 if (m->act_count > ACT_MAX) 1237 m->act_count = ACT_MAX; 1238 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1239 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1240 } else { 1241 if (m->act_count == 0) { 1242 /* 1243 * We turn off page access, so that we have 1244 * more accurate RSS stats. We don't do this 1245 * in the normal page deactivation when the 1246 * system is loaded VM wise, because the 1247 * cost of the large number of page protect 1248 * operations would be higher than the value 1249 * of doing the operation. 1250 */ 1251 vm_page_protect(m, VM_PROT_NONE); 1252 vm_page_deactivate(m); 1253 } else { 1254 m->act_count -= min(m->act_count, ACT_DECLINE); 1255 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1256 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1257 } 1258 } 1259 1260 m = next; 1261 } 1262 crit_exit(); 1263 } 1264 1265 static int 1266 vm_pageout_free_page_calc(vm_size_t count) 1267 { 1268 if (count < vmstats.v_page_count) 1269 return 0; 1270 /* 1271 * free_reserved needs to include enough for the largest swap pager 1272 * structures plus enough for any pv_entry structs when paging. 1273 */ 1274 if (vmstats.v_page_count > 1024) 1275 vmstats.v_free_min = 4 + (vmstats.v_page_count - 1024) / 200; 1276 else 1277 vmstats.v_free_min = 4; 1278 vmstats.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1279 vmstats.v_interrupt_free_min; 1280 vmstats.v_free_reserved = vm_pageout_page_count + 1281 vmstats.v_pageout_free_min + (count / 768) + PQ_L2_SIZE; 1282 vmstats.v_free_severe = vmstats.v_free_min / 2; 1283 vmstats.v_free_min += vmstats.v_free_reserved; 1284 vmstats.v_free_severe += vmstats.v_free_reserved; 1285 return 1; 1286 } 1287 1288 1289 /* 1290 * vm_pageout is the high level pageout daemon. 1291 */ 1292 static void 1293 vm_pageout(void) 1294 { 1295 int pass; 1296 1297 /* 1298 * Initialize some paging parameters. 1299 */ 1300 1301 vmstats.v_interrupt_free_min = 2; 1302 if (vmstats.v_page_count < 2000) 1303 vm_pageout_page_count = 8; 1304 1305 vm_pageout_free_page_calc(vmstats.v_page_count); 1306 /* 1307 * v_free_target and v_cache_min control pageout hysteresis. Note 1308 * that these are more a measure of the VM cache queue hysteresis 1309 * then the VM free queue. Specifically, v_free_target is the 1310 * high water mark (free+cache pages). 1311 * 1312 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1313 * low water mark, while v_free_min is the stop. v_cache_min must 1314 * be big enough to handle memory needs while the pageout daemon 1315 * is signalled and run to free more pages. 1316 */ 1317 if (vmstats.v_free_count > 6144) 1318 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved; 1319 else 1320 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved; 1321 1322 if (vmstats.v_free_count > 2048) { 1323 vmstats.v_cache_min = vmstats.v_free_target; 1324 vmstats.v_cache_max = 2 * vmstats.v_cache_min; 1325 vmstats.v_inactive_target = (3 * vmstats.v_free_target) / 2; 1326 } else { 1327 vmstats.v_cache_min = 0; 1328 vmstats.v_cache_max = 0; 1329 vmstats.v_inactive_target = vmstats.v_free_count / 4; 1330 } 1331 if (vmstats.v_inactive_target > vmstats.v_free_count / 3) 1332 vmstats.v_inactive_target = vmstats.v_free_count / 3; 1333 1334 /* XXX does not really belong here */ 1335 if (vm_page_max_wired == 0) 1336 vm_page_max_wired = vmstats.v_free_count / 3; 1337 1338 if (vm_pageout_stats_max == 0) 1339 vm_pageout_stats_max = vmstats.v_free_target; 1340 1341 /* 1342 * Set interval in seconds for stats scan. 1343 */ 1344 if (vm_pageout_stats_interval == 0) 1345 vm_pageout_stats_interval = 5; 1346 if (vm_pageout_full_stats_interval == 0) 1347 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1348 1349 1350 /* 1351 * Set maximum free per pass 1352 */ 1353 if (vm_pageout_stats_free_max == 0) 1354 vm_pageout_stats_free_max = 5; 1355 1356 swap_pager_swap_init(); 1357 pass = 0; 1358 /* 1359 * The pageout daemon is never done, so loop forever. 1360 */ 1361 while (TRUE) { 1362 int error; 1363 1364 /* 1365 * If we have enough free memory, wakeup waiters. Do 1366 * not clear vm_pages_needed until we reach our target, 1367 * otherwise we may be woken up over and over again and 1368 * waste a lot of cpu. 1369 */ 1370 crit_enter(); 1371 if (vm_pages_needed && !vm_page_count_min()) { 1372 if (vm_paging_needed() <= 0) 1373 vm_pages_needed = 0; 1374 wakeup(&vmstats.v_free_count); 1375 } 1376 if (vm_pages_needed) { 1377 /* 1378 * Still not done, take a second pass without waiting 1379 * (unlimited dirty cleaning), otherwise sleep a bit 1380 * and try again. 1381 */ 1382 ++pass; 1383 if (pass > 1) 1384 tsleep(&vm_pages_needed, 0, "psleep", hz/2); 1385 } else { 1386 /* 1387 * Good enough, sleep & handle stats. Prime the pass 1388 * for the next run. 1389 */ 1390 if (pass > 1) 1391 pass = 1; 1392 else 1393 pass = 0; 1394 error = tsleep(&vm_pages_needed, 1395 0, "psleep", vm_pageout_stats_interval * hz); 1396 if (error && !vm_pages_needed) { 1397 crit_exit(); 1398 pass = 0; 1399 vm_pageout_page_stats(); 1400 continue; 1401 } 1402 } 1403 1404 if (vm_pages_needed) 1405 mycpu->gd_cnt.v_pdwakeups++; 1406 crit_exit(); 1407 vm_pageout_scan(pass); 1408 vm_pageout_deficit = 0; 1409 } 1410 } 1411 1412 void 1413 pagedaemon_wakeup(void) 1414 { 1415 if (!vm_pages_needed && curthread != pagethread) { 1416 vm_pages_needed++; 1417 wakeup(&vm_pages_needed); 1418 } 1419 } 1420 1421 #if !defined(NO_SWAPPING) 1422 static void 1423 vm_req_vmdaemon(void) 1424 { 1425 static int lastrun = 0; 1426 1427 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1428 wakeup(&vm_daemon_needed); 1429 lastrun = ticks; 1430 } 1431 } 1432 1433 static void 1434 vm_daemon(void) 1435 { 1436 struct proc *p; 1437 1438 while (TRUE) { 1439 tsleep(&vm_daemon_needed, 0, "psleep", 0); 1440 if (vm_pageout_req_swapout) { 1441 swapout_procs(vm_pageout_req_swapout); 1442 vm_pageout_req_swapout = 0; 1443 } 1444 /* 1445 * scan the processes for exceeding their rlimits or if 1446 * process is swapped out -- deactivate pages 1447 */ 1448 1449 for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) { 1450 vm_pindex_t limit, size; 1451 1452 /* 1453 * if this is a system process or if we have already 1454 * looked at this process, skip it. 1455 */ 1456 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 1457 continue; 1458 } 1459 /* 1460 * if the process is in a non-running type state, 1461 * don't touch it. 1462 */ 1463 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 1464 continue; 1465 } 1466 /* 1467 * get a limit 1468 */ 1469 limit = OFF_TO_IDX( 1470 qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 1471 p->p_rlimit[RLIMIT_RSS].rlim_max)); 1472 1473 /* 1474 * let processes that are swapped out really be 1475 * swapped out. Set the limit to nothing to get as 1476 * many pages out to swap as possible. 1477 */ 1478 if (p->p_flag & P_SWAPPEDOUT) 1479 limit = 0; 1480 1481 size = vmspace_resident_count(p->p_vmspace); 1482 if (limit >= 0 && size >= limit) { 1483 vm_pageout_map_deactivate_pages( 1484 &p->p_vmspace->vm_map, limit); 1485 } 1486 } 1487 } 1488 } 1489 #endif 1490