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 * Copyright (c) 2005 Yahoo! Technologies Norway AS 9 * All rights reserved. 10 * 11 * This code is derived from software contributed to Berkeley by 12 * The Mach Operating System project at Carnegie-Mellon University. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the University of 25 * California, Berkeley and its contributors. 26 * 4. Neither the name of the University nor the names of its contributors 27 * may be used to endorse or promote products derived from this software 28 * without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 * 42 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 43 * 44 * 45 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 46 * All rights reserved. 47 * 48 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 49 * 50 * Permission to use, copy, modify and distribute this software and 51 * its documentation is hereby granted, provided that both the copyright 52 * notice and this permission notice appear in all copies of the 53 * software, derivative works or modified versions, and any portions 54 * thereof, and that both notices appear in supporting documentation. 55 * 56 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 57 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 58 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 59 * 60 * Carnegie Mellon requests users of this software to return to 61 * 62 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 63 * School of Computer Science 64 * Carnegie Mellon University 65 * Pittsburgh PA 15213-3890 66 * 67 * any improvements or extensions that they make and grant Carnegie the 68 * rights to redistribute these changes. 69 */ 70 71 /* 72 * The proverbial page-out daemon. 73 */ 74 75 #include <sys/cdefs.h> 76 __FBSDID("$FreeBSD$"); 77 78 #include "opt_vm.h" 79 #include <sys/param.h> 80 #include <sys/systm.h> 81 #include <sys/kernel.h> 82 #include <sys/eventhandler.h> 83 #include <sys/lock.h> 84 #include <sys/mutex.h> 85 #include <sys/proc.h> 86 #include <sys/kthread.h> 87 #include <sys/ktr.h> 88 #include <sys/mount.h> 89 #include <sys/resourcevar.h> 90 #include <sys/sched.h> 91 #include <sys/signalvar.h> 92 #include <sys/vnode.h> 93 #include <sys/vmmeter.h> 94 #include <sys/sx.h> 95 #include <sys/sysctl.h> 96 97 #include <vm/vm.h> 98 #include <vm/vm_param.h> 99 #include <vm/vm_object.h> 100 #include <vm/vm_page.h> 101 #include <vm/vm_map.h> 102 #include <vm/vm_pageout.h> 103 #include <vm/vm_pager.h> 104 #include <vm/swap_pager.h> 105 #include <vm/vm_extern.h> 106 #include <vm/uma.h> 107 108 #include <machine/mutex.h> 109 110 /* 111 * System initialization 112 */ 113 114 /* the kernel process "vm_pageout"*/ 115 static void vm_pageout(void); 116 static int vm_pageout_clean(vm_page_t); 117 static void vm_pageout_scan(int pass); 118 119 struct proc *pageproc; 120 121 static struct kproc_desc page_kp = { 122 "pagedaemon", 123 vm_pageout, 124 &pageproc 125 }; 126 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 127 128 #if !defined(NO_SWAPPING) 129 /* the kernel process "vm_daemon"*/ 130 static void vm_daemon(void); 131 static struct proc *vmproc; 132 133 static struct kproc_desc vm_kp = { 134 "vmdaemon", 135 vm_daemon, 136 &vmproc 137 }; 138 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) 139 #endif 140 141 142 int vm_pages_needed; /* Event on which pageout daemon sleeps */ 143 int vm_pageout_deficit; /* Estimated number of pages deficit */ 144 int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 145 146 #if !defined(NO_SWAPPING) 147 static int vm_pageout_req_swapout; /* XXX */ 148 static int vm_daemon_needed; 149 static struct mtx vm_daemon_mtx; 150 /* Allow for use by vm_pageout before vm_daemon is initialized. */ 151 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); 152 #endif 153 static int vm_max_launder = 32; 154 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 155 static int vm_pageout_full_stats_interval = 0; 156 static int vm_pageout_algorithm=0; 157 static int defer_swap_pageouts=0; 158 static int disable_swap_pageouts=0; 159 160 #if defined(NO_SWAPPING) 161 static int vm_swap_enabled=0; 162 static int vm_swap_idle_enabled=0; 163 #else 164 static int vm_swap_enabled=1; 165 static int vm_swap_idle_enabled=0; 166 #endif 167 168 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 169 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 170 171 SYSCTL_INT(_vm, OID_AUTO, max_launder, 172 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 173 174 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 175 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 176 177 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 178 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 179 180 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 181 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 182 183 #if defined(NO_SWAPPING) 184 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 185 CTLFLAG_RD, &vm_swap_enabled, 0, ""); 186 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 187 CTLFLAG_RD, &vm_swap_idle_enabled, 0, ""); 188 #else 189 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 190 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 191 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 192 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 193 #endif 194 195 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 196 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 197 198 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 199 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 200 201 static int pageout_lock_miss; 202 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 203 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 204 205 #define VM_PAGEOUT_PAGE_COUNT 16 206 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 207 208 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 209 210 #if !defined(NO_SWAPPING) 211 static void vm_pageout_map_deactivate_pages(vm_map_t, long); 212 static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long); 213 static void vm_req_vmdaemon(int req); 214 #endif 215 static void vm_pageout_page_stats(void); 216 217 /* 218 * vm_pageout_fallback_object_lock: 219 * 220 * Lock vm object currently associated with `m'. VM_OBJECT_TRYLOCK is 221 * known to have failed and page queue must be either PQ_ACTIVE or 222 * PQ_INACTIVE. To avoid lock order violation, unlock the page queues 223 * while locking the vm object. Use marker page to detect page queue 224 * changes and maintain notion of next page on page queue. Return 225 * TRUE if no changes were detected, FALSE otherwise. vm object is 226 * locked on return. 227 * 228 * This function depends on both the lock portion of struct vm_object 229 * and normal struct vm_page being type stable. 230 */ 231 static boolean_t 232 vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next) 233 { 234 struct vm_page marker; 235 boolean_t unchanged; 236 u_short queue; 237 vm_object_t object; 238 239 /* 240 * Initialize our marker 241 */ 242 bzero(&marker, sizeof(marker)); 243 marker.flags = PG_FICTITIOUS | PG_MARKER; 244 marker.oflags = VPO_BUSY; 245 marker.queue = m->queue; 246 marker.wire_count = 1; 247 248 queue = m->queue; 249 object = m->object; 250 251 TAILQ_INSERT_AFTER(&vm_page_queues[queue].pl, 252 m, &marker, pageq); 253 vm_page_unlock_queues(); 254 VM_OBJECT_LOCK(object); 255 vm_page_lock_queues(); 256 257 /* Page queue might have changed. */ 258 *next = TAILQ_NEXT(&marker, pageq); 259 unchanged = (m->queue == queue && 260 m->object == object && 261 &marker == TAILQ_NEXT(m, pageq)); 262 TAILQ_REMOVE(&vm_page_queues[queue].pl, 263 &marker, pageq); 264 return (unchanged); 265 } 266 267 /* 268 * vm_pageout_clean: 269 * 270 * Clean the page and remove it from the laundry. 271 * 272 * We set the busy bit to cause potential page faults on this page to 273 * block. Note the careful timing, however, the busy bit isn't set till 274 * late and we cannot do anything that will mess with the page. 275 */ 276 static int 277 vm_pageout_clean(m) 278 vm_page_t m; 279 { 280 vm_object_t object; 281 vm_page_t mc[2*vm_pageout_page_count]; 282 int pageout_count; 283 int ib, is, page_base; 284 vm_pindex_t pindex = m->pindex; 285 286 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 287 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 288 289 /* 290 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 291 * with the new swapper, but we could have serious problems paging 292 * out other object types if there is insufficient memory. 293 * 294 * Unfortunately, checking free memory here is far too late, so the 295 * check has been moved up a procedural level. 296 */ 297 298 /* 299 * Can't clean the page if it's busy or held. 300 */ 301 if ((m->hold_count != 0) || 302 ((m->busy != 0) || (m->oflags & VPO_BUSY))) { 303 return 0; 304 } 305 306 mc[vm_pageout_page_count] = m; 307 pageout_count = 1; 308 page_base = vm_pageout_page_count; 309 ib = 1; 310 is = 1; 311 312 /* 313 * Scan object for clusterable pages. 314 * 315 * We can cluster ONLY if: ->> the page is NOT 316 * clean, wired, busy, held, or mapped into a 317 * buffer, and one of the following: 318 * 1) The page is inactive, or a seldom used 319 * active page. 320 * -or- 321 * 2) we force the issue. 322 * 323 * During heavy mmap/modification loads the pageout 324 * daemon can really fragment the underlying file 325 * due to flushing pages out of order and not trying 326 * align the clusters (which leave sporatic out-of-order 327 * holes). To solve this problem we do the reverse scan 328 * first and attempt to align our cluster, then do a 329 * forward scan if room remains. 330 */ 331 object = m->object; 332 more: 333 while (ib && pageout_count < vm_pageout_page_count) { 334 vm_page_t p; 335 336 if (ib > pindex) { 337 ib = 0; 338 break; 339 } 340 341 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) { 342 ib = 0; 343 break; 344 } 345 if ((p->oflags & VPO_BUSY) || p->busy) { 346 ib = 0; 347 break; 348 } 349 vm_page_test_dirty(p); 350 if ((p->dirty & p->valid) == 0 || 351 p->queue != PQ_INACTIVE || 352 p->wire_count != 0 || /* may be held by buf cache */ 353 p->hold_count != 0) { /* may be undergoing I/O */ 354 ib = 0; 355 break; 356 } 357 mc[--page_base] = p; 358 ++pageout_count; 359 ++ib; 360 /* 361 * alignment boundry, stop here and switch directions. Do 362 * not clear ib. 363 */ 364 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 365 break; 366 } 367 368 while (pageout_count < vm_pageout_page_count && 369 pindex + is < object->size) { 370 vm_page_t p; 371 372 if ((p = vm_page_lookup(object, pindex + is)) == NULL) 373 break; 374 if ((p->oflags & VPO_BUSY) || p->busy) { 375 break; 376 } 377 vm_page_test_dirty(p); 378 if ((p->dirty & p->valid) == 0 || 379 p->queue != PQ_INACTIVE || 380 p->wire_count != 0 || /* may be held by buf cache */ 381 p->hold_count != 0) { /* may be undergoing I/O */ 382 break; 383 } 384 mc[page_base + pageout_count] = p; 385 ++pageout_count; 386 ++is; 387 } 388 389 /* 390 * If we exhausted our forward scan, continue with the reverse scan 391 * when possible, even past a page boundry. This catches boundry 392 * conditions. 393 */ 394 if (ib && pageout_count < vm_pageout_page_count) 395 goto more; 396 397 /* 398 * we allow reads during pageouts... 399 */ 400 return (vm_pageout_flush(&mc[page_base], pageout_count, 0)); 401 } 402 403 /* 404 * vm_pageout_flush() - launder the given pages 405 * 406 * The given pages are laundered. Note that we setup for the start of 407 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 408 * reference count all in here rather then in the parent. If we want 409 * the parent to do more sophisticated things we may have to change 410 * the ordering. 411 */ 412 int 413 vm_pageout_flush(vm_page_t *mc, int count, int flags) 414 { 415 vm_object_t object = mc[0]->object; 416 int pageout_status[count]; 417 int numpagedout = 0; 418 int i; 419 420 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 421 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 422 /* 423 * Initiate I/O. Bump the vm_page_t->busy counter and 424 * mark the pages read-only. 425 * 426 * We do not have to fixup the clean/dirty bits here... we can 427 * allow the pager to do it after the I/O completes. 428 * 429 * NOTE! mc[i]->dirty may be partial or fragmented due to an 430 * edge case with file fragments. 431 */ 432 for (i = 0; i < count; i++) { 433 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 434 ("vm_pageout_flush: partially invalid page %p index %d/%d", 435 mc[i], i, count)); 436 vm_page_io_start(mc[i]); 437 pmap_remove_write(mc[i]); 438 } 439 vm_page_unlock_queues(); 440 vm_object_pip_add(object, count); 441 442 vm_pager_put_pages(object, mc, count, flags, pageout_status); 443 444 vm_page_lock_queues(); 445 for (i = 0; i < count; i++) { 446 vm_page_t mt = mc[i]; 447 448 KASSERT(pageout_status[i] == VM_PAGER_PEND || 449 (mt->flags & PG_WRITEABLE) == 0, 450 ("vm_pageout_flush: page %p is not write protected", mt)); 451 switch (pageout_status[i]) { 452 case VM_PAGER_OK: 453 case VM_PAGER_PEND: 454 numpagedout++; 455 break; 456 case VM_PAGER_BAD: 457 /* 458 * Page outside of range of object. Right now we 459 * essentially lose the changes by pretending it 460 * worked. 461 */ 462 pmap_clear_modify(mt); 463 vm_page_undirty(mt); 464 break; 465 case VM_PAGER_ERROR: 466 case VM_PAGER_FAIL: 467 /* 468 * If page couldn't be paged out, then reactivate the 469 * page so it doesn't clog the inactive list. (We 470 * will try paging out it again later). 471 */ 472 vm_page_activate(mt); 473 break; 474 case VM_PAGER_AGAIN: 475 break; 476 } 477 478 /* 479 * If the operation is still going, leave the page busy to 480 * block all other accesses. Also, leave the paging in 481 * progress indicator set so that we don't attempt an object 482 * collapse. 483 */ 484 if (pageout_status[i] != VM_PAGER_PEND) { 485 vm_object_pip_wakeup(object); 486 vm_page_io_finish(mt); 487 if (vm_page_count_severe()) 488 vm_page_try_to_cache(mt); 489 } 490 } 491 return numpagedout; 492 } 493 494 #if !defined(NO_SWAPPING) 495 /* 496 * vm_pageout_object_deactivate_pages 497 * 498 * deactivate enough pages to satisfy the inactive target 499 * requirements or if vm_page_proc_limit is set, then 500 * deactivate all of the pages in the object and its 501 * backing_objects. 502 * 503 * The object and map must be locked. 504 */ 505 static void 506 vm_pageout_object_deactivate_pages(pmap, first_object, desired) 507 pmap_t pmap; 508 vm_object_t first_object; 509 long desired; 510 { 511 vm_object_t backing_object, object; 512 vm_page_t p, next; 513 int actcount, rcount, remove_mode; 514 515 VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED); 516 if (first_object->type == OBJT_DEVICE || first_object->type == OBJT_PHYS) 517 return; 518 for (object = first_object;; object = backing_object) { 519 if (pmap_resident_count(pmap) <= desired) 520 goto unlock_return; 521 if (object->paging_in_progress) 522 goto unlock_return; 523 524 remove_mode = 0; 525 if (object->shadow_count > 1) 526 remove_mode = 1; 527 /* 528 * scan the objects entire memory queue 529 */ 530 rcount = object->resident_page_count; 531 p = TAILQ_FIRST(&object->memq); 532 vm_page_lock_queues(); 533 while (p && (rcount-- > 0)) { 534 if (pmap_resident_count(pmap) <= desired) { 535 vm_page_unlock_queues(); 536 goto unlock_return; 537 } 538 next = TAILQ_NEXT(p, listq); 539 cnt.v_pdpages++; 540 if (p->wire_count != 0 || 541 p->hold_count != 0 || 542 p->busy != 0 || 543 (p->oflags & VPO_BUSY) || 544 (p->flags & PG_UNMANAGED) || 545 !pmap_page_exists_quick(pmap, p)) { 546 p = next; 547 continue; 548 } 549 actcount = pmap_ts_referenced(p); 550 if (actcount) { 551 vm_page_flag_set(p, PG_REFERENCED); 552 } else if (p->flags & PG_REFERENCED) { 553 actcount = 1; 554 } 555 if ((p->queue != PQ_ACTIVE) && 556 (p->flags & PG_REFERENCED)) { 557 vm_page_activate(p); 558 p->act_count += actcount; 559 vm_page_flag_clear(p, PG_REFERENCED); 560 } else if (p->queue == PQ_ACTIVE) { 561 if ((p->flags & PG_REFERENCED) == 0) { 562 p->act_count -= min(p->act_count, ACT_DECLINE); 563 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) { 564 pmap_remove_all(p); 565 vm_page_deactivate(p); 566 } else { 567 vm_pageq_requeue(p); 568 } 569 } else { 570 vm_page_activate(p); 571 vm_page_flag_clear(p, PG_REFERENCED); 572 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 573 p->act_count += ACT_ADVANCE; 574 vm_pageq_requeue(p); 575 } 576 } else if (p->queue == PQ_INACTIVE) { 577 pmap_remove_all(p); 578 } 579 p = next; 580 } 581 vm_page_unlock_queues(); 582 if ((backing_object = object->backing_object) == NULL) 583 goto unlock_return; 584 VM_OBJECT_LOCK(backing_object); 585 if (object != first_object) 586 VM_OBJECT_UNLOCK(object); 587 } 588 unlock_return: 589 if (object != first_object) 590 VM_OBJECT_UNLOCK(object); 591 } 592 593 /* 594 * deactivate some number of pages in a map, try to do it fairly, but 595 * that is really hard to do. 596 */ 597 static void 598 vm_pageout_map_deactivate_pages(map, desired) 599 vm_map_t map; 600 long desired; 601 { 602 vm_map_entry_t tmpe; 603 vm_object_t obj, bigobj; 604 int nothingwired; 605 606 if (!vm_map_trylock(map)) 607 return; 608 609 bigobj = NULL; 610 nothingwired = TRUE; 611 612 /* 613 * first, search out the biggest object, and try to free pages from 614 * that. 615 */ 616 tmpe = map->header.next; 617 while (tmpe != &map->header) { 618 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 619 obj = tmpe->object.vm_object; 620 if (obj != NULL && VM_OBJECT_TRYLOCK(obj)) { 621 if (obj->shadow_count <= 1 && 622 (bigobj == NULL || 623 bigobj->resident_page_count < obj->resident_page_count)) { 624 if (bigobj != NULL) 625 VM_OBJECT_UNLOCK(bigobj); 626 bigobj = obj; 627 } else 628 VM_OBJECT_UNLOCK(obj); 629 } 630 } 631 if (tmpe->wired_count > 0) 632 nothingwired = FALSE; 633 tmpe = tmpe->next; 634 } 635 636 if (bigobj != NULL) { 637 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); 638 VM_OBJECT_UNLOCK(bigobj); 639 } 640 /* 641 * Next, hunt around for other pages to deactivate. We actually 642 * do this search sort of wrong -- .text first is not the best idea. 643 */ 644 tmpe = map->header.next; 645 while (tmpe != &map->header) { 646 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 647 break; 648 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 649 obj = tmpe->object.vm_object; 650 if (obj != NULL) { 651 VM_OBJECT_LOCK(obj); 652 vm_pageout_object_deactivate_pages(map->pmap, obj, desired); 653 VM_OBJECT_UNLOCK(obj); 654 } 655 } 656 tmpe = tmpe->next; 657 } 658 659 /* 660 * Remove all mappings if a process is swapped out, this will free page 661 * table pages. 662 */ 663 if (desired == 0 && nothingwired) { 664 pmap_remove(vm_map_pmap(map), vm_map_min(map), 665 vm_map_max(map)); 666 } 667 vm_map_unlock(map); 668 } 669 #endif /* !defined(NO_SWAPPING) */ 670 671 /* 672 * vm_pageout_scan does the dirty work for the pageout daemon. 673 */ 674 static void 675 vm_pageout_scan(int pass) 676 { 677 vm_page_t m, next; 678 struct vm_page marker; 679 int page_shortage, maxscan, pcount; 680 int addl_page_shortage, addl_page_shortage_init; 681 struct proc *p, *bigproc; 682 struct thread *td; 683 vm_offset_t size, bigsize; 684 vm_object_t object; 685 int actcount; 686 int vnodes_skipped = 0; 687 int maxlaunder; 688 689 /* 690 * Decrease registered cache sizes. 691 */ 692 EVENTHANDLER_INVOKE(vm_lowmem, 0); 693 /* 694 * We do this explicitly after the caches have been drained above. 695 */ 696 uma_reclaim(); 697 698 addl_page_shortage_init = atomic_readandclear_int(&vm_pageout_deficit); 699 700 /* 701 * Calculate the number of pages we want to either free or move 702 * to the cache. 703 */ 704 page_shortage = vm_paging_target() + addl_page_shortage_init; 705 706 /* 707 * Initialize our marker 708 */ 709 bzero(&marker, sizeof(marker)); 710 marker.flags = PG_FICTITIOUS | PG_MARKER; 711 marker.oflags = VPO_BUSY; 712 marker.queue = PQ_INACTIVE; 713 marker.wire_count = 1; 714 715 /* 716 * Start scanning the inactive queue for pages we can move to the 717 * cache or free. The scan will stop when the target is reached or 718 * we have scanned the entire inactive queue. Note that m->act_count 719 * is not used to form decisions for the inactive queue, only for the 720 * active queue. 721 * 722 * maxlaunder limits the number of dirty pages we flush per scan. 723 * For most systems a smaller value (16 or 32) is more robust under 724 * extreme memory and disk pressure because any unnecessary writes 725 * to disk can result in extreme performance degredation. However, 726 * systems with excessive dirty pages (especially when MAP_NOSYNC is 727 * used) will die horribly with limited laundering. If the pageout 728 * daemon cannot clean enough pages in the first pass, we let it go 729 * all out in succeeding passes. 730 */ 731 if ((maxlaunder = vm_max_launder) <= 1) 732 maxlaunder = 1; 733 if (pass) 734 maxlaunder = 10000; 735 vm_page_lock_queues(); 736 rescan0: 737 addl_page_shortage = addl_page_shortage_init; 738 maxscan = cnt.v_inactive_count; 739 740 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 741 m != NULL && maxscan-- > 0 && page_shortage > 0; 742 m = next) { 743 744 cnt.v_pdpages++; 745 746 if (VM_PAGE_GETQUEUE(m) != PQ_INACTIVE) { 747 goto rescan0; 748 } 749 750 next = TAILQ_NEXT(m, pageq); 751 object = m->object; 752 753 /* 754 * skip marker pages 755 */ 756 if (m->flags & PG_MARKER) 757 continue; 758 759 /* 760 * A held page may be undergoing I/O, so skip it. 761 */ 762 if (m->hold_count) { 763 vm_pageq_requeue(m); 764 addl_page_shortage++; 765 continue; 766 } 767 /* 768 * Don't mess with busy pages, keep in the front of the 769 * queue, most likely are being paged out. 770 */ 771 if (!VM_OBJECT_TRYLOCK(object) && 772 (!vm_pageout_fallback_object_lock(m, &next) || 773 m->hold_count != 0)) { 774 VM_OBJECT_UNLOCK(object); 775 addl_page_shortage++; 776 continue; 777 } 778 if (m->busy || (m->oflags & VPO_BUSY)) { 779 VM_OBJECT_UNLOCK(object); 780 addl_page_shortage++; 781 continue; 782 } 783 784 /* 785 * If the object is not being used, we ignore previous 786 * references. 787 */ 788 if (object->ref_count == 0) { 789 vm_page_flag_clear(m, PG_REFERENCED); 790 pmap_clear_reference(m); 791 792 /* 793 * Otherwise, if the page has been referenced while in the 794 * inactive queue, we bump the "activation count" upwards, 795 * making it less likely that the page will be added back to 796 * the inactive queue prematurely again. Here we check the 797 * page tables (or emulated bits, if any), given the upper 798 * level VM system not knowing anything about existing 799 * references. 800 */ 801 } else if (((m->flags & PG_REFERENCED) == 0) && 802 (actcount = pmap_ts_referenced(m))) { 803 vm_page_activate(m); 804 VM_OBJECT_UNLOCK(object); 805 m->act_count += (actcount + ACT_ADVANCE); 806 continue; 807 } 808 809 /* 810 * If the upper level VM system knows about any page 811 * references, we activate the page. We also set the 812 * "activation count" higher than normal so that we will less 813 * likely place pages back onto the inactive queue again. 814 */ 815 if ((m->flags & PG_REFERENCED) != 0) { 816 vm_page_flag_clear(m, PG_REFERENCED); 817 actcount = pmap_ts_referenced(m); 818 vm_page_activate(m); 819 VM_OBJECT_UNLOCK(object); 820 m->act_count += (actcount + ACT_ADVANCE + 1); 821 continue; 822 } 823 824 /* 825 * If the upper level VM system doesn't know anything about 826 * the page being dirty, we have to check for it again. As 827 * far as the VM code knows, any partially dirty pages are 828 * fully dirty. 829 */ 830 if (m->dirty == 0 && !pmap_is_modified(m)) { 831 /* 832 * Avoid a race condition: Unless write access is 833 * removed from the page, another processor could 834 * modify it before all access is removed by the call 835 * to vm_page_cache() below. If vm_page_cache() finds 836 * that the page has been modified when it removes all 837 * access, it panics because it cannot cache dirty 838 * pages. In principle, we could eliminate just write 839 * access here rather than all access. In the expected 840 * case, when there are no last instant modifications 841 * to the page, removing all access will be cheaper 842 * overall. 843 */ 844 if ((m->flags & PG_WRITEABLE) != 0) 845 pmap_remove_all(m); 846 } else { 847 vm_page_dirty(m); 848 } 849 850 if (m->valid == 0) { 851 /* 852 * Invalid pages can be easily freed 853 */ 854 vm_page_free(m); 855 cnt.v_dfree++; 856 --page_shortage; 857 } else if (m->dirty == 0) { 858 /* 859 * Clean pages can be placed onto the cache queue. 860 * This effectively frees them. 861 */ 862 vm_page_cache(m); 863 --page_shortage; 864 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 865 /* 866 * Dirty pages need to be paged out, but flushing 867 * a page is extremely expensive verses freeing 868 * a clean page. Rather then artificially limiting 869 * the number of pages we can flush, we instead give 870 * dirty pages extra priority on the inactive queue 871 * by forcing them to be cycled through the queue 872 * twice before being flushed, after which the 873 * (now clean) page will cycle through once more 874 * before being freed. This significantly extends 875 * the thrash point for a heavily loaded machine. 876 */ 877 vm_page_flag_set(m, PG_WINATCFLS); 878 vm_pageq_requeue(m); 879 } else if (maxlaunder > 0) { 880 /* 881 * We always want to try to flush some dirty pages if 882 * we encounter them, to keep the system stable. 883 * Normally this number is small, but under extreme 884 * pressure where there are insufficient clean pages 885 * on the inactive queue, we may have to go all out. 886 */ 887 int swap_pageouts_ok, vfslocked = 0; 888 struct vnode *vp = NULL; 889 struct mount *mp = NULL; 890 891 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 892 swap_pageouts_ok = 1; 893 } else { 894 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 895 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 896 vm_page_count_min()); 897 898 } 899 900 /* 901 * We don't bother paging objects that are "dead". 902 * Those objects are in a "rundown" state. 903 */ 904 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 905 VM_OBJECT_UNLOCK(object); 906 vm_pageq_requeue(m); 907 continue; 908 } 909 910 /* 911 * Following operations may unlock 912 * vm_page_queue_mtx, invalidating the 'next' 913 * pointer. To prevent an inordinate number 914 * of restarts we use our marker to remember 915 * our place. 916 * 917 */ 918 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, 919 m, &marker, pageq); 920 /* 921 * The object is already known NOT to be dead. It 922 * is possible for the vget() to block the whole 923 * pageout daemon, but the new low-memory handling 924 * code should prevent it. 925 * 926 * The previous code skipped locked vnodes and, worse, 927 * reordered pages in the queue. This results in 928 * completely non-deterministic operation and, on a 929 * busy system, can lead to extremely non-optimal 930 * pageouts. For example, it can cause clean pages 931 * to be freed and dirty pages to be moved to the end 932 * of the queue. Since dirty pages are also moved to 933 * the end of the queue once-cleaned, this gives 934 * way too large a weighting to defering the freeing 935 * of dirty pages. 936 * 937 * We can't wait forever for the vnode lock, we might 938 * deadlock due to a vn_read() getting stuck in 939 * vm_wait while holding this vnode. We skip the 940 * vnode if we can't get it in a reasonable amount 941 * of time. 942 */ 943 if (object->type == OBJT_VNODE) { 944 vp = object->handle; 945 if (vp->v_type == VREG && 946 vn_start_write(vp, &mp, V_NOWAIT) != 0) { 947 KASSERT(mp == NULL, 948 ("vm_pageout_scan: mp != NULL")); 949 ++pageout_lock_miss; 950 if (object->flags & OBJ_MIGHTBEDIRTY) 951 vnodes_skipped++; 952 goto unlock_and_continue; 953 } 954 vm_page_unlock_queues(); 955 vm_object_reference_locked(object); 956 VM_OBJECT_UNLOCK(object); 957 vfslocked = VFS_LOCK_GIANT(vp->v_mount); 958 if (vget(vp, LK_EXCLUSIVE | LK_TIMELOCK, 959 curthread)) { 960 VM_OBJECT_LOCK(object); 961 vm_page_lock_queues(); 962 ++pageout_lock_miss; 963 if (object->flags & OBJ_MIGHTBEDIRTY) 964 vnodes_skipped++; 965 vp = NULL; 966 goto unlock_and_continue; 967 } 968 VM_OBJECT_LOCK(object); 969 vm_page_lock_queues(); 970 /* 971 * The page might have been moved to another 972 * queue during potential blocking in vget() 973 * above. The page might have been freed and 974 * reused for another vnode. 975 */ 976 if (VM_PAGE_GETQUEUE(m) != PQ_INACTIVE || 977 m->object != object || 978 TAILQ_NEXT(m, pageq) != &marker) { 979 if (object->flags & OBJ_MIGHTBEDIRTY) 980 vnodes_skipped++; 981 goto unlock_and_continue; 982 } 983 984 /* 985 * The page may have been busied during the 986 * blocking in vget(). We don't move the 987 * page back onto the end of the queue so that 988 * statistics are more correct if we don't. 989 */ 990 if (m->busy || (m->oflags & VPO_BUSY)) { 991 goto unlock_and_continue; 992 } 993 994 /* 995 * If the page has become held it might 996 * be undergoing I/O, so skip it 997 */ 998 if (m->hold_count) { 999 vm_pageq_requeue(m); 1000 if (object->flags & OBJ_MIGHTBEDIRTY) 1001 vnodes_skipped++; 1002 goto unlock_and_continue; 1003 } 1004 } 1005 1006 /* 1007 * If a page is dirty, then it is either being washed 1008 * (but not yet cleaned) or it is still in the 1009 * laundry. If it is still in the laundry, then we 1010 * start the cleaning operation. 1011 * 1012 * decrement page_shortage on success to account for 1013 * the (future) cleaned page. Otherwise we could wind 1014 * up laundering or cleaning too many pages. 1015 */ 1016 if (vm_pageout_clean(m) != 0) { 1017 --page_shortage; 1018 --maxlaunder; 1019 } 1020 unlock_and_continue: 1021 VM_OBJECT_UNLOCK(object); 1022 if (mp != NULL) { 1023 vm_page_unlock_queues(); 1024 if (vp != NULL) 1025 vput(vp); 1026 VFS_UNLOCK_GIANT(vfslocked); 1027 vm_object_deallocate(object); 1028 vn_finished_write(mp); 1029 vm_page_lock_queues(); 1030 } 1031 next = TAILQ_NEXT(&marker, pageq); 1032 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, 1033 &marker, pageq); 1034 continue; 1035 } 1036 VM_OBJECT_UNLOCK(object); 1037 } 1038 1039 /* 1040 * Compute the number of pages we want to try to move from the 1041 * active queue to the inactive queue. 1042 */ 1043 page_shortage = vm_paging_target() + 1044 cnt.v_inactive_target - cnt.v_inactive_count; 1045 page_shortage += addl_page_shortage; 1046 1047 /* 1048 * Scan the active queue for things we can deactivate. We nominally 1049 * track the per-page activity counter and use it to locate 1050 * deactivation candidates. 1051 */ 1052 pcount = cnt.v_active_count; 1053 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1054 1055 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 1056 1057 KASSERT(VM_PAGE_INQUEUE2(m, PQ_ACTIVE), 1058 ("vm_pageout_scan: page %p isn't active", m)); 1059 1060 next = TAILQ_NEXT(m, pageq); 1061 object = m->object; 1062 if ((m->flags & PG_MARKER) != 0) { 1063 m = next; 1064 continue; 1065 } 1066 if (!VM_OBJECT_TRYLOCK(object) && 1067 !vm_pageout_fallback_object_lock(m, &next)) { 1068 VM_OBJECT_UNLOCK(object); 1069 m = next; 1070 continue; 1071 } 1072 1073 /* 1074 * Don't deactivate pages that are busy. 1075 */ 1076 if ((m->busy != 0) || 1077 (m->oflags & VPO_BUSY) || 1078 (m->hold_count != 0)) { 1079 VM_OBJECT_UNLOCK(object); 1080 vm_pageq_requeue(m); 1081 m = next; 1082 continue; 1083 } 1084 1085 /* 1086 * The count for pagedaemon pages is done after checking the 1087 * page for eligibility... 1088 */ 1089 cnt.v_pdpages++; 1090 1091 /* 1092 * Check to see "how much" the page has been used. 1093 */ 1094 actcount = 0; 1095 if (object->ref_count != 0) { 1096 if (m->flags & PG_REFERENCED) { 1097 actcount += 1; 1098 } 1099 actcount += pmap_ts_referenced(m); 1100 if (actcount) { 1101 m->act_count += ACT_ADVANCE + actcount; 1102 if (m->act_count > ACT_MAX) 1103 m->act_count = ACT_MAX; 1104 } 1105 } 1106 1107 /* 1108 * Since we have "tested" this bit, we need to clear it now. 1109 */ 1110 vm_page_flag_clear(m, PG_REFERENCED); 1111 1112 /* 1113 * Only if an object is currently being used, do we use the 1114 * page activation count stats. 1115 */ 1116 if (actcount && (object->ref_count != 0)) { 1117 vm_pageq_requeue(m); 1118 } else { 1119 m->act_count -= min(m->act_count, ACT_DECLINE); 1120 if (vm_pageout_algorithm || 1121 object->ref_count == 0 || 1122 m->act_count == 0) { 1123 page_shortage--; 1124 if (object->ref_count == 0) { 1125 pmap_remove_all(m); 1126 if (m->dirty == 0) 1127 vm_page_cache(m); 1128 else 1129 vm_page_deactivate(m); 1130 } else { 1131 vm_page_deactivate(m); 1132 } 1133 } else { 1134 vm_pageq_requeue(m); 1135 } 1136 } 1137 VM_OBJECT_UNLOCK(object); 1138 m = next; 1139 } 1140 vm_page_unlock_queues(); 1141 #if !defined(NO_SWAPPING) 1142 /* 1143 * Idle process swapout -- run once per second. 1144 */ 1145 if (vm_swap_idle_enabled) { 1146 static long lsec; 1147 if (time_second != lsec) { 1148 vm_req_vmdaemon(VM_SWAP_IDLE); 1149 lsec = time_second; 1150 } 1151 } 1152 #endif 1153 1154 /* 1155 * If we didn't get enough free pages, and we have skipped a vnode 1156 * in a writeable object, wakeup the sync daemon. And kick swapout 1157 * if we did not get enough free pages. 1158 */ 1159 if (vm_paging_target() > 0) { 1160 if (vnodes_skipped && vm_page_count_min()) 1161 (void) speedup_syncer(); 1162 #if !defined(NO_SWAPPING) 1163 if (vm_swap_enabled && vm_page_count_target()) 1164 vm_req_vmdaemon(VM_SWAP_NORMAL); 1165 #endif 1166 } 1167 1168 /* 1169 * If we are critically low on one of RAM or swap and low on 1170 * the other, kill the largest process. However, we avoid 1171 * doing this on the first pass in order to give ourselves a 1172 * chance to flush out dirty vnode-backed pages and to allow 1173 * active pages to be moved to the inactive queue and reclaimed. 1174 * 1175 * We keep the process bigproc locked once we find it to keep anyone 1176 * from messing with it; however, there is a possibility of 1177 * deadlock if process B is bigproc and one of it's child processes 1178 * attempts to propagate a signal to B while we are waiting for A's 1179 * lock while walking this list. To avoid this, we don't block on 1180 * the process lock but just skip a process if it is already locked. 1181 */ 1182 if (pass != 0 && 1183 ((swap_pager_avail < 64 && vm_page_count_min()) || 1184 (swap_pager_full && vm_paging_target() > 0))) { 1185 bigproc = NULL; 1186 bigsize = 0; 1187 sx_slock(&allproc_lock); 1188 FOREACH_PROC_IN_SYSTEM(p) { 1189 int breakout; 1190 1191 if (PROC_TRYLOCK(p) == 0) 1192 continue; 1193 /* 1194 * If this is a system or protected process, skip it. 1195 */ 1196 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1197 (p->p_flag & P_PROTECTED) || 1198 ((p->p_pid < 48) && (swap_pager_avail != 0))) { 1199 PROC_UNLOCK(p); 1200 continue; 1201 } 1202 /* 1203 * If the process is in a non-running type state, 1204 * don't touch it. Check all the threads individually. 1205 */ 1206 PROC_SLOCK(p); 1207 breakout = 0; 1208 FOREACH_THREAD_IN_PROC(p, td) { 1209 thread_lock(td); 1210 if (!TD_ON_RUNQ(td) && 1211 !TD_IS_RUNNING(td) && 1212 !TD_IS_SLEEPING(td)) { 1213 thread_unlock(td); 1214 breakout = 1; 1215 break; 1216 } 1217 thread_unlock(td); 1218 } 1219 PROC_SUNLOCK(p); 1220 if (breakout) { 1221 PROC_UNLOCK(p); 1222 continue; 1223 } 1224 /* 1225 * get the process size 1226 */ 1227 if (!vm_map_trylock_read(&p->p_vmspace->vm_map)) { 1228 PROC_UNLOCK(p); 1229 continue; 1230 } 1231 size = vmspace_swap_count(p->p_vmspace); 1232 vm_map_unlock_read(&p->p_vmspace->vm_map); 1233 size += vmspace_resident_count(p->p_vmspace); 1234 /* 1235 * if the this process is bigger than the biggest one 1236 * remember it. 1237 */ 1238 if (size > bigsize) { 1239 if (bigproc != NULL) 1240 PROC_UNLOCK(bigproc); 1241 bigproc = p; 1242 bigsize = size; 1243 } else 1244 PROC_UNLOCK(p); 1245 } 1246 sx_sunlock(&allproc_lock); 1247 if (bigproc != NULL) { 1248 killproc(bigproc, "out of swap space"); 1249 PROC_SLOCK(bigproc); 1250 sched_nice(bigproc, PRIO_MIN); 1251 PROC_SUNLOCK(bigproc); 1252 PROC_UNLOCK(bigproc); 1253 wakeup(&cnt.v_free_count); 1254 } 1255 } 1256 } 1257 1258 /* 1259 * This routine tries to maintain the pseudo LRU active queue, 1260 * so that during long periods of time where there is no paging, 1261 * that some statistic accumulation still occurs. This code 1262 * helps the situation where paging just starts to occur. 1263 */ 1264 static void 1265 vm_pageout_page_stats() 1266 { 1267 vm_object_t object; 1268 vm_page_t m,next; 1269 int pcount,tpcount; /* Number of pages to check */ 1270 static int fullintervalcount = 0; 1271 int page_shortage; 1272 1273 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1274 page_shortage = 1275 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1276 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1277 1278 if (page_shortage <= 0) 1279 return; 1280 1281 pcount = cnt.v_active_count; 1282 fullintervalcount += vm_pageout_stats_interval; 1283 if (fullintervalcount < vm_pageout_full_stats_interval) { 1284 tpcount = (vm_pageout_stats_max * cnt.v_active_count) / cnt.v_page_count; 1285 if (pcount > tpcount) 1286 pcount = tpcount; 1287 } else { 1288 fullintervalcount = 0; 1289 } 1290 1291 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1292 while ((m != NULL) && (pcount-- > 0)) { 1293 int actcount; 1294 1295 KASSERT(VM_PAGE_INQUEUE2(m, PQ_ACTIVE), 1296 ("vm_pageout_page_stats: page %p isn't active", m)); 1297 1298 next = TAILQ_NEXT(m, pageq); 1299 object = m->object; 1300 1301 if ((m->flags & PG_MARKER) != 0) { 1302 m = next; 1303 continue; 1304 } 1305 if (!VM_OBJECT_TRYLOCK(object) && 1306 !vm_pageout_fallback_object_lock(m, &next)) { 1307 VM_OBJECT_UNLOCK(object); 1308 m = next; 1309 continue; 1310 } 1311 1312 /* 1313 * Don't deactivate pages that are busy. 1314 */ 1315 if ((m->busy != 0) || 1316 (m->oflags & VPO_BUSY) || 1317 (m->hold_count != 0)) { 1318 VM_OBJECT_UNLOCK(object); 1319 vm_pageq_requeue(m); 1320 m = next; 1321 continue; 1322 } 1323 1324 actcount = 0; 1325 if (m->flags & PG_REFERENCED) { 1326 vm_page_flag_clear(m, PG_REFERENCED); 1327 actcount += 1; 1328 } 1329 1330 actcount += pmap_ts_referenced(m); 1331 if (actcount) { 1332 m->act_count += ACT_ADVANCE + actcount; 1333 if (m->act_count > ACT_MAX) 1334 m->act_count = ACT_MAX; 1335 vm_pageq_requeue(m); 1336 } else { 1337 if (m->act_count == 0) { 1338 /* 1339 * We turn off page access, so that we have 1340 * more accurate RSS stats. We don't do this 1341 * in the normal page deactivation when the 1342 * system is loaded VM wise, because the 1343 * cost of the large number of page protect 1344 * operations would be higher than the value 1345 * of doing the operation. 1346 */ 1347 pmap_remove_all(m); 1348 vm_page_deactivate(m); 1349 } else { 1350 m->act_count -= min(m->act_count, ACT_DECLINE); 1351 vm_pageq_requeue(m); 1352 } 1353 } 1354 VM_OBJECT_UNLOCK(object); 1355 m = next; 1356 } 1357 } 1358 1359 /* 1360 * vm_pageout is the high level pageout daemon. 1361 */ 1362 static void 1363 vm_pageout() 1364 { 1365 int error, pass; 1366 1367 /* 1368 * Initialize some paging parameters. 1369 */ 1370 cnt.v_interrupt_free_min = 2; 1371 if (cnt.v_page_count < 2000) 1372 vm_pageout_page_count = 8; 1373 1374 /* 1375 * v_free_reserved needs to include enough for the largest 1376 * swap pager structures plus enough for any pv_entry structs 1377 * when paging. 1378 */ 1379 if (cnt.v_page_count > 1024) 1380 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1381 else 1382 cnt.v_free_min = 4; 1383 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1384 cnt.v_interrupt_free_min; 1385 cnt.v_free_reserved = vm_pageout_page_count + 1386 cnt.v_pageout_free_min + (cnt.v_page_count / 768); 1387 cnt.v_free_severe = cnt.v_free_min / 2; 1388 cnt.v_free_min += cnt.v_free_reserved; 1389 cnt.v_free_severe += cnt.v_free_reserved; 1390 1391 /* 1392 * v_free_target and v_cache_min control pageout hysteresis. Note 1393 * that these are more a measure of the VM cache queue hysteresis 1394 * then the VM free queue. Specifically, v_free_target is the 1395 * high water mark (free+cache pages). 1396 * 1397 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1398 * low water mark, while v_free_min is the stop. v_cache_min must 1399 * be big enough to handle memory needs while the pageout daemon 1400 * is signalled and run to free more pages. 1401 */ 1402 if (cnt.v_free_count > 6144) 1403 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1404 else 1405 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1406 1407 if (cnt.v_free_count > 2048) { 1408 cnt.v_cache_min = cnt.v_free_target; 1409 cnt.v_cache_max = 2 * cnt.v_cache_min; 1410 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1411 } else { 1412 cnt.v_cache_min = 0; 1413 cnt.v_cache_max = 0; 1414 cnt.v_inactive_target = cnt.v_free_count / 4; 1415 } 1416 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1417 cnt.v_inactive_target = cnt.v_free_count / 3; 1418 1419 /* XXX does not really belong here */ 1420 if (vm_page_max_wired == 0) 1421 vm_page_max_wired = cnt.v_free_count / 3; 1422 1423 if (vm_pageout_stats_max == 0) 1424 vm_pageout_stats_max = cnt.v_free_target; 1425 1426 /* 1427 * Set interval in seconds for stats scan. 1428 */ 1429 if (vm_pageout_stats_interval == 0) 1430 vm_pageout_stats_interval = 5; 1431 if (vm_pageout_full_stats_interval == 0) 1432 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1433 1434 swap_pager_swap_init(); 1435 pass = 0; 1436 /* 1437 * The pageout daemon is never done, so loop forever. 1438 */ 1439 while (TRUE) { 1440 /* 1441 * If we have enough free memory, wakeup waiters. Do 1442 * not clear vm_pages_needed until we reach our target, 1443 * otherwise we may be woken up over and over again and 1444 * waste a lot of cpu. 1445 */ 1446 mtx_lock(&vm_page_queue_free_mtx); 1447 if (vm_pages_needed && !vm_page_count_min()) { 1448 if (!vm_paging_needed()) 1449 vm_pages_needed = 0; 1450 wakeup(&cnt.v_free_count); 1451 } 1452 if (vm_pages_needed) { 1453 /* 1454 * Still not done, take a second pass without waiting 1455 * (unlimited dirty cleaning), otherwise sleep a bit 1456 * and try again. 1457 */ 1458 ++pass; 1459 if (pass > 1) 1460 msleep(&vm_pages_needed, 1461 &vm_page_queue_free_mtx, PVM, "psleep", 1462 hz / 2); 1463 } else { 1464 /* 1465 * Good enough, sleep & handle stats. Prime the pass 1466 * for the next run. 1467 */ 1468 if (pass > 1) 1469 pass = 1; 1470 else 1471 pass = 0; 1472 error = msleep(&vm_pages_needed, 1473 &vm_page_queue_free_mtx, PVM, "psleep", 1474 vm_pageout_stats_interval * hz); 1475 if (error && !vm_pages_needed) { 1476 mtx_unlock(&vm_page_queue_free_mtx); 1477 pass = 0; 1478 vm_page_lock_queues(); 1479 vm_pageout_page_stats(); 1480 vm_page_unlock_queues(); 1481 continue; 1482 } 1483 } 1484 if (vm_pages_needed) 1485 cnt.v_pdwakeups++; 1486 mtx_unlock(&vm_page_queue_free_mtx); 1487 vm_pageout_scan(pass); 1488 } 1489 } 1490 1491 /* 1492 * Unless the free page queue lock is held by the caller, this function 1493 * should be regarded as advisory. Specifically, the caller should 1494 * not msleep() on &cnt.v_free_count following this function unless 1495 * the free page queue lock is held until the msleep() is performed. 1496 */ 1497 void 1498 pagedaemon_wakeup() 1499 { 1500 1501 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1502 vm_pages_needed = 1; 1503 wakeup(&vm_pages_needed); 1504 } 1505 } 1506 1507 #if !defined(NO_SWAPPING) 1508 static void 1509 vm_req_vmdaemon(int req) 1510 { 1511 static int lastrun = 0; 1512 1513 mtx_lock(&vm_daemon_mtx); 1514 vm_pageout_req_swapout |= req; 1515 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1516 wakeup(&vm_daemon_needed); 1517 lastrun = ticks; 1518 } 1519 mtx_unlock(&vm_daemon_mtx); 1520 } 1521 1522 static void 1523 vm_daemon() 1524 { 1525 struct rlimit rsslim; 1526 struct proc *p; 1527 struct thread *td; 1528 int breakout, swapout_flags; 1529 1530 while (TRUE) { 1531 mtx_lock(&vm_daemon_mtx); 1532 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0); 1533 swapout_flags = vm_pageout_req_swapout; 1534 vm_pageout_req_swapout = 0; 1535 mtx_unlock(&vm_daemon_mtx); 1536 if (swapout_flags) 1537 swapout_procs(swapout_flags); 1538 1539 /* 1540 * scan the processes for exceeding their rlimits or if 1541 * process is swapped out -- deactivate pages 1542 */ 1543 sx_slock(&allproc_lock); 1544 FOREACH_PROC_IN_SYSTEM(p) { 1545 vm_pindex_t limit, size; 1546 1547 /* 1548 * if this is a system process or if we have already 1549 * looked at this process, skip it. 1550 */ 1551 PROC_LOCK(p); 1552 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 1553 PROC_UNLOCK(p); 1554 continue; 1555 } 1556 /* 1557 * if the process is in a non-running type state, 1558 * don't touch it. 1559 */ 1560 PROC_SLOCK(p); 1561 breakout = 0; 1562 FOREACH_THREAD_IN_PROC(p, td) { 1563 thread_lock(td); 1564 if (!TD_ON_RUNQ(td) && 1565 !TD_IS_RUNNING(td) && 1566 !TD_IS_SLEEPING(td)) { 1567 thread_unlock(td); 1568 breakout = 1; 1569 break; 1570 } 1571 thread_unlock(td); 1572 } 1573 PROC_SUNLOCK(p); 1574 if (breakout) { 1575 PROC_UNLOCK(p); 1576 continue; 1577 } 1578 /* 1579 * get a limit 1580 */ 1581 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1582 limit = OFF_TO_IDX( 1583 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1584 1585 /* 1586 * let processes that are swapped out really be 1587 * swapped out set the limit to nothing (will force a 1588 * swap-out.) 1589 */ 1590 if ((p->p_flag & P_INMEM) == 0) 1591 limit = 0; /* XXX */ 1592 PROC_UNLOCK(p); 1593 1594 size = vmspace_resident_count(p->p_vmspace); 1595 if (limit >= 0 && size >= limit) { 1596 vm_pageout_map_deactivate_pages( 1597 &p->p_vmspace->vm_map, limit); 1598 } 1599 } 1600 sx_sunlock(&allproc_lock); 1601 } 1602 } 1603 #endif /* !defined(NO_SWAPPING) */ 1604