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, 127 &page_kp); 128 129 #if !defined(NO_SWAPPING) 130 /* the kernel process "vm_daemon"*/ 131 static void vm_daemon(void); 132 static struct proc *vmproc; 133 134 static struct kproc_desc vm_kp = { 135 "vmdaemon", 136 vm_daemon, 137 &vmproc 138 }; 139 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp); 140 #endif 141 142 143 int vm_pages_needed; /* Event on which pageout daemon sleeps */ 144 int vm_pageout_deficit; /* Estimated number of pages deficit */ 145 int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 146 147 #if !defined(NO_SWAPPING) 148 static int vm_pageout_req_swapout; /* XXX */ 149 static int vm_daemon_needed; 150 static struct mtx vm_daemon_mtx; 151 /* Allow for use by vm_pageout before vm_daemon is initialized. */ 152 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); 153 #endif 154 static int vm_max_launder = 32; 155 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 156 static int vm_pageout_full_stats_interval = 0; 157 static int vm_pageout_algorithm=0; 158 static int defer_swap_pageouts=0; 159 static int disable_swap_pageouts=0; 160 161 #if defined(NO_SWAPPING) 162 static int vm_swap_enabled=0; 163 static int vm_swap_idle_enabled=0; 164 #else 165 static int vm_swap_enabled=1; 166 static int vm_swap_idle_enabled=0; 167 #endif 168 169 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 170 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 171 172 SYSCTL_INT(_vm, OID_AUTO, max_launder, 173 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 174 175 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 176 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 177 178 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 179 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 180 181 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 182 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 183 184 #if defined(NO_SWAPPING) 185 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 186 CTLFLAG_RD, &vm_swap_enabled, 0, "Enable entire process swapout"); 187 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 188 CTLFLAG_RD, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 189 #else 190 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 191 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 192 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 193 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 194 #endif 195 196 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 197 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 198 199 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 200 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 201 202 static int pageout_lock_miss; 203 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 204 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 205 206 #define VM_PAGEOUT_PAGE_COUNT 16 207 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 208 209 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 210 SYSCTL_INT(_vm, OID_AUTO, max_wired, 211 CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count"); 212 213 #if !defined(NO_SWAPPING) 214 static void vm_pageout_map_deactivate_pages(vm_map_t, long); 215 static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long); 216 static void vm_req_vmdaemon(int req); 217 #endif 218 static void vm_pageout_page_stats(void); 219 220 /* 221 * vm_pageout_fallback_object_lock: 222 * 223 * Lock vm object currently associated with `m'. VM_OBJECT_TRYLOCK is 224 * known to have failed and page queue must be either PQ_ACTIVE or 225 * PQ_INACTIVE. To avoid lock order violation, unlock the page queues 226 * while locking the vm object. Use marker page to detect page queue 227 * changes and maintain notion of next page on page queue. Return 228 * TRUE if no changes were detected, FALSE otherwise. vm object is 229 * locked on return. 230 * 231 * This function depends on both the lock portion of struct vm_object 232 * and normal struct vm_page being type stable. 233 */ 234 boolean_t 235 vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next) 236 { 237 struct vm_page marker; 238 boolean_t unchanged; 239 u_short queue; 240 vm_object_t object; 241 242 /* 243 * Initialize our marker 244 */ 245 bzero(&marker, sizeof(marker)); 246 marker.flags = PG_FICTITIOUS | PG_MARKER; 247 marker.oflags = VPO_BUSY; 248 marker.queue = m->queue; 249 marker.wire_count = 1; 250 251 queue = m->queue; 252 object = m->object; 253 254 TAILQ_INSERT_AFTER(&vm_page_queues[queue].pl, 255 m, &marker, pageq); 256 vm_page_unlock_queues(); 257 VM_OBJECT_LOCK(object); 258 vm_page_lock_queues(); 259 260 /* Page queue might have changed. */ 261 *next = TAILQ_NEXT(&marker, pageq); 262 unchanged = (m->queue == queue && 263 m->object == object && 264 &marker == TAILQ_NEXT(m, pageq)); 265 TAILQ_REMOVE(&vm_page_queues[queue].pl, 266 &marker, pageq); 267 return (unchanged); 268 } 269 270 /* 271 * vm_pageout_clean: 272 * 273 * Clean the page and remove it from the laundry. 274 * 275 * We set the busy bit to cause potential page faults on this page to 276 * block. Note the careful timing, however, the busy bit isn't set till 277 * late and we cannot do anything that will mess with the page. 278 */ 279 static int 280 vm_pageout_clean(m) 281 vm_page_t m; 282 { 283 vm_object_t object; 284 vm_page_t mc[2*vm_pageout_page_count]; 285 int pageout_count; 286 int ib, is, page_base; 287 vm_pindex_t pindex = m->pindex; 288 289 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 290 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 291 292 /* 293 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 294 * with the new swapper, but we could have serious problems paging 295 * out other object types if there is insufficient memory. 296 * 297 * Unfortunately, checking free memory here is far too late, so the 298 * check has been moved up a procedural level. 299 */ 300 301 /* 302 * Can't clean the page if it's busy or held. 303 */ 304 if ((m->hold_count != 0) || 305 ((m->busy != 0) || (m->oflags & VPO_BUSY))) { 306 return 0; 307 } 308 309 mc[vm_pageout_page_count] = m; 310 pageout_count = 1; 311 page_base = vm_pageout_page_count; 312 ib = 1; 313 is = 1; 314 315 /* 316 * Scan object for clusterable pages. 317 * 318 * We can cluster ONLY if: ->> the page is NOT 319 * clean, wired, busy, held, or mapped into a 320 * buffer, and one of the following: 321 * 1) The page is inactive, or a seldom used 322 * active page. 323 * -or- 324 * 2) we force the issue. 325 * 326 * During heavy mmap/modification loads the pageout 327 * daemon can really fragment the underlying file 328 * due to flushing pages out of order and not trying 329 * align the clusters (which leave sporatic out-of-order 330 * holes). To solve this problem we do the reverse scan 331 * first and attempt to align our cluster, then do a 332 * forward scan if room remains. 333 */ 334 object = m->object; 335 more: 336 while (ib && pageout_count < vm_pageout_page_count) { 337 vm_page_t p; 338 339 if (ib > pindex) { 340 ib = 0; 341 break; 342 } 343 344 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) { 345 ib = 0; 346 break; 347 } 348 if ((p->oflags & VPO_BUSY) || p->busy) { 349 ib = 0; 350 break; 351 } 352 vm_page_test_dirty(p); 353 if ((p->dirty & p->valid) == 0 || 354 p->queue != PQ_INACTIVE || 355 p->wire_count != 0 || /* may be held by buf cache */ 356 p->hold_count != 0) { /* may be undergoing I/O */ 357 ib = 0; 358 break; 359 } 360 mc[--page_base] = p; 361 ++pageout_count; 362 ++ib; 363 /* 364 * alignment boundry, stop here and switch directions. Do 365 * not clear ib. 366 */ 367 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 368 break; 369 } 370 371 while (pageout_count < vm_pageout_page_count && 372 pindex + is < object->size) { 373 vm_page_t p; 374 375 if ((p = vm_page_lookup(object, pindex + is)) == NULL) 376 break; 377 if ((p->oflags & VPO_BUSY) || p->busy) { 378 break; 379 } 380 vm_page_test_dirty(p); 381 if ((p->dirty & p->valid) == 0 || 382 p->queue != PQ_INACTIVE || 383 p->wire_count != 0 || /* may be held by buf cache */ 384 p->hold_count != 0) { /* may be undergoing I/O */ 385 break; 386 } 387 mc[page_base + pageout_count] = p; 388 ++pageout_count; 389 ++is; 390 } 391 392 /* 393 * If we exhausted our forward scan, continue with the reverse scan 394 * when possible, even past a page boundry. This catches boundry 395 * conditions. 396 */ 397 if (ib && pageout_count < vm_pageout_page_count) 398 goto more; 399 400 /* 401 * we allow reads during pageouts... 402 */ 403 return (vm_pageout_flush(&mc[page_base], pageout_count, 0)); 404 } 405 406 /* 407 * vm_pageout_flush() - launder the given pages 408 * 409 * The given pages are laundered. Note that we setup for the start of 410 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 411 * reference count all in here rather then in the parent. If we want 412 * the parent to do more sophisticated things we may have to change 413 * the ordering. 414 */ 415 int 416 vm_pageout_flush(vm_page_t *mc, int count, int flags) 417 { 418 vm_object_t object = mc[0]->object; 419 int pageout_status[count]; 420 int numpagedout = 0; 421 int i; 422 423 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 424 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 425 /* 426 * Initiate I/O. Bump the vm_page_t->busy counter and 427 * mark the pages read-only. 428 * 429 * We do not have to fixup the clean/dirty bits here... we can 430 * allow the pager to do it after the I/O completes. 431 * 432 * NOTE! mc[i]->dirty may be partial or fragmented due to an 433 * edge case with file fragments. 434 */ 435 for (i = 0; i < count; i++) { 436 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 437 ("vm_pageout_flush: partially invalid page %p index %d/%d", 438 mc[i], i, count)); 439 vm_page_io_start(mc[i]); 440 pmap_remove_write(mc[i]); 441 } 442 vm_page_unlock_queues(); 443 vm_object_pip_add(object, count); 444 445 vm_pager_put_pages(object, mc, count, flags, pageout_status); 446 447 vm_page_lock_queues(); 448 for (i = 0; i < count; i++) { 449 vm_page_t mt = mc[i]; 450 451 KASSERT(pageout_status[i] == VM_PAGER_PEND || 452 (mt->flags & PG_WRITEABLE) == 0, 453 ("vm_pageout_flush: page %p is not write protected", mt)); 454 switch (pageout_status[i]) { 455 case VM_PAGER_OK: 456 case VM_PAGER_PEND: 457 numpagedout++; 458 break; 459 case VM_PAGER_BAD: 460 /* 461 * Page outside of range of object. Right now we 462 * essentially lose the changes by pretending it 463 * worked. 464 */ 465 pmap_clear_modify(mt); 466 vm_page_undirty(mt); 467 break; 468 case VM_PAGER_ERROR: 469 case VM_PAGER_FAIL: 470 /* 471 * If page couldn't be paged out, then reactivate the 472 * page so it doesn't clog the inactive list. (We 473 * will try paging out it again later). 474 */ 475 vm_page_activate(mt); 476 break; 477 case VM_PAGER_AGAIN: 478 break; 479 } 480 481 /* 482 * If the operation is still going, leave the page busy to 483 * block all other accesses. Also, leave the paging in 484 * progress indicator set so that we don't attempt an object 485 * collapse. 486 */ 487 if (pageout_status[i] != VM_PAGER_PEND) { 488 vm_object_pip_wakeup(object); 489 vm_page_io_finish(mt); 490 if (vm_page_count_severe()) 491 vm_page_try_to_cache(mt); 492 } 493 } 494 return numpagedout; 495 } 496 497 #if !defined(NO_SWAPPING) 498 /* 499 * vm_pageout_object_deactivate_pages 500 * 501 * deactivate enough pages to satisfy the inactive target 502 * requirements or if vm_page_proc_limit is set, then 503 * deactivate all of the pages in the object and its 504 * backing_objects. 505 * 506 * The object and map must be locked. 507 */ 508 static void 509 vm_pageout_object_deactivate_pages(pmap, first_object, desired) 510 pmap_t pmap; 511 vm_object_t first_object; 512 long desired; 513 { 514 vm_object_t backing_object, object; 515 vm_page_t p, next; 516 int actcount, rcount, remove_mode; 517 518 VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED); 519 if (first_object->type == OBJT_DEVICE || first_object->type == OBJT_PHYS) 520 return; 521 for (object = first_object;; object = backing_object) { 522 if (pmap_resident_count(pmap) <= desired) 523 goto unlock_return; 524 if (object->paging_in_progress) 525 goto unlock_return; 526 527 remove_mode = 0; 528 if (object->shadow_count > 1) 529 remove_mode = 1; 530 /* 531 * scan the objects entire memory queue 532 */ 533 rcount = object->resident_page_count; 534 p = TAILQ_FIRST(&object->memq); 535 vm_page_lock_queues(); 536 while (p && (rcount-- > 0)) { 537 if (pmap_resident_count(pmap) <= desired) { 538 vm_page_unlock_queues(); 539 goto unlock_return; 540 } 541 next = TAILQ_NEXT(p, listq); 542 cnt.v_pdpages++; 543 if (p->wire_count != 0 || 544 p->hold_count != 0 || 545 p->busy != 0 || 546 (p->oflags & VPO_BUSY) || 547 (p->flags & PG_UNMANAGED) || 548 !pmap_page_exists_quick(pmap, p)) { 549 p = next; 550 continue; 551 } 552 actcount = pmap_ts_referenced(p); 553 if (actcount) { 554 vm_page_flag_set(p, PG_REFERENCED); 555 } else if (p->flags & PG_REFERENCED) { 556 actcount = 1; 557 } 558 if ((p->queue != PQ_ACTIVE) && 559 (p->flags & PG_REFERENCED)) { 560 vm_page_activate(p); 561 p->act_count += actcount; 562 vm_page_flag_clear(p, PG_REFERENCED); 563 } else if (p->queue == PQ_ACTIVE) { 564 if ((p->flags & PG_REFERENCED) == 0) { 565 p->act_count -= min(p->act_count, ACT_DECLINE); 566 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) { 567 pmap_remove_all(p); 568 vm_page_deactivate(p); 569 } else { 570 vm_page_requeue(p); 571 } 572 } else { 573 vm_page_activate(p); 574 vm_page_flag_clear(p, PG_REFERENCED); 575 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 576 p->act_count += ACT_ADVANCE; 577 vm_page_requeue(p); 578 } 579 } else if (p->queue == PQ_INACTIVE) { 580 pmap_remove_all(p); 581 } 582 p = next; 583 } 584 vm_page_unlock_queues(); 585 if ((backing_object = object->backing_object) == NULL) 586 goto unlock_return; 587 VM_OBJECT_LOCK(backing_object); 588 if (object != first_object) 589 VM_OBJECT_UNLOCK(object); 590 } 591 unlock_return: 592 if (object != first_object) 593 VM_OBJECT_UNLOCK(object); 594 } 595 596 /* 597 * deactivate some number of pages in a map, try to do it fairly, but 598 * that is really hard to do. 599 */ 600 static void 601 vm_pageout_map_deactivate_pages(map, desired) 602 vm_map_t map; 603 long desired; 604 { 605 vm_map_entry_t tmpe; 606 vm_object_t obj, bigobj; 607 int nothingwired; 608 609 if (!vm_map_trylock(map)) 610 return; 611 612 bigobj = NULL; 613 nothingwired = TRUE; 614 615 /* 616 * first, search out the biggest object, and try to free pages from 617 * that. 618 */ 619 tmpe = map->header.next; 620 while (tmpe != &map->header) { 621 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 622 obj = tmpe->object.vm_object; 623 if (obj != NULL && VM_OBJECT_TRYLOCK(obj)) { 624 if (obj->shadow_count <= 1 && 625 (bigobj == NULL || 626 bigobj->resident_page_count < obj->resident_page_count)) { 627 if (bigobj != NULL) 628 VM_OBJECT_UNLOCK(bigobj); 629 bigobj = obj; 630 } else 631 VM_OBJECT_UNLOCK(obj); 632 } 633 } 634 if (tmpe->wired_count > 0) 635 nothingwired = FALSE; 636 tmpe = tmpe->next; 637 } 638 639 if (bigobj != NULL) { 640 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); 641 VM_OBJECT_UNLOCK(bigobj); 642 } 643 /* 644 * Next, hunt around for other pages to deactivate. We actually 645 * do this search sort of wrong -- .text first is not the best idea. 646 */ 647 tmpe = map->header.next; 648 while (tmpe != &map->header) { 649 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 650 break; 651 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 652 obj = tmpe->object.vm_object; 653 if (obj != NULL) { 654 VM_OBJECT_LOCK(obj); 655 vm_pageout_object_deactivate_pages(map->pmap, obj, desired); 656 VM_OBJECT_UNLOCK(obj); 657 } 658 } 659 tmpe = tmpe->next; 660 } 661 662 /* 663 * Remove all mappings if a process is swapped out, this will free page 664 * table pages. 665 */ 666 if (desired == 0 && nothingwired) { 667 pmap_remove(vm_map_pmap(map), vm_map_min(map), 668 vm_map_max(map)); 669 } 670 vm_map_unlock(map); 671 } 672 #endif /* !defined(NO_SWAPPING) */ 673 674 /* 675 * vm_pageout_scan does the dirty work for the pageout daemon. 676 */ 677 static void 678 vm_pageout_scan(int pass) 679 { 680 vm_page_t m, next; 681 struct vm_page marker; 682 int page_shortage, maxscan, pcount; 683 int addl_page_shortage, addl_page_shortage_init; 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_page_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_page_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_page_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_page_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_page_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_page_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_page_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 if (pass != 0 && 1176 ((swap_pager_avail < 64 && vm_page_count_min()) || 1177 (swap_pager_full && vm_paging_target() > 0))) 1178 vm_pageout_oom(VM_OOM_MEM); 1179 } 1180 1181 1182 void 1183 vm_pageout_oom(int shortage) 1184 { 1185 struct proc *p, *bigproc; 1186 vm_offset_t size, bigsize; 1187 struct thread *td; 1188 1189 /* 1190 * We keep the process bigproc locked once we find it to keep anyone 1191 * from messing with it; however, there is a possibility of 1192 * deadlock if process B is bigproc and one of it's child processes 1193 * attempts to propagate a signal to B while we are waiting for A's 1194 * lock while walking this list. To avoid this, we don't block on 1195 * the process lock but just skip a process if it is already locked. 1196 */ 1197 bigproc = NULL; 1198 bigsize = 0; 1199 sx_slock(&allproc_lock); 1200 FOREACH_PROC_IN_SYSTEM(p) { 1201 int breakout; 1202 1203 if (PROC_TRYLOCK(p) == 0) 1204 continue; 1205 /* 1206 * If this is a system or protected process, skip it. 1207 */ 1208 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1209 (p->p_flag & P_PROTECTED) || 1210 ((p->p_pid < 48) && (swap_pager_avail != 0))) { 1211 PROC_UNLOCK(p); 1212 continue; 1213 } 1214 /* 1215 * If the process is in a non-running type state, 1216 * don't touch it. Check all the threads individually. 1217 */ 1218 breakout = 0; 1219 FOREACH_THREAD_IN_PROC(p, td) { 1220 thread_lock(td); 1221 if (!TD_ON_RUNQ(td) && 1222 !TD_IS_RUNNING(td) && 1223 !TD_IS_SLEEPING(td)) { 1224 thread_unlock(td); 1225 breakout = 1; 1226 break; 1227 } 1228 thread_unlock(td); 1229 } 1230 if (breakout) { 1231 PROC_UNLOCK(p); 1232 continue; 1233 } 1234 /* 1235 * get the process size 1236 */ 1237 if (!vm_map_trylock_read(&p->p_vmspace->vm_map)) { 1238 PROC_UNLOCK(p); 1239 continue; 1240 } 1241 size = vmspace_swap_count(p->p_vmspace); 1242 vm_map_unlock_read(&p->p_vmspace->vm_map); 1243 if (shortage == VM_OOM_MEM) 1244 size += vmspace_resident_count(p->p_vmspace); 1245 /* 1246 * if the this process is bigger than the biggest one 1247 * remember it. 1248 */ 1249 if (size > bigsize) { 1250 if (bigproc != NULL) 1251 PROC_UNLOCK(bigproc); 1252 bigproc = p; 1253 bigsize = size; 1254 } else 1255 PROC_UNLOCK(p); 1256 } 1257 sx_sunlock(&allproc_lock); 1258 if (bigproc != NULL) { 1259 killproc(bigproc, "out of swap space"); 1260 sched_nice(bigproc, PRIO_MIN); 1261 PROC_UNLOCK(bigproc); 1262 wakeup(&cnt.v_free_count); 1263 } 1264 } 1265 1266 /* 1267 * This routine tries to maintain the pseudo LRU active queue, 1268 * so that during long periods of time where there is no paging, 1269 * that some statistic accumulation still occurs. This code 1270 * helps the situation where paging just starts to occur. 1271 */ 1272 static void 1273 vm_pageout_page_stats() 1274 { 1275 vm_object_t object; 1276 vm_page_t m,next; 1277 int pcount,tpcount; /* Number of pages to check */ 1278 static int fullintervalcount = 0; 1279 int page_shortage; 1280 1281 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1282 page_shortage = 1283 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1284 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1285 1286 if (page_shortage <= 0) 1287 return; 1288 1289 pcount = cnt.v_active_count; 1290 fullintervalcount += vm_pageout_stats_interval; 1291 if (fullintervalcount < vm_pageout_full_stats_interval) { 1292 tpcount = (int64_t)vm_pageout_stats_max * cnt.v_active_count / 1293 cnt.v_page_count; 1294 if (pcount > tpcount) 1295 pcount = tpcount; 1296 } else { 1297 fullintervalcount = 0; 1298 } 1299 1300 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1301 while ((m != NULL) && (pcount-- > 0)) { 1302 int actcount; 1303 1304 KASSERT(VM_PAGE_INQUEUE2(m, PQ_ACTIVE), 1305 ("vm_pageout_page_stats: page %p isn't active", m)); 1306 1307 next = TAILQ_NEXT(m, pageq); 1308 object = m->object; 1309 1310 if ((m->flags & PG_MARKER) != 0) { 1311 m = next; 1312 continue; 1313 } 1314 if (!VM_OBJECT_TRYLOCK(object) && 1315 !vm_pageout_fallback_object_lock(m, &next)) { 1316 VM_OBJECT_UNLOCK(object); 1317 m = next; 1318 continue; 1319 } 1320 1321 /* 1322 * Don't deactivate pages that are busy. 1323 */ 1324 if ((m->busy != 0) || 1325 (m->oflags & VPO_BUSY) || 1326 (m->hold_count != 0)) { 1327 VM_OBJECT_UNLOCK(object); 1328 vm_page_requeue(m); 1329 m = next; 1330 continue; 1331 } 1332 1333 actcount = 0; 1334 if (m->flags & PG_REFERENCED) { 1335 vm_page_flag_clear(m, PG_REFERENCED); 1336 actcount += 1; 1337 } 1338 1339 actcount += pmap_ts_referenced(m); 1340 if (actcount) { 1341 m->act_count += ACT_ADVANCE + actcount; 1342 if (m->act_count > ACT_MAX) 1343 m->act_count = ACT_MAX; 1344 vm_page_requeue(m); 1345 } else { 1346 if (m->act_count == 0) { 1347 /* 1348 * We turn off page access, so that we have 1349 * more accurate RSS stats. We don't do this 1350 * in the normal page deactivation when the 1351 * system is loaded VM wise, because the 1352 * cost of the large number of page protect 1353 * operations would be higher than the value 1354 * of doing the operation. 1355 */ 1356 pmap_remove_all(m); 1357 vm_page_deactivate(m); 1358 } else { 1359 m->act_count -= min(m->act_count, ACT_DECLINE); 1360 vm_page_requeue(m); 1361 } 1362 } 1363 VM_OBJECT_UNLOCK(object); 1364 m = next; 1365 } 1366 } 1367 1368 /* 1369 * vm_pageout is the high level pageout daemon. 1370 */ 1371 static void 1372 vm_pageout() 1373 { 1374 int error, pass; 1375 1376 /* 1377 * Initialize some paging parameters. 1378 */ 1379 cnt.v_interrupt_free_min = 2; 1380 if (cnt.v_page_count < 2000) 1381 vm_pageout_page_count = 8; 1382 1383 /* 1384 * v_free_reserved needs to include enough for the largest 1385 * swap pager structures plus enough for any pv_entry structs 1386 * when paging. 1387 */ 1388 if (cnt.v_page_count > 1024) 1389 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1390 else 1391 cnt.v_free_min = 4; 1392 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1393 cnt.v_interrupt_free_min; 1394 cnt.v_free_reserved = vm_pageout_page_count + 1395 cnt.v_pageout_free_min + (cnt.v_page_count / 768); 1396 cnt.v_free_severe = cnt.v_free_min / 2; 1397 cnt.v_free_min += cnt.v_free_reserved; 1398 cnt.v_free_severe += cnt.v_free_reserved; 1399 1400 /* 1401 * v_free_target and v_cache_min control pageout hysteresis. Note 1402 * that these are more a measure of the VM cache queue hysteresis 1403 * then the VM free queue. Specifically, v_free_target is the 1404 * high water mark (free+cache pages). 1405 * 1406 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1407 * low water mark, while v_free_min is the stop. v_cache_min must 1408 * be big enough to handle memory needs while the pageout daemon 1409 * is signalled and run to free more pages. 1410 */ 1411 if (cnt.v_free_count > 6144) 1412 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1413 else 1414 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1415 1416 if (cnt.v_free_count > 2048) { 1417 cnt.v_cache_min = cnt.v_free_target; 1418 cnt.v_cache_max = 2 * cnt.v_cache_min; 1419 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1420 } else { 1421 cnt.v_cache_min = 0; 1422 cnt.v_cache_max = 0; 1423 cnt.v_inactive_target = cnt.v_free_count / 4; 1424 } 1425 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1426 cnt.v_inactive_target = cnt.v_free_count / 3; 1427 1428 /* XXX does not really belong here */ 1429 if (vm_page_max_wired == 0) 1430 vm_page_max_wired = cnt.v_free_count / 3; 1431 1432 if (vm_pageout_stats_max == 0) 1433 vm_pageout_stats_max = cnt.v_free_target; 1434 1435 /* 1436 * Set interval in seconds for stats scan. 1437 */ 1438 if (vm_pageout_stats_interval == 0) 1439 vm_pageout_stats_interval = 5; 1440 if (vm_pageout_full_stats_interval == 0) 1441 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1442 1443 swap_pager_swap_init(); 1444 pass = 0; 1445 /* 1446 * The pageout daemon is never done, so loop forever. 1447 */ 1448 while (TRUE) { 1449 /* 1450 * If we have enough free memory, wakeup waiters. Do 1451 * not clear vm_pages_needed until we reach our target, 1452 * otherwise we may be woken up over and over again and 1453 * waste a lot of cpu. 1454 */ 1455 mtx_lock(&vm_page_queue_free_mtx); 1456 if (vm_pages_needed && !vm_page_count_min()) { 1457 if (!vm_paging_needed()) 1458 vm_pages_needed = 0; 1459 wakeup(&cnt.v_free_count); 1460 } 1461 if (vm_pages_needed) { 1462 /* 1463 * Still not done, take a second pass without waiting 1464 * (unlimited dirty cleaning), otherwise sleep a bit 1465 * and try again. 1466 */ 1467 ++pass; 1468 if (pass > 1) 1469 msleep(&vm_pages_needed, 1470 &vm_page_queue_free_mtx, PVM, "psleep", 1471 hz / 2); 1472 } else { 1473 /* 1474 * Good enough, sleep & handle stats. Prime the pass 1475 * for the next run. 1476 */ 1477 if (pass > 1) 1478 pass = 1; 1479 else 1480 pass = 0; 1481 error = msleep(&vm_pages_needed, 1482 &vm_page_queue_free_mtx, PVM, "psleep", 1483 vm_pageout_stats_interval * hz); 1484 if (error && !vm_pages_needed) { 1485 mtx_unlock(&vm_page_queue_free_mtx); 1486 pass = 0; 1487 vm_page_lock_queues(); 1488 vm_pageout_page_stats(); 1489 vm_page_unlock_queues(); 1490 continue; 1491 } 1492 } 1493 if (vm_pages_needed) 1494 cnt.v_pdwakeups++; 1495 mtx_unlock(&vm_page_queue_free_mtx); 1496 vm_pageout_scan(pass); 1497 } 1498 } 1499 1500 /* 1501 * Unless the free page queue lock is held by the caller, this function 1502 * should be regarded as advisory. Specifically, the caller should 1503 * not msleep() on &cnt.v_free_count following this function unless 1504 * the free page queue lock is held until the msleep() is performed. 1505 */ 1506 void 1507 pagedaemon_wakeup() 1508 { 1509 1510 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1511 vm_pages_needed = 1; 1512 wakeup(&vm_pages_needed); 1513 } 1514 } 1515 1516 #if !defined(NO_SWAPPING) 1517 static void 1518 vm_req_vmdaemon(int req) 1519 { 1520 static int lastrun = 0; 1521 1522 mtx_lock(&vm_daemon_mtx); 1523 vm_pageout_req_swapout |= req; 1524 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1525 wakeup(&vm_daemon_needed); 1526 lastrun = ticks; 1527 } 1528 mtx_unlock(&vm_daemon_mtx); 1529 } 1530 1531 static void 1532 vm_daemon() 1533 { 1534 struct rlimit rsslim; 1535 struct proc *p; 1536 struct thread *td; 1537 int breakout, swapout_flags; 1538 1539 while (TRUE) { 1540 mtx_lock(&vm_daemon_mtx); 1541 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0); 1542 swapout_flags = vm_pageout_req_swapout; 1543 vm_pageout_req_swapout = 0; 1544 mtx_unlock(&vm_daemon_mtx); 1545 if (swapout_flags) 1546 swapout_procs(swapout_flags); 1547 1548 /* 1549 * scan the processes for exceeding their rlimits or if 1550 * process is swapped out -- deactivate pages 1551 */ 1552 sx_slock(&allproc_lock); 1553 FOREACH_PROC_IN_SYSTEM(p) { 1554 vm_pindex_t limit, size; 1555 1556 /* 1557 * if this is a system process or if we have already 1558 * looked at this process, skip it. 1559 */ 1560 PROC_LOCK(p); 1561 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 1562 PROC_UNLOCK(p); 1563 continue; 1564 } 1565 /* 1566 * if the process is in a non-running type state, 1567 * don't touch it. 1568 */ 1569 breakout = 0; 1570 FOREACH_THREAD_IN_PROC(p, td) { 1571 thread_lock(td); 1572 if (!TD_ON_RUNQ(td) && 1573 !TD_IS_RUNNING(td) && 1574 !TD_IS_SLEEPING(td)) { 1575 thread_unlock(td); 1576 breakout = 1; 1577 break; 1578 } 1579 thread_unlock(td); 1580 } 1581 if (breakout) { 1582 PROC_UNLOCK(p); 1583 continue; 1584 } 1585 /* 1586 * get a limit 1587 */ 1588 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1589 limit = OFF_TO_IDX( 1590 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1591 1592 /* 1593 * let processes that are swapped out really be 1594 * swapped out set the limit to nothing (will force a 1595 * swap-out.) 1596 */ 1597 if ((p->p_flag & P_INMEM) == 0) 1598 limit = 0; /* XXX */ 1599 PROC_UNLOCK(p); 1600 1601 size = vmspace_resident_count(p->p_vmspace); 1602 if (limit >= 0 && size >= limit) { 1603 vm_pageout_map_deactivate_pages( 1604 &p->p_vmspace->vm_map, limit); 1605 } 1606 } 1607 sx_sunlock(&allproc_lock); 1608 } 1609 } 1610 #endif /* !defined(NO_SWAPPING) */ 1611