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 /* 109 * System initialization 110 */ 111 112 /* the kernel process "vm_pageout"*/ 113 static void vm_pageout(void); 114 static int vm_pageout_clean(vm_page_t); 115 static void vm_pageout_scan(int pass); 116 117 struct proc *pageproc; 118 119 static struct kproc_desc page_kp = { 120 "pagedaemon", 121 vm_pageout, 122 &pageproc 123 }; 124 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, 125 &page_kp); 126 127 #if !defined(NO_SWAPPING) 128 /* the kernel process "vm_daemon"*/ 129 static void vm_daemon(void); 130 static struct proc *vmproc; 131 132 static struct kproc_desc vm_kp = { 133 "vmdaemon", 134 vm_daemon, 135 &vmproc 136 }; 137 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp); 138 #endif 139 140 141 int vm_pages_needed; /* Event on which pageout daemon sleeps */ 142 int vm_pageout_deficit; /* Estimated number of pages deficit */ 143 int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 144 145 #if !defined(NO_SWAPPING) 146 static int vm_pageout_req_swapout; /* XXX */ 147 static int vm_daemon_needed; 148 static struct mtx vm_daemon_mtx; 149 /* Allow for use by vm_pageout before vm_daemon is initialized. */ 150 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); 151 #endif 152 static int vm_max_launder = 32; 153 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 154 static int vm_pageout_full_stats_interval = 0; 155 static int vm_pageout_algorithm=0; 156 static int defer_swap_pageouts=0; 157 static int disable_swap_pageouts=0; 158 159 #if defined(NO_SWAPPING) 160 static int vm_swap_enabled=0; 161 static int vm_swap_idle_enabled=0; 162 #else 163 static int vm_swap_enabled=1; 164 static int vm_swap_idle_enabled=0; 165 #endif 166 167 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 168 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 169 170 SYSCTL_INT(_vm, OID_AUTO, max_launder, 171 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 172 173 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 174 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 175 176 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 177 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 178 179 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 180 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 181 182 #if defined(NO_SWAPPING) 183 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 184 CTLFLAG_RD, &vm_swap_enabled, 0, "Enable entire process swapout"); 185 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 186 CTLFLAG_RD, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 187 #else 188 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 189 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 190 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 191 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 192 #endif 193 194 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 195 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 196 197 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 198 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 199 200 static int pageout_lock_miss; 201 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 202 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 203 204 #define VM_PAGEOUT_PAGE_COUNT 16 205 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 206 207 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 208 SYSCTL_INT(_vm, OID_AUTO, max_wired, 209 CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count"); 210 211 #if !defined(NO_SWAPPING) 212 static void vm_pageout_map_deactivate_pages(vm_map_t, long); 213 static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long); 214 static void vm_req_vmdaemon(int req); 215 #endif 216 static void vm_pageout_page_stats(void); 217 218 /* 219 * vm_pageout_fallback_object_lock: 220 * 221 * Lock vm object currently associated with `m'. VM_OBJECT_TRYLOCK is 222 * known to have failed and page queue must be either PQ_ACTIVE or 223 * PQ_INACTIVE. To avoid lock order violation, unlock the page queues 224 * while locking the vm object. Use marker page to detect page queue 225 * changes and maintain notion of next page on page queue. Return 226 * TRUE if no changes were detected, FALSE otherwise. vm object is 227 * locked on return. 228 * 229 * This function depends on both the lock portion of struct vm_object 230 * and normal struct vm_page being type stable. 231 */ 232 boolean_t 233 vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next) 234 { 235 struct vm_page marker; 236 boolean_t unchanged; 237 u_short queue; 238 vm_object_t object; 239 240 /* 241 * Initialize our marker 242 */ 243 bzero(&marker, sizeof(marker)); 244 marker.flags = PG_FICTITIOUS | PG_MARKER; 245 marker.oflags = VPO_BUSY; 246 marker.queue = m->queue; 247 marker.wire_count = 1; 248 249 queue = m->queue; 250 object = m->object; 251 252 TAILQ_INSERT_AFTER(&vm_page_queues[queue].pl, 253 m, &marker, pageq); 254 vm_page_unlock_queues(); 255 VM_OBJECT_LOCK(object); 256 vm_page_lock_queues(); 257 258 /* Page queue might have changed. */ 259 *next = TAILQ_NEXT(&marker, pageq); 260 unchanged = (m->queue == queue && 261 m->object == object && 262 &marker == TAILQ_NEXT(m, pageq)); 263 TAILQ_REMOVE(&vm_page_queues[queue].pl, 264 &marker, pageq); 265 return (unchanged); 266 } 267 268 /* 269 * vm_pageout_clean: 270 * 271 * Clean the page and remove it from the laundry. 272 * 273 * We set the busy bit to cause potential page faults on this page to 274 * block. Note the careful timing, however, the busy bit isn't set till 275 * late and we cannot do anything that will mess with the page. 276 */ 277 static int 278 vm_pageout_clean(m) 279 vm_page_t m; 280 { 281 vm_object_t object; 282 vm_page_t mc[2*vm_pageout_page_count]; 283 int pageout_count; 284 int ib, is, page_base; 285 vm_pindex_t pindex = m->pindex; 286 287 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 288 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 289 290 /* 291 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 292 * with the new swapper, but we could have serious problems paging 293 * out other object types if there is insufficient memory. 294 * 295 * Unfortunately, checking free memory here is far too late, so the 296 * check has been moved up a procedural level. 297 */ 298 299 /* 300 * Can't clean the page if it's busy or held. 301 */ 302 if ((m->hold_count != 0) || 303 ((m->busy != 0) || (m->oflags & VPO_BUSY))) { 304 return 0; 305 } 306 307 mc[vm_pageout_page_count] = m; 308 pageout_count = 1; 309 page_base = vm_pageout_page_count; 310 ib = 1; 311 is = 1; 312 313 /* 314 * Scan object for clusterable pages. 315 * 316 * We can cluster ONLY if: ->> the page is NOT 317 * clean, wired, busy, held, or mapped into a 318 * buffer, and one of the following: 319 * 1) The page is inactive, or a seldom used 320 * active page. 321 * -or- 322 * 2) we force the issue. 323 * 324 * During heavy mmap/modification loads the pageout 325 * daemon can really fragment the underlying file 326 * due to flushing pages out of order and not trying 327 * align the clusters (which leave sporatic out-of-order 328 * holes). To solve this problem we do the reverse scan 329 * first and attempt to align our cluster, then do a 330 * forward scan if room remains. 331 */ 332 object = m->object; 333 more: 334 while (ib && pageout_count < vm_pageout_page_count) { 335 vm_page_t p; 336 337 if (ib > pindex) { 338 ib = 0; 339 break; 340 } 341 342 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) { 343 ib = 0; 344 break; 345 } 346 if ((p->oflags & VPO_BUSY) || p->busy) { 347 ib = 0; 348 break; 349 } 350 vm_page_test_dirty(p); 351 if (p->dirty == 0 || 352 p->queue != PQ_INACTIVE || 353 p->wire_count != 0 || /* may be held by buf cache */ 354 p->hold_count != 0) { /* may be undergoing I/O */ 355 ib = 0; 356 break; 357 } 358 mc[--page_base] = p; 359 ++pageout_count; 360 ++ib; 361 /* 362 * alignment boundry, stop here and switch directions. Do 363 * not clear ib. 364 */ 365 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 366 break; 367 } 368 369 while (pageout_count < vm_pageout_page_count && 370 pindex + is < object->size) { 371 vm_page_t p; 372 373 if ((p = vm_page_lookup(object, pindex + is)) == NULL) 374 break; 375 if ((p->oflags & VPO_BUSY) || p->busy) { 376 break; 377 } 378 vm_page_test_dirty(p); 379 if (p->dirty == 0 || 380 p->queue != PQ_INACTIVE || 381 p->wire_count != 0 || /* may be held by buf cache */ 382 p->hold_count != 0) { /* may be undergoing I/O */ 383 break; 384 } 385 mc[page_base + pageout_count] = p; 386 ++pageout_count; 387 ++is; 388 } 389 390 /* 391 * If we exhausted our forward scan, continue with the reverse scan 392 * when possible, even past a page boundry. This catches boundry 393 * conditions. 394 */ 395 if (ib && pageout_count < vm_pageout_page_count) 396 goto more; 397 398 /* 399 * we allow reads during pageouts... 400 */ 401 return (vm_pageout_flush(&mc[page_base], pageout_count, 0)); 402 } 403 404 /* 405 * vm_pageout_flush() - launder the given pages 406 * 407 * The given pages are laundered. Note that we setup for the start of 408 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 409 * reference count all in here rather then in the parent. If we want 410 * the parent to do more sophisticated things we may have to change 411 * the ordering. 412 */ 413 int 414 vm_pageout_flush(vm_page_t *mc, int count, int flags) 415 { 416 vm_object_t object = mc[0]->object; 417 int pageout_status[count]; 418 int numpagedout = 0; 419 int i; 420 421 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 422 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 423 /* 424 * Initiate I/O. Bump the vm_page_t->busy counter and 425 * mark the pages read-only. 426 * 427 * We do not have to fixup the clean/dirty bits here... we can 428 * allow the pager to do it after the I/O completes. 429 * 430 * NOTE! mc[i]->dirty may be partial or fragmented due to an 431 * edge case with file fragments. 432 */ 433 for (i = 0; i < count; i++) { 434 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 435 ("vm_pageout_flush: partially invalid page %p index %d/%d", 436 mc[i], i, count)); 437 vm_page_io_start(mc[i]); 438 pmap_remove_write(mc[i]); 439 } 440 vm_page_unlock_queues(); 441 vm_object_pip_add(object, count); 442 443 vm_pager_put_pages(object, mc, count, flags, pageout_status); 444 445 vm_page_lock_queues(); 446 for (i = 0; i < count; i++) { 447 vm_page_t mt = mc[i]; 448 449 KASSERT(pageout_status[i] == VM_PAGER_PEND || 450 (mt->flags & PG_WRITEABLE) == 0, 451 ("vm_pageout_flush: page %p is not write protected", mt)); 452 switch (pageout_status[i]) { 453 case VM_PAGER_OK: 454 case VM_PAGER_PEND: 455 numpagedout++; 456 break; 457 case VM_PAGER_BAD: 458 /* 459 * Page outside of range of object. Right now we 460 * essentially lose the changes by pretending it 461 * worked. 462 */ 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 || 517 first_object->type == OBJT_SG || 518 first_object->type == OBJT_PHYS) 519 return; 520 for (object = first_object;; object = backing_object) { 521 if (pmap_resident_count(pmap) <= desired) 522 goto unlock_return; 523 if (object->paging_in_progress) 524 goto unlock_return; 525 526 remove_mode = 0; 527 if (object->shadow_count > 1) 528 remove_mode = 1; 529 /* 530 * scan the objects entire memory queue 531 */ 532 rcount = object->resident_page_count; 533 p = TAILQ_FIRST(&object->memq); 534 vm_page_lock_queues(); 535 while (p && (rcount-- > 0)) { 536 if (pmap_resident_count(pmap) <= desired) { 537 vm_page_unlock_queues(); 538 goto unlock_return; 539 } 540 next = TAILQ_NEXT(p, listq); 541 cnt.v_pdpages++; 542 if (p->wire_count != 0 || 543 p->hold_count != 0 || 544 p->busy != 0 || 545 (p->oflags & VPO_BUSY) || 546 (p->flags & PG_UNMANAGED) || 547 !pmap_page_exists_quick(pmap, p)) { 548 p = next; 549 continue; 550 } 551 actcount = pmap_ts_referenced(p); 552 if (actcount) { 553 vm_page_flag_set(p, PG_REFERENCED); 554 } else if (p->flags & PG_REFERENCED) { 555 actcount = 1; 556 } 557 if ((p->queue != PQ_ACTIVE) && 558 (p->flags & PG_REFERENCED)) { 559 vm_page_activate(p); 560 p->act_count += actcount; 561 vm_page_flag_clear(p, PG_REFERENCED); 562 } else if (p->queue == PQ_ACTIVE) { 563 if ((p->flags & PG_REFERENCED) == 0) { 564 p->act_count -= min(p->act_count, ACT_DECLINE); 565 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) { 566 pmap_remove_all(p); 567 vm_page_deactivate(p); 568 } else { 569 vm_page_requeue(p); 570 } 571 } else { 572 vm_page_activate(p); 573 vm_page_flag_clear(p, PG_REFERENCED); 574 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 575 p->act_count += ACT_ADVANCE; 576 vm_page_requeue(p); 577 } 578 } else if (p->queue == PQ_INACTIVE) { 579 pmap_remove_all(p); 580 } 581 p = next; 582 } 583 vm_page_unlock_queues(); 584 if ((backing_object = object->backing_object) == NULL) 585 goto unlock_return; 586 VM_OBJECT_LOCK(backing_object); 587 if (object != first_object) 588 VM_OBJECT_UNLOCK(object); 589 } 590 unlock_return: 591 if (object != first_object) 592 VM_OBJECT_UNLOCK(object); 593 } 594 595 /* 596 * deactivate some number of pages in a map, try to do it fairly, but 597 * that is really hard to do. 598 */ 599 static void 600 vm_pageout_map_deactivate_pages(map, desired) 601 vm_map_t map; 602 long desired; 603 { 604 vm_map_entry_t tmpe; 605 vm_object_t obj, bigobj; 606 int nothingwired; 607 608 if (!vm_map_trylock(map)) 609 return; 610 611 bigobj = NULL; 612 nothingwired = TRUE; 613 614 /* 615 * first, search out the biggest object, and try to free pages from 616 * that. 617 */ 618 tmpe = map->header.next; 619 while (tmpe != &map->header) { 620 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 621 obj = tmpe->object.vm_object; 622 if (obj != NULL && VM_OBJECT_TRYLOCK(obj)) { 623 if (obj->shadow_count <= 1 && 624 (bigobj == NULL || 625 bigobj->resident_page_count < obj->resident_page_count)) { 626 if (bigobj != NULL) 627 VM_OBJECT_UNLOCK(bigobj); 628 bigobj = obj; 629 } else 630 VM_OBJECT_UNLOCK(obj); 631 } 632 } 633 if (tmpe->wired_count > 0) 634 nothingwired = FALSE; 635 tmpe = tmpe->next; 636 } 637 638 if (bigobj != NULL) { 639 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); 640 VM_OBJECT_UNLOCK(bigobj); 641 } 642 /* 643 * Next, hunt around for other pages to deactivate. We actually 644 * do this search sort of wrong -- .text first is not the best idea. 645 */ 646 tmpe = map->header.next; 647 while (tmpe != &map->header) { 648 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 649 break; 650 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 651 obj = tmpe->object.vm_object; 652 if (obj != NULL) { 653 VM_OBJECT_LOCK(obj); 654 vm_pageout_object_deactivate_pages(map->pmap, obj, desired); 655 VM_OBJECT_UNLOCK(obj); 656 } 657 } 658 tmpe = tmpe->next; 659 } 660 661 /* 662 * Remove all mappings if a process is swapped out, this will free page 663 * table pages. 664 */ 665 if (desired == 0 && nothingwired) { 666 pmap_remove(vm_map_pmap(map), vm_map_min(map), 667 vm_map_max(map)); 668 } 669 vm_map_unlock(map); 670 } 671 #endif /* !defined(NO_SWAPPING) */ 672 673 /* 674 * vm_pageout_scan does the dirty work for the pageout daemon. 675 */ 676 static void 677 vm_pageout_scan(int pass) 678 { 679 vm_page_t m, next; 680 struct vm_page marker; 681 int page_shortage, maxscan, pcount; 682 int addl_page_shortage, addl_page_shortage_init; 683 vm_object_t object; 684 int actcount; 685 int vnodes_skipped = 0; 686 int maxlaunder; 687 688 /* 689 * Decrease registered cache sizes. 690 */ 691 EVENTHANDLER_INVOKE(vm_lowmem, 0); 692 /* 693 * We do this explicitly after the caches have been drained above. 694 */ 695 uma_reclaim(); 696 697 addl_page_shortage_init = atomic_readandclear_int(&vm_pageout_deficit); 698 699 /* 700 * Calculate the number of pages we want to either free or move 701 * to the cache. 702 */ 703 page_shortage = vm_paging_target() + addl_page_shortage_init; 704 705 /* 706 * Initialize our marker 707 */ 708 bzero(&marker, sizeof(marker)); 709 marker.flags = PG_FICTITIOUS | PG_MARKER; 710 marker.oflags = VPO_BUSY; 711 marker.queue = PQ_INACTIVE; 712 marker.wire_count = 1; 713 714 /* 715 * Start scanning the inactive queue for pages we can move to the 716 * cache or free. The scan will stop when the target is reached or 717 * we have scanned the entire inactive queue. Note that m->act_count 718 * is not used to form decisions for the inactive queue, only for the 719 * active queue. 720 * 721 * maxlaunder limits the number of dirty pages we flush per scan. 722 * For most systems a smaller value (16 or 32) is more robust under 723 * extreme memory and disk pressure because any unnecessary writes 724 * to disk can result in extreme performance degredation. However, 725 * systems with excessive dirty pages (especially when MAP_NOSYNC is 726 * used) will die horribly with limited laundering. If the pageout 727 * daemon cannot clean enough pages in the first pass, we let it go 728 * all out in succeeding passes. 729 */ 730 if ((maxlaunder = vm_max_launder) <= 1) 731 maxlaunder = 1; 732 if (pass) 733 maxlaunder = 10000; 734 vm_page_lock_queues(); 735 rescan0: 736 addl_page_shortage = addl_page_shortage_init; 737 maxscan = cnt.v_inactive_count; 738 739 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 740 m != NULL && maxscan-- > 0 && page_shortage > 0; 741 m = next) { 742 743 cnt.v_pdpages++; 744 745 if (VM_PAGE_GETQUEUE(m) != PQ_INACTIVE) { 746 goto rescan0; 747 } 748 749 next = TAILQ_NEXT(m, pageq); 750 object = m->object; 751 752 /* 753 * skip marker pages 754 */ 755 if (m->flags & PG_MARKER) 756 continue; 757 758 /* 759 * A held page may be undergoing I/O, so skip it. 760 */ 761 if (m->hold_count) { 762 vm_page_requeue(m); 763 addl_page_shortage++; 764 continue; 765 } 766 /* 767 * Don't mess with busy pages, keep in the front of the 768 * queue, most likely are being paged out. 769 */ 770 if (!VM_OBJECT_TRYLOCK(object) && 771 (!vm_pageout_fallback_object_lock(m, &next) || 772 m->hold_count != 0)) { 773 VM_OBJECT_UNLOCK(object); 774 addl_page_shortage++; 775 continue; 776 } 777 if (m->busy || (m->oflags & VPO_BUSY)) { 778 VM_OBJECT_UNLOCK(object); 779 addl_page_shortage++; 780 continue; 781 } 782 783 /* 784 * If the object is not being used, we ignore previous 785 * references. 786 */ 787 if (object->ref_count == 0) { 788 vm_page_flag_clear(m, PG_REFERENCED); 789 KASSERT(!pmap_page_is_mapped(m), 790 ("vm_pageout_scan: page %p is mapped", 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 does not believe that the page 826 * is fully dirty, but it is mapped for write access, then we 827 * consult the pmap to see if the page's dirty status should 828 * be updated. 829 */ 830 if (m->dirty != VM_PAGE_BITS_ALL && 831 (m->flags & PG_WRITEABLE) != 0) { 832 /* 833 * Avoid a race condition: Unless write access is 834 * removed from the page, another processor could 835 * modify it before all access is removed by the call 836 * to vm_page_cache() below. If vm_page_cache() finds 837 * that the page has been modified when it removes all 838 * access, it panics because it cannot cache dirty 839 * pages. In principle, we could eliminate just write 840 * access here rather than all access. In the expected 841 * case, when there are no last instant modifications 842 * to the page, removing all access will be cheaper 843 * overall. 844 */ 845 if (pmap_is_modified(m)) 846 vm_page_dirty(m); 847 else if (m->dirty == 0) 848 pmap_remove_all(m); 849 } 850 851 if (m->valid == 0) { 852 /* 853 * Invalid pages can be easily freed 854 */ 855 vm_page_free(m); 856 cnt.v_dfree++; 857 --page_shortage; 858 } else if (m->dirty == 0) { 859 /* 860 * Clean pages can be placed onto the cache queue. 861 * This effectively frees them. 862 */ 863 vm_page_cache(m); 864 --page_shortage; 865 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 866 /* 867 * Dirty pages need to be paged out, but flushing 868 * a page is extremely expensive verses freeing 869 * a clean page. Rather then artificially limiting 870 * the number of pages we can flush, we instead give 871 * dirty pages extra priority on the inactive queue 872 * by forcing them to be cycled through the queue 873 * twice before being flushed, after which the 874 * (now clean) page will cycle through once more 875 * before being freed. This significantly extends 876 * the thrash point for a heavily loaded machine. 877 */ 878 vm_page_flag_set(m, PG_WINATCFLS); 879 vm_page_requeue(m); 880 } else if (maxlaunder > 0) { 881 /* 882 * We always want to try to flush some dirty pages if 883 * we encounter them, to keep the system stable. 884 * Normally this number is small, but under extreme 885 * pressure where there are insufficient clean pages 886 * on the inactive queue, we may have to go all out. 887 */ 888 int swap_pageouts_ok, vfslocked = 0; 889 struct vnode *vp = NULL; 890 struct mount *mp = NULL; 891 892 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 893 swap_pageouts_ok = 1; 894 } else { 895 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 896 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 897 vm_page_count_min()); 898 899 } 900 901 /* 902 * We don't bother paging objects that are "dead". 903 * Those objects are in a "rundown" state. 904 */ 905 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 906 VM_OBJECT_UNLOCK(object); 907 vm_page_requeue(m); 908 continue; 909 } 910 911 /* 912 * Following operations may unlock 913 * vm_page_queue_mtx, invalidating the 'next' 914 * pointer. To prevent an inordinate number 915 * of restarts we use our marker to remember 916 * our place. 917 * 918 */ 919 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, 920 m, &marker, pageq); 921 /* 922 * The object is already known NOT to be dead. It 923 * is possible for the vget() to block the whole 924 * pageout daemon, but the new low-memory handling 925 * code should prevent it. 926 * 927 * The previous code skipped locked vnodes and, worse, 928 * reordered pages in the queue. This results in 929 * completely non-deterministic operation and, on a 930 * busy system, can lead to extremely non-optimal 931 * pageouts. For example, it can cause clean pages 932 * to be freed and dirty pages to be moved to the end 933 * of the queue. Since dirty pages are also moved to 934 * the end of the queue once-cleaned, this gives 935 * way too large a weighting to defering the freeing 936 * of dirty pages. 937 * 938 * We can't wait forever for the vnode lock, we might 939 * deadlock due to a vn_read() getting stuck in 940 * vm_wait while holding this vnode. We skip the 941 * vnode if we can't get it in a reasonable amount 942 * of time. 943 */ 944 if (object->type == OBJT_VNODE) { 945 vp = object->handle; 946 if (vp->v_type == VREG && 947 vn_start_write(vp, &mp, V_NOWAIT) != 0) { 948 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 struct vmspace *vm; 1189 1190 /* 1191 * We keep the process bigproc locked once we find it to keep anyone 1192 * from messing with it; however, there is a possibility of 1193 * deadlock if process B is bigproc and one of it's child processes 1194 * attempts to propagate a signal to B while we are waiting for A's 1195 * lock while walking this list. To avoid this, we don't block on 1196 * the process lock but just skip a process if it is already locked. 1197 */ 1198 bigproc = NULL; 1199 bigsize = 0; 1200 sx_slock(&allproc_lock); 1201 FOREACH_PROC_IN_SYSTEM(p) { 1202 int breakout; 1203 1204 if (PROC_TRYLOCK(p) == 0) 1205 continue; 1206 /* 1207 * If this is a system or protected process, skip it. 1208 */ 1209 if ((p->p_flag & (P_INEXEC | P_PROTECTED | P_SYSTEM)) || 1210 (p->p_pid == 1) || 1211 ((p->p_pid < 48) && (swap_pager_avail != 0))) { 1212 PROC_UNLOCK(p); 1213 continue; 1214 } 1215 /* 1216 * If the process is in a non-running type state, 1217 * don't touch it. Check all the threads individually. 1218 */ 1219 breakout = 0; 1220 FOREACH_THREAD_IN_PROC(p, td) { 1221 thread_lock(td); 1222 if (!TD_ON_RUNQ(td) && 1223 !TD_IS_RUNNING(td) && 1224 !TD_IS_SLEEPING(td)) { 1225 thread_unlock(td); 1226 breakout = 1; 1227 break; 1228 } 1229 thread_unlock(td); 1230 } 1231 if (breakout) { 1232 PROC_UNLOCK(p); 1233 continue; 1234 } 1235 /* 1236 * get the process size 1237 */ 1238 vm = vmspace_acquire_ref(p); 1239 if (vm == NULL) { 1240 PROC_UNLOCK(p); 1241 continue; 1242 } 1243 if (!vm_map_trylock_read(&vm->vm_map)) { 1244 vmspace_free(vm); 1245 PROC_UNLOCK(p); 1246 continue; 1247 } 1248 size = vmspace_swap_count(vm); 1249 vm_map_unlock_read(&vm->vm_map); 1250 if (shortage == VM_OOM_MEM) 1251 size += vmspace_resident_count(vm); 1252 vmspace_free(vm); 1253 /* 1254 * if the this process is bigger than the biggest one 1255 * remember it. 1256 */ 1257 if (size > bigsize) { 1258 if (bigproc != NULL) 1259 PROC_UNLOCK(bigproc); 1260 bigproc = p; 1261 bigsize = size; 1262 } else 1263 PROC_UNLOCK(p); 1264 } 1265 sx_sunlock(&allproc_lock); 1266 if (bigproc != NULL) { 1267 killproc(bigproc, "out of swap space"); 1268 sched_nice(bigproc, PRIO_MIN); 1269 PROC_UNLOCK(bigproc); 1270 wakeup(&cnt.v_free_count); 1271 } 1272 } 1273 1274 /* 1275 * This routine tries to maintain the pseudo LRU active queue, 1276 * so that during long periods of time where there is no paging, 1277 * that some statistic accumulation still occurs. This code 1278 * helps the situation where paging just starts to occur. 1279 */ 1280 static void 1281 vm_pageout_page_stats() 1282 { 1283 vm_object_t object; 1284 vm_page_t m,next; 1285 int pcount,tpcount; /* Number of pages to check */ 1286 static int fullintervalcount = 0; 1287 int page_shortage; 1288 1289 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1290 page_shortage = 1291 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1292 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1293 1294 if (page_shortage <= 0) 1295 return; 1296 1297 pcount = cnt.v_active_count; 1298 fullintervalcount += vm_pageout_stats_interval; 1299 if (fullintervalcount < vm_pageout_full_stats_interval) { 1300 tpcount = (int64_t)vm_pageout_stats_max * cnt.v_active_count / 1301 cnt.v_page_count; 1302 if (pcount > tpcount) 1303 pcount = tpcount; 1304 } else { 1305 fullintervalcount = 0; 1306 } 1307 1308 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1309 while ((m != NULL) && (pcount-- > 0)) { 1310 int actcount; 1311 1312 KASSERT(VM_PAGE_INQUEUE2(m, PQ_ACTIVE), 1313 ("vm_pageout_page_stats: page %p isn't active", m)); 1314 1315 next = TAILQ_NEXT(m, pageq); 1316 object = m->object; 1317 1318 if ((m->flags & PG_MARKER) != 0) { 1319 m = next; 1320 continue; 1321 } 1322 if (!VM_OBJECT_TRYLOCK(object) && 1323 !vm_pageout_fallback_object_lock(m, &next)) { 1324 VM_OBJECT_UNLOCK(object); 1325 m = next; 1326 continue; 1327 } 1328 1329 /* 1330 * Don't deactivate pages that are busy. 1331 */ 1332 if ((m->busy != 0) || 1333 (m->oflags & VPO_BUSY) || 1334 (m->hold_count != 0)) { 1335 VM_OBJECT_UNLOCK(object); 1336 vm_page_requeue(m); 1337 m = next; 1338 continue; 1339 } 1340 1341 actcount = 0; 1342 if (m->flags & PG_REFERENCED) { 1343 vm_page_flag_clear(m, PG_REFERENCED); 1344 actcount += 1; 1345 } 1346 1347 actcount += pmap_ts_referenced(m); 1348 if (actcount) { 1349 m->act_count += ACT_ADVANCE + actcount; 1350 if (m->act_count > ACT_MAX) 1351 m->act_count = ACT_MAX; 1352 vm_page_requeue(m); 1353 } else { 1354 if (m->act_count == 0) { 1355 /* 1356 * We turn off page access, so that we have 1357 * more accurate RSS stats. We don't do this 1358 * in the normal page deactivation when the 1359 * system is loaded VM wise, because the 1360 * cost of the large number of page protect 1361 * operations would be higher than the value 1362 * of doing the operation. 1363 */ 1364 pmap_remove_all(m); 1365 vm_page_deactivate(m); 1366 } else { 1367 m->act_count -= min(m->act_count, ACT_DECLINE); 1368 vm_page_requeue(m); 1369 } 1370 } 1371 VM_OBJECT_UNLOCK(object); 1372 m = next; 1373 } 1374 } 1375 1376 /* 1377 * vm_pageout is the high level pageout daemon. 1378 */ 1379 static void 1380 vm_pageout() 1381 { 1382 int error, pass; 1383 1384 /* 1385 * Initialize some paging parameters. 1386 */ 1387 cnt.v_interrupt_free_min = 2; 1388 if (cnt.v_page_count < 2000) 1389 vm_pageout_page_count = 8; 1390 1391 /* 1392 * v_free_reserved needs to include enough for the largest 1393 * swap pager structures plus enough for any pv_entry structs 1394 * when paging. 1395 */ 1396 if (cnt.v_page_count > 1024) 1397 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1398 else 1399 cnt.v_free_min = 4; 1400 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1401 cnt.v_interrupt_free_min; 1402 cnt.v_free_reserved = vm_pageout_page_count + 1403 cnt.v_pageout_free_min + (cnt.v_page_count / 768); 1404 cnt.v_free_severe = cnt.v_free_min / 2; 1405 cnt.v_free_min += cnt.v_free_reserved; 1406 cnt.v_free_severe += cnt.v_free_reserved; 1407 1408 /* 1409 * v_free_target and v_cache_min control pageout hysteresis. Note 1410 * that these are more a measure of the VM cache queue hysteresis 1411 * then the VM free queue. Specifically, v_free_target is the 1412 * high water mark (free+cache pages). 1413 * 1414 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1415 * low water mark, while v_free_min is the stop. v_cache_min must 1416 * be big enough to handle memory needs while the pageout daemon 1417 * is signalled and run to free more pages. 1418 */ 1419 if (cnt.v_free_count > 6144) 1420 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1421 else 1422 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1423 1424 if (cnt.v_free_count > 2048) { 1425 cnt.v_cache_min = cnt.v_free_target; 1426 cnt.v_cache_max = 2 * cnt.v_cache_min; 1427 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1428 } else { 1429 cnt.v_cache_min = 0; 1430 cnt.v_cache_max = 0; 1431 cnt.v_inactive_target = cnt.v_free_count / 4; 1432 } 1433 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1434 cnt.v_inactive_target = cnt.v_free_count / 3; 1435 1436 /* XXX does not really belong here */ 1437 if (vm_page_max_wired == 0) 1438 vm_page_max_wired = cnt.v_free_count / 3; 1439 1440 if (vm_pageout_stats_max == 0) 1441 vm_pageout_stats_max = cnt.v_free_target; 1442 1443 /* 1444 * Set interval in seconds for stats scan. 1445 */ 1446 if (vm_pageout_stats_interval == 0) 1447 vm_pageout_stats_interval = 5; 1448 if (vm_pageout_full_stats_interval == 0) 1449 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1450 1451 swap_pager_swap_init(); 1452 pass = 0; 1453 /* 1454 * The pageout daemon is never done, so loop forever. 1455 */ 1456 while (TRUE) { 1457 /* 1458 * If we have enough free memory, wakeup waiters. Do 1459 * not clear vm_pages_needed until we reach our target, 1460 * otherwise we may be woken up over and over again and 1461 * waste a lot of cpu. 1462 */ 1463 mtx_lock(&vm_page_queue_free_mtx); 1464 if (vm_pages_needed && !vm_page_count_min()) { 1465 if (!vm_paging_needed()) 1466 vm_pages_needed = 0; 1467 wakeup(&cnt.v_free_count); 1468 } 1469 if (vm_pages_needed) { 1470 /* 1471 * Still not done, take a second pass without waiting 1472 * (unlimited dirty cleaning), otherwise sleep a bit 1473 * and try again. 1474 */ 1475 ++pass; 1476 if (pass > 1) 1477 msleep(&vm_pages_needed, 1478 &vm_page_queue_free_mtx, PVM, "psleep", 1479 hz / 2); 1480 } else { 1481 /* 1482 * Good enough, sleep & handle stats. Prime the pass 1483 * for the next run. 1484 */ 1485 if (pass > 1) 1486 pass = 1; 1487 else 1488 pass = 0; 1489 error = msleep(&vm_pages_needed, 1490 &vm_page_queue_free_mtx, PVM, "psleep", 1491 vm_pageout_stats_interval * hz); 1492 if (error && !vm_pages_needed) { 1493 mtx_unlock(&vm_page_queue_free_mtx); 1494 pass = 0; 1495 vm_page_lock_queues(); 1496 vm_pageout_page_stats(); 1497 vm_page_unlock_queues(); 1498 continue; 1499 } 1500 } 1501 if (vm_pages_needed) 1502 cnt.v_pdwakeups++; 1503 mtx_unlock(&vm_page_queue_free_mtx); 1504 vm_pageout_scan(pass); 1505 } 1506 } 1507 1508 /* 1509 * Unless the free page queue lock is held by the caller, this function 1510 * should be regarded as advisory. Specifically, the caller should 1511 * not msleep() on &cnt.v_free_count following this function unless 1512 * the free page queue lock is held until the msleep() is performed. 1513 */ 1514 void 1515 pagedaemon_wakeup() 1516 { 1517 1518 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1519 vm_pages_needed = 1; 1520 wakeup(&vm_pages_needed); 1521 } 1522 } 1523 1524 #if !defined(NO_SWAPPING) 1525 static void 1526 vm_req_vmdaemon(int req) 1527 { 1528 static int lastrun = 0; 1529 1530 mtx_lock(&vm_daemon_mtx); 1531 vm_pageout_req_swapout |= req; 1532 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1533 wakeup(&vm_daemon_needed); 1534 lastrun = ticks; 1535 } 1536 mtx_unlock(&vm_daemon_mtx); 1537 } 1538 1539 static void 1540 vm_daemon() 1541 { 1542 struct rlimit rsslim; 1543 struct proc *p; 1544 struct thread *td; 1545 struct vmspace *vm; 1546 int breakout, swapout_flags; 1547 1548 while (TRUE) { 1549 mtx_lock(&vm_daemon_mtx); 1550 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0); 1551 swapout_flags = vm_pageout_req_swapout; 1552 vm_pageout_req_swapout = 0; 1553 mtx_unlock(&vm_daemon_mtx); 1554 if (swapout_flags) 1555 swapout_procs(swapout_flags); 1556 1557 /* 1558 * scan the processes for exceeding their rlimits or if 1559 * process is swapped out -- deactivate pages 1560 */ 1561 sx_slock(&allproc_lock); 1562 FOREACH_PROC_IN_SYSTEM(p) { 1563 vm_pindex_t limit, size; 1564 1565 /* 1566 * if this is a system process or if we have already 1567 * looked at this process, skip it. 1568 */ 1569 PROC_LOCK(p); 1570 if (p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 1571 PROC_UNLOCK(p); 1572 continue; 1573 } 1574 /* 1575 * if the process is in a non-running type state, 1576 * don't touch it. 1577 */ 1578 breakout = 0; 1579 FOREACH_THREAD_IN_PROC(p, td) { 1580 thread_lock(td); 1581 if (!TD_ON_RUNQ(td) && 1582 !TD_IS_RUNNING(td) && 1583 !TD_IS_SLEEPING(td)) { 1584 thread_unlock(td); 1585 breakout = 1; 1586 break; 1587 } 1588 thread_unlock(td); 1589 } 1590 if (breakout) { 1591 PROC_UNLOCK(p); 1592 continue; 1593 } 1594 /* 1595 * get a limit 1596 */ 1597 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1598 limit = OFF_TO_IDX( 1599 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1600 1601 /* 1602 * let processes that are swapped out really be 1603 * swapped out set the limit to nothing (will force a 1604 * swap-out.) 1605 */ 1606 if ((p->p_flag & P_INMEM) == 0) 1607 limit = 0; /* XXX */ 1608 vm = vmspace_acquire_ref(p); 1609 PROC_UNLOCK(p); 1610 if (vm == NULL) 1611 continue; 1612 1613 size = vmspace_resident_count(vm); 1614 if (limit >= 0 && size >= limit) { 1615 vm_pageout_map_deactivate_pages( 1616 &vm->vm_map, limit); 1617 } 1618 vmspace_free(vm); 1619 } 1620 sx_sunlock(&allproc_lock); 1621 } 1622 } 1623 #endif /* !defined(NO_SWAPPING) */ 1624