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 KASSERT(mp != NULL, 955 ("vp %p with NULL v_mount", vp)); 956 vm_page_unlock_queues(); 957 vm_object_reference_locked(object); 958 VM_OBJECT_UNLOCK(object); 959 vfslocked = VFS_LOCK_GIANT(vp->v_mount); 960 if (vget(vp, LK_EXCLUSIVE | LK_TIMELOCK, 961 curthread)) { 962 VM_OBJECT_LOCK(object); 963 vm_page_lock_queues(); 964 ++pageout_lock_miss; 965 if (object->flags & OBJ_MIGHTBEDIRTY) 966 vnodes_skipped++; 967 vp = NULL; 968 goto unlock_and_continue; 969 } 970 VM_OBJECT_LOCK(object); 971 vm_page_lock_queues(); 972 /* 973 * The page might have been moved to another 974 * queue during potential blocking in vget() 975 * above. The page might have been freed and 976 * reused for another vnode. 977 */ 978 if (VM_PAGE_GETQUEUE(m) != PQ_INACTIVE || 979 m->object != object || 980 TAILQ_NEXT(m, pageq) != &marker) { 981 if (object->flags & OBJ_MIGHTBEDIRTY) 982 vnodes_skipped++; 983 goto unlock_and_continue; 984 } 985 986 /* 987 * The page may have been busied during the 988 * blocking in vget(). We don't move the 989 * page back onto the end of the queue so that 990 * statistics are more correct if we don't. 991 */ 992 if (m->busy || (m->oflags & VPO_BUSY)) { 993 goto unlock_and_continue; 994 } 995 996 /* 997 * If the page has become held it might 998 * be undergoing I/O, so skip it 999 */ 1000 if (m->hold_count) { 1001 vm_page_requeue(m); 1002 if (object->flags & OBJ_MIGHTBEDIRTY) 1003 vnodes_skipped++; 1004 goto unlock_and_continue; 1005 } 1006 } 1007 1008 /* 1009 * If a page is dirty, then it is either being washed 1010 * (but not yet cleaned) or it is still in the 1011 * laundry. If it is still in the laundry, then we 1012 * start the cleaning operation. 1013 * 1014 * decrement page_shortage on success to account for 1015 * the (future) cleaned page. Otherwise we could wind 1016 * up laundering or cleaning too many pages. 1017 */ 1018 if (vm_pageout_clean(m) != 0) { 1019 --page_shortage; 1020 --maxlaunder; 1021 } 1022 unlock_and_continue: 1023 VM_OBJECT_UNLOCK(object); 1024 if (mp != NULL) { 1025 vm_page_unlock_queues(); 1026 if (vp != NULL) 1027 vput(vp); 1028 VFS_UNLOCK_GIANT(vfslocked); 1029 vm_object_deallocate(object); 1030 vn_finished_write(mp); 1031 vm_page_lock_queues(); 1032 } 1033 next = TAILQ_NEXT(&marker, pageq); 1034 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, 1035 &marker, pageq); 1036 continue; 1037 } 1038 VM_OBJECT_UNLOCK(object); 1039 } 1040 1041 /* 1042 * Compute the number of pages we want to try to move from the 1043 * active queue to the inactive queue. 1044 */ 1045 page_shortage = vm_paging_target() + 1046 cnt.v_inactive_target - cnt.v_inactive_count; 1047 page_shortage += addl_page_shortage; 1048 1049 /* 1050 * Scan the active queue for things we can deactivate. We nominally 1051 * track the per-page activity counter and use it to locate 1052 * deactivation candidates. 1053 */ 1054 pcount = cnt.v_active_count; 1055 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1056 1057 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 1058 1059 KASSERT(VM_PAGE_INQUEUE2(m, PQ_ACTIVE), 1060 ("vm_pageout_scan: page %p isn't active", m)); 1061 1062 next = TAILQ_NEXT(m, pageq); 1063 object = m->object; 1064 if ((m->flags & PG_MARKER) != 0) { 1065 m = next; 1066 continue; 1067 } 1068 if (!VM_OBJECT_TRYLOCK(object) && 1069 !vm_pageout_fallback_object_lock(m, &next)) { 1070 VM_OBJECT_UNLOCK(object); 1071 m = next; 1072 continue; 1073 } 1074 1075 /* 1076 * Don't deactivate pages that are busy. 1077 */ 1078 if ((m->busy != 0) || 1079 (m->oflags & VPO_BUSY) || 1080 (m->hold_count != 0)) { 1081 VM_OBJECT_UNLOCK(object); 1082 vm_page_requeue(m); 1083 m = next; 1084 continue; 1085 } 1086 1087 /* 1088 * The count for pagedaemon pages is done after checking the 1089 * page for eligibility... 1090 */ 1091 cnt.v_pdpages++; 1092 1093 /* 1094 * Check to see "how much" the page has been used. 1095 */ 1096 actcount = 0; 1097 if (object->ref_count != 0) { 1098 if (m->flags & PG_REFERENCED) { 1099 actcount += 1; 1100 } 1101 actcount += pmap_ts_referenced(m); 1102 if (actcount) { 1103 m->act_count += ACT_ADVANCE + actcount; 1104 if (m->act_count > ACT_MAX) 1105 m->act_count = ACT_MAX; 1106 } 1107 } 1108 1109 /* 1110 * Since we have "tested" this bit, we need to clear it now. 1111 */ 1112 vm_page_flag_clear(m, PG_REFERENCED); 1113 1114 /* 1115 * Only if an object is currently being used, do we use the 1116 * page activation count stats. 1117 */ 1118 if (actcount && (object->ref_count != 0)) { 1119 vm_page_requeue(m); 1120 } else { 1121 m->act_count -= min(m->act_count, ACT_DECLINE); 1122 if (vm_pageout_algorithm || 1123 object->ref_count == 0 || 1124 m->act_count == 0) { 1125 page_shortage--; 1126 if (object->ref_count == 0) { 1127 pmap_remove_all(m); 1128 if (m->dirty == 0) 1129 vm_page_cache(m); 1130 else 1131 vm_page_deactivate(m); 1132 } else { 1133 vm_page_deactivate(m); 1134 } 1135 } else { 1136 vm_page_requeue(m); 1137 } 1138 } 1139 VM_OBJECT_UNLOCK(object); 1140 m = next; 1141 } 1142 vm_page_unlock_queues(); 1143 #if !defined(NO_SWAPPING) 1144 /* 1145 * Idle process swapout -- run once per second. 1146 */ 1147 if (vm_swap_idle_enabled) { 1148 static long lsec; 1149 if (time_second != lsec) { 1150 vm_req_vmdaemon(VM_SWAP_IDLE); 1151 lsec = time_second; 1152 } 1153 } 1154 #endif 1155 1156 /* 1157 * If we didn't get enough free pages, and we have skipped a vnode 1158 * in a writeable object, wakeup the sync daemon. And kick swapout 1159 * if we did not get enough free pages. 1160 */ 1161 if (vm_paging_target() > 0) { 1162 if (vnodes_skipped && vm_page_count_min()) 1163 (void) speedup_syncer(); 1164 #if !defined(NO_SWAPPING) 1165 if (vm_swap_enabled && vm_page_count_target()) 1166 vm_req_vmdaemon(VM_SWAP_NORMAL); 1167 #endif 1168 } 1169 1170 /* 1171 * If we are critically low on one of RAM or swap and low on 1172 * the other, kill the largest process. However, we avoid 1173 * doing this on the first pass in order to give ourselves a 1174 * chance to flush out dirty vnode-backed pages and to allow 1175 * active pages to be moved to the inactive queue and reclaimed. 1176 */ 1177 if (pass != 0 && 1178 ((swap_pager_avail < 64 && vm_page_count_min()) || 1179 (swap_pager_full && vm_paging_target() > 0))) 1180 vm_pageout_oom(VM_OOM_MEM); 1181 } 1182 1183 1184 void 1185 vm_pageout_oom(int shortage) 1186 { 1187 struct proc *p, *bigproc; 1188 vm_offset_t size, bigsize; 1189 struct thread *td; 1190 struct vmspace *vm; 1191 1192 /* 1193 * We keep the process bigproc locked once we find it to keep anyone 1194 * from messing with it; however, there is a possibility of 1195 * deadlock if process B is bigproc and one of it's child processes 1196 * attempts to propagate a signal to B while we are waiting for A's 1197 * lock while walking this list. To avoid this, we don't block on 1198 * the process lock but just skip a process if it is already locked. 1199 */ 1200 bigproc = NULL; 1201 bigsize = 0; 1202 sx_slock(&allproc_lock); 1203 FOREACH_PROC_IN_SYSTEM(p) { 1204 int breakout; 1205 1206 if (PROC_TRYLOCK(p) == 0) 1207 continue; 1208 /* 1209 * If this is a system or protected process, skip it. 1210 */ 1211 if ((p->p_flag & (P_INEXEC | P_PROTECTED | P_SYSTEM)) || 1212 (p->p_pid == 1) || 1213 ((p->p_pid < 48) && (swap_pager_avail != 0))) { 1214 PROC_UNLOCK(p); 1215 continue; 1216 } 1217 /* 1218 * If the process is in a non-running type state, 1219 * don't touch it. Check all the threads individually. 1220 */ 1221 breakout = 0; 1222 FOREACH_THREAD_IN_PROC(p, td) { 1223 thread_lock(td); 1224 if (!TD_ON_RUNQ(td) && 1225 !TD_IS_RUNNING(td) && 1226 !TD_IS_SLEEPING(td)) { 1227 thread_unlock(td); 1228 breakout = 1; 1229 break; 1230 } 1231 thread_unlock(td); 1232 } 1233 if (breakout) { 1234 PROC_UNLOCK(p); 1235 continue; 1236 } 1237 /* 1238 * get the process size 1239 */ 1240 vm = vmspace_acquire_ref(p); 1241 if (vm == NULL) { 1242 PROC_UNLOCK(p); 1243 continue; 1244 } 1245 if (!vm_map_trylock_read(&vm->vm_map)) { 1246 vmspace_free(vm); 1247 PROC_UNLOCK(p); 1248 continue; 1249 } 1250 size = vmspace_swap_count(vm); 1251 vm_map_unlock_read(&vm->vm_map); 1252 if (shortage == VM_OOM_MEM) 1253 size += vmspace_resident_count(vm); 1254 vmspace_free(vm); 1255 /* 1256 * if the this process is bigger than the biggest one 1257 * remember it. 1258 */ 1259 if (size > bigsize) { 1260 if (bigproc != NULL) 1261 PROC_UNLOCK(bigproc); 1262 bigproc = p; 1263 bigsize = size; 1264 } else 1265 PROC_UNLOCK(p); 1266 } 1267 sx_sunlock(&allproc_lock); 1268 if (bigproc != NULL) { 1269 killproc(bigproc, "out of swap space"); 1270 sched_nice(bigproc, PRIO_MIN); 1271 PROC_UNLOCK(bigproc); 1272 wakeup(&cnt.v_free_count); 1273 } 1274 } 1275 1276 /* 1277 * This routine tries to maintain the pseudo LRU active queue, 1278 * so that during long periods of time where there is no paging, 1279 * that some statistic accumulation still occurs. This code 1280 * helps the situation where paging just starts to occur. 1281 */ 1282 static void 1283 vm_pageout_page_stats() 1284 { 1285 vm_object_t object; 1286 vm_page_t m,next; 1287 int pcount,tpcount; /* Number of pages to check */ 1288 static int fullintervalcount = 0; 1289 int page_shortage; 1290 1291 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1292 page_shortage = 1293 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1294 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1295 1296 if (page_shortage <= 0) 1297 return; 1298 1299 pcount = cnt.v_active_count; 1300 fullintervalcount += vm_pageout_stats_interval; 1301 if (fullintervalcount < vm_pageout_full_stats_interval) { 1302 tpcount = (int64_t)vm_pageout_stats_max * cnt.v_active_count / 1303 cnt.v_page_count; 1304 if (pcount > tpcount) 1305 pcount = tpcount; 1306 } else { 1307 fullintervalcount = 0; 1308 } 1309 1310 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1311 while ((m != NULL) && (pcount-- > 0)) { 1312 int actcount; 1313 1314 KASSERT(VM_PAGE_INQUEUE2(m, PQ_ACTIVE), 1315 ("vm_pageout_page_stats: page %p isn't active", m)); 1316 1317 next = TAILQ_NEXT(m, pageq); 1318 object = m->object; 1319 1320 if ((m->flags & PG_MARKER) != 0) { 1321 m = next; 1322 continue; 1323 } 1324 if (!VM_OBJECT_TRYLOCK(object) && 1325 !vm_pageout_fallback_object_lock(m, &next)) { 1326 VM_OBJECT_UNLOCK(object); 1327 m = next; 1328 continue; 1329 } 1330 1331 /* 1332 * Don't deactivate pages that are busy. 1333 */ 1334 if ((m->busy != 0) || 1335 (m->oflags & VPO_BUSY) || 1336 (m->hold_count != 0)) { 1337 VM_OBJECT_UNLOCK(object); 1338 vm_page_requeue(m); 1339 m = next; 1340 continue; 1341 } 1342 1343 actcount = 0; 1344 if (m->flags & PG_REFERENCED) { 1345 vm_page_flag_clear(m, PG_REFERENCED); 1346 actcount += 1; 1347 } 1348 1349 actcount += pmap_ts_referenced(m); 1350 if (actcount) { 1351 m->act_count += ACT_ADVANCE + actcount; 1352 if (m->act_count > ACT_MAX) 1353 m->act_count = ACT_MAX; 1354 vm_page_requeue(m); 1355 } else { 1356 if (m->act_count == 0) { 1357 /* 1358 * We turn off page access, so that we have 1359 * more accurate RSS stats. We don't do this 1360 * in the normal page deactivation when the 1361 * system is loaded VM wise, because the 1362 * cost of the large number of page protect 1363 * operations would be higher than the value 1364 * of doing the operation. 1365 */ 1366 pmap_remove_all(m); 1367 vm_page_deactivate(m); 1368 } else { 1369 m->act_count -= min(m->act_count, ACT_DECLINE); 1370 vm_page_requeue(m); 1371 } 1372 } 1373 VM_OBJECT_UNLOCK(object); 1374 m = next; 1375 } 1376 } 1377 1378 /* 1379 * vm_pageout is the high level pageout daemon. 1380 */ 1381 static void 1382 vm_pageout() 1383 { 1384 int error, pass; 1385 1386 /* 1387 * Initialize some paging parameters. 1388 */ 1389 cnt.v_interrupt_free_min = 2; 1390 if (cnt.v_page_count < 2000) 1391 vm_pageout_page_count = 8; 1392 1393 /* 1394 * v_free_reserved needs to include enough for the largest 1395 * swap pager structures plus enough for any pv_entry structs 1396 * when paging. 1397 */ 1398 if (cnt.v_page_count > 1024) 1399 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1400 else 1401 cnt.v_free_min = 4; 1402 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1403 cnt.v_interrupt_free_min; 1404 cnt.v_free_reserved = vm_pageout_page_count + 1405 cnt.v_pageout_free_min + (cnt.v_page_count / 768); 1406 cnt.v_free_severe = cnt.v_free_min / 2; 1407 cnt.v_free_min += cnt.v_free_reserved; 1408 cnt.v_free_severe += cnt.v_free_reserved; 1409 1410 /* 1411 * v_free_target and v_cache_min control pageout hysteresis. Note 1412 * that these are more a measure of the VM cache queue hysteresis 1413 * then the VM free queue. Specifically, v_free_target is the 1414 * high water mark (free+cache pages). 1415 * 1416 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1417 * low water mark, while v_free_min is the stop. v_cache_min must 1418 * be big enough to handle memory needs while the pageout daemon 1419 * is signalled and run to free more pages. 1420 */ 1421 if (cnt.v_free_count > 6144) 1422 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1423 else 1424 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1425 1426 if (cnt.v_free_count > 2048) { 1427 cnt.v_cache_min = cnt.v_free_target; 1428 cnt.v_cache_max = 2 * cnt.v_cache_min; 1429 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1430 } else { 1431 cnt.v_cache_min = 0; 1432 cnt.v_cache_max = 0; 1433 cnt.v_inactive_target = cnt.v_free_count / 4; 1434 } 1435 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1436 cnt.v_inactive_target = cnt.v_free_count / 3; 1437 1438 /* XXX does not really belong here */ 1439 if (vm_page_max_wired == 0) 1440 vm_page_max_wired = cnt.v_free_count / 3; 1441 1442 if (vm_pageout_stats_max == 0) 1443 vm_pageout_stats_max = cnt.v_free_target; 1444 1445 /* 1446 * Set interval in seconds for stats scan. 1447 */ 1448 if (vm_pageout_stats_interval == 0) 1449 vm_pageout_stats_interval = 5; 1450 if (vm_pageout_full_stats_interval == 0) 1451 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1452 1453 swap_pager_swap_init(); 1454 pass = 0; 1455 /* 1456 * The pageout daemon is never done, so loop forever. 1457 */ 1458 while (TRUE) { 1459 /* 1460 * If we have enough free memory, wakeup waiters. Do 1461 * not clear vm_pages_needed until we reach our target, 1462 * otherwise we may be woken up over and over again and 1463 * waste a lot of cpu. 1464 */ 1465 mtx_lock(&vm_page_queue_free_mtx); 1466 if (vm_pages_needed && !vm_page_count_min()) { 1467 if (!vm_paging_needed()) 1468 vm_pages_needed = 0; 1469 wakeup(&cnt.v_free_count); 1470 } 1471 if (vm_pages_needed) { 1472 /* 1473 * Still not done, take a second pass without waiting 1474 * (unlimited dirty cleaning), otherwise sleep a bit 1475 * and try again. 1476 */ 1477 ++pass; 1478 if (pass > 1) 1479 msleep(&vm_pages_needed, 1480 &vm_page_queue_free_mtx, PVM, "psleep", 1481 hz / 2); 1482 } else { 1483 /* 1484 * Good enough, sleep & handle stats. Prime the pass 1485 * for the next run. 1486 */ 1487 if (pass > 1) 1488 pass = 1; 1489 else 1490 pass = 0; 1491 error = msleep(&vm_pages_needed, 1492 &vm_page_queue_free_mtx, PVM, "psleep", 1493 vm_pageout_stats_interval * hz); 1494 if (error && !vm_pages_needed) { 1495 mtx_unlock(&vm_page_queue_free_mtx); 1496 pass = 0; 1497 vm_page_lock_queues(); 1498 vm_pageout_page_stats(); 1499 vm_page_unlock_queues(); 1500 continue; 1501 } 1502 } 1503 if (vm_pages_needed) 1504 cnt.v_pdwakeups++; 1505 mtx_unlock(&vm_page_queue_free_mtx); 1506 vm_pageout_scan(pass); 1507 } 1508 } 1509 1510 /* 1511 * Unless the free page queue lock is held by the caller, this function 1512 * should be regarded as advisory. Specifically, the caller should 1513 * not msleep() on &cnt.v_free_count following this function unless 1514 * the free page queue lock is held until the msleep() is performed. 1515 */ 1516 void 1517 pagedaemon_wakeup() 1518 { 1519 1520 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1521 vm_pages_needed = 1; 1522 wakeup(&vm_pages_needed); 1523 } 1524 } 1525 1526 #if !defined(NO_SWAPPING) 1527 static void 1528 vm_req_vmdaemon(int req) 1529 { 1530 static int lastrun = 0; 1531 1532 mtx_lock(&vm_daemon_mtx); 1533 vm_pageout_req_swapout |= req; 1534 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1535 wakeup(&vm_daemon_needed); 1536 lastrun = ticks; 1537 } 1538 mtx_unlock(&vm_daemon_mtx); 1539 } 1540 1541 static void 1542 vm_daemon() 1543 { 1544 struct rlimit rsslim; 1545 struct proc *p; 1546 struct thread *td; 1547 struct vmspace *vm; 1548 int breakout, swapout_flags; 1549 1550 while (TRUE) { 1551 mtx_lock(&vm_daemon_mtx); 1552 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0); 1553 swapout_flags = vm_pageout_req_swapout; 1554 vm_pageout_req_swapout = 0; 1555 mtx_unlock(&vm_daemon_mtx); 1556 if (swapout_flags) 1557 swapout_procs(swapout_flags); 1558 1559 /* 1560 * scan the processes for exceeding their rlimits or if 1561 * process is swapped out -- deactivate pages 1562 */ 1563 sx_slock(&allproc_lock); 1564 FOREACH_PROC_IN_SYSTEM(p) { 1565 vm_pindex_t limit, size; 1566 1567 /* 1568 * if this is a system process or if we have already 1569 * looked at this process, skip it. 1570 */ 1571 PROC_LOCK(p); 1572 if (p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 1573 PROC_UNLOCK(p); 1574 continue; 1575 } 1576 /* 1577 * if the process is in a non-running type state, 1578 * don't touch it. 1579 */ 1580 breakout = 0; 1581 FOREACH_THREAD_IN_PROC(p, td) { 1582 thread_lock(td); 1583 if (!TD_ON_RUNQ(td) && 1584 !TD_IS_RUNNING(td) && 1585 !TD_IS_SLEEPING(td)) { 1586 thread_unlock(td); 1587 breakout = 1; 1588 break; 1589 } 1590 thread_unlock(td); 1591 } 1592 if (breakout) { 1593 PROC_UNLOCK(p); 1594 continue; 1595 } 1596 /* 1597 * get a limit 1598 */ 1599 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1600 limit = OFF_TO_IDX( 1601 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1602 1603 /* 1604 * let processes that are swapped out really be 1605 * swapped out set the limit to nothing (will force a 1606 * swap-out.) 1607 */ 1608 if ((p->p_flag & P_INMEM) == 0) 1609 limit = 0; /* XXX */ 1610 vm = vmspace_acquire_ref(p); 1611 PROC_UNLOCK(p); 1612 if (vm == NULL) 1613 continue; 1614 1615 size = vmspace_resident_count(vm); 1616 if (limit >= 0 && size >= limit) { 1617 vm_pageout_map_deactivate_pages( 1618 &vm->vm_map, limit); 1619 } 1620 vmspace_free(vm); 1621 } 1622 sx_sunlock(&allproc_lock); 1623 } 1624 } 1625 #endif /* !defined(NO_SWAPPING) */ 1626