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->hold_count != 0) { /* may be undergoing I/O */ 354 ib = 0; 355 break; 356 } 357 mc[--page_base] = p; 358 ++pageout_count; 359 ++ib; 360 /* 361 * alignment boundry, stop here and switch directions. Do 362 * not clear ib. 363 */ 364 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 365 break; 366 } 367 368 while (pageout_count < vm_pageout_page_count && 369 pindex + is < object->size) { 370 vm_page_t p; 371 372 if ((p = vm_page_lookup(object, pindex + is)) == NULL) 373 break; 374 if ((p->oflags & VPO_BUSY) || p->busy) { 375 break; 376 } 377 vm_page_test_dirty(p); 378 if (p->dirty == 0 || 379 p->queue != PQ_INACTIVE || 380 p->hold_count != 0) { /* may be undergoing I/O */ 381 break; 382 } 383 mc[page_base + pageout_count] = p; 384 ++pageout_count; 385 ++is; 386 } 387 388 /* 389 * If we exhausted our forward scan, continue with the reverse scan 390 * when possible, even past a page boundry. This catches boundry 391 * conditions. 392 */ 393 if (ib && pageout_count < vm_pageout_page_count) 394 goto more; 395 396 /* 397 * we allow reads during pageouts... 398 */ 399 return (vm_pageout_flush(&mc[page_base], pageout_count, 0)); 400 } 401 402 /* 403 * vm_pageout_flush() - launder the given pages 404 * 405 * The given pages are laundered. Note that we setup for the start of 406 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 407 * reference count all in here rather then in the parent. If we want 408 * the parent to do more sophisticated things we may have to change 409 * the ordering. 410 */ 411 int 412 vm_pageout_flush(vm_page_t *mc, int count, int flags) 413 { 414 vm_object_t object = mc[0]->object; 415 int pageout_status[count]; 416 int numpagedout = 0; 417 int i; 418 419 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 420 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 421 /* 422 * Initiate I/O. Bump the vm_page_t->busy counter and 423 * mark the pages read-only. 424 * 425 * We do not have to fixup the clean/dirty bits here... we can 426 * allow the pager to do it after the I/O completes. 427 * 428 * NOTE! mc[i]->dirty may be partial or fragmented due to an 429 * edge case with file fragments. 430 */ 431 for (i = 0; i < count; i++) { 432 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 433 ("vm_pageout_flush: partially invalid page %p index %d/%d", 434 mc[i], i, count)); 435 vm_page_io_start(mc[i]); 436 pmap_remove_write(mc[i]); 437 } 438 vm_page_unlock_queues(); 439 vm_object_pip_add(object, count); 440 441 vm_pager_put_pages(object, mc, count, flags, pageout_status); 442 443 vm_page_lock_queues(); 444 for (i = 0; i < count; i++) { 445 vm_page_t mt = mc[i]; 446 447 KASSERT(pageout_status[i] == VM_PAGER_PEND || 448 (mt->flags & PG_WRITEABLE) == 0, 449 ("vm_pageout_flush: page %p is not write protected", mt)); 450 switch (pageout_status[i]) { 451 case VM_PAGER_OK: 452 case VM_PAGER_PEND: 453 numpagedout++; 454 break; 455 case VM_PAGER_BAD: 456 /* 457 * Page outside of range of object. Right now we 458 * essentially lose the changes by pretending it 459 * worked. 460 */ 461 vm_page_undirty(mt); 462 break; 463 case VM_PAGER_ERROR: 464 case VM_PAGER_FAIL: 465 /* 466 * If page couldn't be paged out, then reactivate the 467 * page so it doesn't clog the inactive list. (We 468 * will try paging out it again later). 469 */ 470 vm_page_activate(mt); 471 break; 472 case VM_PAGER_AGAIN: 473 break; 474 } 475 476 /* 477 * If the operation is still going, leave the page busy to 478 * block all other accesses. Also, leave the paging in 479 * progress indicator set so that we don't attempt an object 480 * collapse. 481 */ 482 if (pageout_status[i] != VM_PAGER_PEND) { 483 vm_object_pip_wakeup(object); 484 vm_page_io_finish(mt); 485 if (vm_page_count_severe()) 486 vm_page_try_to_cache(mt); 487 } 488 } 489 return numpagedout; 490 } 491 492 #if !defined(NO_SWAPPING) 493 /* 494 * vm_pageout_object_deactivate_pages 495 * 496 * deactivate enough pages to satisfy the inactive target 497 * requirements or if vm_page_proc_limit is set, then 498 * deactivate all of the pages in the object and its 499 * backing_objects. 500 * 501 * The object and map must be locked. 502 */ 503 static void 504 vm_pageout_object_deactivate_pages(pmap, first_object, desired) 505 pmap_t pmap; 506 vm_object_t first_object; 507 long desired; 508 { 509 vm_object_t backing_object, object; 510 vm_page_t p, next; 511 int actcount, rcount, remove_mode; 512 513 VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED); 514 if (first_object->type == OBJT_DEVICE || 515 first_object->type == OBJT_SG || 516 first_object->type == OBJT_PHYS) 517 return; 518 for (object = first_object;; object = backing_object) { 519 if (pmap_resident_count(pmap) <= desired) 520 goto unlock_return; 521 if (object->paging_in_progress) 522 goto unlock_return; 523 524 remove_mode = 0; 525 if (object->shadow_count > 1) 526 remove_mode = 1; 527 /* 528 * scan the objects entire memory queue 529 */ 530 rcount = object->resident_page_count; 531 p = TAILQ_FIRST(&object->memq); 532 vm_page_lock_queues(); 533 while (p && (rcount-- > 0)) { 534 if (pmap_resident_count(pmap) <= desired) { 535 vm_page_unlock_queues(); 536 goto unlock_return; 537 } 538 next = TAILQ_NEXT(p, listq); 539 cnt.v_pdpages++; 540 if (p->wire_count != 0 || 541 p->hold_count != 0 || 542 p->busy != 0 || 543 (p->oflags & VPO_BUSY) || 544 (p->flags & PG_UNMANAGED) || 545 !pmap_page_exists_quick(pmap, p)) { 546 p = next; 547 continue; 548 } 549 actcount = pmap_ts_referenced(p); 550 if (actcount) { 551 vm_page_flag_set(p, PG_REFERENCED); 552 } else if (p->flags & PG_REFERENCED) { 553 actcount = 1; 554 } 555 if ((p->queue != PQ_ACTIVE) && 556 (p->flags & PG_REFERENCED)) { 557 vm_page_activate(p); 558 p->act_count += actcount; 559 vm_page_flag_clear(p, PG_REFERENCED); 560 } else if (p->queue == PQ_ACTIVE) { 561 if ((p->flags & PG_REFERENCED) == 0) { 562 p->act_count -= min(p->act_count, ACT_DECLINE); 563 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) { 564 pmap_remove_all(p); 565 vm_page_deactivate(p); 566 } else { 567 vm_page_requeue(p); 568 } 569 } else { 570 vm_page_activate(p); 571 vm_page_flag_clear(p, PG_REFERENCED); 572 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 573 p->act_count += ACT_ADVANCE; 574 vm_page_requeue(p); 575 } 576 } else if (p->queue == PQ_INACTIVE) { 577 pmap_remove_all(p); 578 } 579 p = next; 580 } 581 vm_page_unlock_queues(); 582 if ((backing_object = object->backing_object) == NULL) 583 goto unlock_return; 584 VM_OBJECT_LOCK(backing_object); 585 if (object != first_object) 586 VM_OBJECT_UNLOCK(object); 587 } 588 unlock_return: 589 if (object != first_object) 590 VM_OBJECT_UNLOCK(object); 591 } 592 593 /* 594 * deactivate some number of pages in a map, try to do it fairly, but 595 * that is really hard to do. 596 */ 597 static void 598 vm_pageout_map_deactivate_pages(map, desired) 599 vm_map_t map; 600 long desired; 601 { 602 vm_map_entry_t tmpe; 603 vm_object_t obj, bigobj; 604 int nothingwired; 605 606 if (!vm_map_trylock(map)) 607 return; 608 609 bigobj = NULL; 610 nothingwired = TRUE; 611 612 /* 613 * first, search out the biggest object, and try to free pages from 614 * that. 615 */ 616 tmpe = map->header.next; 617 while (tmpe != &map->header) { 618 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 619 obj = tmpe->object.vm_object; 620 if (obj != NULL && VM_OBJECT_TRYLOCK(obj)) { 621 if (obj->shadow_count <= 1 && 622 (bigobj == NULL || 623 bigobj->resident_page_count < obj->resident_page_count)) { 624 if (bigobj != NULL) 625 VM_OBJECT_UNLOCK(bigobj); 626 bigobj = obj; 627 } else 628 VM_OBJECT_UNLOCK(obj); 629 } 630 } 631 if (tmpe->wired_count > 0) 632 nothingwired = FALSE; 633 tmpe = tmpe->next; 634 } 635 636 if (bigobj != NULL) { 637 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); 638 VM_OBJECT_UNLOCK(bigobj); 639 } 640 /* 641 * Next, hunt around for other pages to deactivate. We actually 642 * do this search sort of wrong -- .text first is not the best idea. 643 */ 644 tmpe = map->header.next; 645 while (tmpe != &map->header) { 646 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 647 break; 648 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 649 obj = tmpe->object.vm_object; 650 if (obj != NULL) { 651 VM_OBJECT_LOCK(obj); 652 vm_pageout_object_deactivate_pages(map->pmap, obj, desired); 653 VM_OBJECT_UNLOCK(obj); 654 } 655 } 656 tmpe = tmpe->next; 657 } 658 659 /* 660 * Remove all mappings if a process is swapped out, this will free page 661 * table pages. 662 */ 663 if (desired == 0 && nothingwired) { 664 pmap_remove(vm_map_pmap(map), vm_map_min(map), 665 vm_map_max(map)); 666 } 667 vm_map_unlock(map); 668 } 669 #endif /* !defined(NO_SWAPPING) */ 670 671 /* 672 * vm_pageout_scan does the dirty work for the pageout daemon. 673 */ 674 static void 675 vm_pageout_scan(int pass) 676 { 677 vm_page_t m, next; 678 struct vm_page marker; 679 int page_shortage, maxscan, pcount; 680 int addl_page_shortage, addl_page_shortage_init; 681 vm_object_t object; 682 int actcount; 683 int vnodes_skipped = 0; 684 int maxlaunder; 685 686 /* 687 * Decrease registered cache sizes. 688 */ 689 EVENTHANDLER_INVOKE(vm_lowmem, 0); 690 /* 691 * We do this explicitly after the caches have been drained above. 692 */ 693 uma_reclaim(); 694 695 addl_page_shortage_init = atomic_readandclear_int(&vm_pageout_deficit); 696 697 /* 698 * Calculate the number of pages we want to either free or move 699 * to the cache. 700 */ 701 page_shortage = vm_paging_target() + addl_page_shortage_init; 702 703 /* 704 * Initialize our marker 705 */ 706 bzero(&marker, sizeof(marker)); 707 marker.flags = PG_FICTITIOUS | PG_MARKER; 708 marker.oflags = VPO_BUSY; 709 marker.queue = PQ_INACTIVE; 710 marker.wire_count = 1; 711 712 /* 713 * Start scanning the inactive queue for pages we can move to the 714 * cache or free. The scan will stop when the target is reached or 715 * we have scanned the entire inactive queue. Note that m->act_count 716 * is not used to form decisions for the inactive queue, only for the 717 * active queue. 718 * 719 * maxlaunder limits the number of dirty pages we flush per scan. 720 * For most systems a smaller value (16 or 32) is more robust under 721 * extreme memory and disk pressure because any unnecessary writes 722 * to disk can result in extreme performance degredation. However, 723 * systems with excessive dirty pages (especially when MAP_NOSYNC is 724 * used) will die horribly with limited laundering. If the pageout 725 * daemon cannot clean enough pages in the first pass, we let it go 726 * all out in succeeding passes. 727 */ 728 if ((maxlaunder = vm_max_launder) <= 1) 729 maxlaunder = 1; 730 if (pass) 731 maxlaunder = 10000; 732 vm_page_lock_queues(); 733 rescan0: 734 addl_page_shortage = addl_page_shortage_init; 735 maxscan = cnt.v_inactive_count; 736 737 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 738 m != NULL && maxscan-- > 0 && page_shortage > 0; 739 m = next) { 740 741 cnt.v_pdpages++; 742 743 if (VM_PAGE_GETQUEUE(m) != PQ_INACTIVE) { 744 goto rescan0; 745 } 746 747 next = TAILQ_NEXT(m, pageq); 748 object = m->object; 749 750 /* 751 * skip marker pages 752 */ 753 if (m->flags & PG_MARKER) 754 continue; 755 756 /* 757 * A held page may be undergoing I/O, so skip it. 758 */ 759 if (m->hold_count) { 760 vm_page_requeue(m); 761 addl_page_shortage++; 762 continue; 763 } 764 /* 765 * Don't mess with busy pages, keep in the front of the 766 * queue, most likely are being paged out. 767 */ 768 if (!VM_OBJECT_TRYLOCK(object) && 769 (!vm_pageout_fallback_object_lock(m, &next) || 770 m->hold_count != 0)) { 771 VM_OBJECT_UNLOCK(object); 772 addl_page_shortage++; 773 continue; 774 } 775 if (m->busy || (m->oflags & VPO_BUSY)) { 776 VM_OBJECT_UNLOCK(object); 777 addl_page_shortage++; 778 continue; 779 } 780 781 /* 782 * If the object is not being used, we ignore previous 783 * references. 784 */ 785 if (object->ref_count == 0) { 786 vm_page_flag_clear(m, PG_REFERENCED); 787 KASSERT(!pmap_page_is_mapped(m), 788 ("vm_pageout_scan: page %p is mapped", m)); 789 790 /* 791 * Otherwise, if the page has been referenced while in the 792 * inactive queue, we bump the "activation count" upwards, 793 * making it less likely that the page will be added back to 794 * the inactive queue prematurely again. Here we check the 795 * page tables (or emulated bits, if any), given the upper 796 * level VM system not knowing anything about existing 797 * references. 798 */ 799 } else if (((m->flags & PG_REFERENCED) == 0) && 800 (actcount = pmap_ts_referenced(m))) { 801 vm_page_activate(m); 802 VM_OBJECT_UNLOCK(object); 803 m->act_count += (actcount + ACT_ADVANCE); 804 continue; 805 } 806 807 /* 808 * If the upper level VM system knows about any page 809 * references, we activate the page. We also set the 810 * "activation count" higher than normal so that we will less 811 * likely place pages back onto the inactive queue again. 812 */ 813 if ((m->flags & PG_REFERENCED) != 0) { 814 vm_page_flag_clear(m, PG_REFERENCED); 815 actcount = pmap_ts_referenced(m); 816 vm_page_activate(m); 817 VM_OBJECT_UNLOCK(object); 818 m->act_count += (actcount + ACT_ADVANCE + 1); 819 continue; 820 } 821 822 /* 823 * If the upper level VM system does not believe that the page 824 * is fully dirty, but it is mapped for write access, then we 825 * consult the pmap to see if the page's dirty status should 826 * be updated. 827 */ 828 if (m->dirty != VM_PAGE_BITS_ALL && 829 (m->flags & PG_WRITEABLE) != 0) { 830 /* 831 * Avoid a race condition: Unless write access is 832 * removed from the page, another processor could 833 * modify it before all access is removed by the call 834 * to vm_page_cache() below. If vm_page_cache() finds 835 * that the page has been modified when it removes all 836 * access, it panics because it cannot cache dirty 837 * pages. In principle, we could eliminate just write 838 * access here rather than all access. In the expected 839 * case, when there are no last instant modifications 840 * to the page, removing all access will be cheaper 841 * overall. 842 */ 843 if (pmap_is_modified(m)) 844 vm_page_dirty(m); 845 else if (m->dirty == 0) 846 pmap_remove_all(m); 847 } 848 849 if (m->valid == 0) { 850 /* 851 * Invalid pages can be easily freed 852 */ 853 vm_page_free(m); 854 cnt.v_dfree++; 855 --page_shortage; 856 } else if (m->dirty == 0) { 857 /* 858 * Clean pages can be placed onto the cache queue. 859 * This effectively frees them. 860 */ 861 vm_page_cache(m); 862 --page_shortage; 863 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 864 /* 865 * Dirty pages need to be paged out, but flushing 866 * a page is extremely expensive verses freeing 867 * a clean page. Rather then artificially limiting 868 * the number of pages we can flush, we instead give 869 * dirty pages extra priority on the inactive queue 870 * by forcing them to be cycled through the queue 871 * twice before being flushed, after which the 872 * (now clean) page will cycle through once more 873 * before being freed. This significantly extends 874 * the thrash point for a heavily loaded machine. 875 */ 876 vm_page_flag_set(m, PG_WINATCFLS); 877 vm_page_requeue(m); 878 } else if (maxlaunder > 0) { 879 /* 880 * We always want to try to flush some dirty pages if 881 * we encounter them, to keep the system stable. 882 * Normally this number is small, but under extreme 883 * pressure where there are insufficient clean pages 884 * on the inactive queue, we may have to go all out. 885 */ 886 int swap_pageouts_ok, vfslocked = 0; 887 struct vnode *vp = NULL; 888 struct mount *mp = NULL; 889 890 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 891 swap_pageouts_ok = 1; 892 } else { 893 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 894 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 895 vm_page_count_min()); 896 897 } 898 899 /* 900 * We don't bother paging objects that are "dead". 901 * Those objects are in a "rundown" state. 902 */ 903 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 904 VM_OBJECT_UNLOCK(object); 905 vm_page_requeue(m); 906 continue; 907 } 908 909 /* 910 * Following operations may unlock 911 * vm_page_queue_mtx, invalidating the 'next' 912 * pointer. To prevent an inordinate number 913 * of restarts we use our marker to remember 914 * our place. 915 * 916 */ 917 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, 918 m, &marker, pageq); 919 /* 920 * The object is already known NOT to be dead. It 921 * is possible for the vget() to block the whole 922 * pageout daemon, but the new low-memory handling 923 * code should prevent it. 924 * 925 * The previous code skipped locked vnodes and, worse, 926 * reordered pages in the queue. This results in 927 * completely non-deterministic operation and, on a 928 * busy system, can lead to extremely non-optimal 929 * pageouts. For example, it can cause clean pages 930 * to be freed and dirty pages to be moved to the end 931 * of the queue. Since dirty pages are also moved to 932 * the end of the queue once-cleaned, this gives 933 * way too large a weighting to defering the freeing 934 * of dirty pages. 935 * 936 * We can't wait forever for the vnode lock, we might 937 * deadlock due to a vn_read() getting stuck in 938 * vm_wait while holding this vnode. We skip the 939 * vnode if we can't get it in a reasonable amount 940 * of time. 941 */ 942 if (object->type == OBJT_VNODE) { 943 vp = object->handle; 944 if (vp->v_type == VREG && 945 vn_start_write(vp, &mp, V_NOWAIT) != 0) { 946 mp = NULL; 947 ++pageout_lock_miss; 948 if (object->flags & OBJ_MIGHTBEDIRTY) 949 vnodes_skipped++; 950 goto unlock_and_continue; 951 } 952 KASSERT(mp != NULL, 953 ("vp %p with NULL v_mount", vp)); 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 KASSERT(!pmap_page_is_mapped(m), 1126 ("vm_pageout_scan: page %p is mapped", m)); 1127 if (m->dirty == 0) 1128 vm_page_cache(m); 1129 else 1130 vm_page_deactivate(m); 1131 } else { 1132 vm_page_deactivate(m); 1133 } 1134 } else { 1135 vm_page_requeue(m); 1136 } 1137 } 1138 VM_OBJECT_UNLOCK(object); 1139 m = next; 1140 } 1141 vm_page_unlock_queues(); 1142 #if !defined(NO_SWAPPING) 1143 /* 1144 * Idle process swapout -- run once per second. 1145 */ 1146 if (vm_swap_idle_enabled) { 1147 static long lsec; 1148 if (time_second != lsec) { 1149 vm_req_vmdaemon(VM_SWAP_IDLE); 1150 lsec = time_second; 1151 } 1152 } 1153 #endif 1154 1155 /* 1156 * If we didn't get enough free pages, and we have skipped a vnode 1157 * in a writeable object, wakeup the sync daemon. And kick swapout 1158 * if we did not get enough free pages. 1159 */ 1160 if (vm_paging_target() > 0) { 1161 if (vnodes_skipped && vm_page_count_min()) 1162 (void) speedup_syncer(); 1163 #if !defined(NO_SWAPPING) 1164 if (vm_swap_enabled && vm_page_count_target()) 1165 vm_req_vmdaemon(VM_SWAP_NORMAL); 1166 #endif 1167 } 1168 1169 /* 1170 * If we are critically low on one of RAM or swap and low on 1171 * the other, kill the largest process. However, we avoid 1172 * doing this on the first pass in order to give ourselves a 1173 * chance to flush out dirty vnode-backed pages and to allow 1174 * active pages to be moved to the inactive queue and reclaimed. 1175 */ 1176 if (pass != 0 && 1177 ((swap_pager_avail < 64 && vm_page_count_min()) || 1178 (swap_pager_full && vm_paging_target() > 0))) 1179 vm_pageout_oom(VM_OOM_MEM); 1180 } 1181 1182 1183 void 1184 vm_pageout_oom(int shortage) 1185 { 1186 struct proc *p, *bigproc; 1187 vm_offset_t size, bigsize; 1188 struct thread *td; 1189 struct vmspace *vm; 1190 1191 /* 1192 * We keep the process bigproc locked once we find it to keep anyone 1193 * from messing with it; however, there is a possibility of 1194 * deadlock if process B is bigproc and one of it's child processes 1195 * attempts to propagate a signal to B while we are waiting for A's 1196 * lock while walking this list. To avoid this, we don't block on 1197 * the process lock but just skip a process if it is already locked. 1198 */ 1199 bigproc = NULL; 1200 bigsize = 0; 1201 sx_slock(&allproc_lock); 1202 FOREACH_PROC_IN_SYSTEM(p) { 1203 int breakout; 1204 1205 if (PROC_TRYLOCK(p) == 0) 1206 continue; 1207 /* 1208 * If this is a system, protected or killed process, skip it. 1209 */ 1210 if ((p->p_flag & (P_INEXEC | P_PROTECTED | P_SYSTEM)) || 1211 (p->p_pid == 1) || P_KILLED(p) || 1212 ((p->p_pid < 48) && (swap_pager_avail != 0))) { 1213 PROC_UNLOCK(p); 1214 continue; 1215 } 1216 /* 1217 * If the process is in a non-running type state, 1218 * don't touch it. Check all the threads individually. 1219 */ 1220 breakout = 0; 1221 FOREACH_THREAD_IN_PROC(p, td) { 1222 thread_lock(td); 1223 if (!TD_ON_RUNQ(td) && 1224 !TD_IS_RUNNING(td) && 1225 !TD_IS_SLEEPING(td)) { 1226 thread_unlock(td); 1227 breakout = 1; 1228 break; 1229 } 1230 thread_unlock(td); 1231 } 1232 if (breakout) { 1233 PROC_UNLOCK(p); 1234 continue; 1235 } 1236 /* 1237 * get the process size 1238 */ 1239 vm = vmspace_acquire_ref(p); 1240 if (vm == NULL) { 1241 PROC_UNLOCK(p); 1242 continue; 1243 } 1244 if (!vm_map_trylock_read(&vm->vm_map)) { 1245 vmspace_free(vm); 1246 PROC_UNLOCK(p); 1247 continue; 1248 } 1249 size = vmspace_swap_count(vm); 1250 vm_map_unlock_read(&vm->vm_map); 1251 if (shortage == VM_OOM_MEM) 1252 size += vmspace_resident_count(vm); 1253 vmspace_free(vm); 1254 /* 1255 * if the this process is bigger than the biggest one 1256 * remember it. 1257 */ 1258 if (size > bigsize) { 1259 if (bigproc != NULL) 1260 PROC_UNLOCK(bigproc); 1261 bigproc = p; 1262 bigsize = size; 1263 } else 1264 PROC_UNLOCK(p); 1265 } 1266 sx_sunlock(&allproc_lock); 1267 if (bigproc != NULL) { 1268 killproc(bigproc, "out of swap space"); 1269 sched_nice(bigproc, PRIO_MIN); 1270 PROC_UNLOCK(bigproc); 1271 wakeup(&cnt.v_free_count); 1272 } 1273 } 1274 1275 /* 1276 * This routine tries to maintain the pseudo LRU active queue, 1277 * so that during long periods of time where there is no paging, 1278 * that some statistic accumulation still occurs. This code 1279 * helps the situation where paging just starts to occur. 1280 */ 1281 static void 1282 vm_pageout_page_stats() 1283 { 1284 vm_object_t object; 1285 vm_page_t m,next; 1286 int pcount,tpcount; /* Number of pages to check */ 1287 static int fullintervalcount = 0; 1288 int page_shortage; 1289 1290 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1291 page_shortage = 1292 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1293 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1294 1295 if (page_shortage <= 0) 1296 return; 1297 1298 pcount = cnt.v_active_count; 1299 fullintervalcount += vm_pageout_stats_interval; 1300 if (fullintervalcount < vm_pageout_full_stats_interval) { 1301 tpcount = (int64_t)vm_pageout_stats_max * cnt.v_active_count / 1302 cnt.v_page_count; 1303 if (pcount > tpcount) 1304 pcount = tpcount; 1305 } else { 1306 fullintervalcount = 0; 1307 } 1308 1309 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1310 while ((m != NULL) && (pcount-- > 0)) { 1311 int actcount; 1312 1313 KASSERT(VM_PAGE_INQUEUE2(m, PQ_ACTIVE), 1314 ("vm_pageout_page_stats: page %p isn't active", m)); 1315 1316 next = TAILQ_NEXT(m, pageq); 1317 object = m->object; 1318 1319 if ((m->flags & PG_MARKER) != 0) { 1320 m = next; 1321 continue; 1322 } 1323 if (!VM_OBJECT_TRYLOCK(object) && 1324 !vm_pageout_fallback_object_lock(m, &next)) { 1325 VM_OBJECT_UNLOCK(object); 1326 m = next; 1327 continue; 1328 } 1329 1330 /* 1331 * Don't deactivate pages that are busy. 1332 */ 1333 if ((m->busy != 0) || 1334 (m->oflags & VPO_BUSY) || 1335 (m->hold_count != 0)) { 1336 VM_OBJECT_UNLOCK(object); 1337 vm_page_requeue(m); 1338 m = next; 1339 continue; 1340 } 1341 1342 actcount = 0; 1343 if (m->flags & PG_REFERENCED) { 1344 vm_page_flag_clear(m, PG_REFERENCED); 1345 actcount += 1; 1346 } 1347 1348 actcount += pmap_ts_referenced(m); 1349 if (actcount) { 1350 m->act_count += ACT_ADVANCE + actcount; 1351 if (m->act_count > ACT_MAX) 1352 m->act_count = ACT_MAX; 1353 vm_page_requeue(m); 1354 } else { 1355 if (m->act_count == 0) { 1356 /* 1357 * We turn off page access, so that we have 1358 * more accurate RSS stats. We don't do this 1359 * in the normal page deactivation when the 1360 * system is loaded VM wise, because the 1361 * cost of the large number of page protect 1362 * operations would be higher than the value 1363 * of doing the operation. 1364 */ 1365 pmap_remove_all(m); 1366 vm_page_deactivate(m); 1367 } else { 1368 m->act_count -= min(m->act_count, ACT_DECLINE); 1369 vm_page_requeue(m); 1370 } 1371 } 1372 VM_OBJECT_UNLOCK(object); 1373 m = next; 1374 } 1375 } 1376 1377 /* 1378 * vm_pageout is the high level pageout daemon. 1379 */ 1380 static void 1381 vm_pageout() 1382 { 1383 int error, pass; 1384 1385 /* 1386 * Initialize some paging parameters. 1387 */ 1388 cnt.v_interrupt_free_min = 2; 1389 if (cnt.v_page_count < 2000) 1390 vm_pageout_page_count = 8; 1391 1392 /* 1393 * v_free_reserved needs to include enough for the largest 1394 * swap pager structures plus enough for any pv_entry structs 1395 * when paging. 1396 */ 1397 if (cnt.v_page_count > 1024) 1398 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1399 else 1400 cnt.v_free_min = 4; 1401 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1402 cnt.v_interrupt_free_min; 1403 cnt.v_free_reserved = vm_pageout_page_count + 1404 cnt.v_pageout_free_min + (cnt.v_page_count / 768); 1405 cnt.v_free_severe = cnt.v_free_min / 2; 1406 cnt.v_free_min += cnt.v_free_reserved; 1407 cnt.v_free_severe += cnt.v_free_reserved; 1408 1409 /* 1410 * v_free_target and v_cache_min control pageout hysteresis. Note 1411 * that these are more a measure of the VM cache queue hysteresis 1412 * then the VM free queue. Specifically, v_free_target is the 1413 * high water mark (free+cache pages). 1414 * 1415 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1416 * low water mark, while v_free_min is the stop. v_cache_min must 1417 * be big enough to handle memory needs while the pageout daemon 1418 * is signalled and run to free more pages. 1419 */ 1420 if (cnt.v_free_count > 6144) 1421 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1422 else 1423 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1424 1425 if (cnt.v_free_count > 2048) { 1426 cnt.v_cache_min = cnt.v_free_target; 1427 cnt.v_cache_max = 2 * cnt.v_cache_min; 1428 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1429 } else { 1430 cnt.v_cache_min = 0; 1431 cnt.v_cache_max = 0; 1432 cnt.v_inactive_target = cnt.v_free_count / 4; 1433 } 1434 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1435 cnt.v_inactive_target = cnt.v_free_count / 3; 1436 1437 /* XXX does not really belong here */ 1438 if (vm_page_max_wired == 0) 1439 vm_page_max_wired = cnt.v_free_count / 3; 1440 1441 if (vm_pageout_stats_max == 0) 1442 vm_pageout_stats_max = cnt.v_free_target; 1443 1444 /* 1445 * Set interval in seconds for stats scan. 1446 */ 1447 if (vm_pageout_stats_interval == 0) 1448 vm_pageout_stats_interval = 5; 1449 if (vm_pageout_full_stats_interval == 0) 1450 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1451 1452 swap_pager_swap_init(); 1453 pass = 0; 1454 /* 1455 * The pageout daemon is never done, so loop forever. 1456 */ 1457 while (TRUE) { 1458 /* 1459 * If we have enough free memory, wakeup waiters. Do 1460 * not clear vm_pages_needed until we reach our target, 1461 * otherwise we may be woken up over and over again and 1462 * waste a lot of cpu. 1463 */ 1464 mtx_lock(&vm_page_queue_free_mtx); 1465 if (vm_pages_needed && !vm_page_count_min()) { 1466 if (!vm_paging_needed()) 1467 vm_pages_needed = 0; 1468 wakeup(&cnt.v_free_count); 1469 } 1470 if (vm_pages_needed) { 1471 /* 1472 * Still not done, take a second pass without waiting 1473 * (unlimited dirty cleaning), otherwise sleep a bit 1474 * and try again. 1475 */ 1476 ++pass; 1477 if (pass > 1) 1478 msleep(&vm_pages_needed, 1479 &vm_page_queue_free_mtx, PVM, "psleep", 1480 hz / 2); 1481 } else { 1482 /* 1483 * Good enough, sleep & handle stats. Prime the pass 1484 * for the next run. 1485 */ 1486 if (pass > 1) 1487 pass = 1; 1488 else 1489 pass = 0; 1490 error = msleep(&vm_pages_needed, 1491 &vm_page_queue_free_mtx, PVM, "psleep", 1492 vm_pageout_stats_interval * hz); 1493 if (error && !vm_pages_needed) { 1494 mtx_unlock(&vm_page_queue_free_mtx); 1495 pass = 0; 1496 vm_page_lock_queues(); 1497 vm_pageout_page_stats(); 1498 vm_page_unlock_queues(); 1499 continue; 1500 } 1501 } 1502 if (vm_pages_needed) 1503 cnt.v_pdwakeups++; 1504 mtx_unlock(&vm_page_queue_free_mtx); 1505 vm_pageout_scan(pass); 1506 } 1507 } 1508 1509 /* 1510 * Unless the free page queue lock is held by the caller, this function 1511 * should be regarded as advisory. Specifically, the caller should 1512 * not msleep() on &cnt.v_free_count following this function unless 1513 * the free page queue lock is held until the msleep() is performed. 1514 */ 1515 void 1516 pagedaemon_wakeup() 1517 { 1518 1519 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1520 vm_pages_needed = 1; 1521 wakeup(&vm_pages_needed); 1522 } 1523 } 1524 1525 #if !defined(NO_SWAPPING) 1526 static void 1527 vm_req_vmdaemon(int req) 1528 { 1529 static int lastrun = 0; 1530 1531 mtx_lock(&vm_daemon_mtx); 1532 vm_pageout_req_swapout |= req; 1533 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1534 wakeup(&vm_daemon_needed); 1535 lastrun = ticks; 1536 } 1537 mtx_unlock(&vm_daemon_mtx); 1538 } 1539 1540 static void 1541 vm_daemon() 1542 { 1543 struct rlimit rsslim; 1544 struct proc *p; 1545 struct thread *td; 1546 struct vmspace *vm; 1547 int breakout, swapout_flags; 1548 1549 while (TRUE) { 1550 mtx_lock(&vm_daemon_mtx); 1551 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0); 1552 swapout_flags = vm_pageout_req_swapout; 1553 vm_pageout_req_swapout = 0; 1554 mtx_unlock(&vm_daemon_mtx); 1555 if (swapout_flags) 1556 swapout_procs(swapout_flags); 1557 1558 /* 1559 * scan the processes for exceeding their rlimits or if 1560 * process is swapped out -- deactivate pages 1561 */ 1562 sx_slock(&allproc_lock); 1563 FOREACH_PROC_IN_SYSTEM(p) { 1564 vm_pindex_t limit, size; 1565 1566 /* 1567 * if this is a system process or if we have already 1568 * looked at this process, skip it. 1569 */ 1570 PROC_LOCK(p); 1571 if (p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 1572 PROC_UNLOCK(p); 1573 continue; 1574 } 1575 /* 1576 * if the process is in a non-running type state, 1577 * don't touch it. 1578 */ 1579 breakout = 0; 1580 FOREACH_THREAD_IN_PROC(p, td) { 1581 thread_lock(td); 1582 if (!TD_ON_RUNQ(td) && 1583 !TD_IS_RUNNING(td) && 1584 !TD_IS_SLEEPING(td)) { 1585 thread_unlock(td); 1586 breakout = 1; 1587 break; 1588 } 1589 thread_unlock(td); 1590 } 1591 if (breakout) { 1592 PROC_UNLOCK(p); 1593 continue; 1594 } 1595 /* 1596 * get a limit 1597 */ 1598 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1599 limit = OFF_TO_IDX( 1600 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1601 1602 /* 1603 * let processes that are swapped out really be 1604 * swapped out set the limit to nothing (will force a 1605 * swap-out.) 1606 */ 1607 if ((p->p_flag & P_INMEM) == 0) 1608 limit = 0; /* XXX */ 1609 vm = vmspace_acquire_ref(p); 1610 PROC_UNLOCK(p); 1611 if (vm == NULL) 1612 continue; 1613 1614 size = vmspace_resident_count(vm); 1615 if (limit >= 0 && size >= limit) { 1616 vm_pageout_map_deactivate_pages( 1617 &vm->vm_map, limit); 1618 } 1619 vmspace_free(vm); 1620 } 1621 sx_sunlock(&allproc_lock); 1622 } 1623 } 1624 #endif /* !defined(NO_SWAPPING) */ 1625