1 /*- 2 * Copyright (c) 1991 Regents of the University of California. 3 * All rights reserved. 4 * Copyright (c) 1994 John S. Dyson 5 * All rights reserved. 6 * Copyright (c) 1994 David Greenman 7 * All rights reserved. 8 * Copyright (c) 2005 Yahoo! Technologies Norway AS 9 * All rights reserved. 10 * 11 * This code is derived from software contributed to Berkeley by 12 * The Mach Operating System project at Carnegie-Mellon University. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the University of 25 * California, Berkeley and its contributors. 26 * 4. Neither the name of the University nor the names of its contributors 27 * may be used to endorse or promote products derived from this software 28 * without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 * 42 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 43 * 44 * 45 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 46 * All rights reserved. 47 * 48 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 49 * 50 * Permission to use, copy, modify and distribute this software and 51 * its documentation is hereby granted, provided that both the copyright 52 * notice and this permission notice appear in all copies of the 53 * software, derivative works or modified versions, and any portions 54 * thereof, and that both notices appear in supporting documentation. 55 * 56 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 57 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 58 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 59 * 60 * Carnegie Mellon requests users of this software to return to 61 * 62 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 63 * School of Computer Science 64 * Carnegie Mellon University 65 * Pittsburgh PA 15213-3890 66 * 67 * any improvements or extensions that they make and grant Carnegie the 68 * rights to redistribute these changes. 69 */ 70 71 /* 72 * The proverbial page-out daemon. 73 */ 74 75 #include <sys/cdefs.h> 76 __FBSDID("$FreeBSD$"); 77 78 #include "opt_vm.h" 79 #include <sys/param.h> 80 #include <sys/systm.h> 81 #include <sys/kernel.h> 82 #include <sys/eventhandler.h> 83 #include <sys/lock.h> 84 #include <sys/mutex.h> 85 #include <sys/proc.h> 86 #include <sys/kthread.h> 87 #include <sys/ktr.h> 88 #include <sys/mount.h> 89 #include <sys/resourcevar.h> 90 #include <sys/sched.h> 91 #include <sys/signalvar.h> 92 #include <sys/vnode.h> 93 #include <sys/vmmeter.h> 94 #include <sys/sx.h> 95 #include <sys/sysctl.h> 96 97 #include <vm/vm.h> 98 #include <vm/vm_param.h> 99 #include <vm/vm_object.h> 100 #include <vm/vm_page.h> 101 #include <vm/vm_map.h> 102 #include <vm/vm_pageout.h> 103 #include <vm/vm_pager.h> 104 #include <vm/swap_pager.h> 105 #include <vm/vm_extern.h> 106 #include <vm/uma.h> 107 108 #include <machine/mutex.h> 109 110 /* 111 * System initialization 112 */ 113 114 /* the kernel process "vm_pageout"*/ 115 static void vm_pageout(void); 116 static int vm_pageout_clean(vm_page_t); 117 static void vm_pageout_scan(int pass); 118 119 struct proc *pageproc; 120 121 static struct kproc_desc page_kp = { 122 "pagedaemon", 123 vm_pageout, 124 &pageproc 125 }; 126 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 127 128 #if !defined(NO_SWAPPING) 129 /* the kernel process "vm_daemon"*/ 130 static void vm_daemon(void); 131 static struct proc *vmproc; 132 133 static struct kproc_desc vm_kp = { 134 "vmdaemon", 135 vm_daemon, 136 &vmproc 137 }; 138 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) 139 #endif 140 141 142 int vm_pages_needed; /* Event on which pageout daemon sleeps */ 143 int vm_pageout_deficit; /* Estimated number of pages deficit */ 144 int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 145 146 #if !defined(NO_SWAPPING) 147 static int vm_pageout_req_swapout; /* XXX */ 148 static int vm_daemon_needed; 149 static struct mtx vm_daemon_mtx; 150 /* Allow for use by vm_pageout before vm_daemon is initialized. */ 151 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); 152 #endif 153 static int vm_max_launder = 32; 154 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 155 static int vm_pageout_full_stats_interval = 0; 156 static int vm_pageout_algorithm=0; 157 static int defer_swap_pageouts=0; 158 static int disable_swap_pageouts=0; 159 160 #if defined(NO_SWAPPING) 161 static int vm_swap_enabled=0; 162 static int vm_swap_idle_enabled=0; 163 #else 164 static int vm_swap_enabled=1; 165 static int vm_swap_idle_enabled=0; 166 #endif 167 168 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 169 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 170 171 SYSCTL_INT(_vm, OID_AUTO, max_launder, 172 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 173 174 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 175 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 176 177 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 178 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 179 180 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 181 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 182 183 #if defined(NO_SWAPPING) 184 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 185 CTLFLAG_RD, &vm_swap_enabled, 0, ""); 186 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 187 CTLFLAG_RD, &vm_swap_idle_enabled, 0, ""); 188 #else 189 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 190 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 191 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 192 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 193 #endif 194 195 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 196 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 197 198 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 199 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 200 201 static int pageout_lock_miss; 202 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 203 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 204 205 #define VM_PAGEOUT_PAGE_COUNT 16 206 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 207 208 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 209 SYSCTL_INT(_vm, OID_AUTO, max_wired, 210 CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count"); 211 212 #if !defined(NO_SWAPPING) 213 static void vm_pageout_map_deactivate_pages(vm_map_t, long); 214 static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long); 215 static void vm_req_vmdaemon(int req); 216 #endif 217 static void vm_pageout_page_stats(void); 218 219 /* 220 * vm_pageout_fallback_object_lock: 221 * 222 * Lock vm object currently associated with `m'. VM_OBJECT_TRYLOCK is 223 * known to have failed and page queue must be either PQ_ACTIVE or 224 * PQ_INACTIVE. To avoid lock order violation, unlock the page queues 225 * while locking the vm object. Use marker page to detect page queue 226 * changes and maintain notion of next page on page queue. Return 227 * TRUE if no changes were detected, FALSE otherwise. vm object is 228 * locked on return. 229 * 230 * This function depends on both the lock portion of struct vm_object 231 * and normal struct vm_page being type stable. 232 */ 233 boolean_t 234 vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next) 235 { 236 struct vm_page marker; 237 boolean_t unchanged; 238 u_short queue; 239 vm_object_t object; 240 241 /* 242 * Initialize our marker 243 */ 244 bzero(&marker, sizeof(marker)); 245 marker.flags = PG_FICTITIOUS | PG_MARKER; 246 marker.oflags = VPO_BUSY; 247 marker.queue = m->queue; 248 marker.wire_count = 1; 249 250 queue = m->queue; 251 object = m->object; 252 253 TAILQ_INSERT_AFTER(&vm_page_queues[queue].pl, 254 m, &marker, pageq); 255 vm_page_unlock_queues(); 256 VM_OBJECT_LOCK(object); 257 vm_page_lock_queues(); 258 259 /* Page queue might have changed. */ 260 *next = TAILQ_NEXT(&marker, pageq); 261 unchanged = (m->queue == queue && 262 m->object == object && 263 &marker == TAILQ_NEXT(m, pageq)); 264 TAILQ_REMOVE(&vm_page_queues[queue].pl, 265 &marker, pageq); 266 return (unchanged); 267 } 268 269 /* 270 * vm_pageout_clean: 271 * 272 * Clean the page and remove it from the laundry. 273 * 274 * We set the busy bit to cause potential page faults on this page to 275 * block. Note the careful timing, however, the busy bit isn't set till 276 * late and we cannot do anything that will mess with the page. 277 */ 278 static int 279 vm_pageout_clean(m) 280 vm_page_t m; 281 { 282 vm_object_t object; 283 vm_page_t mc[2*vm_pageout_page_count]; 284 int pageout_count; 285 int ib, is, page_base; 286 vm_pindex_t pindex = m->pindex; 287 288 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 289 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 290 291 /* 292 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 293 * with the new swapper, but we could have serious problems paging 294 * out other object types if there is insufficient memory. 295 * 296 * Unfortunately, checking free memory here is far too late, so the 297 * check has been moved up a procedural level. 298 */ 299 300 /* 301 * Can't clean the page if it's busy or held. 302 */ 303 if ((m->hold_count != 0) || 304 ((m->busy != 0) || (m->oflags & VPO_BUSY))) { 305 return 0; 306 } 307 308 mc[vm_pageout_page_count] = m; 309 pageout_count = 1; 310 page_base = vm_pageout_page_count; 311 ib = 1; 312 is = 1; 313 314 /* 315 * Scan object for clusterable pages. 316 * 317 * We can cluster ONLY if: ->> the page is NOT 318 * clean, wired, busy, held, or mapped into a 319 * buffer, and one of the following: 320 * 1) The page is inactive, or a seldom used 321 * active page. 322 * -or- 323 * 2) we force the issue. 324 * 325 * During heavy mmap/modification loads the pageout 326 * daemon can really fragment the underlying file 327 * due to flushing pages out of order and not trying 328 * align the clusters (which leave sporatic out-of-order 329 * holes). To solve this problem we do the reverse scan 330 * first and attempt to align our cluster, then do a 331 * forward scan if room remains. 332 */ 333 object = m->object; 334 more: 335 while (ib && pageout_count < vm_pageout_page_count) { 336 vm_page_t p; 337 338 if (ib > pindex) { 339 ib = 0; 340 break; 341 } 342 343 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) { 344 ib = 0; 345 break; 346 } 347 if ((p->oflags & VPO_BUSY) || p->busy) { 348 ib = 0; 349 break; 350 } 351 vm_page_test_dirty(p); 352 if ((p->dirty & p->valid) == 0 || 353 p->queue != PQ_INACTIVE || 354 p->wire_count != 0 || /* may be held by buf cache */ 355 p->hold_count != 0) { /* may be undergoing I/O */ 356 ib = 0; 357 break; 358 } 359 mc[--page_base] = p; 360 ++pageout_count; 361 ++ib; 362 /* 363 * alignment boundry, stop here and switch directions. Do 364 * not clear ib. 365 */ 366 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 367 break; 368 } 369 370 while (pageout_count < vm_pageout_page_count && 371 pindex + is < object->size) { 372 vm_page_t p; 373 374 if ((p = vm_page_lookup(object, pindex + is)) == NULL) 375 break; 376 if ((p->oflags & VPO_BUSY) || p->busy) { 377 break; 378 } 379 vm_page_test_dirty(p); 380 if ((p->dirty & p->valid) == 0 || 381 p->queue != PQ_INACTIVE || 382 p->wire_count != 0 || /* may be held by buf cache */ 383 p->hold_count != 0) { /* may be undergoing I/O */ 384 break; 385 } 386 mc[page_base + pageout_count] = p; 387 ++pageout_count; 388 ++is; 389 } 390 391 /* 392 * If we exhausted our forward scan, continue with the reverse scan 393 * when possible, even past a page boundry. This catches boundry 394 * conditions. 395 */ 396 if (ib && pageout_count < vm_pageout_page_count) 397 goto more; 398 399 /* 400 * we allow reads during pageouts... 401 */ 402 return (vm_pageout_flush(&mc[page_base], pageout_count, 0)); 403 } 404 405 /* 406 * vm_pageout_flush() - launder the given pages 407 * 408 * The given pages are laundered. Note that we setup for the start of 409 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 410 * reference count all in here rather then in the parent. If we want 411 * the parent to do more sophisticated things we may have to change 412 * the ordering. 413 */ 414 int 415 vm_pageout_flush(vm_page_t *mc, int count, int flags) 416 { 417 vm_object_t object = mc[0]->object; 418 int pageout_status[count]; 419 int numpagedout = 0; 420 int i; 421 422 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 423 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 424 /* 425 * Initiate I/O. Bump the vm_page_t->busy counter and 426 * mark the pages read-only. 427 * 428 * We do not have to fixup the clean/dirty bits here... we can 429 * allow the pager to do it after the I/O completes. 430 * 431 * NOTE! mc[i]->dirty may be partial or fragmented due to an 432 * edge case with file fragments. 433 */ 434 for (i = 0; i < count; i++) { 435 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 436 ("vm_pageout_flush: partially invalid page %p index %d/%d", 437 mc[i], i, count)); 438 vm_page_io_start(mc[i]); 439 pmap_remove_write(mc[i]); 440 } 441 vm_page_unlock_queues(); 442 vm_object_pip_add(object, count); 443 444 vm_pager_put_pages(object, mc, count, flags, pageout_status); 445 446 vm_page_lock_queues(); 447 for (i = 0; i < count; i++) { 448 vm_page_t mt = mc[i]; 449 450 KASSERT(pageout_status[i] == VM_PAGER_PEND || 451 (mt->flags & PG_WRITEABLE) == 0, 452 ("vm_pageout_flush: page %p is not write protected", mt)); 453 switch (pageout_status[i]) { 454 case VM_PAGER_OK: 455 case VM_PAGER_PEND: 456 numpagedout++; 457 break; 458 case VM_PAGER_BAD: 459 /* 460 * Page outside of range of object. Right now we 461 * essentially lose the changes by pretending it 462 * worked. 463 */ 464 pmap_clear_modify(mt); 465 vm_page_undirty(mt); 466 break; 467 case VM_PAGER_ERROR: 468 case VM_PAGER_FAIL: 469 /* 470 * If page couldn't be paged out, then reactivate the 471 * page so it doesn't clog the inactive list. (We 472 * will try paging out it again later). 473 */ 474 vm_page_activate(mt); 475 break; 476 case VM_PAGER_AGAIN: 477 break; 478 } 479 480 /* 481 * If the operation is still going, leave the page busy to 482 * block all other accesses. Also, leave the paging in 483 * progress indicator set so that we don't attempt an object 484 * collapse. 485 */ 486 if (pageout_status[i] != VM_PAGER_PEND) { 487 vm_object_pip_wakeup(object); 488 vm_page_io_finish(mt); 489 if (vm_page_count_severe()) 490 vm_page_try_to_cache(mt); 491 } 492 } 493 return numpagedout; 494 } 495 496 #if !defined(NO_SWAPPING) 497 /* 498 * vm_pageout_object_deactivate_pages 499 * 500 * deactivate enough pages to satisfy the inactive target 501 * requirements or if vm_page_proc_limit is set, then 502 * deactivate all of the pages in the object and its 503 * backing_objects. 504 * 505 * The object and map must be locked. 506 */ 507 static void 508 vm_pageout_object_deactivate_pages(pmap, first_object, desired) 509 pmap_t pmap; 510 vm_object_t first_object; 511 long desired; 512 { 513 vm_object_t backing_object, object; 514 vm_page_t p, next; 515 int actcount, rcount, remove_mode; 516 517 VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED); 518 if (first_object->type == OBJT_DEVICE || 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_pageq_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_pageq_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 struct proc *p, *bigproc; 684 struct thread *td; 685 vm_offset_t size, bigsize; 686 vm_object_t object; 687 int actcount; 688 int vnodes_skipped = 0; 689 int maxlaunder; 690 691 /* 692 * Decrease registered cache sizes. 693 */ 694 EVENTHANDLER_INVOKE(vm_lowmem, 0); 695 /* 696 * We do this explicitly after the caches have been drained above. 697 */ 698 uma_reclaim(); 699 700 addl_page_shortage_init = atomic_readandclear_int(&vm_pageout_deficit); 701 702 /* 703 * Calculate the number of pages we want to either free or move 704 * to the cache. 705 */ 706 page_shortage = vm_paging_target() + addl_page_shortage_init; 707 708 /* 709 * Initialize our marker 710 */ 711 bzero(&marker, sizeof(marker)); 712 marker.flags = PG_FICTITIOUS | PG_MARKER; 713 marker.oflags = VPO_BUSY; 714 marker.queue = PQ_INACTIVE; 715 marker.wire_count = 1; 716 717 /* 718 * Start scanning the inactive queue for pages we can move to the 719 * cache or free. The scan will stop when the target is reached or 720 * we have scanned the entire inactive queue. Note that m->act_count 721 * is not used to form decisions for the inactive queue, only for the 722 * active queue. 723 * 724 * maxlaunder limits the number of dirty pages we flush per scan. 725 * For most systems a smaller value (16 or 32) is more robust under 726 * extreme memory and disk pressure because any unnecessary writes 727 * to disk can result in extreme performance degredation. However, 728 * systems with excessive dirty pages (especially when MAP_NOSYNC is 729 * used) will die horribly with limited laundering. If the pageout 730 * daemon cannot clean enough pages in the first pass, we let it go 731 * all out in succeeding passes. 732 */ 733 if ((maxlaunder = vm_max_launder) <= 1) 734 maxlaunder = 1; 735 if (pass) 736 maxlaunder = 10000; 737 vm_page_lock_queues(); 738 rescan0: 739 addl_page_shortage = addl_page_shortage_init; 740 maxscan = cnt.v_inactive_count; 741 742 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 743 m != NULL && maxscan-- > 0 && page_shortage > 0; 744 m = next) { 745 746 cnt.v_pdpages++; 747 748 if (VM_PAGE_GETQUEUE(m) != PQ_INACTIVE) { 749 goto rescan0; 750 } 751 752 next = TAILQ_NEXT(m, pageq); 753 object = m->object; 754 755 /* 756 * skip marker pages 757 */ 758 if (m->flags & PG_MARKER) 759 continue; 760 761 /* 762 * A held page may be undergoing I/O, so skip it. 763 */ 764 if (m->hold_count) { 765 vm_pageq_requeue(m); 766 addl_page_shortage++; 767 continue; 768 } 769 /* 770 * Don't mess with busy pages, keep in the front of the 771 * queue, most likely are being paged out. 772 */ 773 if (!VM_OBJECT_TRYLOCK(object) && 774 (!vm_pageout_fallback_object_lock(m, &next) || 775 m->hold_count != 0)) { 776 VM_OBJECT_UNLOCK(object); 777 addl_page_shortage++; 778 continue; 779 } 780 if (m->busy || (m->oflags & VPO_BUSY)) { 781 VM_OBJECT_UNLOCK(object); 782 addl_page_shortage++; 783 continue; 784 } 785 786 /* 787 * If the object is not being used, we ignore previous 788 * references. 789 */ 790 if (object->ref_count == 0) { 791 vm_page_flag_clear(m, PG_REFERENCED); 792 pmap_clear_reference(m); 793 794 /* 795 * Otherwise, if the page has been referenced while in the 796 * inactive queue, we bump the "activation count" upwards, 797 * making it less likely that the page will be added back to 798 * the inactive queue prematurely again. Here we check the 799 * page tables (or emulated bits, if any), given the upper 800 * level VM system not knowing anything about existing 801 * references. 802 */ 803 } else if (((m->flags & PG_REFERENCED) == 0) && 804 (actcount = pmap_ts_referenced(m))) { 805 vm_page_activate(m); 806 VM_OBJECT_UNLOCK(object); 807 m->act_count += (actcount + ACT_ADVANCE); 808 continue; 809 } 810 811 /* 812 * If the upper level VM system knows about any page 813 * references, we activate the page. We also set the 814 * "activation count" higher than normal so that we will less 815 * likely place pages back onto the inactive queue again. 816 */ 817 if ((m->flags & PG_REFERENCED) != 0) { 818 vm_page_flag_clear(m, PG_REFERENCED); 819 actcount = pmap_ts_referenced(m); 820 vm_page_activate(m); 821 VM_OBJECT_UNLOCK(object); 822 m->act_count += (actcount + ACT_ADVANCE + 1); 823 continue; 824 } 825 826 /* 827 * If the upper level VM system doesn't know anything about 828 * the page being dirty, we have to check for it again. As 829 * far as the VM code knows, any partially dirty pages are 830 * fully dirty. 831 */ 832 if (m->dirty == 0 && !pmap_is_modified(m)) { 833 /* 834 * Avoid a race condition: Unless write access is 835 * removed from the page, another processor could 836 * modify it before all access is removed by the call 837 * to vm_page_cache() below. If vm_page_cache() finds 838 * that the page has been modified when it removes all 839 * access, it panics because it cannot cache dirty 840 * pages. In principle, we could eliminate just write 841 * access here rather than all access. In the expected 842 * case, when there are no last instant modifications 843 * to the page, removing all access will be cheaper 844 * overall. 845 */ 846 if ((m->flags & PG_WRITEABLE) != 0) 847 pmap_remove_all(m); 848 } else { 849 vm_page_dirty(m); 850 } 851 852 if (m->valid == 0) { 853 /* 854 * Invalid pages can be easily freed 855 */ 856 vm_page_free(m); 857 cnt.v_dfree++; 858 --page_shortage; 859 } else if (m->dirty == 0) { 860 /* 861 * Clean pages can be placed onto the cache queue. 862 * This effectively frees them. 863 */ 864 vm_page_cache(m); 865 --page_shortage; 866 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 867 /* 868 * Dirty pages need to be paged out, but flushing 869 * a page is extremely expensive verses freeing 870 * a clean page. Rather then artificially limiting 871 * the number of pages we can flush, we instead give 872 * dirty pages extra priority on the inactive queue 873 * by forcing them to be cycled through the queue 874 * twice before being flushed, after which the 875 * (now clean) page will cycle through once more 876 * before being freed. This significantly extends 877 * the thrash point for a heavily loaded machine. 878 */ 879 vm_page_flag_set(m, PG_WINATCFLS); 880 vm_pageq_requeue(m); 881 } else if (maxlaunder > 0) { 882 /* 883 * We always want to try to flush some dirty pages if 884 * we encounter them, to keep the system stable. 885 * Normally this number is small, but under extreme 886 * pressure where there are insufficient clean pages 887 * on the inactive queue, we may have to go all out. 888 */ 889 int swap_pageouts_ok, vfslocked = 0; 890 struct vnode *vp = NULL; 891 struct mount *mp = NULL; 892 893 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 894 swap_pageouts_ok = 1; 895 } else { 896 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 897 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 898 vm_page_count_min()); 899 900 } 901 902 /* 903 * We don't bother paging objects that are "dead". 904 * Those objects are in a "rundown" state. 905 */ 906 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 907 VM_OBJECT_UNLOCK(object); 908 vm_pageq_requeue(m); 909 continue; 910 } 911 912 /* 913 * Following operations may unlock 914 * vm_page_queue_mtx, invalidating the 'next' 915 * pointer. To prevent an inordinate number 916 * of restarts we use our marker to remember 917 * our place. 918 * 919 */ 920 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, 921 m, &marker, pageq); 922 /* 923 * The object is already known NOT to be dead. It 924 * is possible for the vget() to block the whole 925 * pageout daemon, but the new low-memory handling 926 * code should prevent it. 927 * 928 * The previous code skipped locked vnodes and, worse, 929 * reordered pages in the queue. This results in 930 * completely non-deterministic operation and, on a 931 * busy system, can lead to extremely non-optimal 932 * pageouts. For example, it can cause clean pages 933 * to be freed and dirty pages to be moved to the end 934 * of the queue. Since dirty pages are also moved to 935 * the end of the queue once-cleaned, this gives 936 * way too large a weighting to defering the freeing 937 * of dirty pages. 938 * 939 * We can't wait forever for the vnode lock, we might 940 * deadlock due to a vn_read() getting stuck in 941 * vm_wait while holding this vnode. We skip the 942 * vnode if we can't get it in a reasonable amount 943 * of time. 944 */ 945 if (object->type == OBJT_VNODE) { 946 vp = object->handle; 947 if (vp->v_type == VREG && 948 vn_start_write(vp, &mp, V_NOWAIT) != 0) { 949 KASSERT(mp == NULL, 950 ("vm_pageout_scan: mp != NULL")); 951 ++pageout_lock_miss; 952 if (object->flags & OBJ_MIGHTBEDIRTY) 953 vnodes_skipped++; 954 goto unlock_and_continue; 955 } 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_pageq_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_pageq_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_pageq_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_pageq_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 * We keep the process bigproc locked once we find it to keep anyone 1178 * from messing with it; however, there is a possibility of 1179 * deadlock if process B is bigproc and one of it's child processes 1180 * attempts to propagate a signal to B while we are waiting for A's 1181 * lock while walking this list. To avoid this, we don't block on 1182 * the process lock but just skip a process if it is already locked. 1183 */ 1184 if (pass != 0 && 1185 ((swap_pager_avail < 64 && vm_page_count_min()) || 1186 (swap_pager_full && vm_paging_target() > 0))) { 1187 bigproc = NULL; 1188 bigsize = 0; 1189 sx_slock(&allproc_lock); 1190 FOREACH_PROC_IN_SYSTEM(p) { 1191 int breakout; 1192 1193 if (PROC_TRYLOCK(p) == 0) 1194 continue; 1195 /* 1196 * If this is a system or protected process, skip it. 1197 */ 1198 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1199 (p->p_flag & P_PROTECTED) || 1200 ((p->p_pid < 48) && (swap_pager_avail != 0))) { 1201 PROC_UNLOCK(p); 1202 continue; 1203 } 1204 /* 1205 * If the process is in a non-running type state, 1206 * don't touch it. Check all the threads individually. 1207 */ 1208 PROC_SLOCK(p); 1209 breakout = 0; 1210 FOREACH_THREAD_IN_PROC(p, td) { 1211 thread_lock(td); 1212 if (!TD_ON_RUNQ(td) && 1213 !TD_IS_RUNNING(td) && 1214 !TD_IS_SLEEPING(td)) { 1215 thread_unlock(td); 1216 breakout = 1; 1217 break; 1218 } 1219 thread_unlock(td); 1220 } 1221 PROC_SUNLOCK(p); 1222 if (breakout) { 1223 PROC_UNLOCK(p); 1224 continue; 1225 } 1226 /* 1227 * get the process size 1228 */ 1229 if (!vm_map_trylock_read(&p->p_vmspace->vm_map)) { 1230 PROC_UNLOCK(p); 1231 continue; 1232 } 1233 size = vmspace_swap_count(p->p_vmspace); 1234 vm_map_unlock_read(&p->p_vmspace->vm_map); 1235 size += vmspace_resident_count(p->p_vmspace); 1236 /* 1237 * if the this process is bigger than the biggest one 1238 * remember it. 1239 */ 1240 if (size > bigsize) { 1241 if (bigproc != NULL) 1242 PROC_UNLOCK(bigproc); 1243 bigproc = p; 1244 bigsize = size; 1245 } else 1246 PROC_UNLOCK(p); 1247 } 1248 sx_sunlock(&allproc_lock); 1249 if (bigproc != NULL) { 1250 killproc(bigproc, "out of swap space"); 1251 PROC_SLOCK(bigproc); 1252 sched_nice(bigproc, PRIO_MIN); 1253 PROC_SUNLOCK(bigproc); 1254 PROC_UNLOCK(bigproc); 1255 wakeup(&cnt.v_free_count); 1256 } 1257 } 1258 } 1259 1260 /* 1261 * This routine tries to maintain the pseudo LRU active queue, 1262 * so that during long periods of time where there is no paging, 1263 * that some statistic accumulation still occurs. This code 1264 * helps the situation where paging just starts to occur. 1265 */ 1266 static void 1267 vm_pageout_page_stats() 1268 { 1269 vm_object_t object; 1270 vm_page_t m,next; 1271 int pcount,tpcount; /* Number of pages to check */ 1272 static int fullintervalcount = 0; 1273 int page_shortage; 1274 1275 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1276 page_shortage = 1277 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1278 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1279 1280 if (page_shortage <= 0) 1281 return; 1282 1283 pcount = cnt.v_active_count; 1284 fullintervalcount += vm_pageout_stats_interval; 1285 if (fullintervalcount < vm_pageout_full_stats_interval) { 1286 tpcount = (vm_pageout_stats_max * cnt.v_active_count) / cnt.v_page_count; 1287 if (pcount > tpcount) 1288 pcount = tpcount; 1289 } else { 1290 fullintervalcount = 0; 1291 } 1292 1293 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1294 while ((m != NULL) && (pcount-- > 0)) { 1295 int actcount; 1296 1297 KASSERT(VM_PAGE_INQUEUE2(m, PQ_ACTIVE), 1298 ("vm_pageout_page_stats: page %p isn't active", m)); 1299 1300 next = TAILQ_NEXT(m, pageq); 1301 object = m->object; 1302 1303 if ((m->flags & PG_MARKER) != 0) { 1304 m = next; 1305 continue; 1306 } 1307 if (!VM_OBJECT_TRYLOCK(object) && 1308 !vm_pageout_fallback_object_lock(m, &next)) { 1309 VM_OBJECT_UNLOCK(object); 1310 m = next; 1311 continue; 1312 } 1313 1314 /* 1315 * Don't deactivate pages that are busy. 1316 */ 1317 if ((m->busy != 0) || 1318 (m->oflags & VPO_BUSY) || 1319 (m->hold_count != 0)) { 1320 VM_OBJECT_UNLOCK(object); 1321 vm_pageq_requeue(m); 1322 m = next; 1323 continue; 1324 } 1325 1326 actcount = 0; 1327 if (m->flags & PG_REFERENCED) { 1328 vm_page_flag_clear(m, PG_REFERENCED); 1329 actcount += 1; 1330 } 1331 1332 actcount += pmap_ts_referenced(m); 1333 if (actcount) { 1334 m->act_count += ACT_ADVANCE + actcount; 1335 if (m->act_count > ACT_MAX) 1336 m->act_count = ACT_MAX; 1337 vm_pageq_requeue(m); 1338 } else { 1339 if (m->act_count == 0) { 1340 /* 1341 * We turn off page access, so that we have 1342 * more accurate RSS stats. We don't do this 1343 * in the normal page deactivation when the 1344 * system is loaded VM wise, because the 1345 * cost of the large number of page protect 1346 * operations would be higher than the value 1347 * of doing the operation. 1348 */ 1349 pmap_remove_all(m); 1350 vm_page_deactivate(m); 1351 } else { 1352 m->act_count -= min(m->act_count, ACT_DECLINE); 1353 vm_pageq_requeue(m); 1354 } 1355 } 1356 VM_OBJECT_UNLOCK(object); 1357 m = next; 1358 } 1359 } 1360 1361 /* 1362 * vm_pageout is the high level pageout daemon. 1363 */ 1364 static void 1365 vm_pageout() 1366 { 1367 int error, pass; 1368 1369 /* 1370 * Initialize some paging parameters. 1371 */ 1372 cnt.v_interrupt_free_min = 2; 1373 if (cnt.v_page_count < 2000) 1374 vm_pageout_page_count = 8; 1375 1376 /* 1377 * v_free_reserved needs to include enough for the largest 1378 * swap pager structures plus enough for any pv_entry structs 1379 * when paging. 1380 */ 1381 if (cnt.v_page_count > 1024) 1382 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1383 else 1384 cnt.v_free_min = 4; 1385 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1386 cnt.v_interrupt_free_min; 1387 cnt.v_free_reserved = vm_pageout_page_count + 1388 cnt.v_pageout_free_min + (cnt.v_page_count / 768); 1389 cnt.v_free_severe = cnt.v_free_min / 2; 1390 cnt.v_free_min += cnt.v_free_reserved; 1391 cnt.v_free_severe += cnt.v_free_reserved; 1392 1393 /* 1394 * v_free_target and v_cache_min control pageout hysteresis. Note 1395 * that these are more a measure of the VM cache queue hysteresis 1396 * then the VM free queue. Specifically, v_free_target is the 1397 * high water mark (free+cache pages). 1398 * 1399 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1400 * low water mark, while v_free_min is the stop. v_cache_min must 1401 * be big enough to handle memory needs while the pageout daemon 1402 * is signalled and run to free more pages. 1403 */ 1404 if (cnt.v_free_count > 6144) 1405 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1406 else 1407 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1408 1409 if (cnt.v_free_count > 2048) { 1410 cnt.v_cache_min = cnt.v_free_target; 1411 cnt.v_cache_max = 2 * cnt.v_cache_min; 1412 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1413 } else { 1414 cnt.v_cache_min = 0; 1415 cnt.v_cache_max = 0; 1416 cnt.v_inactive_target = cnt.v_free_count / 4; 1417 } 1418 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1419 cnt.v_inactive_target = cnt.v_free_count / 3; 1420 1421 /* XXX does not really belong here */ 1422 if (vm_page_max_wired == 0) 1423 vm_page_max_wired = cnt.v_free_count / 3; 1424 1425 if (vm_pageout_stats_max == 0) 1426 vm_pageout_stats_max = cnt.v_free_target; 1427 1428 /* 1429 * Set interval in seconds for stats scan. 1430 */ 1431 if (vm_pageout_stats_interval == 0) 1432 vm_pageout_stats_interval = 5; 1433 if (vm_pageout_full_stats_interval == 0) 1434 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1435 1436 swap_pager_swap_init(); 1437 pass = 0; 1438 /* 1439 * The pageout daemon is never done, so loop forever. 1440 */ 1441 while (TRUE) { 1442 /* 1443 * If we have enough free memory, wakeup waiters. Do 1444 * not clear vm_pages_needed until we reach our target, 1445 * otherwise we may be woken up over and over again and 1446 * waste a lot of cpu. 1447 */ 1448 mtx_lock(&vm_page_queue_free_mtx); 1449 if (vm_pages_needed && !vm_page_count_min()) { 1450 if (!vm_paging_needed()) 1451 vm_pages_needed = 0; 1452 wakeup(&cnt.v_free_count); 1453 } 1454 if (vm_pages_needed) { 1455 /* 1456 * Still not done, take a second pass without waiting 1457 * (unlimited dirty cleaning), otherwise sleep a bit 1458 * and try again. 1459 */ 1460 ++pass; 1461 if (pass > 1) 1462 msleep(&vm_pages_needed, 1463 &vm_page_queue_free_mtx, PVM, "psleep", 1464 hz / 2); 1465 } else { 1466 /* 1467 * Good enough, sleep & handle stats. Prime the pass 1468 * for the next run. 1469 */ 1470 if (pass > 1) 1471 pass = 1; 1472 else 1473 pass = 0; 1474 error = msleep(&vm_pages_needed, 1475 &vm_page_queue_free_mtx, PVM, "psleep", 1476 vm_pageout_stats_interval * hz); 1477 if (error && !vm_pages_needed) { 1478 mtx_unlock(&vm_page_queue_free_mtx); 1479 pass = 0; 1480 vm_page_lock_queues(); 1481 vm_pageout_page_stats(); 1482 vm_page_unlock_queues(); 1483 continue; 1484 } 1485 } 1486 if (vm_pages_needed) 1487 cnt.v_pdwakeups++; 1488 mtx_unlock(&vm_page_queue_free_mtx); 1489 vm_pageout_scan(pass); 1490 } 1491 } 1492 1493 /* 1494 * Unless the free page queue lock is held by the caller, this function 1495 * should be regarded as advisory. Specifically, the caller should 1496 * not msleep() on &cnt.v_free_count following this function unless 1497 * the free page queue lock is held until the msleep() is performed. 1498 */ 1499 void 1500 pagedaemon_wakeup() 1501 { 1502 1503 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1504 vm_pages_needed = 1; 1505 wakeup(&vm_pages_needed); 1506 } 1507 } 1508 1509 #if !defined(NO_SWAPPING) 1510 static void 1511 vm_req_vmdaemon(int req) 1512 { 1513 static int lastrun = 0; 1514 1515 mtx_lock(&vm_daemon_mtx); 1516 vm_pageout_req_swapout |= req; 1517 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1518 wakeup(&vm_daemon_needed); 1519 lastrun = ticks; 1520 } 1521 mtx_unlock(&vm_daemon_mtx); 1522 } 1523 1524 static void 1525 vm_daemon() 1526 { 1527 struct rlimit rsslim; 1528 struct proc *p; 1529 struct thread *td; 1530 int breakout, swapout_flags; 1531 1532 while (TRUE) { 1533 mtx_lock(&vm_daemon_mtx); 1534 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0); 1535 swapout_flags = vm_pageout_req_swapout; 1536 vm_pageout_req_swapout = 0; 1537 mtx_unlock(&vm_daemon_mtx); 1538 if (swapout_flags) 1539 swapout_procs(swapout_flags); 1540 1541 /* 1542 * scan the processes for exceeding their rlimits or if 1543 * process is swapped out -- deactivate pages 1544 */ 1545 sx_slock(&allproc_lock); 1546 FOREACH_PROC_IN_SYSTEM(p) { 1547 vm_pindex_t limit, size; 1548 1549 /* 1550 * if this is a system process or if we have already 1551 * looked at this process, skip it. 1552 */ 1553 PROC_LOCK(p); 1554 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 1555 PROC_UNLOCK(p); 1556 continue; 1557 } 1558 /* 1559 * if the process is in a non-running type state, 1560 * don't touch it. 1561 */ 1562 PROC_SLOCK(p); 1563 breakout = 0; 1564 FOREACH_THREAD_IN_PROC(p, td) { 1565 thread_lock(td); 1566 if (!TD_ON_RUNQ(td) && 1567 !TD_IS_RUNNING(td) && 1568 !TD_IS_SLEEPING(td)) { 1569 thread_unlock(td); 1570 breakout = 1; 1571 break; 1572 } 1573 thread_unlock(td); 1574 } 1575 PROC_SUNLOCK(p); 1576 if (breakout) { 1577 PROC_UNLOCK(p); 1578 continue; 1579 } 1580 /* 1581 * get a limit 1582 */ 1583 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1584 limit = OFF_TO_IDX( 1585 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1586 1587 /* 1588 * let processes that are swapped out really be 1589 * swapped out set the limit to nothing (will force a 1590 * swap-out.) 1591 */ 1592 if ((p->p_flag & P_INMEM) == 0) 1593 limit = 0; /* XXX */ 1594 PROC_UNLOCK(p); 1595 1596 size = vmspace_resident_count(p->p_vmspace); 1597 if (limit >= 0 && size >= limit) { 1598 vm_pageout_map_deactivate_pages( 1599 &p->p_vmspace->vm_map, limit); 1600 } 1601 } 1602 sx_sunlock(&allproc_lock); 1603 } 1604 } 1605 #endif /* !defined(NO_SWAPPING) */ 1606