vm_pageout.c revision 136996
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 * 9 * This code is derived from software contributed to Berkeley by 10 * The Mach Operating System project at Carnegie-Mellon University. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 41 * 42 * 43 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 44 * All rights reserved. 45 * 46 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 47 * 48 * Permission to use, copy, modify and distribute this software and 49 * its documentation is hereby granted, provided that both the copyright 50 * notice and this permission notice appear in all copies of the 51 * software, derivative works or modified versions, and any portions 52 * thereof, and that both notices appear in supporting documentation. 53 * 54 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 55 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 56 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 57 * 58 * Carnegie Mellon requests users of this software to return to 59 * 60 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 61 * School of Computer Science 62 * Carnegie Mellon University 63 * Pittsburgh PA 15213-3890 64 * 65 * any improvements or extensions that they make and grant Carnegie the 66 * rights to redistribute these changes. 67 */ 68 69/* 70 * The proverbial page-out daemon. 71 */ 72 73#include <sys/cdefs.h> 74__FBSDID("$FreeBSD: head/sys/vm/vm_pageout.c 136996 2004-10-27 18:29:17Z alc $"); 75 76#include "opt_vm.h" 77#include <sys/param.h> 78#include <sys/systm.h> 79#include <sys/kernel.h> 80#include <sys/eventhandler.h> 81#include <sys/lock.h> 82#include <sys/mutex.h> 83#include <sys/proc.h> 84#include <sys/kthread.h> 85#include <sys/ktr.h> 86#include <sys/resourcevar.h> 87#include <sys/sched.h> 88#include <sys/signalvar.h> 89#include <sys/vnode.h> 90#include <sys/vmmeter.h> 91#include <sys/sx.h> 92#include <sys/sysctl.h> 93 94#include <vm/vm.h> 95#include <vm/vm_param.h> 96#include <vm/vm_object.h> 97#include <vm/vm_page.h> 98#include <vm/vm_map.h> 99#include <vm/vm_pageout.h> 100#include <vm/vm_pager.h> 101#include <vm/swap_pager.h> 102#include <vm/vm_extern.h> 103#include <vm/uma.h> 104 105#include <machine/mutex.h> 106 107/* 108 * System initialization 109 */ 110 111/* the kernel process "vm_pageout"*/ 112static void vm_pageout(void); 113static int vm_pageout_clean(vm_page_t); 114static void vm_pageout_pmap_collect(void); 115static void vm_pageout_scan(int pass); 116 117struct proc *pageproc; 118 119static struct kproc_desc page_kp = { 120 "pagedaemon", 121 vm_pageout, 122 &pageproc 123}; 124SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 125 126#if !defined(NO_SWAPPING) 127/* the kernel process "vm_daemon"*/ 128static void vm_daemon(void); 129static struct proc *vmproc; 130 131static struct kproc_desc vm_kp = { 132 "vmdaemon", 133 vm_daemon, 134 &vmproc 135}; 136SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) 137#endif 138 139 140int vm_pages_needed; /* Event on which pageout daemon sleeps */ 141int vm_pageout_deficit; /* Estimated number of pages deficit */ 142int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 143 144#if !defined(NO_SWAPPING) 145static int vm_pageout_req_swapout; /* XXX */ 146static int vm_daemon_needed; 147#endif 148static int vm_max_launder = 32; 149static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 150static int vm_pageout_full_stats_interval = 0; 151static int vm_pageout_algorithm=0; 152static int defer_swap_pageouts=0; 153static int disable_swap_pageouts=0; 154 155#if defined(NO_SWAPPING) 156static int vm_swap_enabled=0; 157static int vm_swap_idle_enabled=0; 158#else 159static int vm_swap_enabled=1; 160static int vm_swap_idle_enabled=0; 161#endif 162 163SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 164 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 165 166SYSCTL_INT(_vm, OID_AUTO, max_launder, 167 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 168 169SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 170 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 171 172SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 173 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 174 175SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 176 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 177 178#if defined(NO_SWAPPING) 179SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 180 CTLFLAG_RD, &vm_swap_enabled, 0, ""); 181SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 182 CTLFLAG_RD, &vm_swap_idle_enabled, 0, ""); 183#else 184SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 185 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 186SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 187 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 188#endif 189 190SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 191 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 192 193SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 194 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 195 196static int pageout_lock_miss; 197SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 198 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 199 200#define VM_PAGEOUT_PAGE_COUNT 16 201int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 202 203int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 204 205#if !defined(NO_SWAPPING) 206static void vm_pageout_map_deactivate_pages(vm_map_t, long); 207static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long); 208static void vm_req_vmdaemon(void); 209#endif 210static void vm_pageout_page_stats(void); 211 212/* 213 * vm_pageout_clean: 214 * 215 * Clean the page and remove it from the laundry. 216 * 217 * We set the busy bit to cause potential page faults on this page to 218 * block. Note the careful timing, however, the busy bit isn't set till 219 * late and we cannot do anything that will mess with the page. 220 */ 221static int 222vm_pageout_clean(m) 223 vm_page_t m; 224{ 225 vm_object_t object; 226 vm_page_t mc[2*vm_pageout_page_count]; 227 int pageout_count; 228 int ib, is, page_base; 229 vm_pindex_t pindex = m->pindex; 230 231 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 232 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 233 234 /* 235 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 236 * with the new swapper, but we could have serious problems paging 237 * out other object types if there is insufficient memory. 238 * 239 * Unfortunately, checking free memory here is far too late, so the 240 * check has been moved up a procedural level. 241 */ 242 243 /* 244 * Don't mess with the page if it's busy, held, or special 245 */ 246 if ((m->hold_count != 0) || 247 ((m->busy != 0) || (m->flags & (PG_BUSY|PG_UNMANAGED)))) { 248 return 0; 249 } 250 251 mc[vm_pageout_page_count] = m; 252 pageout_count = 1; 253 page_base = vm_pageout_page_count; 254 ib = 1; 255 is = 1; 256 257 /* 258 * Scan object for clusterable pages. 259 * 260 * We can cluster ONLY if: ->> the page is NOT 261 * clean, wired, busy, held, or mapped into a 262 * buffer, and one of the following: 263 * 1) The page is inactive, or a seldom used 264 * active page. 265 * -or- 266 * 2) we force the issue. 267 * 268 * During heavy mmap/modification loads the pageout 269 * daemon can really fragment the underlying file 270 * due to flushing pages out of order and not trying 271 * align the clusters (which leave sporatic out-of-order 272 * holes). To solve this problem we do the reverse scan 273 * first and attempt to align our cluster, then do a 274 * forward scan if room remains. 275 */ 276 object = m->object; 277more: 278 while (ib && pageout_count < vm_pageout_page_count) { 279 vm_page_t p; 280 281 if (ib > pindex) { 282 ib = 0; 283 break; 284 } 285 286 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) { 287 ib = 0; 288 break; 289 } 290 if (((p->queue - p->pc) == PQ_CACHE) || 291 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 292 ib = 0; 293 break; 294 } 295 vm_page_test_dirty(p); 296 if ((p->dirty & p->valid) == 0 || 297 p->queue != PQ_INACTIVE || 298 p->wire_count != 0 || /* may be held by buf cache */ 299 p->hold_count != 0) { /* may be undergoing I/O */ 300 ib = 0; 301 break; 302 } 303 mc[--page_base] = p; 304 ++pageout_count; 305 ++ib; 306 /* 307 * alignment boundry, stop here and switch directions. Do 308 * not clear ib. 309 */ 310 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 311 break; 312 } 313 314 while (pageout_count < vm_pageout_page_count && 315 pindex + is < object->size) { 316 vm_page_t p; 317 318 if ((p = vm_page_lookup(object, pindex + is)) == NULL) 319 break; 320 if (((p->queue - p->pc) == PQ_CACHE) || 321 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 322 break; 323 } 324 vm_page_test_dirty(p); 325 if ((p->dirty & p->valid) == 0 || 326 p->queue != PQ_INACTIVE || 327 p->wire_count != 0 || /* may be held by buf cache */ 328 p->hold_count != 0) { /* may be undergoing I/O */ 329 break; 330 } 331 mc[page_base + pageout_count] = p; 332 ++pageout_count; 333 ++is; 334 } 335 336 /* 337 * If we exhausted our forward scan, continue with the reverse scan 338 * when possible, even past a page boundry. This catches boundry 339 * conditions. 340 */ 341 if (ib && pageout_count < vm_pageout_page_count) 342 goto more; 343 344 /* 345 * we allow reads during pageouts... 346 */ 347 return (vm_pageout_flush(&mc[page_base], pageout_count, 0)); 348} 349 350/* 351 * vm_pageout_flush() - launder the given pages 352 * 353 * The given pages are laundered. Note that we setup for the start of 354 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 355 * reference count all in here rather then in the parent. If we want 356 * the parent to do more sophisticated things we may have to change 357 * the ordering. 358 */ 359int 360vm_pageout_flush(vm_page_t *mc, int count, int flags) 361{ 362 vm_object_t object = mc[0]->object; 363 int pageout_status[count]; 364 int numpagedout = 0; 365 int i; 366 367 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 368 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 369 /* 370 * Initiate I/O. Bump the vm_page_t->busy counter and 371 * mark the pages read-only. 372 * 373 * We do not have to fixup the clean/dirty bits here... we can 374 * allow the pager to do it after the I/O completes. 375 * 376 * NOTE! mc[i]->dirty may be partial or fragmented due to an 377 * edge case with file fragments. 378 */ 379 for (i = 0; i < count; i++) { 380 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 381 ("vm_pageout_flush: partially invalid page %p index %d/%d", 382 mc[i], i, count)); 383 vm_page_io_start(mc[i]); 384 pmap_page_protect(mc[i], VM_PROT_READ); 385 } 386 vm_page_unlock_queues(); 387 vm_object_pip_add(object, count); 388 389 vm_pager_put_pages(object, mc, count, 390 (flags | ((object == kernel_object) ? VM_PAGER_PUT_SYNC : 0)), 391 pageout_status); 392 393 vm_page_lock_queues(); 394 for (i = 0; i < count; i++) { 395 vm_page_t mt = mc[i]; 396 397 KASSERT((mt->flags & PG_WRITEABLE) == 0, 398 ("vm_pageout_flush: page %p is not write protected", mt)); 399 switch (pageout_status[i]) { 400 case VM_PAGER_OK: 401 case VM_PAGER_PEND: 402 numpagedout++; 403 break; 404 case VM_PAGER_BAD: 405 /* 406 * Page outside of range of object. Right now we 407 * essentially lose the changes by pretending it 408 * worked. 409 */ 410 pmap_clear_modify(mt); 411 vm_page_undirty(mt); 412 break; 413 case VM_PAGER_ERROR: 414 case VM_PAGER_FAIL: 415 /* 416 * If page couldn't be paged out, then reactivate the 417 * page so it doesn't clog the inactive list. (We 418 * will try paging out it again later). 419 */ 420 vm_page_activate(mt); 421 break; 422 case VM_PAGER_AGAIN: 423 break; 424 } 425 426 /* 427 * If the operation is still going, leave the page busy to 428 * block all other accesses. Also, leave the paging in 429 * progress indicator set so that we don't attempt an object 430 * collapse. 431 */ 432 if (pageout_status[i] != VM_PAGER_PEND) { 433 vm_object_pip_wakeup(object); 434 vm_page_io_finish(mt); 435 if (vm_page_count_severe()) 436 vm_page_try_to_cache(mt); 437 } 438 } 439 return numpagedout; 440} 441 442#if !defined(NO_SWAPPING) 443/* 444 * vm_pageout_object_deactivate_pages 445 * 446 * deactivate enough pages to satisfy the inactive target 447 * requirements or if vm_page_proc_limit is set, then 448 * deactivate all of the pages in the object and its 449 * backing_objects. 450 * 451 * The object and map must be locked. 452 */ 453static void 454vm_pageout_object_deactivate_pages(pmap, first_object, desired) 455 pmap_t pmap; 456 vm_object_t first_object; 457 long desired; 458{ 459 vm_object_t backing_object, object; 460 vm_page_t p, next; 461 int actcount, rcount, remove_mode; 462 463 VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED); 464 if (first_object->type == OBJT_DEVICE || first_object->type == OBJT_PHYS) 465 return; 466 for (object = first_object;; object = backing_object) { 467 if (pmap_resident_count(pmap) <= desired) 468 goto unlock_return; 469 if (object->paging_in_progress) 470 goto unlock_return; 471 472 remove_mode = 0; 473 if (object->shadow_count > 1) 474 remove_mode = 1; 475 /* 476 * scan the objects entire memory queue 477 */ 478 rcount = object->resident_page_count; 479 p = TAILQ_FIRST(&object->memq); 480 vm_page_lock_queues(); 481 while (p && (rcount-- > 0)) { 482 if (pmap_resident_count(pmap) <= desired) { 483 vm_page_unlock_queues(); 484 goto unlock_return; 485 } 486 next = TAILQ_NEXT(p, listq); 487 cnt.v_pdpages++; 488 if (p->wire_count != 0 || 489 p->hold_count != 0 || 490 p->busy != 0 || 491 (p->flags & (PG_BUSY|PG_UNMANAGED)) || 492 !pmap_page_exists_quick(pmap, p)) { 493 p = next; 494 continue; 495 } 496 actcount = pmap_ts_referenced(p); 497 if (actcount) { 498 vm_page_flag_set(p, PG_REFERENCED); 499 } else if (p->flags & PG_REFERENCED) { 500 actcount = 1; 501 } 502 if ((p->queue != PQ_ACTIVE) && 503 (p->flags & PG_REFERENCED)) { 504 vm_page_activate(p); 505 p->act_count += actcount; 506 vm_page_flag_clear(p, PG_REFERENCED); 507 } else if (p->queue == PQ_ACTIVE) { 508 if ((p->flags & PG_REFERENCED) == 0) { 509 p->act_count -= min(p->act_count, ACT_DECLINE); 510 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) { 511 pmap_remove_all(p); 512 vm_page_deactivate(p); 513 } else { 514 vm_pageq_requeue(p); 515 } 516 } else { 517 vm_page_activate(p); 518 vm_page_flag_clear(p, PG_REFERENCED); 519 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 520 p->act_count += ACT_ADVANCE; 521 vm_pageq_requeue(p); 522 } 523 } else if (p->queue == PQ_INACTIVE) { 524 pmap_remove_all(p); 525 } 526 p = next; 527 } 528 vm_page_unlock_queues(); 529 if ((backing_object = object->backing_object) == NULL) 530 goto unlock_return; 531 VM_OBJECT_LOCK(backing_object); 532 if (object != first_object) 533 VM_OBJECT_UNLOCK(object); 534 } 535unlock_return: 536 if (object != first_object) 537 VM_OBJECT_UNLOCK(object); 538} 539 540/* 541 * deactivate some number of pages in a map, try to do it fairly, but 542 * that is really hard to do. 543 */ 544static void 545vm_pageout_map_deactivate_pages(map, desired) 546 vm_map_t map; 547 long desired; 548{ 549 vm_map_entry_t tmpe; 550 vm_object_t obj, bigobj; 551 int nothingwired; 552 553 if (!vm_map_trylock(map)) 554 return; 555 556 bigobj = NULL; 557 nothingwired = TRUE; 558 559 /* 560 * first, search out the biggest object, and try to free pages from 561 * that. 562 */ 563 tmpe = map->header.next; 564 while (tmpe != &map->header) { 565 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 566 obj = tmpe->object.vm_object; 567 if (obj != NULL && VM_OBJECT_TRYLOCK(obj)) { 568 if (obj->shadow_count <= 1 && 569 (bigobj == NULL || 570 bigobj->resident_page_count < obj->resident_page_count)) { 571 if (bigobj != NULL) 572 VM_OBJECT_UNLOCK(bigobj); 573 bigobj = obj; 574 } else 575 VM_OBJECT_UNLOCK(obj); 576 } 577 } 578 if (tmpe->wired_count > 0) 579 nothingwired = FALSE; 580 tmpe = tmpe->next; 581 } 582 583 if (bigobj != NULL) { 584 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); 585 VM_OBJECT_UNLOCK(bigobj); 586 } 587 /* 588 * Next, hunt around for other pages to deactivate. We actually 589 * do this search sort of wrong -- .text first is not the best idea. 590 */ 591 tmpe = map->header.next; 592 while (tmpe != &map->header) { 593 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 594 break; 595 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 596 obj = tmpe->object.vm_object; 597 if (obj != NULL) { 598 VM_OBJECT_LOCK(obj); 599 vm_pageout_object_deactivate_pages(map->pmap, obj, desired); 600 VM_OBJECT_UNLOCK(obj); 601 } 602 } 603 tmpe = tmpe->next; 604 } 605 606 /* 607 * Remove all mappings if a process is swapped out, this will free page 608 * table pages. 609 */ 610 if (desired == 0 && nothingwired) { 611 pmap_remove(vm_map_pmap(map), vm_map_min(map), 612 vm_map_max(map)); 613 } 614 vm_map_unlock(map); 615} 616#endif /* !defined(NO_SWAPPING) */ 617 618/* 619 * This routine is very drastic, but can save the system 620 * in a pinch. 621 */ 622static void 623vm_pageout_pmap_collect(void) 624{ 625 int i; 626 vm_page_t m; 627 static int warningdone; 628 629 if (pmap_pagedaemon_waken == 0) 630 return; 631 if (warningdone < 5) { 632 printf("collecting pv entries -- suggest increasing PMAP_SHPGPERPROC\n"); 633 warningdone++; 634 } 635 vm_page_lock_queues(); 636 for (i = 0; i < vm_page_array_size; i++) { 637 m = &vm_page_array[i]; 638 if (m->wire_count || m->hold_count || m->busy || 639 (m->flags & (PG_BUSY | PG_UNMANAGED))) 640 continue; 641 pmap_remove_all(m); 642 } 643 vm_page_unlock_queues(); 644 pmap_pagedaemon_waken = 0; 645} 646 647/* 648 * vm_pageout_scan does the dirty work for the pageout daemon. 649 */ 650static void 651vm_pageout_scan(int pass) 652{ 653 vm_page_t m, next; 654 struct vm_page marker; 655 int page_shortage, maxscan, pcount; 656 int addl_page_shortage, addl_page_shortage_init; 657 struct proc *p, *bigproc; 658 struct thread *td; 659 vm_offset_t size, bigsize; 660 vm_object_t object; 661 int actcount; 662 int vnodes_skipped = 0; 663 int maxlaunder; 664 665 mtx_lock(&Giant); 666 /* 667 * Decrease registered cache sizes. 668 */ 669 EVENTHANDLER_INVOKE(vm_lowmem, 0); 670 /* 671 * We do this explicitly after the caches have been drained above. 672 */ 673 uma_reclaim(); 674 /* 675 * Do whatever cleanup that the pmap code can. 676 */ 677 vm_pageout_pmap_collect(); 678 679 addl_page_shortage_init = atomic_readandclear_int(&vm_pageout_deficit); 680 681 /* 682 * Calculate the number of pages we want to either free or move 683 * to the cache. 684 */ 685 page_shortage = vm_paging_target() + addl_page_shortage_init; 686 687 /* 688 * Initialize our marker 689 */ 690 bzero(&marker, sizeof(marker)); 691 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 692 marker.queue = PQ_INACTIVE; 693 marker.wire_count = 1; 694 695 /* 696 * Start scanning the inactive queue for pages we can move to the 697 * cache or free. The scan will stop when the target is reached or 698 * we have scanned the entire inactive queue. Note that m->act_count 699 * is not used to form decisions for the inactive queue, only for the 700 * active queue. 701 * 702 * maxlaunder limits the number of dirty pages we flush per scan. 703 * For most systems a smaller value (16 or 32) is more robust under 704 * extreme memory and disk pressure because any unnecessary writes 705 * to disk can result in extreme performance degredation. However, 706 * systems with excessive dirty pages (especially when MAP_NOSYNC is 707 * used) will die horribly with limited laundering. If the pageout 708 * daemon cannot clean enough pages in the first pass, we let it go 709 * all out in succeeding passes. 710 */ 711 if ((maxlaunder = vm_max_launder) <= 1) 712 maxlaunder = 1; 713 if (pass) 714 maxlaunder = 10000; 715 vm_page_lock_queues(); 716rescan0: 717 addl_page_shortage = addl_page_shortage_init; 718 maxscan = cnt.v_inactive_count; 719 720 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 721 m != NULL && maxscan-- > 0 && page_shortage > 0; 722 m = next) { 723 724 cnt.v_pdpages++; 725 726 if (m->queue != PQ_INACTIVE) { 727 goto rescan0; 728 } 729 730 next = TAILQ_NEXT(m, pageq); 731 732 /* 733 * skip marker pages 734 */ 735 if (m->flags & PG_MARKER) 736 continue; 737 738 /* 739 * A held page may be undergoing I/O, so skip it. 740 */ 741 if (m->hold_count) { 742 vm_pageq_requeue(m); 743 addl_page_shortage++; 744 continue; 745 } 746 /* 747 * Don't mess with busy pages, keep in the front of the 748 * queue, most likely are being paged out. 749 */ 750 if (m->busy || (m->flags & PG_BUSY)) { 751 addl_page_shortage++; 752 continue; 753 } 754 755 /* 756 * If the object is not being used, we ignore previous 757 * references. 758 */ 759 if (m->object->ref_count == 0) { 760 vm_page_flag_clear(m, PG_REFERENCED); 761 pmap_clear_reference(m); 762 763 /* 764 * Otherwise, if the page has been referenced while in the 765 * inactive queue, we bump the "activation count" upwards, 766 * making it less likely that the page will be added back to 767 * the inactive queue prematurely again. Here we check the 768 * page tables (or emulated bits, if any), given the upper 769 * level VM system not knowing anything about existing 770 * references. 771 */ 772 } else if (((m->flags & PG_REFERENCED) == 0) && 773 (actcount = pmap_ts_referenced(m))) { 774 vm_page_activate(m); 775 m->act_count += (actcount + ACT_ADVANCE); 776 continue; 777 } 778 779 /* 780 * If the upper level VM system knows about any page 781 * references, we activate the page. We also set the 782 * "activation count" higher than normal so that we will less 783 * likely place pages back onto the inactive queue again. 784 */ 785 if ((m->flags & PG_REFERENCED) != 0) { 786 vm_page_flag_clear(m, PG_REFERENCED); 787 actcount = pmap_ts_referenced(m); 788 vm_page_activate(m); 789 m->act_count += (actcount + ACT_ADVANCE + 1); 790 continue; 791 } 792 793 /* 794 * If the upper level VM system doesn't know anything about 795 * the page being dirty, we have to check for it again. As 796 * far as the VM code knows, any partially dirty pages are 797 * fully dirty. 798 */ 799 if (m->dirty == 0 && !pmap_is_modified(m)) { 800 /* 801 * Avoid a race condition: Unless write access is 802 * removed from the page, another processor could 803 * modify it before all access is removed by the call 804 * to vm_page_cache() below. If vm_page_cache() finds 805 * that the page has been modified when it removes all 806 * access, it panics because it cannot cache dirty 807 * pages. In principle, we could eliminate just write 808 * access here rather than all access. In the expected 809 * case, when there are no last instant modifications 810 * to the page, removing all access will be cheaper 811 * overall. 812 */ 813 if ((m->flags & PG_WRITEABLE) != 0) 814 pmap_remove_all(m); 815 } else { 816 vm_page_dirty(m); 817 } 818 819 object = m->object; 820 if (!VM_OBJECT_TRYLOCK(object)) 821 continue; 822 if (m->valid == 0) { 823 /* 824 * Invalid pages can be easily freed 825 */ 826 vm_page_busy(m); 827 pmap_remove_all(m); 828 vm_page_free(m); 829 cnt.v_dfree++; 830 --page_shortage; 831 } else if (m->dirty == 0) { 832 /* 833 * Clean pages can be placed onto the cache queue. 834 * This effectively frees them. 835 */ 836 vm_page_cache(m); 837 --page_shortage; 838 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 839 /* 840 * Dirty pages need to be paged out, but flushing 841 * a page is extremely expensive verses freeing 842 * a clean page. Rather then artificially limiting 843 * the number of pages we can flush, we instead give 844 * dirty pages extra priority on the inactive queue 845 * by forcing them to be cycled through the queue 846 * twice before being flushed, after which the 847 * (now clean) page will cycle through once more 848 * before being freed. This significantly extends 849 * the thrash point for a heavily loaded machine. 850 */ 851 vm_page_flag_set(m, PG_WINATCFLS); 852 vm_pageq_requeue(m); 853 } else if (maxlaunder > 0) { 854 /* 855 * We always want to try to flush some dirty pages if 856 * we encounter them, to keep the system stable. 857 * Normally this number is small, but under extreme 858 * pressure where there are insufficient clean pages 859 * on the inactive queue, we may have to go all out. 860 */ 861 int swap_pageouts_ok; 862 struct vnode *vp = NULL; 863 struct mount *mp; 864 865 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 866 swap_pageouts_ok = 1; 867 } else { 868 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 869 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 870 vm_page_count_min()); 871 872 } 873 874 /* 875 * We don't bother paging objects that are "dead". 876 * Those objects are in a "rundown" state. 877 */ 878 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 879 VM_OBJECT_UNLOCK(object); 880 vm_pageq_requeue(m); 881 continue; 882 } 883 884 /* 885 * The object is already known NOT to be dead. It 886 * is possible for the vget() to block the whole 887 * pageout daemon, but the new low-memory handling 888 * code should prevent it. 889 * 890 * The previous code skipped locked vnodes and, worse, 891 * reordered pages in the queue. This results in 892 * completely non-deterministic operation and, on a 893 * busy system, can lead to extremely non-optimal 894 * pageouts. For example, it can cause clean pages 895 * to be freed and dirty pages to be moved to the end 896 * of the queue. Since dirty pages are also moved to 897 * the end of the queue once-cleaned, this gives 898 * way too large a weighting to defering the freeing 899 * of dirty pages. 900 * 901 * We can't wait forever for the vnode lock, we might 902 * deadlock due to a vn_read() getting stuck in 903 * vm_wait while holding this vnode. We skip the 904 * vnode if we can't get it in a reasonable amount 905 * of time. 906 */ 907 if (object->type == OBJT_VNODE) { 908 vp = object->handle; 909 mp = NULL; 910 if (vp->v_type == VREG) 911 vn_start_write(vp, &mp, V_NOWAIT); 912 vm_page_unlock_queues(); 913 VI_LOCK(vp); 914 VM_OBJECT_UNLOCK(object); 915 if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK | 916 LK_TIMELOCK, curthread)) { 917 VM_OBJECT_LOCK(object); 918 vm_page_lock_queues(); 919 ++pageout_lock_miss; 920 vn_finished_write(mp); 921 if (object->flags & OBJ_MIGHTBEDIRTY) 922 vnodes_skipped++; 923 VM_OBJECT_UNLOCK(object); 924 continue; 925 } 926 VM_OBJECT_LOCK(object); 927 vm_page_lock_queues(); 928 /* 929 * The page might have been moved to another 930 * queue during potential blocking in vget() 931 * above. The page might have been freed and 932 * reused for another vnode. The object might 933 * have been reused for another vnode. 934 */ 935 if (m->queue != PQ_INACTIVE || 936 m->object != object || 937 object->handle != vp) { 938 if (object->flags & OBJ_MIGHTBEDIRTY) 939 vnodes_skipped++; 940 goto unlock_and_continue; 941 } 942 943 /* 944 * The page may have been busied during the 945 * blocking in vput(); We don't move the 946 * page back onto the end of the queue so that 947 * statistics are more correct if we don't. 948 */ 949 if (m->busy || (m->flags & PG_BUSY)) { 950 goto unlock_and_continue; 951 } 952 953 /* 954 * If the page has become held it might 955 * be undergoing I/O, so skip it 956 */ 957 if (m->hold_count) { 958 vm_pageq_requeue(m); 959 if (object->flags & OBJ_MIGHTBEDIRTY) 960 vnodes_skipped++; 961 goto unlock_and_continue; 962 } 963 } 964 965 /* 966 * If a page is dirty, then it is either being washed 967 * (but not yet cleaned) or it is still in the 968 * laundry. If it is still in the laundry, then we 969 * start the cleaning operation. 970 * 971 * This operation may cluster, invalidating the 'next' 972 * pointer. To prevent an inordinate number of 973 * restarts we use our marker to remember our place. 974 * 975 * decrement page_shortage on success to account for 976 * the (future) cleaned page. Otherwise we could wind 977 * up laundering or cleaning too many pages. 978 */ 979 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq); 980 if (vm_pageout_clean(m) != 0) { 981 --page_shortage; 982 --maxlaunder; 983 } 984 next = TAILQ_NEXT(&marker, pageq); 985 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq); 986unlock_and_continue: 987 VM_OBJECT_UNLOCK(object); 988 if (vp) { 989 vm_page_unlock_queues(); 990 vput(vp); 991 vn_finished_write(mp); 992 vm_page_lock_queues(); 993 } 994 continue; 995 } 996 VM_OBJECT_UNLOCK(object); 997 } 998 999 /* 1000 * Compute the number of pages we want to try to move from the 1001 * active queue to the inactive queue. 1002 */ 1003 page_shortage = vm_paging_target() + 1004 cnt.v_inactive_target - cnt.v_inactive_count; 1005 page_shortage += addl_page_shortage; 1006 1007 /* 1008 * Scan the active queue for things we can deactivate. We nominally 1009 * track the per-page activity counter and use it to locate 1010 * deactivation candidates. 1011 */ 1012 pcount = cnt.v_active_count; 1013 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1014 1015 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 1016 1017 KASSERT(m->queue == PQ_ACTIVE, 1018 ("vm_pageout_scan: page %p isn't active", m)); 1019 1020 next = TAILQ_NEXT(m, pageq); 1021 object = m->object; 1022 if (!VM_OBJECT_TRYLOCK(object)) { 1023 vm_pageq_requeue(m); 1024 continue; 1025 } 1026 1027 /* 1028 * Don't deactivate pages that are busy. 1029 */ 1030 if ((m->busy != 0) || 1031 (m->flags & PG_BUSY) || 1032 (m->hold_count != 0)) { 1033 VM_OBJECT_UNLOCK(object); 1034 vm_pageq_requeue(m); 1035 m = next; 1036 continue; 1037 } 1038 1039 /* 1040 * The count for pagedaemon pages is done after checking the 1041 * page for eligibility... 1042 */ 1043 cnt.v_pdpages++; 1044 1045 /* 1046 * Check to see "how much" the page has been used. 1047 */ 1048 actcount = 0; 1049 if (object->ref_count != 0) { 1050 if (m->flags & PG_REFERENCED) { 1051 actcount += 1; 1052 } 1053 actcount += pmap_ts_referenced(m); 1054 if (actcount) { 1055 m->act_count += ACT_ADVANCE + actcount; 1056 if (m->act_count > ACT_MAX) 1057 m->act_count = ACT_MAX; 1058 } 1059 } 1060 1061 /* 1062 * Since we have "tested" this bit, we need to clear it now. 1063 */ 1064 vm_page_flag_clear(m, PG_REFERENCED); 1065 1066 /* 1067 * Only if an object is currently being used, do we use the 1068 * page activation count stats. 1069 */ 1070 if (actcount && (object->ref_count != 0)) { 1071 vm_pageq_requeue(m); 1072 } else { 1073 m->act_count -= min(m->act_count, ACT_DECLINE); 1074 if (vm_pageout_algorithm || 1075 object->ref_count == 0 || 1076 m->act_count == 0) { 1077 page_shortage--; 1078 if (object->ref_count == 0) { 1079 pmap_remove_all(m); 1080 if (m->dirty == 0) 1081 vm_page_cache(m); 1082 else 1083 vm_page_deactivate(m); 1084 } else { 1085 vm_page_deactivate(m); 1086 } 1087 } else { 1088 vm_pageq_requeue(m); 1089 } 1090 } 1091 VM_OBJECT_UNLOCK(object); 1092 m = next; 1093 } 1094 1095 /* 1096 * We try to maintain some *really* free pages, this allows interrupt 1097 * code to be guaranteed space. Since both cache and free queues 1098 * are considered basically 'free', moving pages from cache to free 1099 * does not effect other calculations. 1100 */ 1101 while (cnt.v_free_count < cnt.v_free_reserved) { 1102 static int cache_rover = 0; 1103 1104 if ((m = vm_page_select_cache(cache_rover)) == NULL) 1105 break; 1106 cache_rover = (m->pc + PQ_PRIME2) & PQ_L2_MASK; 1107 object = m->object; 1108 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1109 vm_page_busy(m); 1110 vm_page_free(m); 1111 VM_OBJECT_UNLOCK(object); 1112 cnt.v_dfree++; 1113 } 1114 vm_page_unlock_queues(); 1115#if !defined(NO_SWAPPING) 1116 /* 1117 * Idle process swapout -- run once per second. 1118 */ 1119 if (vm_swap_idle_enabled) { 1120 static long lsec; 1121 if (time_second != lsec) { 1122 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1123 vm_req_vmdaemon(); 1124 lsec = time_second; 1125 } 1126 } 1127#endif 1128 1129 /* 1130 * If we didn't get enough free pages, and we have skipped a vnode 1131 * in a writeable object, wakeup the sync daemon. And kick swapout 1132 * if we did not get enough free pages. 1133 */ 1134 if (vm_paging_target() > 0) { 1135 if (vnodes_skipped && vm_page_count_min()) 1136 (void) speedup_syncer(); 1137#if !defined(NO_SWAPPING) 1138 if (vm_swap_enabled && vm_page_count_target()) { 1139 vm_req_vmdaemon(); 1140 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1141 } 1142#endif 1143 } 1144 1145 /* 1146 * If we are critically low on one of RAM or swap and low on 1147 * the other, kill the largest process. However, we avoid 1148 * doing this on the first pass in order to give ourselves a 1149 * chance to flush out dirty vnode-backed pages and to allow 1150 * active pages to be moved to the inactive queue and reclaimed. 1151 * 1152 * We keep the process bigproc locked once we find it to keep anyone 1153 * from messing with it; however, there is a possibility of 1154 * deadlock if process B is bigproc and one of it's child processes 1155 * attempts to propagate a signal to B while we are waiting for A's 1156 * lock while walking this list. To avoid this, we don't block on 1157 * the process lock but just skip a process if it is already locked. 1158 */ 1159 if (pass != 0 && 1160 ((swap_pager_avail < 64 && vm_page_count_min()) || 1161 (swap_pager_full && vm_paging_target() > 0))) { 1162 bigproc = NULL; 1163 bigsize = 0; 1164 sx_slock(&allproc_lock); 1165 FOREACH_PROC_IN_SYSTEM(p) { 1166 int breakout; 1167 1168 if (PROC_TRYLOCK(p) == 0) 1169 continue; 1170 /* 1171 * If this is a system or protected process, skip it. 1172 */ 1173 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1174 (p->p_flag & P_PROTECTED) || 1175 ((p->p_pid < 48) && (swap_pager_avail != 0))) { 1176 PROC_UNLOCK(p); 1177 continue; 1178 } 1179 /* 1180 * If the process is in a non-running type state, 1181 * don't touch it. Check all the threads individually. 1182 */ 1183 mtx_lock_spin(&sched_lock); 1184 breakout = 0; 1185 FOREACH_THREAD_IN_PROC(p, td) { 1186 if (!TD_ON_RUNQ(td) && 1187 !TD_IS_RUNNING(td) && 1188 !TD_IS_SLEEPING(td)) { 1189 breakout = 1; 1190 break; 1191 } 1192 } 1193 if (breakout) { 1194 mtx_unlock_spin(&sched_lock); 1195 PROC_UNLOCK(p); 1196 continue; 1197 } 1198 mtx_unlock_spin(&sched_lock); 1199 /* 1200 * get the process size 1201 */ 1202 if (!vm_map_trylock_read(&p->p_vmspace->vm_map)) { 1203 PROC_UNLOCK(p); 1204 continue; 1205 } 1206 size = vmspace_swap_count(p->p_vmspace); 1207 vm_map_unlock_read(&p->p_vmspace->vm_map); 1208 size += vmspace_resident_count(p->p_vmspace); 1209 /* 1210 * if the this process is bigger than the biggest one 1211 * remember it. 1212 */ 1213 if (size > bigsize) { 1214 if (bigproc != NULL) 1215 PROC_UNLOCK(bigproc); 1216 bigproc = p; 1217 bigsize = size; 1218 } else 1219 PROC_UNLOCK(p); 1220 } 1221 sx_sunlock(&allproc_lock); 1222 if (bigproc != NULL) { 1223 killproc(bigproc, "out of swap space"); 1224 mtx_lock_spin(&sched_lock); 1225 sched_nice(bigproc, PRIO_MIN); 1226 mtx_unlock_spin(&sched_lock); 1227 PROC_UNLOCK(bigproc); 1228 wakeup(&cnt.v_free_count); 1229 } 1230 } 1231 mtx_unlock(&Giant); 1232} 1233 1234/* 1235 * This routine tries to maintain the pseudo LRU active queue, 1236 * so that during long periods of time where there is no paging, 1237 * that some statistic accumulation still occurs. This code 1238 * helps the situation where paging just starts to occur. 1239 */ 1240static void 1241vm_pageout_page_stats() 1242{ 1243 vm_page_t m,next; 1244 int pcount,tpcount; /* Number of pages to check */ 1245 static int fullintervalcount = 0; 1246 int page_shortage; 1247 1248 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1249 page_shortage = 1250 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1251 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1252 1253 if (page_shortage <= 0) 1254 return; 1255 1256 pcount = cnt.v_active_count; 1257 fullintervalcount += vm_pageout_stats_interval; 1258 if (fullintervalcount < vm_pageout_full_stats_interval) { 1259 tpcount = (vm_pageout_stats_max * cnt.v_active_count) / cnt.v_page_count; 1260 if (pcount > tpcount) 1261 pcount = tpcount; 1262 } else { 1263 fullintervalcount = 0; 1264 } 1265 1266 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1267 while ((m != NULL) && (pcount-- > 0)) { 1268 int actcount; 1269 1270 KASSERT(m->queue == PQ_ACTIVE, 1271 ("vm_pageout_page_stats: page %p isn't active", m)); 1272 1273 next = TAILQ_NEXT(m, pageq); 1274 /* 1275 * Don't deactivate pages that are busy. 1276 */ 1277 if ((m->busy != 0) || 1278 (m->flags & PG_BUSY) || 1279 (m->hold_count != 0)) { 1280 vm_pageq_requeue(m); 1281 m = next; 1282 continue; 1283 } 1284 1285 actcount = 0; 1286 if (m->flags & PG_REFERENCED) { 1287 vm_page_flag_clear(m, PG_REFERENCED); 1288 actcount += 1; 1289 } 1290 1291 actcount += pmap_ts_referenced(m); 1292 if (actcount) { 1293 m->act_count += ACT_ADVANCE + actcount; 1294 if (m->act_count > ACT_MAX) 1295 m->act_count = ACT_MAX; 1296 vm_pageq_requeue(m); 1297 } else { 1298 if (m->act_count == 0) { 1299 /* 1300 * We turn off page access, so that we have 1301 * more accurate RSS stats. We don't do this 1302 * in the normal page deactivation when the 1303 * system is loaded VM wise, because the 1304 * cost of the large number of page protect 1305 * operations would be higher than the value 1306 * of doing the operation. 1307 */ 1308 pmap_remove_all(m); 1309 vm_page_deactivate(m); 1310 } else { 1311 m->act_count -= min(m->act_count, ACT_DECLINE); 1312 vm_pageq_requeue(m); 1313 } 1314 } 1315 1316 m = next; 1317 } 1318} 1319 1320/* 1321 * vm_pageout is the high level pageout daemon. 1322 */ 1323static void 1324vm_pageout() 1325{ 1326 int error, pass; 1327 1328 /* 1329 * Initialize some paging parameters. 1330 */ 1331 cnt.v_interrupt_free_min = 2; 1332 if (cnt.v_page_count < 2000) 1333 vm_pageout_page_count = 8; 1334 1335 /* 1336 * v_free_reserved needs to include enough for the largest 1337 * swap pager structures plus enough for any pv_entry structs 1338 * when paging. 1339 */ 1340 if (cnt.v_page_count > 1024) 1341 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1342 else 1343 cnt.v_free_min = 4; 1344 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1345 cnt.v_interrupt_free_min; 1346 cnt.v_free_reserved = vm_pageout_page_count + 1347 cnt.v_pageout_free_min + (cnt.v_page_count / 768) + PQ_L2_SIZE; 1348 cnt.v_free_severe = cnt.v_free_min / 2; 1349 cnt.v_free_min += cnt.v_free_reserved; 1350 cnt.v_free_severe += cnt.v_free_reserved; 1351 1352 /* 1353 * v_free_target and v_cache_min control pageout hysteresis. Note 1354 * that these are more a measure of the VM cache queue hysteresis 1355 * then the VM free queue. Specifically, v_free_target is the 1356 * high water mark (free+cache pages). 1357 * 1358 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1359 * low water mark, while v_free_min is the stop. v_cache_min must 1360 * be big enough to handle memory needs while the pageout daemon 1361 * is signalled and run to free more pages. 1362 */ 1363 if (cnt.v_free_count > 6144) 1364 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1365 else 1366 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1367 1368 if (cnt.v_free_count > 2048) { 1369 cnt.v_cache_min = cnt.v_free_target; 1370 cnt.v_cache_max = 2 * cnt.v_cache_min; 1371 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1372 } else { 1373 cnt.v_cache_min = 0; 1374 cnt.v_cache_max = 0; 1375 cnt.v_inactive_target = cnt.v_free_count / 4; 1376 } 1377 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1378 cnt.v_inactive_target = cnt.v_free_count / 3; 1379 1380 /* XXX does not really belong here */ 1381 if (vm_page_max_wired == 0) 1382 vm_page_max_wired = cnt.v_free_count / 3; 1383 1384 if (vm_pageout_stats_max == 0) 1385 vm_pageout_stats_max = cnt.v_free_target; 1386 1387 /* 1388 * Set interval in seconds for stats scan. 1389 */ 1390 if (vm_pageout_stats_interval == 0) 1391 vm_pageout_stats_interval = 5; 1392 if (vm_pageout_full_stats_interval == 0) 1393 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1394 1395 swap_pager_swap_init(); 1396 pass = 0; 1397 /* 1398 * The pageout daemon is never done, so loop forever. 1399 */ 1400 while (TRUE) { 1401 vm_page_lock_queues(); 1402 /* 1403 * If we have enough free memory, wakeup waiters. Do 1404 * not clear vm_pages_needed until we reach our target, 1405 * otherwise we may be woken up over and over again and 1406 * waste a lot of cpu. 1407 */ 1408 if (vm_pages_needed && !vm_page_count_min()) { 1409 if (!vm_paging_needed()) 1410 vm_pages_needed = 0; 1411 wakeup(&cnt.v_free_count); 1412 } 1413 if (vm_pages_needed) { 1414 /* 1415 * Still not done, take a second pass without waiting 1416 * (unlimited dirty cleaning), otherwise sleep a bit 1417 * and try again. 1418 */ 1419 ++pass; 1420 if (pass > 1) 1421 msleep(&vm_pages_needed, &vm_page_queue_mtx, PVM, 1422 "psleep", hz/2); 1423 } else { 1424 /* 1425 * Good enough, sleep & handle stats. Prime the pass 1426 * for the next run. 1427 */ 1428 if (pass > 1) 1429 pass = 1; 1430 else 1431 pass = 0; 1432 error = msleep(&vm_pages_needed, &vm_page_queue_mtx, PVM, 1433 "psleep", vm_pageout_stats_interval * hz); 1434 if (error && !vm_pages_needed) { 1435 pass = 0; 1436 vm_pageout_page_stats(); 1437 vm_page_unlock_queues(); 1438 continue; 1439 } 1440 } 1441 if (vm_pages_needed) 1442 cnt.v_pdwakeups++; 1443 vm_page_unlock_queues(); 1444 vm_pageout_scan(pass); 1445 } 1446} 1447 1448/* 1449 * Unless the page queue lock is held by the caller, this function 1450 * should be regarded as advisory. Specifically, the caller should 1451 * not msleep() on &cnt.v_free_count following this function unless 1452 * the page queue lock is held until the msleep() is performed. 1453 */ 1454void 1455pagedaemon_wakeup() 1456{ 1457 1458 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1459 vm_pages_needed = 1; 1460 wakeup(&vm_pages_needed); 1461 } 1462} 1463 1464#if !defined(NO_SWAPPING) 1465static void 1466vm_req_vmdaemon() 1467{ 1468 static int lastrun = 0; 1469 1470 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1471 wakeup(&vm_daemon_needed); 1472 lastrun = ticks; 1473 } 1474} 1475 1476static void 1477vm_daemon() 1478{ 1479 struct rlimit rsslim; 1480 struct proc *p; 1481 struct thread *td; 1482 int breakout; 1483 1484 mtx_lock(&Giant); 1485 while (TRUE) { 1486 tsleep(&vm_daemon_needed, PPAUSE, "psleep", 0); 1487 if (vm_pageout_req_swapout) { 1488 swapout_procs(vm_pageout_req_swapout); 1489 vm_pageout_req_swapout = 0; 1490 } 1491 /* 1492 * scan the processes for exceeding their rlimits or if 1493 * process is swapped out -- deactivate pages 1494 */ 1495 sx_slock(&allproc_lock); 1496 LIST_FOREACH(p, &allproc, p_list) { 1497 vm_pindex_t limit, size; 1498 1499 /* 1500 * if this is a system process or if we have already 1501 * looked at this process, skip it. 1502 */ 1503 PROC_LOCK(p); 1504 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 1505 PROC_UNLOCK(p); 1506 continue; 1507 } 1508 /* 1509 * if the process is in a non-running type state, 1510 * don't touch it. 1511 */ 1512 mtx_lock_spin(&sched_lock); 1513 breakout = 0; 1514 FOREACH_THREAD_IN_PROC(p, td) { 1515 if (!TD_ON_RUNQ(td) && 1516 !TD_IS_RUNNING(td) && 1517 !TD_IS_SLEEPING(td)) { 1518 breakout = 1; 1519 break; 1520 } 1521 } 1522 mtx_unlock_spin(&sched_lock); 1523 if (breakout) { 1524 PROC_UNLOCK(p); 1525 continue; 1526 } 1527 /* 1528 * get a limit 1529 */ 1530 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1531 limit = OFF_TO_IDX( 1532 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1533 1534 /* 1535 * let processes that are swapped out really be 1536 * swapped out set the limit to nothing (will force a 1537 * swap-out.) 1538 */ 1539 if ((p->p_sflag & PS_INMEM) == 0) 1540 limit = 0; /* XXX */ 1541 PROC_UNLOCK(p); 1542 1543 size = vmspace_resident_count(p->p_vmspace); 1544 if (limit >= 0 && size >= limit) { 1545 vm_pageout_map_deactivate_pages( 1546 &p->p_vmspace->vm_map, limit); 1547 } 1548 } 1549 sx_sunlock(&allproc_lock); 1550 } 1551} 1552#endif /* !defined(NO_SWAPPING) */ 1553