vm_pageout.c revision 112881
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 * $FreeBSD: head/sys/vm/vm_pageout.c 112881 2003-03-31 21:09:57Z wes $ 69 */ 70 71/* 72 * The proverbial page-out daemon. 73 */ 74 75#include "opt_vm.h" 76#include <sys/param.h> 77#include <sys/systm.h> 78#include <sys/kernel.h> 79#include <sys/eventhandler.h> 80#include <sys/lock.h> 81#include <sys/mutex.h> 82#include <sys/proc.h> 83#include <sys/kthread.h> 84#include <sys/ktr.h> 85#include <sys/resourcevar.h> 86#include <sys/sched.h> 87#include <sys/signalvar.h> 88#include <sys/vnode.h> 89#include <sys/vmmeter.h> 90#include <sys/sx.h> 91#include <sys/sysctl.h> 92 93#include <vm/vm.h> 94#include <vm/vm_param.h> 95#include <vm/vm_object.h> 96#include <vm/vm_page.h> 97#include <vm/vm_map.h> 98#include <vm/vm_pageout.h> 99#include <vm/vm_pager.h> 100#include <vm/swap_pager.h> 101#include <vm/vm_extern.h> 102#include <vm/uma.h> 103 104#include <machine/mutex.h> 105 106/* 107 * System initialization 108 */ 109 110/* the kernel process "vm_pageout"*/ 111static void vm_pageout(void); 112static int vm_pageout_clean(vm_page_t); 113static void vm_pageout_page_free(vm_page_t); 114static void vm_pageout_pmap_collect(void); 115static void vm_pageout_scan(int pass); 116static int vm_pageout_free_page_calc(vm_size_t count); 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_stats_free_max=0, 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 178SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max, 179 CTLFLAG_RW, &vm_pageout_stats_free_max, 0, "Not implemented"); 180 181#if defined(NO_SWAPPING) 182SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 183 CTLFLAG_RD, &vm_swap_enabled, 0, ""); 184SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 185 CTLFLAG_RD, &vm_swap_idle_enabled, 0, ""); 186#else 187SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 188 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 189SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 190 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 191#endif 192 193SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 194 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 195 196SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 197 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 198 199static int pageout_lock_miss; 200SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 201 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 202 203#define VM_PAGEOUT_PAGE_COUNT 16 204int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 205 206int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 207 208#if !defined(NO_SWAPPING) 209typedef void freeer_fcn_t(vm_map_t, vm_object_t, vm_pindex_t, int); 210static void vm_pageout_map_deactivate_pages(vm_map_t, vm_pindex_t); 211static freeer_fcn_t vm_pageout_object_deactivate_pages; 212static void vm_req_vmdaemon(void); 213#endif 214static void vm_pageout_page_stats(void); 215 216/* 217 * vm_pageout_clean: 218 * 219 * Clean the page and remove it from the laundry. 220 * 221 * We set the busy bit to cause potential page faults on this page to 222 * block. Note the careful timing, however, the busy bit isn't set till 223 * late and we cannot do anything that will mess with the page. 224 */ 225static int 226vm_pageout_clean(m) 227 vm_page_t m; 228{ 229 vm_object_t object; 230 vm_page_t mc[2*vm_pageout_page_count]; 231 int pageout_count; 232 int ib, is, page_base; 233 vm_pindex_t pindex = m->pindex; 234 235 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 236 237 object = m->object; 238 239 /* 240 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 241 * with the new swapper, but we could have serious problems paging 242 * out other object types if there is insufficient memory. 243 * 244 * Unfortunately, checking free memory here is far too late, so the 245 * check has been moved up a procedural level. 246 */ 247 248 /* 249 * Don't mess with the page if it's busy, held, or special 250 */ 251 if ((m->hold_count != 0) || 252 ((m->busy != 0) || (m->flags & (PG_BUSY|PG_UNMANAGED)))) { 253 return 0; 254 } 255 256 mc[vm_pageout_page_count] = m; 257 pageout_count = 1; 258 page_base = vm_pageout_page_count; 259 ib = 1; 260 is = 1; 261 262 /* 263 * Scan object for clusterable pages. 264 * 265 * We can cluster ONLY if: ->> the page is NOT 266 * clean, wired, busy, held, or mapped into a 267 * buffer, and one of the following: 268 * 1) The page is inactive, or a seldom used 269 * active page. 270 * -or- 271 * 2) we force the issue. 272 * 273 * During heavy mmap/modification loads the pageout 274 * daemon can really fragment the underlying file 275 * due to flushing pages out of order and not trying 276 * align the clusters (which leave sporatic out-of-order 277 * holes). To solve this problem we do the reverse scan 278 * first and attempt to align our cluster, then do a 279 * forward scan if room remains. 280 */ 281more: 282 while (ib && pageout_count < vm_pageout_page_count) { 283 vm_page_t p; 284 285 if (ib > pindex) { 286 ib = 0; 287 break; 288 } 289 290 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) { 291 ib = 0; 292 break; 293 } 294 if (((p->queue - p->pc) == PQ_CACHE) || 295 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 296 ib = 0; 297 break; 298 } 299 vm_page_test_dirty(p); 300 if ((p->dirty & p->valid) == 0 || 301 p->queue != PQ_INACTIVE || 302 p->wire_count != 0 || /* may be held by buf cache */ 303 p->hold_count != 0) { /* may be undergoing I/O */ 304 ib = 0; 305 break; 306 } 307 mc[--page_base] = p; 308 ++pageout_count; 309 ++ib; 310 /* 311 * alignment boundry, stop here and switch directions. Do 312 * not clear ib. 313 */ 314 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 315 break; 316 } 317 318 while (pageout_count < vm_pageout_page_count && 319 pindex + is < object->size) { 320 vm_page_t p; 321 322 if ((p = vm_page_lookup(object, pindex + is)) == NULL) 323 break; 324 if (((p->queue - p->pc) == PQ_CACHE) || 325 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 326 break; 327 } 328 vm_page_test_dirty(p); 329 if ((p->dirty & p->valid) == 0 || 330 p->queue != PQ_INACTIVE || 331 p->wire_count != 0 || /* may be held by buf cache */ 332 p->hold_count != 0) { /* may be undergoing I/O */ 333 break; 334 } 335 mc[page_base + pageout_count] = p; 336 ++pageout_count; 337 ++is; 338 } 339 340 /* 341 * If we exhausted our forward scan, continue with the reverse scan 342 * when possible, even past a page boundry. This catches boundry 343 * conditions. 344 */ 345 if (ib && pageout_count < vm_pageout_page_count) 346 goto more; 347 348 /* 349 * we allow reads during pageouts... 350 */ 351 return vm_pageout_flush(&mc[page_base], pageout_count, 0); 352} 353 354/* 355 * vm_pageout_flush() - launder the given pages 356 * 357 * The given pages are laundered. Note that we setup for the start of 358 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 359 * reference count all in here rather then in the parent. If we want 360 * the parent to do more sophisticated things we may have to change 361 * the ordering. 362 */ 363int 364vm_pageout_flush(mc, count, flags) 365 vm_page_t *mc; 366 int count; 367 int flags; 368{ 369 vm_object_t object; 370 int pageout_status[count]; 371 int numpagedout = 0; 372 int i; 373 374 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 375 /* 376 * Initiate I/O. Bump the vm_page_t->busy counter and 377 * mark the pages read-only. 378 * 379 * We do not have to fixup the clean/dirty bits here... we can 380 * allow the pager to do it after the I/O completes. 381 * 382 * NOTE! mc[i]->dirty may be partial or fragmented due to an 383 * edge case with file fragments. 384 */ 385 for (i = 0; i < count; i++) { 386 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush page %p index %d/%d: partially invalid page", mc[i], i, count)); 387 vm_page_io_start(mc[i]); 388 pmap_page_protect(mc[i], VM_PROT_READ); 389 } 390 object = mc[0]->object; 391 vm_page_unlock_queues(); 392 vm_object_pip_add(object, count); 393 394 vm_pager_put_pages(object, mc, count, 395 (flags | ((object == kernel_object) ? VM_PAGER_PUT_SYNC : 0)), 396 pageout_status); 397 398 vm_page_lock_queues(); 399 for (i = 0; i < count; i++) { 400 vm_page_t mt = mc[i]; 401 402 switch (pageout_status[i]) { 403 case VM_PAGER_OK: 404 numpagedout++; 405 break; 406 case VM_PAGER_PEND: 407 numpagedout++; 408 break; 409 case VM_PAGER_BAD: 410 /* 411 * Page outside of range of object. Right now we 412 * essentially lose the changes by pretending it 413 * worked. 414 */ 415 pmap_clear_modify(mt); 416 vm_page_undirty(mt); 417 break; 418 case VM_PAGER_ERROR: 419 case VM_PAGER_FAIL: 420 /* 421 * If page couldn't be paged out, then reactivate the 422 * page so it doesn't clog the inactive list. (We 423 * will try paging out it again later). 424 */ 425 vm_page_activate(mt); 426 break; 427 case VM_PAGER_AGAIN: 428 break; 429 } 430 431 /* 432 * If the operation is still going, leave the page busy to 433 * block all other accesses. Also, leave the paging in 434 * progress indicator set so that we don't attempt an object 435 * collapse. 436 */ 437 if (pageout_status[i] != VM_PAGER_PEND) { 438 vm_object_pip_wakeup(object); 439 vm_page_io_finish(mt); 440 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt)) 441 pmap_page_protect(mt, VM_PROT_READ); 442 } 443 } 444 return numpagedout; 445} 446 447#if !defined(NO_SWAPPING) 448/* 449 * vm_pageout_object_deactivate_pages 450 * 451 * deactivate enough pages to satisfy the inactive target 452 * requirements or if vm_page_proc_limit is set, then 453 * deactivate all of the pages in the object and its 454 * backing_objects. 455 * 456 * The object and map must be locked. 457 */ 458static void 459vm_pageout_object_deactivate_pages(map, object, desired, map_remove_only) 460 vm_map_t map; 461 vm_object_t object; 462 vm_pindex_t desired; 463 int map_remove_only; 464{ 465 vm_page_t p, next; 466 int actcount, rcount, remove_mode; 467 468 GIANT_REQUIRED; 469 if (object->type == OBJT_DEVICE || object->type == OBJT_PHYS) 470 return; 471 472 while (object) { 473 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 474 return; 475 if (object->paging_in_progress) 476 return; 477 478 remove_mode = map_remove_only; 479 if (object->shadow_count > 1) 480 remove_mode = 1; 481 /* 482 * scan the objects entire memory queue 483 */ 484 rcount = object->resident_page_count; 485 p = TAILQ_FIRST(&object->memq); 486 vm_page_lock_queues(); 487 while (p && (rcount-- > 0)) { 488 if (pmap_resident_count(map->pmap) <= desired) { 489 vm_page_unlock_queues(); 490 return; 491 } 492 next = TAILQ_NEXT(p, listq); 493 cnt.v_pdpages++; 494 if (p->wire_count != 0 || 495 p->hold_count != 0 || 496 p->busy != 0 || 497 (p->flags & (PG_BUSY|PG_UNMANAGED)) || 498 !pmap_page_exists_quick(vm_map_pmap(map), p)) { 499 p = next; 500 continue; 501 } 502 actcount = pmap_ts_referenced(p); 503 if (actcount) { 504 vm_page_flag_set(p, PG_REFERENCED); 505 } else if (p->flags & PG_REFERENCED) { 506 actcount = 1; 507 } 508 if ((p->queue != PQ_ACTIVE) && 509 (p->flags & PG_REFERENCED)) { 510 vm_page_activate(p); 511 p->act_count += actcount; 512 vm_page_flag_clear(p, PG_REFERENCED); 513 } else if (p->queue == PQ_ACTIVE) { 514 if ((p->flags & PG_REFERENCED) == 0) { 515 p->act_count -= min(p->act_count, ACT_DECLINE); 516 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) { 517 pmap_remove_all(p); 518 vm_page_deactivate(p); 519 } else { 520 vm_pageq_requeue(p); 521 } 522 } else { 523 vm_page_activate(p); 524 vm_page_flag_clear(p, PG_REFERENCED); 525 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 526 p->act_count += ACT_ADVANCE; 527 vm_pageq_requeue(p); 528 } 529 } else if (p->queue == PQ_INACTIVE) { 530 pmap_remove_all(p); 531 } 532 p = next; 533 } 534 vm_page_unlock_queues(); 535 object = object->backing_object; 536 } 537} 538 539/* 540 * deactivate some number of pages in a map, try to do it fairly, but 541 * that is really hard to do. 542 */ 543static void 544vm_pageout_map_deactivate_pages(map, desired) 545 vm_map_t map; 546 vm_pindex_t desired; 547{ 548 vm_map_entry_t tmpe; 549 vm_object_t obj, bigobj; 550 int nothingwired; 551 552 GIANT_REQUIRED; 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) && (obj->shadow_count <= 1) && 568 ((bigobj == NULL) || 569 (bigobj->resident_page_count < obj->resident_page_count))) { 570 bigobj = obj; 571 } 572 } 573 if (tmpe->wired_count > 0) 574 nothingwired = FALSE; 575 tmpe = tmpe->next; 576 } 577 578 if (bigobj) 579 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 580 581 /* 582 * Next, hunt around for other pages to deactivate. We actually 583 * do this search sort of wrong -- .text first is not the best idea. 584 */ 585 tmpe = map->header.next; 586 while (tmpe != &map->header) { 587 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 588 break; 589 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 590 obj = tmpe->object.vm_object; 591 if (obj) 592 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 593 } 594 tmpe = tmpe->next; 595 } 596 597 /* 598 * Remove all mappings if a process is swapped out, this will free page 599 * table pages. 600 */ 601 if (desired == 0 && nothingwired) { 602 vm_page_lock_queues(); 603 pmap_remove(vm_map_pmap(map), vm_map_min(map), 604 vm_map_max(map)); 605 vm_page_unlock_queues(); 606 } 607 vm_map_unlock(map); 608} 609#endif /* !defined(NO_SWAPPING) */ 610 611/* 612 * Don't try to be fancy - being fancy can lead to VOP_LOCK's and therefore 613 * to vnode deadlocks. We only do it for OBJT_DEFAULT and OBJT_SWAP objects 614 * which we know can be trivially freed. 615 */ 616static void 617vm_pageout_page_free(vm_page_t m) 618{ 619 vm_object_t object = m->object; 620 int type = object->type; 621 622 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 623 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 624 vm_object_reference(object); 625 vm_page_busy(m); 626 pmap_remove_all(m); 627 vm_page_free(m); 628 cnt.v_dfree++; 629 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 630 vm_object_deallocate(object); 631} 632 633/* 634 * This routine is very drastic, but can save the system 635 * in a pinch. 636 */ 637static void 638vm_pageout_pmap_collect(void) 639{ 640 int i; 641 vm_page_t m; 642 static int warningdone; 643 644 if (pmap_pagedaemon_waken == 0) 645 return; 646 if (warningdone < 5) { 647 printf("collecting pv entries -- suggest increasing PMAP_SHPGPERPROC\n"); 648 warningdone++; 649 } 650 vm_page_lock_queues(); 651 for (i = 0; i < vm_page_array_size; i++) { 652 m = &vm_page_array[i]; 653 if (m->wire_count || m->hold_count || m->busy || 654 (m->flags & (PG_BUSY | PG_UNMANAGED))) 655 continue; 656 pmap_remove_all(m); 657 } 658 vm_page_unlock_queues(); 659 pmap_pagedaemon_waken = 0; 660} 661 662/* 663 * vm_pageout_scan does the dirty work for the pageout daemon. 664 */ 665static void 666vm_pageout_scan(int pass) 667{ 668 vm_page_t m, next; 669 struct vm_page marker; 670 int save_page_shortage; 671 int save_inactive_count; 672 int page_shortage, maxscan, pcount; 673 int addl_page_shortage, addl_page_shortage_init; 674 struct proc *p, *bigproc; 675 vm_offset_t size, bigsize; 676 vm_object_t object; 677 int actcount; 678 int vnodes_skipped = 0; 679 int maxlaunder; 680 int s; 681 struct thread *td; 682 683 GIANT_REQUIRED; 684 /* 685 * Decrease registered cache sizes. 686 */ 687 EVENTHANDLER_INVOKE(vm_lowmem, 0); 688 /* 689 * We do this explicitly after the caches have been drained above. 690 */ 691 uma_reclaim(); 692 /* 693 * Do whatever cleanup that the pmap code can. 694 */ 695 vm_pageout_pmap_collect(); 696 697 addl_page_shortage_init = atomic_readandclear_int(&vm_pageout_deficit); 698 699 /* 700 * Calculate the number of pages we want to either free or move 701 * to the cache. 702 */ 703 page_shortage = vm_paging_target() + addl_page_shortage_init; 704 save_page_shortage = page_shortage; 705 save_inactive_count = cnt.v_inactive_count; 706 707 /* 708 * Initialize our marker 709 */ 710 bzero(&marker, sizeof(marker)); 711 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 712 marker.queue = PQ_INACTIVE; 713 marker.wire_count = 1; 714 715 /* 716 * Start scanning the inactive queue for pages we can move to the 717 * cache or free. The scan will stop when the target is reached or 718 * we have scanned the entire inactive queue. Note that m->act_count 719 * is not used to form decisions for the inactive queue, only for the 720 * active queue. 721 * 722 * maxlaunder limits the number of dirty pages we flush per scan. 723 * For most systems a smaller value (16 or 32) is more robust under 724 * extreme memory and disk pressure because any unnecessary writes 725 * to disk can result in extreme performance degredation. However, 726 * systems with excessive dirty pages (especially when MAP_NOSYNC is 727 * used) will die horribly with limited laundering. If the pageout 728 * daemon cannot clean enough pages in the first pass, we let it go 729 * all out in succeeding passes. 730 */ 731 if ((maxlaunder = vm_max_launder) <= 1) 732 maxlaunder = 1; 733 if (pass) 734 maxlaunder = 10000; 735rescan0: 736 addl_page_shortage = addl_page_shortage_init; 737 maxscan = cnt.v_inactive_count; 738 739 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 740 m != NULL && maxscan-- > 0 && page_shortage > 0; 741 m = next) { 742 743 cnt.v_pdpages++; 744 745 if (m->queue != PQ_INACTIVE) { 746 goto rescan0; 747 } 748 749 next = TAILQ_NEXT(m, pageq); 750 751 /* 752 * skip marker pages 753 */ 754 if (m->flags & PG_MARKER) 755 continue; 756 757 /* 758 * A held page may be undergoing I/O, so skip it. 759 */ 760 if (m->hold_count) { 761 vm_pageq_requeue(m); 762 addl_page_shortage++; 763 continue; 764 } 765 /* 766 * Don't mess with busy pages, keep in the front of the 767 * queue, most likely are being paged out. 768 */ 769 if (m->busy || (m->flags & PG_BUSY)) { 770 addl_page_shortage++; 771 continue; 772 } 773 774 vm_page_lock_queues(); 775 /* 776 * If the object is not being used, we ignore previous 777 * references. 778 */ 779 if (m->object->ref_count == 0) { 780 vm_page_flag_clear(m, PG_REFERENCED); 781 pmap_clear_reference(m); 782 783 /* 784 * Otherwise, if the page has been referenced while in the 785 * inactive queue, we bump the "activation count" upwards, 786 * making it less likely that the page will be added back to 787 * the inactive queue prematurely again. Here we check the 788 * page tables (or emulated bits, if any), given the upper 789 * level VM system not knowing anything about existing 790 * references. 791 */ 792 } else if (((m->flags & PG_REFERENCED) == 0) && 793 (actcount = pmap_ts_referenced(m))) { 794 vm_page_activate(m); 795 vm_page_unlock_queues(); 796 m->act_count += (actcount + ACT_ADVANCE); 797 continue; 798 } 799 800 /* 801 * If the upper level VM system knows about any page 802 * references, we activate the page. We also set the 803 * "activation count" higher than normal so that we will less 804 * likely place pages back onto the inactive queue again. 805 */ 806 if ((m->flags & PG_REFERENCED) != 0) { 807 vm_page_flag_clear(m, PG_REFERENCED); 808 actcount = pmap_ts_referenced(m); 809 vm_page_activate(m); 810 vm_page_unlock_queues(); 811 m->act_count += (actcount + ACT_ADVANCE + 1); 812 continue; 813 } 814 815 /* 816 * If the upper level VM system doesn't know anything about 817 * the page being dirty, we have to check for it again. As 818 * far as the VM code knows, any partially dirty pages are 819 * fully dirty. 820 */ 821 if (m->dirty == 0) { 822 vm_page_test_dirty(m); 823 } else { 824 vm_page_dirty(m); 825 } 826 vm_page_unlock_queues(); 827 828 /* 829 * Invalid pages can be easily freed 830 */ 831 if (m->valid == 0) { 832 vm_page_lock_queues(); 833 vm_pageout_page_free(m); 834 vm_page_unlock_queues(); 835 --page_shortage; 836 837 /* 838 * Clean pages can be placed onto the cache queue. This 839 * effectively frees them. 840 */ 841 } else if (m->dirty == 0) { 842 vm_page_lock_queues(); 843 vm_page_cache(m); 844 vm_page_unlock_queues(); 845 --page_shortage; 846 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 847 /* 848 * Dirty pages need to be paged out, but flushing 849 * a page is extremely expensive verses freeing 850 * a clean page. Rather then artificially limiting 851 * the number of pages we can flush, we instead give 852 * dirty pages extra priority on the inactive queue 853 * by forcing them to be cycled through the queue 854 * twice before being flushed, after which the 855 * (now clean) page will cycle through once more 856 * before being freed. This significantly extends 857 * the thrash point for a heavily loaded machine. 858 */ 859 vm_page_lock_queues(); 860 vm_page_flag_set(m, PG_WINATCFLS); 861 vm_pageq_requeue(m); 862 vm_page_unlock_queues(); 863 } else if (maxlaunder > 0) { 864 /* 865 * We always want to try to flush some dirty pages if 866 * we encounter them, to keep the system stable. 867 * Normally this number is small, but under extreme 868 * pressure where there are insufficient clean pages 869 * on the inactive queue, we may have to go all out. 870 */ 871 int swap_pageouts_ok; 872 struct vnode *vp = NULL; 873 struct mount *mp; 874 875 object = m->object; 876 877 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 878 swap_pageouts_ok = 1; 879 } else { 880 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 881 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 882 vm_page_count_min()); 883 884 } 885 886 /* 887 * We don't bother paging objects that are "dead". 888 * Those objects are in a "rundown" state. 889 */ 890 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 891 vm_pageq_requeue(m); 892 continue; 893 } 894 895 /* 896 * The object is already known NOT to be dead. It 897 * is possible for the vget() to block the whole 898 * pageout daemon, but the new low-memory handling 899 * code should prevent it. 900 * 901 * The previous code skipped locked vnodes and, worse, 902 * reordered pages in the queue. This results in 903 * completely non-deterministic operation and, on a 904 * busy system, can lead to extremely non-optimal 905 * pageouts. For example, it can cause clean pages 906 * to be freed and dirty pages to be moved to the end 907 * of the queue. Since dirty pages are also moved to 908 * the end of the queue once-cleaned, this gives 909 * way too large a weighting to defering the freeing 910 * of dirty pages. 911 * 912 * We can't wait forever for the vnode lock, we might 913 * deadlock due to a vn_read() getting stuck in 914 * vm_wait while holding this vnode. We skip the 915 * vnode if we can't get it in a reasonable amount 916 * of time. 917 */ 918 if (object->type == OBJT_VNODE) { 919 vp = object->handle; 920 921 mp = NULL; 922 if (vp->v_type == VREG) 923 vn_start_write(vp, &mp, V_NOWAIT); 924 if (vget(vp, LK_EXCLUSIVE|LK_TIMELOCK, curthread)) { 925 ++pageout_lock_miss; 926 vn_finished_write(mp); 927 if (object->flags & OBJ_MIGHTBEDIRTY) 928 vnodes_skipped++; 929 continue; 930 } 931 932 /* 933 * The page might have been moved to another 934 * queue during potential blocking in vget() 935 * above. The page might have been freed and 936 * reused for another vnode. The object might 937 * have been reused for another vnode. 938 */ 939 if (m->queue != PQ_INACTIVE || 940 m->object != object || 941 object->handle != vp) { 942 if (object->flags & OBJ_MIGHTBEDIRTY) 943 vnodes_skipped++; 944 vput(vp); 945 vn_finished_write(mp); 946 continue; 947 } 948 949 /* 950 * The page may have been busied during the 951 * blocking in vput(); We don't move the 952 * page back onto the end of the queue so that 953 * statistics are more correct if we don't. 954 */ 955 if (m->busy || (m->flags & PG_BUSY)) { 956 vput(vp); 957 vn_finished_write(mp); 958 continue; 959 } 960 961 /* 962 * If the page has become held it might 963 * be undergoing I/O, so skip it 964 */ 965 if (m->hold_count) { 966 vm_pageq_requeue(m); 967 if (object->flags & OBJ_MIGHTBEDIRTY) 968 vnodes_skipped++; 969 vput(vp); 970 vn_finished_write(mp); 971 continue; 972 } 973 } 974 975 /* 976 * If a page is dirty, then it is either being washed 977 * (but not yet cleaned) or it is still in the 978 * laundry. If it is still in the laundry, then we 979 * start the cleaning operation. 980 * 981 * This operation may cluster, invalidating the 'next' 982 * pointer. To prevent an inordinate number of 983 * restarts we use our marker to remember our place. 984 * 985 * decrement page_shortage on success to account for 986 * the (future) cleaned page. Otherwise we could wind 987 * up laundering or cleaning too many pages. 988 */ 989 vm_page_lock_queues(); 990 s = splvm(); 991 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq); 992 splx(s); 993 if (vm_pageout_clean(m) != 0) { 994 --page_shortage; 995 --maxlaunder; 996 } 997 s = splvm(); 998 next = TAILQ_NEXT(&marker, pageq); 999 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq); 1000 splx(s); 1001 vm_page_unlock_queues(); 1002 if (vp) { 1003 vput(vp); 1004 vn_finished_write(mp); 1005 } 1006 } 1007 } 1008 1009 /* 1010 * Compute the number of pages we want to try to move from the 1011 * active queue to the inactive queue. 1012 */ 1013 page_shortage = vm_paging_target() + 1014 cnt.v_inactive_target - cnt.v_inactive_count; 1015 page_shortage += addl_page_shortage; 1016 1017 vm_page_lock_queues(); 1018 /* 1019 * Scan the active queue for things we can deactivate. We nominally 1020 * track the per-page activity counter and use it to locate 1021 * deactivation candidates. 1022 */ 1023 pcount = cnt.v_active_count; 1024 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1025 1026 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 1027 1028 /* 1029 * This is a consistency check, and should likely be a panic 1030 * or warning. 1031 */ 1032 if (m->queue != PQ_ACTIVE) { 1033 break; 1034 } 1035 1036 next = TAILQ_NEXT(m, pageq); 1037 /* 1038 * Don't deactivate pages that are busy. 1039 */ 1040 if ((m->busy != 0) || 1041 (m->flags & PG_BUSY) || 1042 (m->hold_count != 0)) { 1043 vm_pageq_requeue(m); 1044 m = next; 1045 continue; 1046 } 1047 1048 /* 1049 * The count for pagedaemon pages is done after checking the 1050 * page for eligibility... 1051 */ 1052 cnt.v_pdpages++; 1053 1054 /* 1055 * Check to see "how much" the page has been used. 1056 */ 1057 actcount = 0; 1058 if (m->object->ref_count != 0) { 1059 if (m->flags & PG_REFERENCED) { 1060 actcount += 1; 1061 } 1062 actcount += pmap_ts_referenced(m); 1063 if (actcount) { 1064 m->act_count += ACT_ADVANCE + actcount; 1065 if (m->act_count > ACT_MAX) 1066 m->act_count = ACT_MAX; 1067 } 1068 } 1069 1070 /* 1071 * Since we have "tested" this bit, we need to clear it now. 1072 */ 1073 vm_page_flag_clear(m, PG_REFERENCED); 1074 1075 /* 1076 * Only if an object is currently being used, do we use the 1077 * page activation count stats. 1078 */ 1079 if (actcount && (m->object->ref_count != 0)) { 1080 vm_pageq_requeue(m); 1081 } else { 1082 m->act_count -= min(m->act_count, ACT_DECLINE); 1083 if (vm_pageout_algorithm || 1084 m->object->ref_count == 0 || 1085 m->act_count == 0) { 1086 page_shortage--; 1087 if (m->object->ref_count == 0) { 1088 pmap_remove_all(m); 1089 if (m->dirty == 0) 1090 vm_page_cache(m); 1091 else 1092 vm_page_deactivate(m); 1093 } else { 1094 vm_page_deactivate(m); 1095 } 1096 } else { 1097 vm_pageq_requeue(m); 1098 } 1099 } 1100 m = next; 1101 } 1102 s = splvm(); 1103 1104 /* 1105 * We try to maintain some *really* free pages, this allows interrupt 1106 * code to be guaranteed space. Since both cache and free queues 1107 * are considered basically 'free', moving pages from cache to free 1108 * does not effect other calculations. 1109 */ 1110 while (cnt.v_free_count < cnt.v_free_reserved) { 1111 static int cache_rover = 0; 1112 m = vm_pageq_find(PQ_CACHE, cache_rover, FALSE); 1113 if (!m) 1114 break; 1115 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || 1116 m->busy || 1117 m->hold_count || 1118 m->wire_count) { 1119#ifdef INVARIANTS 1120 printf("Warning: busy page %p found in cache\n", m); 1121#endif 1122 vm_page_deactivate(m); 1123 continue; 1124 } 1125 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK; 1126 vm_pageout_page_free(m); 1127 } 1128 splx(s); 1129 vm_page_unlock_queues(); 1130#if !defined(NO_SWAPPING) 1131 /* 1132 * Idle process swapout -- run once per second. 1133 */ 1134 if (vm_swap_idle_enabled) { 1135 static long lsec; 1136 if (time_second != lsec) { 1137 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1138 vm_req_vmdaemon(); 1139 lsec = time_second; 1140 } 1141 } 1142#endif 1143 1144 /* 1145 * If we didn't get enough free pages, and we have skipped a vnode 1146 * in a writeable object, wakeup the sync daemon. And kick swapout 1147 * if we did not get enough free pages. 1148 */ 1149 if (vm_paging_target() > 0) { 1150 if (vnodes_skipped && vm_page_count_min()) 1151 (void) speedup_syncer(); 1152#if !defined(NO_SWAPPING) 1153 if (vm_swap_enabled && vm_page_count_target()) { 1154 vm_req_vmdaemon(); 1155 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1156 } 1157#endif 1158 } 1159 1160 /* 1161 * If we are out of swap and were not able to reach our paging 1162 * target, kill the largest process. 1163 * 1164 * We keep the process bigproc locked once we find it to keep anyone 1165 * from messing with it; however, there is a possibility of 1166 * deadlock if process B is bigproc and one of it's child processes 1167 * attempts to propagate a signal to B while we are waiting for A's 1168 * lock while walking this list. To avoid this, we don't block on 1169 * the process lock but just skip a process if it is already locked. 1170 */ 1171 if ((vm_swap_size < 64 && vm_page_count_min()) || 1172 (swap_pager_full && vm_paging_target() > 0)) { 1173#if 0 1174 if ((vm_swap_size < 64 || swap_pager_full) && vm_page_count_min()) { 1175#endif 1176 bigproc = NULL; 1177 bigsize = 0; 1178 sx_slock(&allproc_lock); 1179 FOREACH_PROC_IN_SYSTEM(p) { 1180 int breakout; 1181 /* 1182 * If this process is already locked, skip it. 1183 */ 1184 if (PROC_TRYLOCK(p) == 0) 1185 continue; 1186 /* 1187 * If this is a system or protected process, skip it. 1188 */ 1189 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1190 (p->p_flag & P_PROTECTED) || 1191 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1192 PROC_UNLOCK(p); 1193 continue; 1194 } 1195 /* 1196 * if the process is in a non-running type state, 1197 * don't touch it. Check all the threads individually. 1198 */ 1199 mtx_lock_spin(&sched_lock); 1200 breakout = 0; 1201 FOREACH_THREAD_IN_PROC(p, td) { 1202 if (!TD_ON_RUNQ(td) && 1203 !TD_IS_RUNNING(td) && 1204 !TD_IS_SLEEPING(td)) { 1205 breakout = 1; 1206 break; 1207 } 1208 } 1209 if (breakout) { 1210 mtx_unlock_spin(&sched_lock); 1211 PROC_UNLOCK(p); 1212 continue; 1213 } 1214 mtx_unlock_spin(&sched_lock); 1215 /* 1216 * get the process size 1217 */ 1218 if (!vm_map_trylock_read(&p->p_vmspace->vm_map)) { 1219 PROC_UNLOCK(p); 1220 continue; 1221 } 1222 size = vmspace_swap_count(p->p_vmspace); 1223 vm_map_unlock_read(&p->p_vmspace->vm_map); 1224 size += vmspace_resident_count(p->p_vmspace); 1225 /* 1226 * if the this process is bigger than the biggest one 1227 * remember it. 1228 */ 1229 if (size > bigsize) { 1230 if (bigproc != NULL) 1231 PROC_UNLOCK(bigproc); 1232 bigproc = p; 1233 bigsize = size; 1234 } else 1235 PROC_UNLOCK(p); 1236 } 1237 sx_sunlock(&allproc_lock); 1238 if (bigproc != NULL) { 1239 struct ksegrp *kg; 1240 killproc(bigproc, "out of swap space"); 1241 mtx_lock_spin(&sched_lock); 1242 FOREACH_KSEGRP_IN_PROC(bigproc, kg) { 1243 sched_nice(kg, PRIO_MIN); /* XXXKSE ??? */ 1244 } 1245 mtx_unlock_spin(&sched_lock); 1246 PROC_UNLOCK(bigproc); 1247 wakeup(&cnt.v_free_count); 1248 } 1249 } 1250} 1251 1252/* 1253 * This routine tries to maintain the pseudo LRU active queue, 1254 * so that during long periods of time where there is no paging, 1255 * that some statistic accumulation still occurs. This code 1256 * helps the situation where paging just starts to occur. 1257 */ 1258static void 1259vm_pageout_page_stats() 1260{ 1261 vm_page_t m,next; 1262 int pcount,tpcount; /* Number of pages to check */ 1263 static int fullintervalcount = 0; 1264 int page_shortage; 1265 int s0; 1266 1267 page_shortage = 1268 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1269 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1270 1271 if (page_shortage <= 0) 1272 return; 1273 1274 s0 = splvm(); 1275 vm_page_lock_queues(); 1276 pcount = cnt.v_active_count; 1277 fullintervalcount += vm_pageout_stats_interval; 1278 if (fullintervalcount < vm_pageout_full_stats_interval) { 1279 tpcount = (vm_pageout_stats_max * cnt.v_active_count) / cnt.v_page_count; 1280 if (pcount > tpcount) 1281 pcount = tpcount; 1282 } else { 1283 fullintervalcount = 0; 1284 } 1285 1286 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1287 while ((m != NULL) && (pcount-- > 0)) { 1288 int actcount; 1289 1290 if (m->queue != PQ_ACTIVE) { 1291 break; 1292 } 1293 1294 next = TAILQ_NEXT(m, pageq); 1295 /* 1296 * Don't deactivate pages that are busy. 1297 */ 1298 if ((m->busy != 0) || 1299 (m->flags & PG_BUSY) || 1300 (m->hold_count != 0)) { 1301 vm_pageq_requeue(m); 1302 m = next; 1303 continue; 1304 } 1305 1306 actcount = 0; 1307 if (m->flags & PG_REFERENCED) { 1308 vm_page_flag_clear(m, PG_REFERENCED); 1309 actcount += 1; 1310 } 1311 1312 actcount += pmap_ts_referenced(m); 1313 if (actcount) { 1314 m->act_count += ACT_ADVANCE + actcount; 1315 if (m->act_count > ACT_MAX) 1316 m->act_count = ACT_MAX; 1317 vm_pageq_requeue(m); 1318 } else { 1319 if (m->act_count == 0) { 1320 /* 1321 * We turn off page access, so that we have 1322 * more accurate RSS stats. We don't do this 1323 * in the normal page deactivation when the 1324 * system is loaded VM wise, because the 1325 * cost of the large number of page protect 1326 * operations would be higher than the value 1327 * of doing the operation. 1328 */ 1329 pmap_remove_all(m); 1330 vm_page_deactivate(m); 1331 } else { 1332 m->act_count -= min(m->act_count, ACT_DECLINE); 1333 vm_pageq_requeue(m); 1334 } 1335 } 1336 1337 m = next; 1338 } 1339 vm_page_unlock_queues(); 1340 splx(s0); 1341} 1342 1343static int 1344vm_pageout_free_page_calc(count) 1345vm_size_t count; 1346{ 1347 if (count < cnt.v_page_count) 1348 return 0; 1349 /* 1350 * free_reserved needs to include enough for the largest swap pager 1351 * structures plus enough for any pv_entry structs when paging. 1352 */ 1353 if (cnt.v_page_count > 1024) 1354 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1355 else 1356 cnt.v_free_min = 4; 1357 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1358 cnt.v_interrupt_free_min; 1359 cnt.v_free_reserved = vm_pageout_page_count + 1360 cnt.v_pageout_free_min + (count / 768) + PQ_L2_SIZE; 1361 cnt.v_free_severe = cnt.v_free_min / 2; 1362 cnt.v_free_min += cnt.v_free_reserved; 1363 cnt.v_free_severe += cnt.v_free_reserved; 1364 return 1; 1365} 1366 1367/* 1368 * vm_pageout is the high level pageout daemon. 1369 */ 1370static void 1371vm_pageout() 1372{ 1373 int error, pass, s; 1374 1375 mtx_lock(&Giant); 1376 1377 /* 1378 * Initialize some paging parameters. 1379 */ 1380 cnt.v_interrupt_free_min = 2; 1381 if (cnt.v_page_count < 2000) 1382 vm_pageout_page_count = 8; 1383 1384 vm_pageout_free_page_calc(cnt.v_page_count); 1385 /* 1386 * v_free_target and v_cache_min control pageout hysteresis. Note 1387 * that these are more a measure of the VM cache queue hysteresis 1388 * then the VM free queue. Specifically, v_free_target is the 1389 * high water mark (free+cache pages). 1390 * 1391 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1392 * low water mark, while v_free_min is the stop. v_cache_min must 1393 * be big enough to handle memory needs while the pageout daemon 1394 * is signalled and run to free more pages. 1395 */ 1396 if (cnt.v_free_count > 6144) 1397 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1398 else 1399 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1400 1401 if (cnt.v_free_count > 2048) { 1402 cnt.v_cache_min = cnt.v_free_target; 1403 cnt.v_cache_max = 2 * cnt.v_cache_min; 1404 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1405 } else { 1406 cnt.v_cache_min = 0; 1407 cnt.v_cache_max = 0; 1408 cnt.v_inactive_target = cnt.v_free_count / 4; 1409 } 1410 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1411 cnt.v_inactive_target = cnt.v_free_count / 3; 1412 1413 /* XXX does not really belong here */ 1414 if (vm_page_max_wired == 0) 1415 vm_page_max_wired = cnt.v_free_count / 3; 1416 1417 if (vm_pageout_stats_max == 0) 1418 vm_pageout_stats_max = cnt.v_free_target; 1419 1420 /* 1421 * Set interval in seconds for stats scan. 1422 */ 1423 if (vm_pageout_stats_interval == 0) 1424 vm_pageout_stats_interval = 5; 1425 if (vm_pageout_full_stats_interval == 0) 1426 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1427 1428 /* 1429 * Set maximum free per pass 1430 */ 1431 if (vm_pageout_stats_free_max == 0) 1432 vm_pageout_stats_free_max = 5; 1433 1434 swap_pager_swap_init(); 1435 pass = 0; 1436 /* 1437 * The pageout daemon is never done, so loop forever. 1438 */ 1439 while (TRUE) { 1440 s = splvm(); 1441 vm_page_lock_queues(); 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 if (vm_pages_needed && !vm_page_count_min()) { 1449 if (!vm_paging_needed()) 1450 vm_pages_needed = 0; 1451 wakeup(&cnt.v_free_count); 1452 } 1453 if (vm_pages_needed) { 1454 /* 1455 * Still not done, take a second pass without waiting 1456 * (unlimited dirty cleaning), otherwise sleep a bit 1457 * and try again. 1458 */ 1459 ++pass; 1460 if (pass > 1) 1461 msleep(&vm_pages_needed, &vm_page_queue_mtx, PVM, 1462 "psleep", hz/2); 1463 } else { 1464 /* 1465 * Good enough, sleep & handle stats. Prime the pass 1466 * for the next run. 1467 */ 1468 if (pass > 1) 1469 pass = 1; 1470 else 1471 pass = 0; 1472 error = msleep(&vm_pages_needed, &vm_page_queue_mtx, PVM, 1473 "psleep", vm_pageout_stats_interval * hz); 1474 if (error && !vm_pages_needed) { 1475 vm_page_unlock_queues(); 1476 splx(s); 1477 pass = 0; 1478 vm_pageout_page_stats(); 1479 continue; 1480 } 1481 } 1482 if (vm_pages_needed) 1483 cnt.v_pdwakeups++; 1484 vm_page_unlock_queues(); 1485 splx(s); 1486 vm_pageout_scan(pass); 1487 } 1488} 1489 1490/* 1491 * Unless the page queue lock is held by the caller, this function 1492 * should be regarded as advisory. Specifically, the caller should 1493 * not msleep() on &cnt.v_free_count following this function unless 1494 * the page queue lock is held until the msleep() is performed. 1495 */ 1496void 1497pagedaemon_wakeup() 1498{ 1499 1500 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1501 vm_pages_needed = 1; 1502 wakeup(&vm_pages_needed); 1503 } 1504} 1505 1506#if !defined(NO_SWAPPING) 1507static void 1508vm_req_vmdaemon() 1509{ 1510 static int lastrun = 0; 1511 1512 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1513 wakeup(&vm_daemon_needed); 1514 lastrun = ticks; 1515 } 1516} 1517 1518static void 1519vm_daemon() 1520{ 1521 struct proc *p; 1522 int breakout; 1523 struct thread *td; 1524 1525 mtx_lock(&Giant); 1526 while (TRUE) { 1527 tsleep(&vm_daemon_needed, PPAUSE, "psleep", 0); 1528 if (vm_pageout_req_swapout) { 1529 swapout_procs(vm_pageout_req_swapout); 1530 vm_pageout_req_swapout = 0; 1531 } 1532 /* 1533 * scan the processes for exceeding their rlimits or if 1534 * process is swapped out -- deactivate pages 1535 */ 1536 sx_slock(&allproc_lock); 1537 LIST_FOREACH(p, &allproc, p_list) { 1538 vm_pindex_t limit, size; 1539 1540 /* 1541 * if this is a system process or if we have already 1542 * looked at this process, skip it. 1543 */ 1544 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 1545 continue; 1546 } 1547 /* 1548 * if the process is in a non-running type state, 1549 * don't touch it. 1550 */ 1551 mtx_lock_spin(&sched_lock); 1552 breakout = 0; 1553 FOREACH_THREAD_IN_PROC(p, td) { 1554 if (!TD_ON_RUNQ(td) && 1555 !TD_IS_RUNNING(td) && 1556 !TD_IS_SLEEPING(td)) { 1557 breakout = 1; 1558 break; 1559 } 1560 } 1561 if (breakout) { 1562 mtx_unlock_spin(&sched_lock); 1563 continue; 1564 } 1565 /* 1566 * get a limit 1567 */ 1568 limit = OFF_TO_IDX( 1569 qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 1570 p->p_rlimit[RLIMIT_RSS].rlim_max)); 1571 1572 /* 1573 * let processes that are swapped out really be 1574 * swapped out set the limit to nothing (will force a 1575 * swap-out.) 1576 */ 1577 if ((p->p_sflag & PS_INMEM) == 0) 1578 limit = 0; /* XXX */ 1579 mtx_unlock_spin(&sched_lock); 1580 1581 size = vmspace_resident_count(p->p_vmspace); 1582 if (limit >= 0 && size >= limit) { 1583 vm_pageout_map_deactivate_pages( 1584 &p->p_vmspace->vm_map, limit); 1585 } 1586 } 1587 sx_sunlock(&allproc_lock); 1588 } 1589} 1590#endif /* !defined(NO_SWAPPING) */ 1591