1/*- 2 * Copyright (c) 1991 Regents of the University of California. 3 * All rights reserved. 4 * Copyright (c) 1994 John S. Dyson 5 * All rights reserved. 6 * Copyright (c) 1994 David Greenman 7 * All rights reserved. 8 * Copyright (c) 2005 Yahoo! Technologies Norway AS 9 * All rights reserved. 10 * 11 * This code is derived from software contributed to Berkeley by 12 * The Mach Operating System project at Carnegie-Mellon University. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the University of 25 * California, Berkeley and its contributors. 26 * 4. Neither the name of the University nor the names of its contributors 27 * may be used to endorse or promote products derived from this software 28 * without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 * 42 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 43 * 44 * 45 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 46 * All rights reserved. 47 * 48 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 49 * 50 * Permission to use, copy, modify and distribute this software and 51 * its documentation is hereby granted, provided that both the copyright 52 * notice and this permission notice appear in all copies of the 53 * software, derivative works or modified versions, and any portions 54 * thereof, and that both notices appear in supporting documentation. 55 * 56 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 57 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 58 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 59 * 60 * Carnegie Mellon requests users of this software to return to 61 * 62 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 63 * School of Computer Science 64 * Carnegie Mellon University 65 * Pittsburgh PA 15213-3890 66 * 67 * any improvements or extensions that they make and grant Carnegie the 68 * rights to redistribute these changes. 69 */ 70 71/* 72 * The proverbial page-out daemon. 73 */ 74 75#include <sys/cdefs.h> 76__FBSDID("$FreeBSD$"); 77 78#include "opt_vm.h" 79#include <sys/param.h> 80#include <sys/systm.h> 81#include <sys/kernel.h> 82#include <sys/eventhandler.h> 83#include <sys/lock.h> 84#include <sys/mutex.h> 85#include <sys/proc.h> 86#include <sys/kthread.h> 87#include <sys/ktr.h> 88#include <sys/mount.h> 89#include <sys/racct.h> 90#include <sys/resourcevar.h> 91#include <sys/sched.h> 92#include <sys/signalvar.h> 93#include <sys/vnode.h> 94#include <sys/vmmeter.h> 95#include <sys/sx.h> 96#include <sys/sysctl.h> 97 98#include <vm/vm.h> 99#include <vm/vm_param.h> 100#include <vm/vm_object.h> 101#include <vm/vm_page.h> 102#include <vm/vm_map.h> 103#include <vm/vm_pageout.h> 104#include <vm/vm_pager.h> 105#include <vm/swap_pager.h> 106#include <vm/vm_extern.h> 107#include <vm/uma.h> 108 109/* 110 * System initialization 111 */ 112 113/* the kernel process "vm_pageout"*/ 114static void vm_pageout(void); 115static int vm_pageout_clean(vm_page_t); 116static void vm_pageout_scan(int pass); 117 118struct proc *pageproc; 119 120static struct kproc_desc page_kp = { 121 "pagedaemon", 122 vm_pageout, 123 &pageproc 124}; 125SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, 126 &page_kp); 127 128#if !defined(NO_SWAPPING) 129/* the kernel process "vm_daemon"*/ 130static void vm_daemon(void); 131static struct proc *vmproc; 132 133static struct kproc_desc vm_kp = { 134 "vmdaemon", 135 vm_daemon, 136 &vmproc 137}; 138SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp); 139#endif 140 141 142int vm_pages_needed; /* Event on which pageout daemon sleeps */ 143int vm_pageout_deficit; /* Estimated number of pages deficit */ 144int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 145 146#if !defined(NO_SWAPPING) 147static int vm_pageout_req_swapout; /* XXX */ 148static int vm_daemon_needed; 149static struct mtx vm_daemon_mtx; 150/* Allow for use by vm_pageout before vm_daemon is initialized. */ 151MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); 152#endif 153static int vm_max_launder = 32; 154static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 155static int vm_pageout_full_stats_interval = 0; 156static int vm_pageout_algorithm=0; 157static int defer_swap_pageouts=0; 158static int disable_swap_pageouts=0; 159 160#if defined(NO_SWAPPING) 161static int vm_swap_enabled=0; 162static int vm_swap_idle_enabled=0; 163#else 164static int vm_swap_enabled=1; 165static int vm_swap_idle_enabled=0; 166#endif 167 168SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 169 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 170 171SYSCTL_INT(_vm, OID_AUTO, max_launder, 172 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 173 174SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 175 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 176 177SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 178 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 179 180SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 181 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 182 183#if defined(NO_SWAPPING) 184SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 185 CTLFLAG_RD, &vm_swap_enabled, 0, "Enable entire process swapout"); 186SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 187 CTLFLAG_RD, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 188#else 189SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 190 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 191SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 192 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 193#endif 194 195SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 196 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 197 198SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 199 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 200 201static int pageout_lock_miss; 202SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 203 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 204 205#define VM_PAGEOUT_PAGE_COUNT 16 206int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 207 208int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 209SYSCTL_INT(_vm, OID_AUTO, max_wired, 210 CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count"); 211 212#if !defined(NO_SWAPPING) 213static void vm_pageout_map_deactivate_pages(vm_map_t, long); 214static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long); 215static void vm_req_vmdaemon(int req); 216#endif 217static void vm_pageout_page_stats(void); 218 219/* 220 * Initialize a dummy page for marking the caller's place in the specified 221 * paging queue. In principle, this function only needs to set the flag 222 * PG_MARKER. Nonetheless, it sets the flag VPO_BUSY and initializes the hold 223 * count to one as safety precautions. 224 */ 225static void 226vm_pageout_init_marker(vm_page_t marker, u_short queue) 227{ 228 229 bzero(marker, sizeof(*marker)); 230 marker->flags = PG_MARKER; 231 marker->oflags = VPO_BUSY; 232 marker->queue = queue; 233 marker->hold_count = 1; 234} 235 236/* 237 * vm_pageout_fallback_object_lock: 238 * 239 * Lock vm object currently associated with `m'. VM_OBJECT_TRYLOCK is 240 * known to have failed and page queue must be either PQ_ACTIVE or 241 * PQ_INACTIVE. To avoid lock order violation, unlock the page queues 242 * while locking the vm object. Use marker page to detect page queue 243 * changes and maintain notion of next page on page queue. Return 244 * TRUE if no changes were detected, FALSE otherwise. vm object is 245 * locked on return. 246 * 247 * This function depends on both the lock portion of struct vm_object 248 * and normal struct vm_page being type stable. 249 */ 250boolean_t 251vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next) 252{ 253 struct vm_page marker; 254 boolean_t unchanged; 255 u_short queue; 256 vm_object_t object; 257 258 queue = m->queue; 259 vm_pageout_init_marker(&marker, queue); 260 object = m->object; 261 262 TAILQ_INSERT_AFTER(&vm_page_queues[queue].pl, 263 m, &marker, pageq); 264 vm_page_unlock_queues(); 265 vm_page_unlock(m); 266 VM_OBJECT_LOCK(object); 267 vm_page_lock(m); 268 vm_page_lock_queues(); 269 270 /* Page queue might have changed. */ 271 *next = TAILQ_NEXT(&marker, pageq); 272 unchanged = (m->queue == queue && 273 m->object == object && 274 &marker == TAILQ_NEXT(m, pageq)); 275 TAILQ_REMOVE(&vm_page_queues[queue].pl, 276 &marker, pageq); 277 return (unchanged); 278} 279 280/* 281 * Lock the page while holding the page queue lock. Use marker page 282 * to detect page queue changes and maintain notion of next page on 283 * page queue. Return TRUE if no changes were detected, FALSE 284 * otherwise. The page is locked on return. The page queue lock might 285 * be dropped and reacquired. 286 * 287 * This function depends on normal struct vm_page being type stable. 288 */ 289boolean_t 290vm_pageout_page_lock(vm_page_t m, vm_page_t *next) 291{ 292 struct vm_page marker; 293 boolean_t unchanged; 294 u_short queue; 295 296 vm_page_lock_assert(m, MA_NOTOWNED); 297 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 298 299 if (vm_page_trylock(m)) 300 return (TRUE); 301 302 queue = m->queue; 303 vm_pageout_init_marker(&marker, queue); 304 305 TAILQ_INSERT_AFTER(&vm_page_queues[queue].pl, m, &marker, pageq); 306 vm_page_unlock_queues(); 307 vm_page_lock(m); 308 vm_page_lock_queues(); 309 310 /* Page queue might have changed. */ 311 *next = TAILQ_NEXT(&marker, pageq); 312 unchanged = (m->queue == queue && &marker == TAILQ_NEXT(m, pageq)); 313 TAILQ_REMOVE(&vm_page_queues[queue].pl, &marker, pageq); 314 return (unchanged); 315} 316 317/* 318 * vm_pageout_clean: 319 * 320 * Clean the page and remove it from the laundry. 321 * 322 * We set the busy bit to cause potential page faults on this page to 323 * block. Note the careful timing, however, the busy bit isn't set till 324 * late and we cannot do anything that will mess with the page. 325 */ 326static int 327vm_pageout_clean(vm_page_t m) 328{ 329 vm_object_t object; 330 vm_page_t mc[2*vm_pageout_page_count], pb, ps; 331 int pageout_count; 332 int ib, is, page_base; 333 vm_pindex_t pindex = m->pindex; 334 335 vm_page_lock_assert(m, MA_OWNED); 336 object = m->object; 337 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 338 339 /* 340 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 341 * with the new swapper, but we could have serious problems paging 342 * out other object types if there is insufficient memory. 343 * 344 * Unfortunately, checking free memory here is far too late, so the 345 * check has been moved up a procedural level. 346 */ 347 348 /* 349 * Can't clean the page if it's busy or held. 350 */ 351 KASSERT(m->busy == 0 && (m->oflags & VPO_BUSY) == 0, 352 ("vm_pageout_clean: page %p is busy", m)); 353 KASSERT(m->hold_count == 0, ("vm_pageout_clean: page %p is held", m)); 354 vm_page_unlock(m); 355 356 mc[vm_pageout_page_count] = pb = ps = m; 357 pageout_count = 1; 358 page_base = vm_pageout_page_count; 359 ib = 1; 360 is = 1; 361 362 /* 363 * Scan object for clusterable pages. 364 * 365 * We can cluster ONLY if: ->> the page is NOT 366 * clean, wired, busy, held, or mapped into a 367 * buffer, and one of the following: 368 * 1) The page is inactive, or a seldom used 369 * active page. 370 * -or- 371 * 2) we force the issue. 372 * 373 * During heavy mmap/modification loads the pageout 374 * daemon can really fragment the underlying file 375 * due to flushing pages out of order and not trying 376 * align the clusters (which leave sporatic out-of-order 377 * holes). To solve this problem we do the reverse scan 378 * first and attempt to align our cluster, then do a 379 * forward scan if room remains. 380 */ 381more: 382 while (ib && pageout_count < vm_pageout_page_count) { 383 vm_page_t p; 384 385 if (ib > pindex) { 386 ib = 0; 387 break; 388 } 389 390 if ((p = vm_page_prev(pb)) == NULL || 391 (p->oflags & VPO_BUSY) != 0 || p->busy != 0) { 392 ib = 0; 393 break; 394 } 395 vm_page_lock(p); 396 vm_page_test_dirty(p); 397 if (p->dirty == 0 || 398 p->queue != PQ_INACTIVE || 399 p->hold_count != 0) { /* may be undergoing I/O */ 400 vm_page_unlock(p); 401 ib = 0; 402 break; 403 } 404 vm_page_unlock(p); 405 mc[--page_base] = pb = p; 406 ++pageout_count; 407 ++ib; 408 /* 409 * alignment boundry, stop here and switch directions. Do 410 * not clear ib. 411 */ 412 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 413 break; 414 } 415 416 while (pageout_count < vm_pageout_page_count && 417 pindex + is < object->size) { 418 vm_page_t p; 419 420 if ((p = vm_page_next(ps)) == NULL || 421 (p->oflags & VPO_BUSY) != 0 || p->busy != 0) 422 break; 423 vm_page_lock(p); 424 vm_page_test_dirty(p); 425 if (p->dirty == 0 || 426 p->queue != PQ_INACTIVE || 427 p->hold_count != 0) { /* may be undergoing I/O */ 428 vm_page_unlock(p); 429 break; 430 } 431 vm_page_unlock(p); 432 mc[page_base + pageout_count] = ps = p; 433 ++pageout_count; 434 ++is; 435 } 436 437 /* 438 * If we exhausted our forward scan, continue with the reverse scan 439 * when possible, even past a page boundry. This catches boundry 440 * conditions. 441 */ 442 if (ib && pageout_count < vm_pageout_page_count) 443 goto more; 444 445 /* 446 * we allow reads during pageouts... 447 */ 448 return (vm_pageout_flush(&mc[page_base], pageout_count, 0, 0, NULL, 449 NULL)); 450} 451 452/* 453 * vm_pageout_flush() - launder the given pages 454 * 455 * The given pages are laundered. Note that we setup for the start of 456 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 457 * reference count all in here rather then in the parent. If we want 458 * the parent to do more sophisticated things we may have to change 459 * the ordering. 460 * 461 * Returned runlen is the count of pages between mreq and first 462 * page after mreq with status VM_PAGER_AGAIN. 463 * *eio is set to TRUE if pager returned VM_PAGER_ERROR or VM_PAGER_FAIL 464 * for any page in runlen set. 465 */ 466int 467vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen, 468 boolean_t *eio) 469{ 470 vm_object_t object = mc[0]->object; 471 int pageout_status[count]; 472 int numpagedout = 0; 473 int i, runlen; 474 475 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 476 mtx_assert(&vm_page_queue_mtx, MA_NOTOWNED); 477 478 /* 479 * Initiate I/O. Bump the vm_page_t->busy counter and 480 * mark the pages read-only. 481 * 482 * We do not have to fixup the clean/dirty bits here... we can 483 * allow the pager to do it after the I/O completes. 484 * 485 * NOTE! mc[i]->dirty may be partial or fragmented due to an 486 * edge case with file fragments. 487 */ 488 for (i = 0; i < count; i++) { 489 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 490 ("vm_pageout_flush: partially invalid page %p index %d/%d", 491 mc[i], i, count)); 492 vm_page_io_start(mc[i]); 493 pmap_remove_write(mc[i]); 494 } 495 vm_object_pip_add(object, count); 496 497 vm_pager_put_pages(object, mc, count, flags, pageout_status); 498 499 runlen = count - mreq; 500 if (eio != NULL) 501 *eio = FALSE; 502 for (i = 0; i < count; i++) { 503 vm_page_t mt = mc[i]; 504 505 KASSERT(pageout_status[i] == VM_PAGER_PEND || 506 !pmap_page_is_write_mapped(mt), 507 ("vm_pageout_flush: page %p is not write protected", mt)); 508 switch (pageout_status[i]) { 509 case VM_PAGER_OK: 510 case VM_PAGER_PEND: 511 numpagedout++; 512 break; 513 case VM_PAGER_BAD: 514 /* 515 * Page outside of range of object. Right now we 516 * essentially lose the changes by pretending it 517 * worked. 518 */ 519 vm_page_undirty(mt); 520 break; 521 case VM_PAGER_ERROR: 522 case VM_PAGER_FAIL: 523 /* 524 * If page couldn't be paged out, then reactivate the 525 * page so it doesn't clog the inactive list. (We 526 * will try paging out it again later). 527 */ 528 vm_page_lock(mt); 529 vm_page_activate(mt); 530 vm_page_unlock(mt); 531 if (eio != NULL && i >= mreq && i - mreq < runlen) 532 *eio = TRUE; 533 break; 534 case VM_PAGER_AGAIN: 535 if (i >= mreq && i - mreq < runlen) 536 runlen = i - mreq; 537 break; 538 } 539 540 /* 541 * If the operation is still going, leave the page busy to 542 * block all other accesses. Also, leave the paging in 543 * progress indicator set so that we don't attempt an object 544 * collapse. 545 */ 546 if (pageout_status[i] != VM_PAGER_PEND) { 547 vm_object_pip_wakeup(object); 548 vm_page_io_finish(mt); 549 if (vm_page_count_severe()) { 550 vm_page_lock(mt); 551 vm_page_try_to_cache(mt); 552 vm_page_unlock(mt); 553 } 554 } 555 } 556 if (prunlen != NULL) 557 *prunlen = runlen; 558 return (numpagedout); 559} 560 561#if !defined(NO_SWAPPING) 562/* 563 * vm_pageout_object_deactivate_pages 564 * 565 * Deactivate enough pages to satisfy the inactive target 566 * requirements. 567 * 568 * The object and map must be locked. 569 */ 570static void 571vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object, 572 long desired) 573{ 574 vm_object_t backing_object, object; 575 vm_page_t p; 576 int actcount, remove_mode; 577 578 VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED); 579 if (first_object->type == OBJT_DEVICE || 580 first_object->type == OBJT_SG) 581 return; 582 for (object = first_object;; object = backing_object) { 583 if (pmap_resident_count(pmap) <= desired) 584 goto unlock_return; 585 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 586 if (object->type == OBJT_PHYS || object->paging_in_progress) 587 goto unlock_return; 588 589 remove_mode = 0; 590 if (object->shadow_count > 1) 591 remove_mode = 1; 592 /* 593 * Scan the object's entire memory queue. 594 */ 595 TAILQ_FOREACH(p, &object->memq, listq) { 596 if (pmap_resident_count(pmap) <= desired) 597 goto unlock_return; 598 if ((p->oflags & VPO_BUSY) != 0 || p->busy != 0) 599 continue; 600 PCPU_INC(cnt.v_pdpages); 601 vm_page_lock(p); 602 if (p->wire_count != 0 || p->hold_count != 0 || 603 !pmap_page_exists_quick(pmap, p)) { 604 vm_page_unlock(p); 605 continue; 606 } 607 actcount = pmap_ts_referenced(p); 608 if ((p->aflags & PGA_REFERENCED) != 0) { 609 if (actcount == 0) 610 actcount = 1; 611 vm_page_aflag_clear(p, PGA_REFERENCED); 612 } 613 if (p->queue != PQ_ACTIVE && actcount != 0) { 614 vm_page_activate(p); 615 p->act_count += actcount; 616 } else if (p->queue == PQ_ACTIVE) { 617 if (actcount == 0) { 618 p->act_count -= min(p->act_count, 619 ACT_DECLINE); 620 if (!remove_mode && 621 (vm_pageout_algorithm || 622 p->act_count == 0)) { 623 pmap_remove_all(p); 624 vm_page_deactivate(p); 625 } else { 626 vm_page_lock_queues(); 627 vm_page_requeue(p); 628 vm_page_unlock_queues(); 629 } 630 } else { 631 vm_page_activate(p); 632 if (p->act_count < ACT_MAX - 633 ACT_ADVANCE) 634 p->act_count += ACT_ADVANCE; 635 vm_page_lock_queues(); 636 vm_page_requeue(p); 637 vm_page_unlock_queues(); 638 } 639 } else if (p->queue == PQ_INACTIVE) 640 pmap_remove_all(p); 641 vm_page_unlock(p); 642 } 643 if ((backing_object = object->backing_object) == NULL) 644 goto unlock_return; 645 VM_OBJECT_LOCK(backing_object); 646 if (object != first_object) 647 VM_OBJECT_UNLOCK(object); 648 } 649unlock_return: 650 if (object != first_object) 651 VM_OBJECT_UNLOCK(object); 652} 653 654/* 655 * deactivate some number of pages in a map, try to do it fairly, but 656 * that is really hard to do. 657 */ 658static void 659vm_pageout_map_deactivate_pages(map, desired) 660 vm_map_t map; 661 long desired; 662{ 663 vm_map_entry_t tmpe; 664 vm_object_t obj, bigobj; 665 int nothingwired; 666 667 if (!vm_map_trylock(map)) 668 return; 669 670 bigobj = NULL; 671 nothingwired = TRUE; 672 673 /* 674 * first, search out the biggest object, and try to free pages from 675 * that. 676 */ 677 tmpe = map->header.next; 678 while (tmpe != &map->header) { 679 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 680 obj = tmpe->object.vm_object; 681 if (obj != NULL && VM_OBJECT_TRYLOCK(obj)) { 682 if (obj->shadow_count <= 1 && 683 (bigobj == NULL || 684 bigobj->resident_page_count < obj->resident_page_count)) { 685 if (bigobj != NULL) 686 VM_OBJECT_UNLOCK(bigobj); 687 bigobj = obj; 688 } else 689 VM_OBJECT_UNLOCK(obj); 690 } 691 } 692 if (tmpe->wired_count > 0) 693 nothingwired = FALSE; 694 tmpe = tmpe->next; 695 } 696 697 if (bigobj != NULL) { 698 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); 699 VM_OBJECT_UNLOCK(bigobj); 700 } 701 /* 702 * Next, hunt around for other pages to deactivate. We actually 703 * do this search sort of wrong -- .text first is not the best idea. 704 */ 705 tmpe = map->header.next; 706 while (tmpe != &map->header) { 707 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 708 break; 709 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 710 obj = tmpe->object.vm_object; 711 if (obj != NULL) { 712 VM_OBJECT_LOCK(obj); 713 vm_pageout_object_deactivate_pages(map->pmap, obj, desired); 714 VM_OBJECT_UNLOCK(obj); 715 } 716 } 717 tmpe = tmpe->next; 718 } 719 720 /* 721 * Remove all mappings if a process is swapped out, this will free page 722 * table pages. 723 */ 724 if (desired == 0 && nothingwired) { 725 pmap_remove(vm_map_pmap(map), vm_map_min(map), 726 vm_map_max(map)); 727 } 728 vm_map_unlock(map); 729} 730#endif /* !defined(NO_SWAPPING) */ 731 732/* 733 * vm_pageout_scan does the dirty work for the pageout daemon. 734 */ 735static void 736vm_pageout_scan(int pass) 737{ 738 vm_page_t m, next; 739 struct vm_page marker; 740 int page_shortage, maxscan, pcount; 741 int addl_page_shortage; 742 vm_object_t object; 743 int actcount; 744 int vnodes_skipped = 0; 745 int maxlaunder; 746 boolean_t queues_locked; 747 748 /* 749 * Decrease registered cache sizes. 750 */ 751 EVENTHANDLER_INVOKE(vm_lowmem, 0); 752 /* 753 * We do this explicitly after the caches have been drained above. 754 */ 755 uma_reclaim(); 756 757 /* 758 * The addl_page_shortage is the number of temporarily 759 * stuck pages in the inactive queue. In other words, the 760 * number of pages from cnt.v_inactive_count that should be 761 * discounted in setting the target for the active queue scan. 762 */ 763 addl_page_shortage = atomic_readandclear_int(&vm_pageout_deficit); 764 765 /* 766 * Calculate the number of pages we want to either free or move 767 * to the cache. 768 */ 769 page_shortage = vm_paging_target() + addl_page_shortage; 770 771 vm_pageout_init_marker(&marker, PQ_INACTIVE); 772 773 /* 774 * Start scanning the inactive queue for pages we can move to the 775 * cache or free. The scan will stop when the target is reached or 776 * we have scanned the entire inactive queue. Note that m->act_count 777 * is not used to form decisions for the inactive queue, only for the 778 * active queue. 779 * 780 * maxlaunder limits the number of dirty pages we flush per scan. 781 * For most systems a smaller value (16 or 32) is more robust under 782 * extreme memory and disk pressure because any unnecessary writes 783 * to disk can result in extreme performance degredation. However, 784 * systems with excessive dirty pages (especially when MAP_NOSYNC is 785 * used) will die horribly with limited laundering. If the pageout 786 * daemon cannot clean enough pages in the first pass, we let it go 787 * all out in succeeding passes. 788 */ 789 if ((maxlaunder = vm_max_launder) <= 1) 790 maxlaunder = 1; 791 if (pass) 792 maxlaunder = 10000; 793 vm_page_lock_queues(); 794 queues_locked = TRUE; 795 maxscan = cnt.v_inactive_count; 796 797 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 798 m != NULL && maxscan-- > 0 && page_shortage > 0; 799 m = next) { 800 KASSERT(queues_locked, ("unlocked queues")); 801 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 802 KASSERT(m->queue == PQ_INACTIVE, ("Inactive queue %p", m)); 803 804 cnt.v_pdpages++; 805 next = TAILQ_NEXT(m, pageq); 806 807 /* 808 * skip marker pages 809 */ 810 if (m->flags & PG_MARKER) 811 continue; 812 813 KASSERT((m->flags & PG_FICTITIOUS) == 0, 814 ("Fictitious page %p cannot be in inactive queue", m)); 815 KASSERT((m->oflags & VPO_UNMANAGED) == 0, 816 ("Unmanaged page %p cannot be in inactive queue", m)); 817 818 /* 819 * The page or object lock acquisitions fail if the 820 * page was removed from the queue or moved to a 821 * different position within the queue. In either 822 * case, addl_page_shortage should not be incremented. 823 */ 824 if (!vm_pageout_page_lock(m, &next)) { 825 vm_page_unlock(m); 826 continue; 827 } 828 object = m->object; 829 if (!VM_OBJECT_TRYLOCK(object) && 830 !vm_pageout_fallback_object_lock(m, &next)) { 831 vm_page_unlock(m); 832 VM_OBJECT_UNLOCK(object); 833 continue; 834 } 835 836 /* 837 * Don't mess with busy pages, keep them at at the 838 * front of the queue, most likely they are being 839 * paged out. Increment addl_page_shortage for busy 840 * pages, because they may leave the inactive queue 841 * shortly after page scan is finished. 842 */ 843 if (m->busy != 0 || (m->oflags & VPO_BUSY) != 0) { 844 vm_page_unlock(m); 845 VM_OBJECT_UNLOCK(object); 846 addl_page_shortage++; 847 continue; 848 } 849 850 /* 851 * We unlock vm_page_queue_mtx, invalidating the 852 * 'next' pointer. Use our marker to remember our 853 * place. 854 */ 855 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, 856 m, &marker, pageq); 857 vm_page_unlock_queues(); 858 queues_locked = FALSE; 859 860 /* 861 * If the object is not being used, we ignore previous 862 * references. 863 */ 864 if (object->ref_count == 0) { 865 vm_page_aflag_clear(m, PGA_REFERENCED); 866 KASSERT(!pmap_page_is_mapped(m), 867 ("vm_pageout_scan: page %p is mapped", m)); 868 869 /* 870 * Otherwise, if the page has been referenced while in the 871 * inactive queue, we bump the "activation count" upwards, 872 * making it less likely that the page will be added back to 873 * the inactive queue prematurely again. Here we check the 874 * page tables (or emulated bits, if any), given the upper 875 * level VM system not knowing anything about existing 876 * references. 877 */ 878 } else if ((m->aflags & PGA_REFERENCED) == 0 && 879 (actcount = pmap_ts_referenced(m)) != 0) { 880 vm_page_activate(m); 881 vm_page_unlock(m); 882 m->act_count += actcount + ACT_ADVANCE; 883 VM_OBJECT_UNLOCK(object); 884 goto relock_queues; 885 } 886 887 /* 888 * If the upper level VM system knows about any page 889 * references, we activate the page. We also set the 890 * "activation count" higher than normal so that we will less 891 * likely place pages back onto the inactive queue again. 892 */ 893 if ((m->aflags & PGA_REFERENCED) != 0) { 894 vm_page_aflag_clear(m, PGA_REFERENCED); 895 actcount = pmap_ts_referenced(m); 896 vm_page_activate(m); 897 vm_page_unlock(m); 898 m->act_count += actcount + ACT_ADVANCE + 1; 899 VM_OBJECT_UNLOCK(object); 900 goto relock_queues; 901 } 902 903 if (m->hold_count != 0) { 904 vm_page_unlock(m); 905 VM_OBJECT_UNLOCK(object); 906 907 /* 908 * Held pages are essentially stuck in the 909 * queue. So, they ought to be discounted 910 * from cnt.v_inactive_count. See the 911 * calculation of the page_shortage for the 912 * loop over the active queue below. 913 */ 914 addl_page_shortage++; 915 goto relock_queues; 916 } 917 918 /* 919 * If the upper level VM system does not believe that the page 920 * is fully dirty, but it is mapped for write access, then we 921 * consult the pmap to see if the page's dirty status should 922 * be updated. 923 */ 924 if (m->dirty != VM_PAGE_BITS_ALL && 925 pmap_page_is_write_mapped(m)) { 926 /* 927 * Avoid a race condition: Unless write access is 928 * removed from the page, another processor could 929 * modify it before all access is removed by the call 930 * to vm_page_cache() below. If vm_page_cache() finds 931 * that the page has been modified when it removes all 932 * access, it panics because it cannot cache dirty 933 * pages. In principle, we could eliminate just write 934 * access here rather than all access. In the expected 935 * case, when there are no last instant modifications 936 * to the page, removing all access will be cheaper 937 * overall. 938 */ 939 if (pmap_is_modified(m)) 940 vm_page_dirty(m); 941 else if (m->dirty == 0) 942 pmap_remove_all(m); 943 } 944 945 if (m->valid == 0) { 946 /* 947 * Invalid pages can be easily freed 948 */ 949 vm_page_free(m); 950 PCPU_INC(cnt.v_dfree); 951 --page_shortage; 952 } else if (m->dirty == 0) { 953 /* 954 * Clean pages can be placed onto the cache queue. 955 * This effectively frees them. 956 */ 957 vm_page_cache(m); 958 --page_shortage; 959 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 960 /* 961 * Dirty pages need to be paged out, but flushing 962 * a page is extremely expensive verses freeing 963 * a clean page. Rather then artificially limiting 964 * the number of pages we can flush, we instead give 965 * dirty pages extra priority on the inactive queue 966 * by forcing them to be cycled through the queue 967 * twice before being flushed, after which the 968 * (now clean) page will cycle through once more 969 * before being freed. This significantly extends 970 * the thrash point for a heavily loaded machine. 971 */ 972 m->flags |= PG_WINATCFLS; 973 vm_page_lock_queues(); 974 queues_locked = TRUE; 975 vm_page_requeue(m); 976 } else if (maxlaunder > 0) { 977 /* 978 * We always want to try to flush some dirty pages if 979 * we encounter them, to keep the system stable. 980 * Normally this number is small, but under extreme 981 * pressure where there are insufficient clean pages 982 * on the inactive queue, we may have to go all out. 983 */ 984 int swap_pageouts_ok, vfslocked = 0; 985 struct vnode *vp = NULL; 986 struct mount *mp = NULL; 987 988 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 989 swap_pageouts_ok = 1; 990 } else { 991 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 992 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 993 vm_page_count_min()); 994 995 } 996 997 /* 998 * We don't bother paging objects that are "dead". 999 * Those objects are in a "rundown" state. 1000 */ 1001 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 1002 vm_page_lock_queues(); 1003 vm_page_unlock(m); 1004 VM_OBJECT_UNLOCK(object); 1005 queues_locked = TRUE; 1006 vm_page_requeue(m); 1007 goto relock_queues; 1008 } 1009 1010 /* 1011 * The object is already known NOT to be dead. It 1012 * is possible for the vget() to block the whole 1013 * pageout daemon, but the new low-memory handling 1014 * code should prevent it. 1015 * 1016 * The previous code skipped locked vnodes and, worse, 1017 * reordered pages in the queue. This results in 1018 * completely non-deterministic operation and, on a 1019 * busy system, can lead to extremely non-optimal 1020 * pageouts. For example, it can cause clean pages 1021 * to be freed and dirty pages to be moved to the end 1022 * of the queue. Since dirty pages are also moved to 1023 * the end of the queue once-cleaned, this gives 1024 * way too large a weighting to defering the freeing 1025 * of dirty pages. 1026 * 1027 * We can't wait forever for the vnode lock, we might 1028 * deadlock due to a vn_read() getting stuck in 1029 * vm_wait while holding this vnode. We skip the 1030 * vnode if we can't get it in a reasonable amount 1031 * of time. 1032 */ 1033 if (object->type == OBJT_VNODE) { 1034 vm_page_unlock(m); 1035 vp = object->handle; 1036 if (vp->v_type == VREG && 1037 vn_start_write(vp, &mp, V_NOWAIT) != 0) { 1038 mp = NULL; 1039 ++pageout_lock_miss; 1040 if (object->flags & OBJ_MIGHTBEDIRTY) 1041 vnodes_skipped++; 1042 goto unlock_and_continue; 1043 } 1044 KASSERT(mp != NULL, 1045 ("vp %p with NULL v_mount", vp)); 1046 vm_object_reference_locked(object); 1047 VM_OBJECT_UNLOCK(object); 1048 vfslocked = VFS_LOCK_GIANT(vp->v_mount); 1049 if (vget(vp, LK_EXCLUSIVE | LK_TIMELOCK, 1050 curthread)) { 1051 VM_OBJECT_LOCK(object); 1052 ++pageout_lock_miss; 1053 if (object->flags & OBJ_MIGHTBEDIRTY) 1054 vnodes_skipped++; 1055 vp = NULL; 1056 goto unlock_and_continue; 1057 } 1058 VM_OBJECT_LOCK(object); 1059 vm_page_lock(m); 1060 vm_page_lock_queues(); 1061 queues_locked = TRUE; 1062 /* 1063 * The page might have been moved to another 1064 * queue during potential blocking in vget() 1065 * above. The page might have been freed and 1066 * reused for another vnode. 1067 */ 1068 if (m->queue != PQ_INACTIVE || 1069 m->object != object || 1070 TAILQ_NEXT(m, pageq) != &marker) { 1071 vm_page_unlock(m); 1072 if (object->flags & OBJ_MIGHTBEDIRTY) 1073 vnodes_skipped++; 1074 goto unlock_and_continue; 1075 } 1076 1077 /* 1078 * The page may have been busied during the 1079 * blocking in vget(). We don't move the 1080 * page back onto the end of the queue so that 1081 * statistics are more correct if we don't. 1082 */ 1083 if (m->busy || (m->oflags & VPO_BUSY)) { 1084 vm_page_unlock(m); 1085 goto unlock_and_continue; 1086 } 1087 1088 /* 1089 * If the page has become held it might 1090 * be undergoing I/O, so skip it 1091 */ 1092 if (m->hold_count) { 1093 vm_page_unlock(m); 1094 vm_page_requeue(m); 1095 if (object->flags & OBJ_MIGHTBEDIRTY) 1096 vnodes_skipped++; 1097 goto unlock_and_continue; 1098 } 1099 vm_page_unlock_queues(); 1100 queues_locked = FALSE; 1101 } 1102 1103 /* 1104 * If a page is dirty, then it is either being washed 1105 * (but not yet cleaned) or it is still in the 1106 * laundry. If it is still in the laundry, then we 1107 * start the cleaning operation. 1108 * 1109 * decrement page_shortage on success to account for 1110 * the (future) cleaned page. Otherwise we could wind 1111 * up laundering or cleaning too many pages. 1112 */ 1113 if (vm_pageout_clean(m) != 0) { 1114 --page_shortage; 1115 --maxlaunder; 1116 } 1117unlock_and_continue: 1118 vm_page_lock_assert(m, MA_NOTOWNED); 1119 VM_OBJECT_UNLOCK(object); 1120 if (mp != NULL) { 1121 if (queues_locked) { 1122 vm_page_unlock_queues(); 1123 queues_locked = FALSE; 1124 } 1125 if (vp != NULL) 1126 vput(vp); 1127 VFS_UNLOCK_GIANT(vfslocked); 1128 vm_object_deallocate(object); 1129 vn_finished_write(mp); 1130 } 1131 vm_page_lock_assert(m, MA_NOTOWNED); 1132 goto relock_queues; 1133 } 1134 vm_page_unlock(m); 1135 VM_OBJECT_UNLOCK(object); 1136relock_queues: 1137 if (!queues_locked) { 1138 vm_page_lock_queues(); 1139 queues_locked = TRUE; 1140 } 1141 next = TAILQ_NEXT(&marker, pageq); 1142 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, 1143 &marker, pageq); 1144 } 1145 1146 /* 1147 * Compute the number of pages we want to try to move from the 1148 * active queue to the inactive queue. 1149 */ 1150 page_shortage = vm_paging_target() + 1151 cnt.v_inactive_target - cnt.v_inactive_count; 1152 page_shortage += addl_page_shortage; 1153 1154 /* 1155 * Scan the active queue for things we can deactivate. We nominally 1156 * track the per-page activity counter and use it to locate 1157 * deactivation candidates. 1158 */ 1159 pcount = cnt.v_active_count; 1160 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1161 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1162 1163 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 1164 1165 KASSERT(m->queue == PQ_ACTIVE, 1166 ("vm_pageout_scan: page %p isn't active", m)); 1167 1168 next = TAILQ_NEXT(m, pageq); 1169 if ((m->flags & PG_MARKER) != 0) { 1170 m = next; 1171 continue; 1172 } 1173 KASSERT((m->flags & PG_FICTITIOUS) == 0, 1174 ("Fictitious page %p cannot be in active queue", m)); 1175 KASSERT((m->oflags & VPO_UNMANAGED) == 0, 1176 ("Unmanaged page %p cannot be in active queue", m)); 1177 if (!vm_pageout_page_lock(m, &next)) { 1178 vm_page_unlock(m); 1179 m = next; 1180 continue; 1181 } 1182 object = m->object; 1183 if (!VM_OBJECT_TRYLOCK(object) && 1184 !vm_pageout_fallback_object_lock(m, &next)) { 1185 VM_OBJECT_UNLOCK(object); 1186 vm_page_unlock(m); 1187 m = next; 1188 continue; 1189 } 1190 1191 /* 1192 * Don't deactivate pages that are busy. 1193 */ 1194 if ((m->busy != 0) || 1195 (m->oflags & VPO_BUSY) || 1196 (m->hold_count != 0)) { 1197 vm_page_unlock(m); 1198 VM_OBJECT_UNLOCK(object); 1199 vm_page_requeue(m); 1200 m = next; 1201 continue; 1202 } 1203 1204 /* 1205 * The count for pagedaemon pages is done after checking the 1206 * page for eligibility... 1207 */ 1208 cnt.v_pdpages++; 1209 1210 /* 1211 * Check to see "how much" the page has been used. 1212 */ 1213 actcount = 0; 1214 if (object->ref_count != 0) { 1215 if (m->aflags & PGA_REFERENCED) { 1216 actcount += 1; 1217 } 1218 actcount += pmap_ts_referenced(m); 1219 if (actcount) { 1220 m->act_count += ACT_ADVANCE + actcount; 1221 if (m->act_count > ACT_MAX) 1222 m->act_count = ACT_MAX; 1223 } 1224 } 1225 1226 /* 1227 * Since we have "tested" this bit, we need to clear it now. 1228 */ 1229 vm_page_aflag_clear(m, PGA_REFERENCED); 1230 1231 /* 1232 * Only if an object is currently being used, do we use the 1233 * page activation count stats. 1234 */ 1235 if (actcount && (object->ref_count != 0)) { 1236 vm_page_requeue(m); 1237 } else { 1238 m->act_count -= min(m->act_count, ACT_DECLINE); 1239 if (vm_pageout_algorithm || 1240 object->ref_count == 0 || 1241 m->act_count == 0) { 1242 page_shortage--; 1243 if (object->ref_count == 0) { 1244 KASSERT(!pmap_page_is_mapped(m), 1245 ("vm_pageout_scan: page %p is mapped", m)); 1246 if (m->dirty == 0) 1247 vm_page_cache(m); 1248 else 1249 vm_page_deactivate(m); 1250 } else { 1251 vm_page_deactivate(m); 1252 } 1253 } else { 1254 vm_page_requeue(m); 1255 } 1256 } 1257 vm_page_unlock(m); 1258 VM_OBJECT_UNLOCK(object); 1259 m = next; 1260 } 1261 vm_page_unlock_queues(); 1262#if !defined(NO_SWAPPING) 1263 /* 1264 * Idle process swapout -- run once per second. 1265 */ 1266 if (vm_swap_idle_enabled) { 1267 static long lsec; 1268 if (time_second != lsec) { 1269 vm_req_vmdaemon(VM_SWAP_IDLE); 1270 lsec = time_second; 1271 } 1272 } 1273#endif 1274 1275 /* 1276 * If we didn't get enough free pages, and we have skipped a vnode 1277 * in a writeable object, wakeup the sync daemon. And kick swapout 1278 * if we did not get enough free pages. 1279 */ 1280 if (vm_paging_target() > 0) { 1281 if (vnodes_skipped && vm_page_count_min()) 1282 (void) speedup_syncer(); 1283#if !defined(NO_SWAPPING) 1284 if (vm_swap_enabled && vm_page_count_target()) 1285 vm_req_vmdaemon(VM_SWAP_NORMAL); 1286#endif 1287 } 1288 1289 /* 1290 * If we are critically low on one of RAM or swap and low on 1291 * the other, kill the largest process. However, we avoid 1292 * doing this on the first pass in order to give ourselves a 1293 * chance to flush out dirty vnode-backed pages and to allow 1294 * active pages to be moved to the inactive queue and reclaimed. 1295 */ 1296 if (pass != 0 && 1297 ((swap_pager_avail < 64 && vm_page_count_min()) || 1298 (swap_pager_full && vm_paging_target() > 0))) 1299 vm_pageout_oom(VM_OOM_MEM); 1300} 1301 1302 1303void 1304vm_pageout_oom(int shortage) 1305{ 1306 struct proc *p, *bigproc; 1307 vm_offset_t size, bigsize; 1308 struct thread *td; 1309 struct vmspace *vm; 1310 1311 /* 1312 * We keep the process bigproc locked once we find it to keep anyone 1313 * from messing with it; however, there is a possibility of 1314 * deadlock if process B is bigproc and one of it's child processes 1315 * attempts to propagate a signal to B while we are waiting for A's 1316 * lock while walking this list. To avoid this, we don't block on 1317 * the process lock but just skip a process if it is already locked. 1318 */ 1319 bigproc = NULL; 1320 bigsize = 0; 1321 sx_slock(&allproc_lock); 1322 FOREACH_PROC_IN_SYSTEM(p) { 1323 int breakout; 1324 1325 if (PROC_TRYLOCK(p) == 0) 1326 continue; 1327 /* 1328 * If this is a system, protected or killed process, skip it. 1329 */ 1330 if (p->p_state != PRS_NORMAL || 1331 (p->p_flag & (P_INEXEC | P_PROTECTED | P_SYSTEM)) || 1332 (p->p_pid == 1) || P_KILLED(p) || 1333 ((p->p_pid < 48) && (swap_pager_avail != 0))) { 1334 PROC_UNLOCK(p); 1335 continue; 1336 } 1337 /* 1338 * If the process is in a non-running type state, 1339 * don't touch it. Check all the threads individually. 1340 */ 1341 breakout = 0; 1342 FOREACH_THREAD_IN_PROC(p, td) { 1343 thread_lock(td); 1344 if (!TD_ON_RUNQ(td) && 1345 !TD_IS_RUNNING(td) && 1346 !TD_IS_SLEEPING(td) && 1347 !TD_IS_SUSPENDED(td)) { 1348 thread_unlock(td); 1349 breakout = 1; 1350 break; 1351 } 1352 thread_unlock(td); 1353 } 1354 if (breakout) { 1355 PROC_UNLOCK(p); 1356 continue; 1357 } 1358 /* 1359 * get the process size 1360 */ 1361 vm = vmspace_acquire_ref(p); 1362 if (vm == NULL) { 1363 PROC_UNLOCK(p); 1364 continue; 1365 } 1366 if (!vm_map_trylock_read(&vm->vm_map)) { 1367 vmspace_free(vm); 1368 PROC_UNLOCK(p); 1369 continue; 1370 } 1371 size = vmspace_swap_count(vm); 1372 vm_map_unlock_read(&vm->vm_map); 1373 if (shortage == VM_OOM_MEM) 1374 size += vmspace_resident_count(vm); 1375 vmspace_free(vm); 1376 /* 1377 * if the this process is bigger than the biggest one 1378 * remember it. 1379 */ 1380 if (size > bigsize) { 1381 if (bigproc != NULL) 1382 PROC_UNLOCK(bigproc); 1383 bigproc = p; 1384 bigsize = size; 1385 } else 1386 PROC_UNLOCK(p); 1387 } 1388 sx_sunlock(&allproc_lock); 1389 if (bigproc != NULL) { 1390 killproc(bigproc, "out of swap space"); 1391 sched_nice(bigproc, PRIO_MIN); 1392 PROC_UNLOCK(bigproc); 1393 wakeup(&cnt.v_free_count); 1394 } 1395} 1396 1397/* 1398 * This routine tries to maintain the pseudo LRU active queue, 1399 * so that during long periods of time where there is no paging, 1400 * that some statistic accumulation still occurs. This code 1401 * helps the situation where paging just starts to occur. 1402 */ 1403static void 1404vm_pageout_page_stats() 1405{ 1406 vm_object_t object; 1407 vm_page_t m,next; 1408 int pcount,tpcount; /* Number of pages to check */ 1409 static int fullintervalcount = 0; 1410 int page_shortage; 1411 1412 page_shortage = 1413 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1414 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1415 1416 if (page_shortage <= 0) 1417 return; 1418 1419 vm_page_lock_queues(); 1420 pcount = cnt.v_active_count; 1421 fullintervalcount += vm_pageout_stats_interval; 1422 if (fullintervalcount < vm_pageout_full_stats_interval) { 1423 tpcount = (int64_t)vm_pageout_stats_max * cnt.v_active_count / 1424 cnt.v_page_count; 1425 if (pcount > tpcount) 1426 pcount = tpcount; 1427 } else { 1428 fullintervalcount = 0; 1429 } 1430 1431 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1432 while ((m != NULL) && (pcount-- > 0)) { 1433 int actcount; 1434 1435 KASSERT(m->queue == PQ_ACTIVE, 1436 ("vm_pageout_page_stats: page %p isn't active", m)); 1437 1438 next = TAILQ_NEXT(m, pageq); 1439 if ((m->flags & PG_MARKER) != 0) { 1440 m = next; 1441 continue; 1442 } 1443 vm_page_lock_assert(m, MA_NOTOWNED); 1444 if (!vm_pageout_page_lock(m, &next)) { 1445 vm_page_unlock(m); 1446 m = next; 1447 continue; 1448 } 1449 object = m->object; 1450 if (!VM_OBJECT_TRYLOCK(object) && 1451 !vm_pageout_fallback_object_lock(m, &next)) { 1452 VM_OBJECT_UNLOCK(object); 1453 vm_page_unlock(m); 1454 m = next; 1455 continue; 1456 } 1457 1458 /* 1459 * Don't deactivate pages that are busy. 1460 */ 1461 if ((m->busy != 0) || 1462 (m->oflags & VPO_BUSY) || 1463 (m->hold_count != 0)) { 1464 vm_page_unlock(m); 1465 VM_OBJECT_UNLOCK(object); 1466 vm_page_requeue(m); 1467 m = next; 1468 continue; 1469 } 1470 1471 actcount = 0; 1472 if (m->aflags & PGA_REFERENCED) { 1473 vm_page_aflag_clear(m, PGA_REFERENCED); 1474 actcount += 1; 1475 } 1476 1477 actcount += pmap_ts_referenced(m); 1478 if (actcount) { 1479 m->act_count += ACT_ADVANCE + actcount; 1480 if (m->act_count > ACT_MAX) 1481 m->act_count = ACT_MAX; 1482 vm_page_requeue(m); 1483 } else { 1484 if (m->act_count == 0) { 1485 /* 1486 * We turn off page access, so that we have 1487 * more accurate RSS stats. We don't do this 1488 * in the normal page deactivation when the 1489 * system is loaded VM wise, because the 1490 * cost of the large number of page protect 1491 * operations would be higher than the value 1492 * of doing the operation. 1493 */ 1494 pmap_remove_all(m); 1495 vm_page_deactivate(m); 1496 } else { 1497 m->act_count -= min(m->act_count, ACT_DECLINE); 1498 vm_page_requeue(m); 1499 } 1500 } 1501 vm_page_unlock(m); 1502 VM_OBJECT_UNLOCK(object); 1503 m = next; 1504 } 1505 vm_page_unlock_queues(); 1506} 1507 1508/* 1509 * vm_pageout is the high level pageout daemon. 1510 */ 1511static void 1512vm_pageout() 1513{ 1514 int error, pass; 1515 1516 /* 1517 * Initialize some paging parameters. 1518 */ 1519 cnt.v_interrupt_free_min = 2; 1520 if (cnt.v_page_count < 2000) 1521 vm_pageout_page_count = 8; 1522 1523 /* 1524 * v_free_reserved needs to include enough for the largest 1525 * swap pager structures plus enough for any pv_entry structs 1526 * when paging. 1527 */ 1528 if (cnt.v_page_count > 1024) 1529 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1530 else 1531 cnt.v_free_min = 4; 1532 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1533 cnt.v_interrupt_free_min; 1534 cnt.v_free_reserved = vm_pageout_page_count + 1535 cnt.v_pageout_free_min + (cnt.v_page_count / 768); 1536 cnt.v_free_severe = cnt.v_free_min / 2; 1537 cnt.v_free_min += cnt.v_free_reserved; 1538 cnt.v_free_severe += cnt.v_free_reserved; 1539 1540 /* 1541 * v_free_target and v_cache_min control pageout hysteresis. Note 1542 * that these are more a measure of the VM cache queue hysteresis 1543 * then the VM free queue. Specifically, v_free_target is the 1544 * high water mark (free+cache pages). 1545 * 1546 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1547 * low water mark, while v_free_min is the stop. v_cache_min must 1548 * be big enough to handle memory needs while the pageout daemon 1549 * is signalled and run to free more pages. 1550 */ 1551 if (cnt.v_free_count > 6144) 1552 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1553 else 1554 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1555 1556 if (cnt.v_free_count > 2048) { 1557 cnt.v_cache_min = cnt.v_free_target; 1558 cnt.v_cache_max = 2 * cnt.v_cache_min; 1559 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1560 } else { 1561 cnt.v_cache_min = 0; 1562 cnt.v_cache_max = 0; 1563 cnt.v_inactive_target = cnt.v_free_count / 4; 1564 } 1565 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1566 cnt.v_inactive_target = cnt.v_free_count / 3; 1567 1568 /* XXX does not really belong here */ 1569 if (vm_page_max_wired == 0) 1570 vm_page_max_wired = cnt.v_free_count / 3; 1571 1572 if (vm_pageout_stats_max == 0) 1573 vm_pageout_stats_max = cnt.v_free_target; 1574 1575 /* 1576 * Set interval in seconds for stats scan. 1577 */ 1578 if (vm_pageout_stats_interval == 0) 1579 vm_pageout_stats_interval = 5; 1580 if (vm_pageout_full_stats_interval == 0) 1581 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1582 1583 swap_pager_swap_init(); 1584 pass = 0; 1585 /* 1586 * The pageout daemon is never done, so loop forever. 1587 */ 1588 while (TRUE) { 1589 /* 1590 * If we have enough free memory, wakeup waiters. Do 1591 * not clear vm_pages_needed until we reach our target, 1592 * otherwise we may be woken up over and over again and 1593 * waste a lot of cpu. 1594 */ 1595 mtx_lock(&vm_page_queue_free_mtx); 1596 if (vm_pages_needed && !vm_page_count_min()) { 1597 if (!vm_paging_needed()) 1598 vm_pages_needed = 0; 1599 wakeup(&cnt.v_free_count); 1600 } 1601 if (vm_pages_needed) { 1602 /* 1603 * Still not done, take a second pass without waiting 1604 * (unlimited dirty cleaning), otherwise sleep a bit 1605 * and try again. 1606 */ 1607 ++pass; 1608 if (pass > 1) 1609 msleep(&vm_pages_needed, 1610 &vm_page_queue_free_mtx, PVM, "psleep", 1611 hz / 2); 1612 } else { 1613 /* 1614 * Good enough, sleep & handle stats. Prime the pass 1615 * for the next run. 1616 */ 1617 if (pass > 1) 1618 pass = 1; 1619 else 1620 pass = 0; 1621 error = msleep(&vm_pages_needed, 1622 &vm_page_queue_free_mtx, PVM, "psleep", 1623 vm_pageout_stats_interval * hz); 1624 if (error && !vm_pages_needed) { 1625 mtx_unlock(&vm_page_queue_free_mtx); 1626 pass = 0; 1627 vm_pageout_page_stats(); 1628 continue; 1629 } 1630 } 1631 if (vm_pages_needed) 1632 cnt.v_pdwakeups++; 1633 mtx_unlock(&vm_page_queue_free_mtx); 1634 vm_pageout_scan(pass); 1635 } 1636} 1637 1638/* 1639 * Unless the free page queue lock is held by the caller, this function 1640 * should be regarded as advisory. Specifically, the caller should 1641 * not msleep() on &cnt.v_free_count following this function unless 1642 * the free page queue lock is held until the msleep() is performed. 1643 */ 1644void 1645pagedaemon_wakeup() 1646{ 1647 1648 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1649 vm_pages_needed = 1; 1650 wakeup(&vm_pages_needed); 1651 } 1652} 1653 1654#if !defined(NO_SWAPPING) 1655static void 1656vm_req_vmdaemon(int req) 1657{ 1658 static int lastrun = 0; 1659 1660 mtx_lock(&vm_daemon_mtx); 1661 vm_pageout_req_swapout |= req; 1662 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1663 wakeup(&vm_daemon_needed); 1664 lastrun = ticks; 1665 } 1666 mtx_unlock(&vm_daemon_mtx); 1667} 1668 1669static void 1670vm_daemon() 1671{ 1672 struct rlimit rsslim; 1673 struct proc *p; 1674 struct thread *td; 1675 struct vmspace *vm; 1676 int breakout, swapout_flags, tryagain, attempts; 1677#ifdef RACCT 1678 uint64_t rsize, ravailable; 1679#endif 1680 1681 while (TRUE) { 1682 mtx_lock(&vm_daemon_mtx); 1683#ifdef RACCT 1684 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", hz); 1685#else 1686 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0); 1687#endif 1688 swapout_flags = vm_pageout_req_swapout; 1689 vm_pageout_req_swapout = 0; 1690 mtx_unlock(&vm_daemon_mtx); 1691 if (swapout_flags) 1692 swapout_procs(swapout_flags); 1693 1694 /* 1695 * scan the processes for exceeding their rlimits or if 1696 * process is swapped out -- deactivate pages 1697 */ 1698 tryagain = 0; 1699 attempts = 0; 1700again: 1701 attempts++; 1702 sx_slock(&allproc_lock); 1703 FOREACH_PROC_IN_SYSTEM(p) { 1704 vm_pindex_t limit, size; 1705 1706 /* 1707 * if this is a system process or if we have already 1708 * looked at this process, skip it. 1709 */ 1710 PROC_LOCK(p); 1711 if (p->p_state != PRS_NORMAL || 1712 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 1713 PROC_UNLOCK(p); 1714 continue; 1715 } 1716 /* 1717 * if the process is in a non-running type state, 1718 * don't touch it. 1719 */ 1720 breakout = 0; 1721 FOREACH_THREAD_IN_PROC(p, td) { 1722 thread_lock(td); 1723 if (!TD_ON_RUNQ(td) && 1724 !TD_IS_RUNNING(td) && 1725 !TD_IS_SLEEPING(td) && 1726 !TD_IS_SUSPENDED(td)) { 1727 thread_unlock(td); 1728 breakout = 1; 1729 break; 1730 } 1731 thread_unlock(td); 1732 } 1733 if (breakout) { 1734 PROC_UNLOCK(p); 1735 continue; 1736 } 1737 /* 1738 * get a limit 1739 */ 1740 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1741 limit = OFF_TO_IDX( 1742 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1743 1744 /* 1745 * let processes that are swapped out really be 1746 * swapped out set the limit to nothing (will force a 1747 * swap-out.) 1748 */ 1749 if ((p->p_flag & P_INMEM) == 0) 1750 limit = 0; /* XXX */ 1751 vm = vmspace_acquire_ref(p); 1752 PROC_UNLOCK(p); 1753 if (vm == NULL) 1754 continue; 1755 1756 size = vmspace_resident_count(vm); 1757 if (limit >= 0 && size >= limit) { 1758 vm_pageout_map_deactivate_pages( 1759 &vm->vm_map, limit); 1760 } 1761#ifdef RACCT 1762 rsize = IDX_TO_OFF(size); 1763 PROC_LOCK(p); 1764 racct_set(p, RACCT_RSS, rsize); 1765 ravailable = racct_get_available(p, RACCT_RSS); 1766 PROC_UNLOCK(p); 1767 if (rsize > ravailable) { 1768 /* 1769 * Don't be overly aggressive; this might be 1770 * an innocent process, and the limit could've 1771 * been exceeded by some memory hog. Don't 1772 * try to deactivate more than 1/4th of process' 1773 * resident set size. 1774 */ 1775 if (attempts <= 8) { 1776 if (ravailable < rsize - (rsize / 4)) 1777 ravailable = rsize - (rsize / 4); 1778 } 1779 vm_pageout_map_deactivate_pages( 1780 &vm->vm_map, OFF_TO_IDX(ravailable)); 1781 /* Update RSS usage after paging out. */ 1782 size = vmspace_resident_count(vm); 1783 rsize = IDX_TO_OFF(size); 1784 PROC_LOCK(p); 1785 racct_set(p, RACCT_RSS, rsize); 1786 PROC_UNLOCK(p); 1787 if (rsize > ravailable) 1788 tryagain = 1; 1789 } 1790#endif 1791 vmspace_free(vm); 1792 } 1793 sx_sunlock(&allproc_lock); 1794 if (tryagain != 0 && attempts <= 10) 1795 goto again; 1796 } 1797} 1798#endif /* !defined(NO_SWAPPING) */ 1799