vm_pageout.c revision 288296
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: stable/10/sys/vm/vm_pageout.c 288296 2015-09-27 04:47:08Z alc $"); 77 78#include "opt_vm.h" 79#include "opt_kdtrace.h" 80#include <sys/param.h> 81#include <sys/systm.h> 82#include <sys/kernel.h> 83#include <sys/eventhandler.h> 84#include <sys/lock.h> 85#include <sys/mutex.h> 86#include <sys/proc.h> 87#include <sys/kthread.h> 88#include <sys/ktr.h> 89#include <sys/mount.h> 90#include <sys/racct.h> 91#include <sys/resourcevar.h> 92#include <sys/sched.h> 93#include <sys/sdt.h> 94#include <sys/signalvar.h> 95#include <sys/smp.h> 96#include <sys/time.h> 97#include <sys/vnode.h> 98#include <sys/vmmeter.h> 99#include <sys/rwlock.h> 100#include <sys/sx.h> 101#include <sys/sysctl.h> 102 103#include <vm/vm.h> 104#include <vm/vm_param.h> 105#include <vm/vm_object.h> 106#include <vm/vm_page.h> 107#include <vm/vm_map.h> 108#include <vm/vm_pageout.h> 109#include <vm/vm_pager.h> 110#include <vm/vm_phys.h> 111#include <vm/swap_pager.h> 112#include <vm/vm_extern.h> 113#include <vm/uma.h> 114 115/* 116 * System initialization 117 */ 118 119/* the kernel process "vm_pageout"*/ 120static void vm_pageout(void); 121static void vm_pageout_init(void); 122static int vm_pageout_clean(vm_page_t); 123static void vm_pageout_scan(struct vm_domain *vmd, int pass); 124static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass); 125 126SYSINIT(pagedaemon_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, vm_pageout_init, 127 NULL); 128 129struct proc *pageproc; 130 131static struct kproc_desc page_kp = { 132 "pagedaemon", 133 vm_pageout, 134 &pageproc 135}; 136SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start, 137 &page_kp); 138 139SDT_PROVIDER_DEFINE(vm); 140SDT_PROBE_DEFINE(vm, , , vm__lowmem_cache); 141SDT_PROBE_DEFINE(vm, , , vm__lowmem_scan); 142 143#if !defined(NO_SWAPPING) 144/* the kernel process "vm_daemon"*/ 145static void vm_daemon(void); 146static struct proc *vmproc; 147 148static struct kproc_desc vm_kp = { 149 "vmdaemon", 150 vm_daemon, 151 &vmproc 152}; 153SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp); 154#endif 155 156 157int vm_pages_needed; /* Event on which pageout daemon sleeps */ 158int vm_pageout_deficit; /* Estimated number of pages deficit */ 159int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 160int vm_pageout_wakeup_thresh; 161 162#if !defined(NO_SWAPPING) 163static int vm_pageout_req_swapout; /* XXX */ 164static int vm_daemon_needed; 165static struct mtx vm_daemon_mtx; 166/* Allow for use by vm_pageout before vm_daemon is initialized. */ 167MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); 168#endif 169static int vm_max_launder = 32; 170static int vm_pageout_update_period; 171static int defer_swap_pageouts; 172static int disable_swap_pageouts; 173static int lowmem_period = 10; 174static time_t lowmem_uptime; 175 176#if defined(NO_SWAPPING) 177static int vm_swap_enabled = 0; 178static int vm_swap_idle_enabled = 0; 179#else 180static int vm_swap_enabled = 1; 181static int vm_swap_idle_enabled = 0; 182#endif 183 184SYSCTL_INT(_vm, OID_AUTO, pageout_wakeup_thresh, 185 CTLFLAG_RW, &vm_pageout_wakeup_thresh, 0, 186 "free page threshold for waking up the pageout daemon"); 187 188SYSCTL_INT(_vm, OID_AUTO, max_launder, 189 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 190 191SYSCTL_INT(_vm, OID_AUTO, pageout_update_period, 192 CTLFLAG_RW, &vm_pageout_update_period, 0, 193 "Maximum active LRU update period"); 194 195SYSCTL_INT(_vm, OID_AUTO, lowmem_period, CTLFLAG_RW, &lowmem_period, 0, 196 "Low memory callback period"); 197 198#if defined(NO_SWAPPING) 199SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 200 CTLFLAG_RD, &vm_swap_enabled, 0, "Enable entire process swapout"); 201SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 202 CTLFLAG_RD, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 203#else 204SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 205 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 206SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 207 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 208#endif 209 210SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 211 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 212 213SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 214 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 215 216static int pageout_lock_miss; 217SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 218 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 219 220#define VM_PAGEOUT_PAGE_COUNT 16 221int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 222 223int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 224SYSCTL_INT(_vm, OID_AUTO, max_wired, 225 CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count"); 226 227static boolean_t vm_pageout_fallback_object_lock(vm_page_t, vm_page_t *); 228static boolean_t vm_pageout_launder(struct vm_pagequeue *pq, int, vm_paddr_t, 229 vm_paddr_t); 230#if !defined(NO_SWAPPING) 231static void vm_pageout_map_deactivate_pages(vm_map_t, long); 232static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long); 233static void vm_req_vmdaemon(int req); 234#endif 235static boolean_t vm_pageout_page_lock(vm_page_t, vm_page_t *); 236 237/* 238 * Initialize a dummy page for marking the caller's place in the specified 239 * paging queue. In principle, this function only needs to set the flag 240 * PG_MARKER. Nonetheless, it wirte busies and initializes the hold count 241 * to one as safety precautions. 242 */ 243static void 244vm_pageout_init_marker(vm_page_t marker, u_short queue) 245{ 246 247 bzero(marker, sizeof(*marker)); 248 marker->flags = PG_MARKER; 249 marker->busy_lock = VPB_SINGLE_EXCLUSIVER; 250 marker->queue = queue; 251 marker->hold_count = 1; 252} 253 254/* 255 * vm_pageout_fallback_object_lock: 256 * 257 * Lock vm object currently associated with `m'. VM_OBJECT_TRYWLOCK is 258 * known to have failed and page queue must be either PQ_ACTIVE or 259 * PQ_INACTIVE. To avoid lock order violation, unlock the page queues 260 * while locking the vm object. Use marker page to detect page queue 261 * changes and maintain notion of next page on page queue. Return 262 * TRUE if no changes were detected, FALSE otherwise. vm object is 263 * locked on return. 264 * 265 * This function depends on both the lock portion of struct vm_object 266 * and normal struct vm_page being type stable. 267 */ 268static boolean_t 269vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next) 270{ 271 struct vm_page marker; 272 struct vm_pagequeue *pq; 273 boolean_t unchanged; 274 u_short queue; 275 vm_object_t object; 276 277 queue = m->queue; 278 vm_pageout_init_marker(&marker, queue); 279 pq = vm_page_pagequeue(m); 280 object = m->object; 281 282 TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q); 283 vm_pagequeue_unlock(pq); 284 vm_page_unlock(m); 285 VM_OBJECT_WLOCK(object); 286 vm_page_lock(m); 287 vm_pagequeue_lock(pq); 288 289 /* Page queue might have changed. */ 290 *next = TAILQ_NEXT(&marker, plinks.q); 291 unchanged = (m->queue == queue && 292 m->object == object && 293 &marker == TAILQ_NEXT(m, plinks.q)); 294 TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q); 295 return (unchanged); 296} 297 298/* 299 * Lock the page while holding the page queue lock. Use marker page 300 * to detect page queue changes and maintain notion of next page on 301 * page queue. Return TRUE if no changes were detected, FALSE 302 * otherwise. The page is locked on return. The page queue lock might 303 * be dropped and reacquired. 304 * 305 * This function depends on normal struct vm_page being type stable. 306 */ 307static boolean_t 308vm_pageout_page_lock(vm_page_t m, vm_page_t *next) 309{ 310 struct vm_page marker; 311 struct vm_pagequeue *pq; 312 boolean_t unchanged; 313 u_short queue; 314 315 vm_page_lock_assert(m, MA_NOTOWNED); 316 if (vm_page_trylock(m)) 317 return (TRUE); 318 319 queue = m->queue; 320 vm_pageout_init_marker(&marker, queue); 321 pq = vm_page_pagequeue(m); 322 323 TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q); 324 vm_pagequeue_unlock(pq); 325 vm_page_lock(m); 326 vm_pagequeue_lock(pq); 327 328 /* Page queue might have changed. */ 329 *next = TAILQ_NEXT(&marker, plinks.q); 330 unchanged = (m->queue == queue && &marker == TAILQ_NEXT(m, plinks.q)); 331 TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q); 332 return (unchanged); 333} 334 335/* 336 * vm_pageout_clean: 337 * 338 * Clean the page and remove it from the laundry. 339 * 340 * We set the busy bit to cause potential page faults on this page to 341 * block. Note the careful timing, however, the busy bit isn't set till 342 * late and we cannot do anything that will mess with the page. 343 */ 344static int 345vm_pageout_clean(vm_page_t m) 346{ 347 vm_object_t object; 348 vm_page_t mc[2*vm_pageout_page_count], pb, ps; 349 int pageout_count; 350 int ib, is, page_base; 351 vm_pindex_t pindex = m->pindex; 352 353 vm_page_lock_assert(m, MA_OWNED); 354 object = m->object; 355 VM_OBJECT_ASSERT_WLOCKED(object); 356 357 /* 358 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 359 * with the new swapper, but we could have serious problems paging 360 * out other object types if there is insufficient memory. 361 * 362 * Unfortunately, checking free memory here is far too late, so the 363 * check has been moved up a procedural level. 364 */ 365 366 /* 367 * Can't clean the page if it's busy or held. 368 */ 369 vm_page_assert_unbusied(m); 370 KASSERT(m->hold_count == 0, ("vm_pageout_clean: page %p is held", m)); 371 vm_page_unlock(m); 372 373 mc[vm_pageout_page_count] = pb = ps = m; 374 pageout_count = 1; 375 page_base = vm_pageout_page_count; 376 ib = 1; 377 is = 1; 378 379 /* 380 * Scan object for clusterable pages. 381 * 382 * We can cluster ONLY if: ->> the page is NOT 383 * clean, wired, busy, held, or mapped into a 384 * buffer, and one of the following: 385 * 1) The page is inactive, or a seldom used 386 * active page. 387 * -or- 388 * 2) we force the issue. 389 * 390 * During heavy mmap/modification loads the pageout 391 * daemon can really fragment the underlying file 392 * due to flushing pages out of order and not trying 393 * align the clusters (which leave sporatic out-of-order 394 * holes). To solve this problem we do the reverse scan 395 * first and attempt to align our cluster, then do a 396 * forward scan if room remains. 397 */ 398more: 399 while (ib && pageout_count < vm_pageout_page_count) { 400 vm_page_t p; 401 402 if (ib > pindex) { 403 ib = 0; 404 break; 405 } 406 407 if ((p = vm_page_prev(pb)) == NULL || vm_page_busied(p)) { 408 ib = 0; 409 break; 410 } 411 vm_page_test_dirty(p); 412 if (p->dirty == 0) { 413 ib = 0; 414 break; 415 } 416 vm_page_lock(p); 417 if (p->queue != PQ_INACTIVE || 418 p->hold_count != 0) { /* may be undergoing I/O */ 419 vm_page_unlock(p); 420 ib = 0; 421 break; 422 } 423 vm_page_unlock(p); 424 mc[--page_base] = pb = p; 425 ++pageout_count; 426 ++ib; 427 /* 428 * alignment boundry, stop here and switch directions. Do 429 * not clear ib. 430 */ 431 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 432 break; 433 } 434 435 while (pageout_count < vm_pageout_page_count && 436 pindex + is < object->size) { 437 vm_page_t p; 438 439 if ((p = vm_page_next(ps)) == NULL || vm_page_busied(p)) 440 break; 441 vm_page_test_dirty(p); 442 if (p->dirty == 0) 443 break; 444 vm_page_lock(p); 445 if (p->queue != PQ_INACTIVE || 446 p->hold_count != 0) { /* may be undergoing I/O */ 447 vm_page_unlock(p); 448 break; 449 } 450 vm_page_unlock(p); 451 mc[page_base + pageout_count] = ps = p; 452 ++pageout_count; 453 ++is; 454 } 455 456 /* 457 * If we exhausted our forward scan, continue with the reverse scan 458 * when possible, even past a page boundry. This catches boundry 459 * conditions. 460 */ 461 if (ib && pageout_count < vm_pageout_page_count) 462 goto more; 463 464 /* 465 * we allow reads during pageouts... 466 */ 467 return (vm_pageout_flush(&mc[page_base], pageout_count, 0, 0, NULL, 468 NULL)); 469} 470 471/* 472 * vm_pageout_flush() - launder the given pages 473 * 474 * The given pages are laundered. Note that we setup for the start of 475 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 476 * reference count all in here rather then in the parent. If we want 477 * the parent to do more sophisticated things we may have to change 478 * the ordering. 479 * 480 * Returned runlen is the count of pages between mreq and first 481 * page after mreq with status VM_PAGER_AGAIN. 482 * *eio is set to TRUE if pager returned VM_PAGER_ERROR or VM_PAGER_FAIL 483 * for any page in runlen set. 484 */ 485int 486vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen, 487 boolean_t *eio) 488{ 489 vm_object_t object = mc[0]->object; 490 int pageout_status[count]; 491 int numpagedout = 0; 492 int i, runlen; 493 494 VM_OBJECT_ASSERT_WLOCKED(object); 495 496 /* 497 * Initiate I/O. Bump the vm_page_t->busy counter and 498 * mark the pages read-only. 499 * 500 * We do not have to fixup the clean/dirty bits here... we can 501 * allow the pager to do it after the I/O completes. 502 * 503 * NOTE! mc[i]->dirty may be partial or fragmented due to an 504 * edge case with file fragments. 505 */ 506 for (i = 0; i < count; i++) { 507 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 508 ("vm_pageout_flush: partially invalid page %p index %d/%d", 509 mc[i], i, count)); 510 vm_page_sbusy(mc[i]); 511 pmap_remove_write(mc[i]); 512 } 513 vm_object_pip_add(object, count); 514 515 vm_pager_put_pages(object, mc, count, flags, pageout_status); 516 517 runlen = count - mreq; 518 if (eio != NULL) 519 *eio = FALSE; 520 for (i = 0; i < count; i++) { 521 vm_page_t mt = mc[i]; 522 523 KASSERT(pageout_status[i] == VM_PAGER_PEND || 524 !pmap_page_is_write_mapped(mt), 525 ("vm_pageout_flush: page %p is not write protected", mt)); 526 switch (pageout_status[i]) { 527 case VM_PAGER_OK: 528 case VM_PAGER_PEND: 529 numpagedout++; 530 break; 531 case VM_PAGER_BAD: 532 /* 533 * Page outside of range of object. Right now we 534 * essentially lose the changes by pretending it 535 * worked. 536 */ 537 vm_page_undirty(mt); 538 break; 539 case VM_PAGER_ERROR: 540 case VM_PAGER_FAIL: 541 /* 542 * If page couldn't be paged out, then reactivate the 543 * page so it doesn't clog the inactive list. (We 544 * will try paging out it again later). 545 */ 546 vm_page_lock(mt); 547 vm_page_activate(mt); 548 vm_page_unlock(mt); 549 if (eio != NULL && i >= mreq && i - mreq < runlen) 550 *eio = TRUE; 551 break; 552 case VM_PAGER_AGAIN: 553 if (i >= mreq && i - mreq < runlen) 554 runlen = i - mreq; 555 break; 556 } 557 558 /* 559 * If the operation is still going, leave the page busy to 560 * block all other accesses. Also, leave the paging in 561 * progress indicator set so that we don't attempt an object 562 * collapse. 563 */ 564 if (pageout_status[i] != VM_PAGER_PEND) { 565 vm_object_pip_wakeup(object); 566 vm_page_sunbusy(mt); 567 if (vm_page_count_severe()) { 568 vm_page_lock(mt); 569 vm_page_try_to_cache(mt); 570 vm_page_unlock(mt); 571 } 572 } 573 } 574 if (prunlen != NULL) 575 *prunlen = runlen; 576 return (numpagedout); 577} 578 579static boolean_t 580vm_pageout_launder(struct vm_pagequeue *pq, int tries, vm_paddr_t low, 581 vm_paddr_t high) 582{ 583 struct mount *mp; 584 struct vnode *vp; 585 vm_object_t object; 586 vm_paddr_t pa; 587 vm_page_t m, m_tmp, next; 588 int lockmode; 589 590 vm_pagequeue_lock(pq); 591 TAILQ_FOREACH_SAFE(m, &pq->pq_pl, plinks.q, next) { 592 if ((m->flags & PG_MARKER) != 0) 593 continue; 594 pa = VM_PAGE_TO_PHYS(m); 595 if (pa < low || pa + PAGE_SIZE > high) 596 continue; 597 if (!vm_pageout_page_lock(m, &next) || m->hold_count != 0) { 598 vm_page_unlock(m); 599 continue; 600 } 601 object = m->object; 602 if ((!VM_OBJECT_TRYWLOCK(object) && 603 (!vm_pageout_fallback_object_lock(m, &next) || 604 m->hold_count != 0)) || vm_page_busied(m)) { 605 vm_page_unlock(m); 606 VM_OBJECT_WUNLOCK(object); 607 continue; 608 } 609 vm_page_test_dirty(m); 610 if (m->dirty == 0 && object->ref_count != 0) 611 pmap_remove_all(m); 612 if (m->dirty != 0) { 613 vm_page_unlock(m); 614 if (tries == 0 || (object->flags & OBJ_DEAD) != 0) { 615 VM_OBJECT_WUNLOCK(object); 616 continue; 617 } 618 if (object->type == OBJT_VNODE) { 619 vm_pagequeue_unlock(pq); 620 vp = object->handle; 621 vm_object_reference_locked(object); 622 VM_OBJECT_WUNLOCK(object); 623 (void)vn_start_write(vp, &mp, V_WAIT); 624 lockmode = MNT_SHARED_WRITES(vp->v_mount) ? 625 LK_SHARED : LK_EXCLUSIVE; 626 vn_lock(vp, lockmode | LK_RETRY); 627 VM_OBJECT_WLOCK(object); 628 vm_object_page_clean(object, 0, 0, OBJPC_SYNC); 629 VM_OBJECT_WUNLOCK(object); 630 VOP_UNLOCK(vp, 0); 631 vm_object_deallocate(object); 632 vn_finished_write(mp); 633 return (TRUE); 634 } else if (object->type == OBJT_SWAP || 635 object->type == OBJT_DEFAULT) { 636 vm_pagequeue_unlock(pq); 637 m_tmp = m; 638 vm_pageout_flush(&m_tmp, 1, VM_PAGER_PUT_SYNC, 639 0, NULL, NULL); 640 VM_OBJECT_WUNLOCK(object); 641 return (TRUE); 642 } 643 } else { 644 /* 645 * Dequeue here to prevent lock recursion in 646 * vm_page_cache(). 647 */ 648 vm_page_dequeue_locked(m); 649 vm_page_cache(m); 650 vm_page_unlock(m); 651 } 652 VM_OBJECT_WUNLOCK(object); 653 } 654 vm_pagequeue_unlock(pq); 655 return (FALSE); 656} 657 658/* 659 * Increase the number of cached pages. The specified value, "tries", 660 * determines which categories of pages are cached: 661 * 662 * 0: All clean, inactive pages within the specified physical address range 663 * are cached. Will not sleep. 664 * 1: The vm_lowmem handlers are called. All inactive pages within 665 * the specified physical address range are cached. May sleep. 666 * 2: The vm_lowmem handlers are called. All inactive and active pages 667 * within the specified physical address range are cached. May sleep. 668 */ 669void 670vm_pageout_grow_cache(int tries, vm_paddr_t low, vm_paddr_t high) 671{ 672 int actl, actmax, inactl, inactmax, dom, initial_dom; 673 static int start_dom = 0; 674 675 if (tries > 0) { 676 /* 677 * Decrease registered cache sizes. The vm_lowmem handlers 678 * may acquire locks and/or sleep, so they can only be invoked 679 * when "tries" is greater than zero. 680 */ 681 SDT_PROBE0(vm, , , vm__lowmem_cache); 682 EVENTHANDLER_INVOKE(vm_lowmem, 0); 683 684 /* 685 * We do this explicitly after the caches have been drained 686 * above. 687 */ 688 uma_reclaim(); 689 } 690 691 /* 692 * Make the next scan start on the next domain. 693 */ 694 initial_dom = atomic_fetchadd_int(&start_dom, 1) % vm_ndomains; 695 696 inactl = 0; 697 inactmax = cnt.v_inactive_count; 698 actl = 0; 699 actmax = tries < 2 ? 0 : cnt.v_active_count; 700 dom = initial_dom; 701 702 /* 703 * Scan domains in round-robin order, first inactive queues, 704 * then active. Since domain usually owns large physically 705 * contiguous chunk of memory, it makes sense to completely 706 * exhaust one domain before switching to next, while growing 707 * the pool of contiguous physical pages. 708 * 709 * Do not even start launder a domain which cannot contain 710 * the specified address range, as indicated by segments 711 * constituting the domain. 712 */ 713again: 714 if (inactl < inactmax) { 715 if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs, 716 low, high) && 717 vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_INACTIVE], 718 tries, low, high)) { 719 inactl++; 720 goto again; 721 } 722 if (++dom == vm_ndomains) 723 dom = 0; 724 if (dom != initial_dom) 725 goto again; 726 } 727 if (actl < actmax) { 728 if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs, 729 low, high) && 730 vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_ACTIVE], 731 tries, low, high)) { 732 actl++; 733 goto again; 734 } 735 if (++dom == vm_ndomains) 736 dom = 0; 737 if (dom != initial_dom) 738 goto again; 739 } 740} 741 742#if !defined(NO_SWAPPING) 743/* 744 * vm_pageout_object_deactivate_pages 745 * 746 * Deactivate enough pages to satisfy the inactive target 747 * requirements. 748 * 749 * The object and map must be locked. 750 */ 751static void 752vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object, 753 long desired) 754{ 755 vm_object_t backing_object, object; 756 vm_page_t p; 757 int act_delta, remove_mode; 758 759 VM_OBJECT_ASSERT_LOCKED(first_object); 760 if ((first_object->flags & OBJ_FICTITIOUS) != 0) 761 return; 762 for (object = first_object;; object = backing_object) { 763 if (pmap_resident_count(pmap) <= desired) 764 goto unlock_return; 765 VM_OBJECT_ASSERT_LOCKED(object); 766 if ((object->flags & OBJ_UNMANAGED) != 0 || 767 object->paging_in_progress != 0) 768 goto unlock_return; 769 770 remove_mode = 0; 771 if (object->shadow_count > 1) 772 remove_mode = 1; 773 /* 774 * Scan the object's entire memory queue. 775 */ 776 TAILQ_FOREACH(p, &object->memq, listq) { 777 if (pmap_resident_count(pmap) <= desired) 778 goto unlock_return; 779 if (vm_page_busied(p)) 780 continue; 781 PCPU_INC(cnt.v_pdpages); 782 vm_page_lock(p); 783 if (p->wire_count != 0 || p->hold_count != 0 || 784 !pmap_page_exists_quick(pmap, p)) { 785 vm_page_unlock(p); 786 continue; 787 } 788 act_delta = pmap_ts_referenced(p); 789 if ((p->aflags & PGA_REFERENCED) != 0) { 790 if (act_delta == 0) 791 act_delta = 1; 792 vm_page_aflag_clear(p, PGA_REFERENCED); 793 } 794 if (p->queue != PQ_ACTIVE && act_delta != 0) { 795 vm_page_activate(p); 796 p->act_count += act_delta; 797 } else if (p->queue == PQ_ACTIVE) { 798 if (act_delta == 0) { 799 p->act_count -= min(p->act_count, 800 ACT_DECLINE); 801 if (!remove_mode && p->act_count == 0) { 802 pmap_remove_all(p); 803 vm_page_deactivate(p); 804 } else 805 vm_page_requeue(p); 806 } else { 807 vm_page_activate(p); 808 if (p->act_count < ACT_MAX - 809 ACT_ADVANCE) 810 p->act_count += ACT_ADVANCE; 811 vm_page_requeue(p); 812 } 813 } else if (p->queue == PQ_INACTIVE) 814 pmap_remove_all(p); 815 vm_page_unlock(p); 816 } 817 if ((backing_object = object->backing_object) == NULL) 818 goto unlock_return; 819 VM_OBJECT_RLOCK(backing_object); 820 if (object != first_object) 821 VM_OBJECT_RUNLOCK(object); 822 } 823unlock_return: 824 if (object != first_object) 825 VM_OBJECT_RUNLOCK(object); 826} 827 828/* 829 * deactivate some number of pages in a map, try to do it fairly, but 830 * that is really hard to do. 831 */ 832static void 833vm_pageout_map_deactivate_pages(map, desired) 834 vm_map_t map; 835 long desired; 836{ 837 vm_map_entry_t tmpe; 838 vm_object_t obj, bigobj; 839 int nothingwired; 840 841 if (!vm_map_trylock(map)) 842 return; 843 844 bigobj = NULL; 845 nothingwired = TRUE; 846 847 /* 848 * first, search out the biggest object, and try to free pages from 849 * that. 850 */ 851 tmpe = map->header.next; 852 while (tmpe != &map->header) { 853 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 854 obj = tmpe->object.vm_object; 855 if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) { 856 if (obj->shadow_count <= 1 && 857 (bigobj == NULL || 858 bigobj->resident_page_count < obj->resident_page_count)) { 859 if (bigobj != NULL) 860 VM_OBJECT_RUNLOCK(bigobj); 861 bigobj = obj; 862 } else 863 VM_OBJECT_RUNLOCK(obj); 864 } 865 } 866 if (tmpe->wired_count > 0) 867 nothingwired = FALSE; 868 tmpe = tmpe->next; 869 } 870 871 if (bigobj != NULL) { 872 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); 873 VM_OBJECT_RUNLOCK(bigobj); 874 } 875 /* 876 * Next, hunt around for other pages to deactivate. We actually 877 * do this search sort of wrong -- .text first is not the best idea. 878 */ 879 tmpe = map->header.next; 880 while (tmpe != &map->header) { 881 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 882 break; 883 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 884 obj = tmpe->object.vm_object; 885 if (obj != NULL) { 886 VM_OBJECT_RLOCK(obj); 887 vm_pageout_object_deactivate_pages(map->pmap, obj, desired); 888 VM_OBJECT_RUNLOCK(obj); 889 } 890 } 891 tmpe = tmpe->next; 892 } 893 894#ifdef __ia64__ 895 /* 896 * Remove all non-wired, managed mappings if a process is swapped out. 897 * This will free page table pages. 898 */ 899 if (desired == 0) 900 pmap_remove_pages(map->pmap); 901#else 902 /* 903 * Remove all mappings if a process is swapped out, this will free page 904 * table pages. 905 */ 906 if (desired == 0 && nothingwired) { 907 pmap_remove(vm_map_pmap(map), vm_map_min(map), 908 vm_map_max(map)); 909 } 910#endif 911 912 vm_map_unlock(map); 913} 914#endif /* !defined(NO_SWAPPING) */ 915 916/* 917 * vm_pageout_scan does the dirty work for the pageout daemon. 918 * 919 * pass 0 - Update active LRU/deactivate pages 920 * pass 1 - Move inactive to cache or free 921 * pass 2 - Launder dirty pages 922 */ 923static void 924vm_pageout_scan(struct vm_domain *vmd, int pass) 925{ 926 vm_page_t m, next; 927 struct vm_pagequeue *pq; 928 vm_object_t object; 929 long min_scan; 930 int act_delta, addl_page_shortage, deficit, maxscan, page_shortage; 931 int vnodes_skipped = 0; 932 int maxlaunder, scan_tick, scanned; 933 int lockmode; 934 boolean_t queues_locked; 935 936 /* 937 * If we need to reclaim memory ask kernel caches to return 938 * some. We rate limit to avoid thrashing. 939 */ 940 if (vmd == &vm_dom[0] && pass > 0 && 941 (time_uptime - lowmem_uptime) >= lowmem_period) { 942 /* 943 * Decrease registered cache sizes. 944 */ 945 SDT_PROBE0(vm, , , vm__lowmem_scan); 946 EVENTHANDLER_INVOKE(vm_lowmem, 0); 947 /* 948 * We do this explicitly after the caches have been 949 * drained above. 950 */ 951 uma_reclaim(); 952 lowmem_uptime = time_uptime; 953 } 954 955 /* 956 * The addl_page_shortage is the number of temporarily 957 * stuck pages in the inactive queue. In other words, the 958 * number of pages from the inactive count that should be 959 * discounted in setting the target for the active queue scan. 960 */ 961 addl_page_shortage = 0; 962 963 /* 964 * Calculate the number of pages we want to either free or move 965 * to the cache. 966 */ 967 if (pass > 0) { 968 deficit = atomic_readandclear_int(&vm_pageout_deficit); 969 page_shortage = vm_paging_target() + deficit; 970 } else 971 page_shortage = deficit = 0; 972 973 /* 974 * maxlaunder limits the number of dirty pages we flush per scan. 975 * For most systems a smaller value (16 or 32) is more robust under 976 * extreme memory and disk pressure because any unnecessary writes 977 * to disk can result in extreme performance degredation. However, 978 * systems with excessive dirty pages (especially when MAP_NOSYNC is 979 * used) will die horribly with limited laundering. If the pageout 980 * daemon cannot clean enough pages in the first pass, we let it go 981 * all out in succeeding passes. 982 */ 983 if ((maxlaunder = vm_max_launder) <= 1) 984 maxlaunder = 1; 985 if (pass > 1) 986 maxlaunder = 10000; 987 988 /* 989 * Start scanning the inactive queue for pages we can move to the 990 * cache or free. The scan will stop when the target is reached or 991 * we have scanned the entire inactive queue. Note that m->act_count 992 * is not used to form decisions for the inactive queue, only for the 993 * active queue. 994 */ 995 pq = &vmd->vmd_pagequeues[PQ_INACTIVE]; 996 maxscan = pq->pq_cnt; 997 vm_pagequeue_lock(pq); 998 queues_locked = TRUE; 999 for (m = TAILQ_FIRST(&pq->pq_pl); 1000 m != NULL && maxscan-- > 0 && page_shortage > 0; 1001 m = next) { 1002 vm_pagequeue_assert_locked(pq); 1003 KASSERT(queues_locked, ("unlocked queues")); 1004 KASSERT(m->queue == PQ_INACTIVE, ("Inactive queue %p", m)); 1005 1006 PCPU_INC(cnt.v_pdpages); 1007 next = TAILQ_NEXT(m, plinks.q); 1008 1009 /* 1010 * skip marker pages 1011 */ 1012 if (m->flags & PG_MARKER) 1013 continue; 1014 1015 KASSERT((m->flags & PG_FICTITIOUS) == 0, 1016 ("Fictitious page %p cannot be in inactive queue", m)); 1017 KASSERT((m->oflags & VPO_UNMANAGED) == 0, 1018 ("Unmanaged page %p cannot be in inactive queue", m)); 1019 1020 /* 1021 * The page or object lock acquisitions fail if the 1022 * page was removed from the queue or moved to a 1023 * different position within the queue. In either 1024 * case, addl_page_shortage should not be incremented. 1025 */ 1026 if (!vm_pageout_page_lock(m, &next)) { 1027 vm_page_unlock(m); 1028 continue; 1029 } 1030 object = m->object; 1031 if (!VM_OBJECT_TRYWLOCK(object) && 1032 !vm_pageout_fallback_object_lock(m, &next)) { 1033 vm_page_unlock(m); 1034 VM_OBJECT_WUNLOCK(object); 1035 continue; 1036 } 1037 1038 /* 1039 * Don't mess with busy pages, keep them at at the 1040 * front of the queue, most likely they are being 1041 * paged out. Increment addl_page_shortage for busy 1042 * pages, because they may leave the inactive queue 1043 * shortly after page scan is finished. 1044 */ 1045 if (vm_page_busied(m)) { 1046 vm_page_unlock(m); 1047 VM_OBJECT_WUNLOCK(object); 1048 addl_page_shortage++; 1049 continue; 1050 } 1051 1052 /* 1053 * We unlock the inactive page queue, invalidating the 1054 * 'next' pointer. Use our marker to remember our 1055 * place. 1056 */ 1057 TAILQ_INSERT_AFTER(&pq->pq_pl, m, &vmd->vmd_marker, plinks.q); 1058 vm_pagequeue_unlock(pq); 1059 queues_locked = FALSE; 1060 1061 /* 1062 * We bump the activation count if the page has been 1063 * referenced while in the inactive queue. This makes 1064 * it less likely that the page will be added back to the 1065 * inactive queue prematurely again. Here we check the 1066 * page tables (or emulated bits, if any), given the upper 1067 * level VM system not knowing anything about existing 1068 * references. 1069 */ 1070 act_delta = 0; 1071 if ((m->aflags & PGA_REFERENCED) != 0) { 1072 vm_page_aflag_clear(m, PGA_REFERENCED); 1073 act_delta = 1; 1074 } 1075 if (object->ref_count != 0) { 1076 act_delta += pmap_ts_referenced(m); 1077 } else { 1078 KASSERT(!pmap_page_is_mapped(m), 1079 ("vm_pageout_scan: page %p is mapped", m)); 1080 } 1081 1082 /* 1083 * If the upper level VM system knows about any page 1084 * references, we reactivate the page or requeue it. 1085 */ 1086 if (act_delta != 0) { 1087 if (object->ref_count) { 1088 vm_page_activate(m); 1089 m->act_count += act_delta + ACT_ADVANCE; 1090 } else { 1091 vm_pagequeue_lock(pq); 1092 queues_locked = TRUE; 1093 vm_page_requeue_locked(m); 1094 } 1095 VM_OBJECT_WUNLOCK(object); 1096 vm_page_unlock(m); 1097 goto relock_queues; 1098 } 1099 1100 if (m->hold_count != 0) { 1101 vm_page_unlock(m); 1102 VM_OBJECT_WUNLOCK(object); 1103 1104 /* 1105 * Held pages are essentially stuck in the 1106 * queue. So, they ought to be discounted 1107 * from the inactive count. See the 1108 * calculation of the page_shortage for the 1109 * loop over the active queue below. 1110 */ 1111 addl_page_shortage++; 1112 goto relock_queues; 1113 } 1114 1115 /* 1116 * If the page appears to be clean at the machine-independent 1117 * layer, then remove all of its mappings from the pmap in 1118 * anticipation of placing it onto the cache queue. If, 1119 * however, any of the page's mappings allow write access, 1120 * then the page may still be modified until the last of those 1121 * mappings are removed. 1122 */ 1123 if (object->ref_count != 0) { 1124 vm_page_test_dirty(m); 1125 if (m->dirty == 0) 1126 pmap_remove_all(m); 1127 } 1128 1129 if (m->valid == 0) { 1130 /* 1131 * Invalid pages can be easily freed 1132 */ 1133 vm_page_free(m); 1134 PCPU_INC(cnt.v_dfree); 1135 --page_shortage; 1136 } else if (m->dirty == 0) { 1137 /* 1138 * Clean pages can be placed onto the cache queue. 1139 * This effectively frees them. 1140 */ 1141 vm_page_cache(m); 1142 --page_shortage; 1143 } else if ((m->flags & PG_WINATCFLS) == 0 && pass < 2) { 1144 /* 1145 * Dirty pages need to be paged out, but flushing 1146 * a page is extremely expensive verses freeing 1147 * a clean page. Rather then artificially limiting 1148 * the number of pages we can flush, we instead give 1149 * dirty pages extra priority on the inactive queue 1150 * by forcing them to be cycled through the queue 1151 * twice before being flushed, after which the 1152 * (now clean) page will cycle through once more 1153 * before being freed. This significantly extends 1154 * the thrash point for a heavily loaded machine. 1155 */ 1156 m->flags |= PG_WINATCFLS; 1157 vm_pagequeue_lock(pq); 1158 queues_locked = TRUE; 1159 vm_page_requeue_locked(m); 1160 } else if (maxlaunder > 0) { 1161 /* 1162 * We always want to try to flush some dirty pages if 1163 * we encounter them, to keep the system stable. 1164 * Normally this number is small, but under extreme 1165 * pressure where there are insufficient clean pages 1166 * on the inactive queue, we may have to go all out. 1167 */ 1168 int swap_pageouts_ok; 1169 struct vnode *vp = NULL; 1170 struct mount *mp = NULL; 1171 1172 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 1173 swap_pageouts_ok = 1; 1174 } else { 1175 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 1176 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 1177 vm_page_count_min()); 1178 1179 } 1180 1181 /* 1182 * We don't bother paging objects that are "dead". 1183 * Those objects are in a "rundown" state. 1184 */ 1185 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 1186 vm_pagequeue_lock(pq); 1187 vm_page_unlock(m); 1188 VM_OBJECT_WUNLOCK(object); 1189 queues_locked = TRUE; 1190 vm_page_requeue_locked(m); 1191 goto relock_queues; 1192 } 1193 1194 /* 1195 * The object is already known NOT to be dead. It 1196 * is possible for the vget() to block the whole 1197 * pageout daemon, but the new low-memory handling 1198 * code should prevent it. 1199 * 1200 * The previous code skipped locked vnodes and, worse, 1201 * reordered pages in the queue. This results in 1202 * completely non-deterministic operation and, on a 1203 * busy system, can lead to extremely non-optimal 1204 * pageouts. For example, it can cause clean pages 1205 * to be freed and dirty pages to be moved to the end 1206 * of the queue. Since dirty pages are also moved to 1207 * the end of the queue once-cleaned, this gives 1208 * way too large a weighting to defering the freeing 1209 * of dirty pages. 1210 * 1211 * We can't wait forever for the vnode lock, we might 1212 * deadlock due to a vn_read() getting stuck in 1213 * vm_wait while holding this vnode. We skip the 1214 * vnode if we can't get it in a reasonable amount 1215 * of time. 1216 */ 1217 if (object->type == OBJT_VNODE) { 1218 vm_page_unlock(m); 1219 vp = object->handle; 1220 if (vp->v_type == VREG && 1221 vn_start_write(vp, &mp, V_NOWAIT) != 0) { 1222 mp = NULL; 1223 ++pageout_lock_miss; 1224 if (object->flags & OBJ_MIGHTBEDIRTY) 1225 vnodes_skipped++; 1226 goto unlock_and_continue; 1227 } 1228 KASSERT(mp != NULL, 1229 ("vp %p with NULL v_mount", vp)); 1230 vm_object_reference_locked(object); 1231 VM_OBJECT_WUNLOCK(object); 1232 lockmode = MNT_SHARED_WRITES(vp->v_mount) ? 1233 LK_SHARED : LK_EXCLUSIVE; 1234 if (vget(vp, lockmode | LK_TIMELOCK, 1235 curthread)) { 1236 VM_OBJECT_WLOCK(object); 1237 ++pageout_lock_miss; 1238 if (object->flags & OBJ_MIGHTBEDIRTY) 1239 vnodes_skipped++; 1240 vp = NULL; 1241 goto unlock_and_continue; 1242 } 1243 VM_OBJECT_WLOCK(object); 1244 vm_page_lock(m); 1245 vm_pagequeue_lock(pq); 1246 queues_locked = TRUE; 1247 /* 1248 * The page might have been moved to another 1249 * queue during potential blocking in vget() 1250 * above. The page might have been freed and 1251 * reused for another vnode. 1252 */ 1253 if (m->queue != PQ_INACTIVE || 1254 m->object != object || 1255 TAILQ_NEXT(m, plinks.q) != &vmd->vmd_marker) { 1256 vm_page_unlock(m); 1257 if (object->flags & OBJ_MIGHTBEDIRTY) 1258 vnodes_skipped++; 1259 goto unlock_and_continue; 1260 } 1261 1262 /* 1263 * The page may have been busied during the 1264 * blocking in vget(). We don't move the 1265 * page back onto the end of the queue so that 1266 * statistics are more correct if we don't. 1267 */ 1268 if (vm_page_busied(m)) { 1269 vm_page_unlock(m); 1270 addl_page_shortage++; 1271 goto unlock_and_continue; 1272 } 1273 1274 /* 1275 * If the page has become held it might 1276 * be undergoing I/O, so skip it 1277 */ 1278 if (m->hold_count != 0) { 1279 vm_page_unlock(m); 1280 addl_page_shortage++; 1281 if (object->flags & OBJ_MIGHTBEDIRTY) 1282 vnodes_skipped++; 1283 goto unlock_and_continue; 1284 } 1285 vm_pagequeue_unlock(pq); 1286 queues_locked = FALSE; 1287 } 1288 1289 /* 1290 * If a page is dirty, then it is either being washed 1291 * (but not yet cleaned) or it is still in the 1292 * laundry. If it is still in the laundry, then we 1293 * start the cleaning operation. 1294 * 1295 * decrement page_shortage on success to account for 1296 * the (future) cleaned page. Otherwise we could wind 1297 * up laundering or cleaning too many pages. 1298 */ 1299 if (vm_pageout_clean(m) != 0) { 1300 --page_shortage; 1301 --maxlaunder; 1302 } 1303unlock_and_continue: 1304 vm_page_lock_assert(m, MA_NOTOWNED); 1305 VM_OBJECT_WUNLOCK(object); 1306 if (mp != NULL) { 1307 if (queues_locked) { 1308 vm_pagequeue_unlock(pq); 1309 queues_locked = FALSE; 1310 } 1311 if (vp != NULL) 1312 vput(vp); 1313 vm_object_deallocate(object); 1314 vn_finished_write(mp); 1315 } 1316 vm_page_lock_assert(m, MA_NOTOWNED); 1317 goto relock_queues; 1318 } 1319 vm_page_unlock(m); 1320 VM_OBJECT_WUNLOCK(object); 1321relock_queues: 1322 if (!queues_locked) { 1323 vm_pagequeue_lock(pq); 1324 queues_locked = TRUE; 1325 } 1326 next = TAILQ_NEXT(&vmd->vmd_marker, plinks.q); 1327 TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_marker, plinks.q); 1328 } 1329 vm_pagequeue_unlock(pq); 1330 1331#if !defined(NO_SWAPPING) 1332 /* 1333 * Wakeup the swapout daemon if we didn't cache or free the targeted 1334 * number of pages. 1335 */ 1336 if (vm_swap_enabled && page_shortage > 0) 1337 vm_req_vmdaemon(VM_SWAP_NORMAL); 1338#endif 1339 1340 /* 1341 * Wakeup the sync daemon if we skipped a vnode in a writeable object 1342 * and we didn't cache or free enough pages. 1343 */ 1344 if (vnodes_skipped > 0 && page_shortage > cnt.v_free_target - 1345 cnt.v_free_min) 1346 (void)speedup_syncer(); 1347 1348 /* 1349 * Compute the number of pages we want to try to move from the 1350 * active queue to the inactive queue. 1351 */ 1352 page_shortage = cnt.v_inactive_target - cnt.v_inactive_count + 1353 vm_paging_target() + deficit + addl_page_shortage; 1354 1355 pq = &vmd->vmd_pagequeues[PQ_ACTIVE]; 1356 vm_pagequeue_lock(pq); 1357 maxscan = pq->pq_cnt; 1358 1359 /* 1360 * If we're just idle polling attempt to visit every 1361 * active page within 'update_period' seconds. 1362 */ 1363 scan_tick = ticks; 1364 if (vm_pageout_update_period != 0) { 1365 min_scan = pq->pq_cnt; 1366 min_scan *= scan_tick - vmd->vmd_last_active_scan; 1367 min_scan /= hz * vm_pageout_update_period; 1368 } else 1369 min_scan = 0; 1370 if (min_scan > 0 || (page_shortage > 0 && maxscan > 0)) 1371 vmd->vmd_last_active_scan = scan_tick; 1372 1373 /* 1374 * Scan the active queue for pages that can be deactivated. Update 1375 * the per-page activity counter and use it to identify deactivation 1376 * candidates. 1377 */ 1378 for (m = TAILQ_FIRST(&pq->pq_pl), scanned = 0; m != NULL && (scanned < 1379 min_scan || (page_shortage > 0 && scanned < maxscan)); m = next, 1380 scanned++) { 1381 1382 KASSERT(m->queue == PQ_ACTIVE, 1383 ("vm_pageout_scan: page %p isn't active", m)); 1384 1385 next = TAILQ_NEXT(m, plinks.q); 1386 if ((m->flags & PG_MARKER) != 0) 1387 continue; 1388 KASSERT((m->flags & PG_FICTITIOUS) == 0, 1389 ("Fictitious page %p cannot be in active queue", m)); 1390 KASSERT((m->oflags & VPO_UNMANAGED) == 0, 1391 ("Unmanaged page %p cannot be in active queue", m)); 1392 if (!vm_pageout_page_lock(m, &next)) { 1393 vm_page_unlock(m); 1394 continue; 1395 } 1396 1397 /* 1398 * The count for pagedaemon pages is done after checking the 1399 * page for eligibility... 1400 */ 1401 PCPU_INC(cnt.v_pdpages); 1402 1403 /* 1404 * Check to see "how much" the page has been used. 1405 */ 1406 act_delta = 0; 1407 if (m->aflags & PGA_REFERENCED) { 1408 vm_page_aflag_clear(m, PGA_REFERENCED); 1409 act_delta += 1; 1410 } 1411 /* 1412 * Unlocked object ref count check. Two races are possible. 1413 * 1) The ref was transitioning to zero and we saw non-zero, 1414 * the pmap bits will be checked unnecessarily. 1415 * 2) The ref was transitioning to one and we saw zero. 1416 * The page lock prevents a new reference to this page so 1417 * we need not check the reference bits. 1418 */ 1419 if (m->object->ref_count != 0) 1420 act_delta += pmap_ts_referenced(m); 1421 1422 /* 1423 * Advance or decay the act_count based on recent usage. 1424 */ 1425 if (act_delta) { 1426 m->act_count += ACT_ADVANCE + act_delta; 1427 if (m->act_count > ACT_MAX) 1428 m->act_count = ACT_MAX; 1429 } else { 1430 m->act_count -= min(m->act_count, ACT_DECLINE); 1431 act_delta = m->act_count; 1432 } 1433 1434 /* 1435 * Move this page to the tail of the active or inactive 1436 * queue depending on usage. 1437 */ 1438 if (act_delta == 0) { 1439 /* Dequeue to avoid later lock recursion. */ 1440 vm_page_dequeue_locked(m); 1441 vm_page_deactivate(m); 1442 page_shortage--; 1443 } else 1444 vm_page_requeue_locked(m); 1445 vm_page_unlock(m); 1446 } 1447 vm_pagequeue_unlock(pq); 1448#if !defined(NO_SWAPPING) 1449 /* 1450 * Idle process swapout -- run once per second. 1451 */ 1452 if (vm_swap_idle_enabled) { 1453 static long lsec; 1454 if (time_second != lsec) { 1455 vm_req_vmdaemon(VM_SWAP_IDLE); 1456 lsec = time_second; 1457 } 1458 } 1459#endif 1460 1461 /* 1462 * If we are critically low on one of RAM or swap and low on 1463 * the other, kill the largest process. However, we avoid 1464 * doing this on the first pass in order to give ourselves a 1465 * chance to flush out dirty vnode-backed pages and to allow 1466 * active pages to be moved to the inactive queue and reclaimed. 1467 */ 1468 vm_pageout_mightbe_oom(vmd, pass); 1469} 1470 1471static int vm_pageout_oom_vote; 1472 1473/* 1474 * The pagedaemon threads randlomly select one to perform the 1475 * OOM. Trying to kill processes before all pagedaemons 1476 * failed to reach free target is premature. 1477 */ 1478static void 1479vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass) 1480{ 1481 int old_vote; 1482 1483 if (pass <= 1 || !((swap_pager_avail < 64 && vm_page_count_min()) || 1484 (swap_pager_full && vm_paging_target() > 0))) { 1485 if (vmd->vmd_oom) { 1486 vmd->vmd_oom = FALSE; 1487 atomic_subtract_int(&vm_pageout_oom_vote, 1); 1488 } 1489 return; 1490 } 1491 1492 if (vmd->vmd_oom) 1493 return; 1494 1495 vmd->vmd_oom = TRUE; 1496 old_vote = atomic_fetchadd_int(&vm_pageout_oom_vote, 1); 1497 if (old_vote != vm_ndomains - 1) 1498 return; 1499 1500 /* 1501 * The current pagedaemon thread is the last in the quorum to 1502 * start OOM. Initiate the selection and signaling of the 1503 * victim. 1504 */ 1505 vm_pageout_oom(VM_OOM_MEM); 1506 1507 /* 1508 * After one round of OOM terror, recall our vote. On the 1509 * next pass, current pagedaemon would vote again if the low 1510 * memory condition is still there, due to vmd_oom being 1511 * false. 1512 */ 1513 vmd->vmd_oom = FALSE; 1514 atomic_subtract_int(&vm_pageout_oom_vote, 1); 1515} 1516 1517void 1518vm_pageout_oom(int shortage) 1519{ 1520 struct proc *p, *bigproc; 1521 vm_offset_t size, bigsize; 1522 struct thread *td; 1523 struct vmspace *vm; 1524 1525 /* 1526 * We keep the process bigproc locked once we find it to keep anyone 1527 * from messing with it; however, there is a possibility of 1528 * deadlock if process B is bigproc and one of it's child processes 1529 * attempts to propagate a signal to B while we are waiting for A's 1530 * lock while walking this list. To avoid this, we don't block on 1531 * the process lock but just skip a process if it is already locked. 1532 */ 1533 bigproc = NULL; 1534 bigsize = 0; 1535 sx_slock(&allproc_lock); 1536 FOREACH_PROC_IN_SYSTEM(p) { 1537 int breakout; 1538 1539 PROC_LOCK(p); 1540 1541 /* 1542 * If this is a system, protected or killed process, skip it. 1543 */ 1544 if (p->p_state != PRS_NORMAL || (p->p_flag & (P_INEXEC | 1545 P_PROTECTED | P_SYSTEM | P_WEXIT)) != 0 || 1546 p->p_pid == 1 || P_KILLED(p) || 1547 (p->p_pid < 48 && swap_pager_avail != 0)) { 1548 PROC_UNLOCK(p); 1549 continue; 1550 } 1551 /* 1552 * If the process is in a non-running type state, 1553 * don't touch it. Check all the threads individually. 1554 */ 1555 breakout = 0; 1556 FOREACH_THREAD_IN_PROC(p, td) { 1557 thread_lock(td); 1558 if (!TD_ON_RUNQ(td) && 1559 !TD_IS_RUNNING(td) && 1560 !TD_IS_SLEEPING(td) && 1561 !TD_IS_SUSPENDED(td)) { 1562 thread_unlock(td); 1563 breakout = 1; 1564 break; 1565 } 1566 thread_unlock(td); 1567 } 1568 if (breakout) { 1569 PROC_UNLOCK(p); 1570 continue; 1571 } 1572 /* 1573 * get the process size 1574 */ 1575 vm = vmspace_acquire_ref(p); 1576 if (vm == NULL) { 1577 PROC_UNLOCK(p); 1578 continue; 1579 } 1580 _PHOLD(p); 1581 if (!vm_map_trylock_read(&vm->vm_map)) { 1582 _PRELE(p); 1583 PROC_UNLOCK(p); 1584 vmspace_free(vm); 1585 continue; 1586 } 1587 PROC_UNLOCK(p); 1588 size = vmspace_swap_count(vm); 1589 vm_map_unlock_read(&vm->vm_map); 1590 if (shortage == VM_OOM_MEM) 1591 size += vmspace_resident_count(vm); 1592 vmspace_free(vm); 1593 /* 1594 * if the this process is bigger than the biggest one 1595 * remember it. 1596 */ 1597 if (size > bigsize) { 1598 if (bigproc != NULL) 1599 PRELE(bigproc); 1600 bigproc = p; 1601 bigsize = size; 1602 } else { 1603 PRELE(p); 1604 } 1605 } 1606 sx_sunlock(&allproc_lock); 1607 if (bigproc != NULL) { 1608 PROC_LOCK(bigproc); 1609 killproc(bigproc, "out of swap space"); 1610 sched_nice(bigproc, PRIO_MIN); 1611 _PRELE(bigproc); 1612 PROC_UNLOCK(bigproc); 1613 wakeup(&cnt.v_free_count); 1614 } 1615} 1616 1617static void 1618vm_pageout_worker(void *arg) 1619{ 1620 struct vm_domain *domain; 1621 int domidx; 1622 1623 domidx = (uintptr_t)arg; 1624 domain = &vm_dom[domidx]; 1625 1626 /* 1627 * XXXKIB It could be useful to bind pageout daemon threads to 1628 * the cores belonging to the domain, from which vm_page_array 1629 * is allocated. 1630 */ 1631 1632 KASSERT(domain->vmd_segs != 0, ("domain without segments")); 1633 domain->vmd_last_active_scan = ticks; 1634 vm_pageout_init_marker(&domain->vmd_marker, PQ_INACTIVE); 1635 1636 /* 1637 * The pageout daemon worker is never done, so loop forever. 1638 */ 1639 while (TRUE) { 1640 /* 1641 * If we have enough free memory, wakeup waiters. Do 1642 * not clear vm_pages_needed until we reach our target, 1643 * otherwise we may be woken up over and over again and 1644 * waste a lot of cpu. 1645 */ 1646 mtx_lock(&vm_page_queue_free_mtx); 1647 if (vm_pages_needed && !vm_page_count_min()) { 1648 if (!vm_paging_needed()) 1649 vm_pages_needed = 0; 1650 wakeup(&cnt.v_free_count); 1651 } 1652 if (vm_pages_needed) { 1653 /* 1654 * We're still not done. Either vm_pages_needed was 1655 * set by another thread during the previous scan 1656 * (typically, this happens during a level 0 scan) or 1657 * vm_pages_needed was already set and the scan failed 1658 * to free enough pages. If we haven't yet performed 1659 * a level >= 2 scan (unlimited dirty cleaning), then 1660 * upgrade the level and scan again now. Otherwise, 1661 * sleep a bit and try again later. While sleeping, 1662 * vm_pages_needed can be cleared. 1663 */ 1664 if (domain->vmd_pass > 1) 1665 msleep(&vm_pages_needed, 1666 &vm_page_queue_free_mtx, PVM, "psleep", 1667 hz / 2); 1668 } else { 1669 /* 1670 * Good enough, sleep until required to refresh 1671 * stats. 1672 */ 1673 msleep(&vm_pages_needed, &vm_page_queue_free_mtx, 1674 PVM, "psleep", hz); 1675 } 1676 if (vm_pages_needed) { 1677 cnt.v_pdwakeups++; 1678 domain->vmd_pass++; 1679 } else 1680 domain->vmd_pass = 0; 1681 mtx_unlock(&vm_page_queue_free_mtx); 1682 vm_pageout_scan(domain, domain->vmd_pass); 1683 } 1684} 1685 1686/* 1687 * vm_pageout_init initialises basic pageout daemon settings. 1688 */ 1689static void 1690vm_pageout_init(void) 1691{ 1692 /* 1693 * Initialize some paging parameters. 1694 */ 1695 cnt.v_interrupt_free_min = 2; 1696 if (cnt.v_page_count < 2000) 1697 vm_pageout_page_count = 8; 1698 1699 /* 1700 * v_free_reserved needs to include enough for the largest 1701 * swap pager structures plus enough for any pv_entry structs 1702 * when paging. 1703 */ 1704 if (cnt.v_page_count > 1024) 1705 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1706 else 1707 cnt.v_free_min = 4; 1708 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1709 cnt.v_interrupt_free_min; 1710 cnt.v_free_reserved = vm_pageout_page_count + 1711 cnt.v_pageout_free_min + (cnt.v_page_count / 768); 1712 cnt.v_free_severe = cnt.v_free_min / 2; 1713 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1714 cnt.v_free_min += cnt.v_free_reserved; 1715 cnt.v_free_severe += cnt.v_free_reserved; 1716 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1717 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1718 cnt.v_inactive_target = cnt.v_free_count / 3; 1719 1720 /* 1721 * Set the default wakeup threshold to be 10% above the minimum 1722 * page limit. This keeps the steady state out of shortfall. 1723 */ 1724 vm_pageout_wakeup_thresh = (cnt.v_free_min / 10) * 11; 1725 1726 /* 1727 * Set interval in seconds for active scan. We want to visit each 1728 * page at least once every ten minutes. This is to prevent worst 1729 * case paging behaviors with stale active LRU. 1730 */ 1731 if (vm_pageout_update_period == 0) 1732 vm_pageout_update_period = 600; 1733 1734 /* XXX does not really belong here */ 1735 if (vm_page_max_wired == 0) 1736 vm_page_max_wired = cnt.v_free_count / 3; 1737} 1738 1739/* 1740 * vm_pageout is the high level pageout daemon. 1741 */ 1742static void 1743vm_pageout(void) 1744{ 1745 int error; 1746#if MAXMEMDOM > 1 1747 int i; 1748#endif 1749 1750 swap_pager_swap_init(); 1751#if MAXMEMDOM > 1 1752 for (i = 1; i < vm_ndomains; i++) { 1753 error = kthread_add(vm_pageout_worker, (void *)(uintptr_t)i, 1754 curproc, NULL, 0, 0, "dom%d", i); 1755 if (error != 0) { 1756 panic("starting pageout for domain %d, error %d\n", 1757 i, error); 1758 } 1759 } 1760#endif 1761 error = kthread_add(uma_reclaim_worker, NULL, curproc, NULL, 1762 0, 0, "uma"); 1763 if (error != 0) 1764 panic("starting uma_reclaim helper, error %d\n", error); 1765 vm_pageout_worker((void *)(uintptr_t)0); 1766} 1767 1768/* 1769 * Unless the free page queue lock is held by the caller, this function 1770 * should be regarded as advisory. Specifically, the caller should 1771 * not msleep() on &cnt.v_free_count following this function unless 1772 * the free page queue lock is held until the msleep() is performed. 1773 */ 1774void 1775pagedaemon_wakeup(void) 1776{ 1777 1778 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1779 vm_pages_needed = 1; 1780 wakeup(&vm_pages_needed); 1781 } 1782} 1783 1784#if !defined(NO_SWAPPING) 1785static void 1786vm_req_vmdaemon(int req) 1787{ 1788 static int lastrun = 0; 1789 1790 mtx_lock(&vm_daemon_mtx); 1791 vm_pageout_req_swapout |= req; 1792 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1793 wakeup(&vm_daemon_needed); 1794 lastrun = ticks; 1795 } 1796 mtx_unlock(&vm_daemon_mtx); 1797} 1798 1799static void 1800vm_daemon(void) 1801{ 1802 struct rlimit rsslim; 1803 struct proc *p; 1804 struct thread *td; 1805 struct vmspace *vm; 1806 int breakout, swapout_flags, tryagain, attempts; 1807#ifdef RACCT 1808 uint64_t rsize, ravailable; 1809#endif 1810 1811 while (TRUE) { 1812 mtx_lock(&vm_daemon_mtx); 1813 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 1814#ifdef RACCT 1815 racct_enable ? hz : 0 1816#else 1817 0 1818#endif 1819 ); 1820 swapout_flags = vm_pageout_req_swapout; 1821 vm_pageout_req_swapout = 0; 1822 mtx_unlock(&vm_daemon_mtx); 1823 if (swapout_flags) 1824 swapout_procs(swapout_flags); 1825 1826 /* 1827 * scan the processes for exceeding their rlimits or if 1828 * process is swapped out -- deactivate pages 1829 */ 1830 tryagain = 0; 1831 attempts = 0; 1832again: 1833 attempts++; 1834 sx_slock(&allproc_lock); 1835 FOREACH_PROC_IN_SYSTEM(p) { 1836 vm_pindex_t limit, size; 1837 1838 /* 1839 * if this is a system process or if we have already 1840 * looked at this process, skip it. 1841 */ 1842 PROC_LOCK(p); 1843 if (p->p_state != PRS_NORMAL || 1844 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 1845 PROC_UNLOCK(p); 1846 continue; 1847 } 1848 /* 1849 * if the process is in a non-running type state, 1850 * don't touch it. 1851 */ 1852 breakout = 0; 1853 FOREACH_THREAD_IN_PROC(p, td) { 1854 thread_lock(td); 1855 if (!TD_ON_RUNQ(td) && 1856 !TD_IS_RUNNING(td) && 1857 !TD_IS_SLEEPING(td) && 1858 !TD_IS_SUSPENDED(td)) { 1859 thread_unlock(td); 1860 breakout = 1; 1861 break; 1862 } 1863 thread_unlock(td); 1864 } 1865 if (breakout) { 1866 PROC_UNLOCK(p); 1867 continue; 1868 } 1869 /* 1870 * get a limit 1871 */ 1872 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1873 limit = OFF_TO_IDX( 1874 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1875 1876 /* 1877 * let processes that are swapped out really be 1878 * swapped out set the limit to nothing (will force a 1879 * swap-out.) 1880 */ 1881 if ((p->p_flag & P_INMEM) == 0) 1882 limit = 0; /* XXX */ 1883 vm = vmspace_acquire_ref(p); 1884 PROC_UNLOCK(p); 1885 if (vm == NULL) 1886 continue; 1887 1888 size = vmspace_resident_count(vm); 1889 if (size >= limit) { 1890 vm_pageout_map_deactivate_pages( 1891 &vm->vm_map, limit); 1892 } 1893#ifdef RACCT 1894 if (racct_enable) { 1895 rsize = IDX_TO_OFF(size); 1896 PROC_LOCK(p); 1897 racct_set(p, RACCT_RSS, rsize); 1898 ravailable = racct_get_available(p, RACCT_RSS); 1899 PROC_UNLOCK(p); 1900 if (rsize > ravailable) { 1901 /* 1902 * Don't be overly aggressive; this 1903 * might be an innocent process, 1904 * and the limit could've been exceeded 1905 * by some memory hog. Don't try 1906 * to deactivate more than 1/4th 1907 * of process' resident set size. 1908 */ 1909 if (attempts <= 8) { 1910 if (ravailable < rsize - 1911 (rsize / 4)) { 1912 ravailable = rsize - 1913 (rsize / 4); 1914 } 1915 } 1916 vm_pageout_map_deactivate_pages( 1917 &vm->vm_map, 1918 OFF_TO_IDX(ravailable)); 1919 /* Update RSS usage after paging out. */ 1920 size = vmspace_resident_count(vm); 1921 rsize = IDX_TO_OFF(size); 1922 PROC_LOCK(p); 1923 racct_set(p, RACCT_RSS, rsize); 1924 PROC_UNLOCK(p); 1925 if (rsize > ravailable) 1926 tryagain = 1; 1927 } 1928 } 1929#endif 1930 vmspace_free(vm); 1931 } 1932 sx_sunlock(&allproc_lock); 1933 if (tryagain != 0 && attempts <= 10) 1934 goto again; 1935 } 1936} 1937#endif /* !defined(NO_SWAPPING) */ 1938