1 /*- 2 * SPDX-License-Identifier: (BSD-4-Clause AND MIT-CMU) 3 * 4 * Copyright (c) 1991 Regents of the University of California. 5 * All rights reserved. 6 * Copyright (c) 1994 John S. Dyson 7 * All rights reserved. 8 * Copyright (c) 1994 David Greenman 9 * All rights reserved. 10 * Copyright (c) 2005 Yahoo! Technologies Norway AS 11 * All rights reserved. 12 * 13 * This code is derived from software contributed to Berkeley by 14 * The Mach Operating System project at Carnegie-Mellon University. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 3. All advertising materials mentioning features or use of this software 25 * must display the following acknowledgement: 26 * This product includes software developed by the University of 27 * California, Berkeley and its contributors. 28 * 4. Neither the name of the University nor the names of its contributors 29 * may be used to endorse or promote products derived from this software 30 * without specific prior written permission. 31 * 32 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 33 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 34 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 35 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 36 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 37 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 38 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 40 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 41 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 42 * SUCH DAMAGE. 43 * 44 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 45 * 46 * 47 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 48 * All rights reserved. 49 * 50 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 51 * 52 * Permission to use, copy, modify and distribute this software and 53 * its documentation is hereby granted, provided that both the copyright 54 * notice and this permission notice appear in all copies of the 55 * software, derivative works or modified versions, and any portions 56 * thereof, and that both notices appear in supporting documentation. 57 * 58 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 59 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 60 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 61 * 62 * Carnegie Mellon requests users of this software to return to 63 * 64 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 65 * School of Computer Science 66 * Carnegie Mellon University 67 * Pittsburgh PA 15213-3890 68 * 69 * any improvements or extensions that they make and grant Carnegie the 70 * rights to redistribute these changes. 71 */ 72 73 /* 74 * The proverbial page-out daemon. 75 */ 76 77 #include <sys/cdefs.h> 78 __FBSDID("$FreeBSD$"); 79 80 #include "opt_vm.h" 81 82 #include <sys/param.h> 83 #include <sys/systm.h> 84 #include <sys/kernel.h> 85 #include <sys/eventhandler.h> 86 #include <sys/lock.h> 87 #include <sys/mutex.h> 88 #include <sys/proc.h> 89 #include <sys/kthread.h> 90 #include <sys/ktr.h> 91 #include <sys/mount.h> 92 #include <sys/racct.h> 93 #include <sys/resourcevar.h> 94 #include <sys/sched.h> 95 #include <sys/sdt.h> 96 #include <sys/signalvar.h> 97 #include <sys/smp.h> 98 #include <sys/time.h> 99 #include <sys/vnode.h> 100 #include <sys/vmmeter.h> 101 #include <sys/rwlock.h> 102 #include <sys/sx.h> 103 #include <sys/sysctl.h> 104 105 #include <vm/vm.h> 106 #include <vm/vm_param.h> 107 #include <vm/vm_object.h> 108 #include <vm/vm_page.h> 109 #include <vm/vm_map.h> 110 #include <vm/vm_pageout.h> 111 #include <vm/vm_pager.h> 112 #include <vm/vm_phys.h> 113 #include <vm/vm_pagequeue.h> 114 #include <vm/swap_pager.h> 115 #include <vm/vm_extern.h> 116 #include <vm/uma.h> 117 118 /* 119 * System initialization 120 */ 121 122 /* the kernel process "vm_pageout"*/ 123 static void vm_pageout(void); 124 static void vm_pageout_init(void); 125 static int vm_pageout_clean(vm_page_t m, int *numpagedout); 126 static int vm_pageout_cluster(vm_page_t m); 127 static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int page_shortage, 128 int starting_page_shortage); 129 130 SYSINIT(pagedaemon_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, vm_pageout_init, 131 NULL); 132 133 struct proc *pageproc; 134 135 static struct kproc_desc page_kp = { 136 "pagedaemon", 137 vm_pageout, 138 &pageproc 139 }; 140 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start, 141 &page_kp); 142 143 SDT_PROVIDER_DEFINE(vm); 144 SDT_PROBE_DEFINE(vm, , , vm__lowmem_scan); 145 146 /* Pagedaemon activity rates, in subdivisions of one second. */ 147 #define VM_LAUNDER_RATE 10 148 #define VM_INACT_SCAN_RATE 10 149 150 static int vm_pageout_oom_seq = 12; 151 152 static int vm_pageout_update_period; 153 static int disable_swap_pageouts; 154 static int lowmem_period = 10; 155 static time_t lowmem_uptime; 156 static int swapdev_enabled; 157 158 static int vm_panic_on_oom = 0; 159 160 SYSCTL_INT(_vm, OID_AUTO, panic_on_oom, 161 CTLFLAG_RWTUN, &vm_panic_on_oom, 0, 162 "panic on out of memory instead of killing the largest process"); 163 164 SYSCTL_INT(_vm, OID_AUTO, pageout_update_period, 165 CTLFLAG_RWTUN, &vm_pageout_update_period, 0, 166 "Maximum active LRU update period"); 167 168 SYSCTL_INT(_vm, OID_AUTO, lowmem_period, CTLFLAG_RWTUN, &lowmem_period, 0, 169 "Low memory callback period"); 170 171 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 172 CTLFLAG_RWTUN, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 173 174 static int pageout_lock_miss; 175 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 176 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 177 178 SYSCTL_INT(_vm, OID_AUTO, pageout_oom_seq, 179 CTLFLAG_RWTUN, &vm_pageout_oom_seq, 0, 180 "back-to-back calls to oom detector to start OOM"); 181 182 static int act_scan_laundry_weight = 3; 183 SYSCTL_INT(_vm, OID_AUTO, act_scan_laundry_weight, CTLFLAG_RWTUN, 184 &act_scan_laundry_weight, 0, 185 "weight given to clean vs. dirty pages in active queue scans"); 186 187 static u_int vm_background_launder_rate = 4096; 188 SYSCTL_UINT(_vm, OID_AUTO, background_launder_rate, CTLFLAG_RWTUN, 189 &vm_background_launder_rate, 0, 190 "background laundering rate, in kilobytes per second"); 191 192 static u_int vm_background_launder_max = 20 * 1024; 193 SYSCTL_UINT(_vm, OID_AUTO, background_launder_max, CTLFLAG_RWTUN, 194 &vm_background_launder_max, 0, "background laundering cap, in kilobytes"); 195 196 int vm_pageout_page_count = 32; 197 198 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 199 SYSCTL_INT(_vm, OID_AUTO, max_wired, 200 CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count"); 201 202 static u_int isqrt(u_int num); 203 static int vm_pageout_launder(struct vm_domain *vmd, int launder, 204 bool in_shortfall); 205 static void vm_pageout_laundry_worker(void *arg); 206 207 struct scan_state { 208 struct vm_batchqueue bq; 209 struct vm_pagequeue *pq; 210 vm_page_t marker; 211 int maxscan; 212 int scanned; 213 }; 214 215 static void 216 vm_pageout_init_scan(struct scan_state *ss, struct vm_pagequeue *pq, 217 vm_page_t marker, vm_page_t after, int maxscan) 218 { 219 220 vm_pagequeue_assert_locked(pq); 221 KASSERT((marker->aflags & PGA_ENQUEUED) == 0, 222 ("marker %p already enqueued", marker)); 223 224 if (after == NULL) 225 TAILQ_INSERT_HEAD(&pq->pq_pl, marker, plinks.q); 226 else 227 TAILQ_INSERT_AFTER(&pq->pq_pl, after, marker, plinks.q); 228 vm_page_aflag_set(marker, PGA_ENQUEUED); 229 230 vm_batchqueue_init(&ss->bq); 231 ss->pq = pq; 232 ss->marker = marker; 233 ss->maxscan = maxscan; 234 ss->scanned = 0; 235 vm_pagequeue_unlock(pq); 236 } 237 238 static void 239 vm_pageout_end_scan(struct scan_state *ss) 240 { 241 struct vm_pagequeue *pq; 242 243 pq = ss->pq; 244 vm_pagequeue_assert_locked(pq); 245 KASSERT((ss->marker->aflags & PGA_ENQUEUED) != 0, 246 ("marker %p not enqueued", ss->marker)); 247 248 TAILQ_REMOVE(&pq->pq_pl, ss->marker, plinks.q); 249 vm_page_aflag_clear(ss->marker, PGA_ENQUEUED); 250 VM_CNT_ADD(v_pdpages, ss->scanned); 251 } 252 253 /* 254 * Add a small number of queued pages to a batch queue for later processing 255 * without the corresponding queue lock held. The caller must have enqueued a 256 * marker page at the desired start point for the scan. Pages will be 257 * physically dequeued if the caller so requests. Otherwise, the returned 258 * batch may contain marker pages, and it is up to the caller to handle them. 259 * 260 * When processing the batch queue, vm_page_queue() must be used to 261 * determine whether the page has been logically dequeued by another thread. 262 * Once this check is performed, the page lock guarantees that the page will 263 * not be disassociated from the queue. 264 */ 265 static __always_inline void 266 vm_pageout_collect_batch(struct scan_state *ss, const bool dequeue) 267 { 268 struct vm_pagequeue *pq; 269 vm_page_t m, marker; 270 271 marker = ss->marker; 272 pq = ss->pq; 273 274 KASSERT((marker->aflags & PGA_ENQUEUED) != 0, 275 ("marker %p not enqueued", ss->marker)); 276 277 vm_pagequeue_lock(pq); 278 for (m = TAILQ_NEXT(marker, plinks.q); m != NULL && 279 ss->scanned < ss->maxscan && ss->bq.bq_cnt < VM_BATCHQUEUE_SIZE; 280 m = TAILQ_NEXT(m, plinks.q), ss->scanned++) { 281 if ((m->flags & PG_MARKER) == 0) { 282 KASSERT((m->aflags & PGA_ENQUEUED) != 0, 283 ("page %p not enqueued", m)); 284 KASSERT((m->flags & PG_FICTITIOUS) == 0, 285 ("Fictitious page %p cannot be in page queue", m)); 286 KASSERT((m->oflags & VPO_UNMANAGED) == 0, 287 ("Unmanaged page %p cannot be in page queue", m)); 288 } else if (dequeue) 289 continue; 290 291 (void)vm_batchqueue_insert(&ss->bq, m); 292 if (dequeue) { 293 TAILQ_REMOVE(&pq->pq_pl, m, plinks.q); 294 vm_page_aflag_clear(m, PGA_ENQUEUED); 295 } 296 } 297 TAILQ_REMOVE(&pq->pq_pl, marker, plinks.q); 298 if (__predict_true(m != NULL)) 299 TAILQ_INSERT_BEFORE(m, marker, plinks.q); 300 else 301 TAILQ_INSERT_TAIL(&pq->pq_pl, marker, plinks.q); 302 if (dequeue) 303 vm_pagequeue_cnt_add(pq, -ss->bq.bq_cnt); 304 vm_pagequeue_unlock(pq); 305 } 306 307 /* Return the next page to be scanned, or NULL if the scan is complete. */ 308 static __always_inline vm_page_t 309 vm_pageout_next(struct scan_state *ss, const bool dequeue) 310 { 311 312 if (ss->bq.bq_cnt == 0) 313 vm_pageout_collect_batch(ss, dequeue); 314 return (vm_batchqueue_pop(&ss->bq)); 315 } 316 317 /* 318 * Scan for pages at adjacent offsets within the given page's object that are 319 * eligible for laundering, form a cluster of these pages and the given page, 320 * and launder that cluster. 321 */ 322 static int 323 vm_pageout_cluster(vm_page_t m) 324 { 325 vm_object_t object; 326 vm_page_t mc[2 * vm_pageout_page_count], p, pb, ps; 327 vm_pindex_t pindex; 328 int ib, is, page_base, pageout_count; 329 330 vm_page_assert_locked(m); 331 object = m->object; 332 VM_OBJECT_ASSERT_WLOCKED(object); 333 pindex = m->pindex; 334 335 vm_page_assert_unbusied(m); 336 KASSERT(!vm_page_held(m), ("page %p is held", m)); 337 338 pmap_remove_write(m); 339 vm_page_unlock(m); 340 341 mc[vm_pageout_page_count] = pb = ps = m; 342 pageout_count = 1; 343 page_base = vm_pageout_page_count; 344 ib = 1; 345 is = 1; 346 347 /* 348 * We can cluster only if the page is not clean, busy, or held, and 349 * the page is in the laundry queue. 350 * 351 * During heavy mmap/modification loads the pageout 352 * daemon can really fragment the underlying file 353 * due to flushing pages out of order and not trying to 354 * align the clusters (which leaves sporadic out-of-order 355 * holes). To solve this problem we do the reverse scan 356 * first and attempt to align our cluster, then do a 357 * forward scan if room remains. 358 */ 359 more: 360 while (ib != 0 && pageout_count < vm_pageout_page_count) { 361 if (ib > pindex) { 362 ib = 0; 363 break; 364 } 365 if ((p = vm_page_prev(pb)) == NULL || vm_page_busied(p)) { 366 ib = 0; 367 break; 368 } 369 vm_page_test_dirty(p); 370 if (p->dirty == 0) { 371 ib = 0; 372 break; 373 } 374 vm_page_lock(p); 375 if (vm_page_held(p) || !vm_page_in_laundry(p)) { 376 vm_page_unlock(p); 377 ib = 0; 378 break; 379 } 380 pmap_remove_write(p); 381 vm_page_unlock(p); 382 mc[--page_base] = pb = p; 383 ++pageout_count; 384 ++ib; 385 386 /* 387 * We are at an alignment boundary. Stop here, and switch 388 * directions. Do not clear ib. 389 */ 390 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 391 break; 392 } 393 while (pageout_count < vm_pageout_page_count && 394 pindex + is < object->size) { 395 if ((p = vm_page_next(ps)) == NULL || vm_page_busied(p)) 396 break; 397 vm_page_test_dirty(p); 398 if (p->dirty == 0) 399 break; 400 vm_page_lock(p); 401 if (vm_page_held(p) || !vm_page_in_laundry(p)) { 402 vm_page_unlock(p); 403 break; 404 } 405 pmap_remove_write(p); 406 vm_page_unlock(p); 407 mc[page_base + pageout_count] = ps = p; 408 ++pageout_count; 409 ++is; 410 } 411 412 /* 413 * If we exhausted our forward scan, continue with the reverse scan 414 * when possible, even past an alignment boundary. This catches 415 * boundary conditions. 416 */ 417 if (ib != 0 && pageout_count < vm_pageout_page_count) 418 goto more; 419 420 return (vm_pageout_flush(&mc[page_base], pageout_count, 421 VM_PAGER_PUT_NOREUSE, 0, NULL, NULL)); 422 } 423 424 /* 425 * vm_pageout_flush() - launder the given pages 426 * 427 * The given pages are laundered. Note that we setup for the start of 428 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 429 * reference count all in here rather then in the parent. If we want 430 * the parent to do more sophisticated things we may have to change 431 * the ordering. 432 * 433 * Returned runlen is the count of pages between mreq and first 434 * page after mreq with status VM_PAGER_AGAIN. 435 * *eio is set to TRUE if pager returned VM_PAGER_ERROR or VM_PAGER_FAIL 436 * for any page in runlen set. 437 */ 438 int 439 vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen, 440 boolean_t *eio) 441 { 442 vm_object_t object = mc[0]->object; 443 int pageout_status[count]; 444 int numpagedout = 0; 445 int i, runlen; 446 447 VM_OBJECT_ASSERT_WLOCKED(object); 448 449 /* 450 * Initiate I/O. Mark the pages busy and verify that they're valid 451 * and read-only. 452 * 453 * We do not have to fixup the clean/dirty bits here... we can 454 * allow the pager to do it after the I/O completes. 455 * 456 * NOTE! mc[i]->dirty may be partial or fragmented due to an 457 * edge case with file fragments. 458 */ 459 for (i = 0; i < count; i++) { 460 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 461 ("vm_pageout_flush: partially invalid page %p index %d/%d", 462 mc[i], i, count)); 463 KASSERT((mc[i]->aflags & PGA_WRITEABLE) == 0, 464 ("vm_pageout_flush: writeable page %p", mc[i])); 465 vm_page_sbusy(mc[i]); 466 } 467 vm_object_pip_add(object, count); 468 469 vm_pager_put_pages(object, mc, count, flags, pageout_status); 470 471 runlen = count - mreq; 472 if (eio != NULL) 473 *eio = FALSE; 474 for (i = 0; i < count; i++) { 475 vm_page_t mt = mc[i]; 476 477 KASSERT(pageout_status[i] == VM_PAGER_PEND || 478 !pmap_page_is_write_mapped(mt), 479 ("vm_pageout_flush: page %p is not write protected", mt)); 480 switch (pageout_status[i]) { 481 case VM_PAGER_OK: 482 vm_page_lock(mt); 483 if (vm_page_in_laundry(mt)) 484 vm_page_deactivate_noreuse(mt); 485 vm_page_unlock(mt); 486 /* FALLTHROUGH */ 487 case VM_PAGER_PEND: 488 numpagedout++; 489 break; 490 case VM_PAGER_BAD: 491 /* 492 * The page is outside the object's range. We pretend 493 * that the page out worked and clean the page, so the 494 * changes will be lost if the page is reclaimed by 495 * the page daemon. 496 */ 497 vm_page_undirty(mt); 498 vm_page_lock(mt); 499 if (vm_page_in_laundry(mt)) 500 vm_page_deactivate_noreuse(mt); 501 vm_page_unlock(mt); 502 break; 503 case VM_PAGER_ERROR: 504 case VM_PAGER_FAIL: 505 /* 506 * If the page couldn't be paged out to swap because the 507 * pager wasn't able to find space, place the page in 508 * the PQ_UNSWAPPABLE holding queue. This is an 509 * optimization that prevents the page daemon from 510 * wasting CPU cycles on pages that cannot be reclaimed 511 * becase no swap device is configured. 512 * 513 * Otherwise, reactivate the page so that it doesn't 514 * clog the laundry and inactive queues. (We will try 515 * paging it out again later.) 516 */ 517 vm_page_lock(mt); 518 if (object->type == OBJT_SWAP && 519 pageout_status[i] == VM_PAGER_FAIL) { 520 vm_page_unswappable(mt); 521 numpagedout++; 522 } else 523 vm_page_activate(mt); 524 vm_page_unlock(mt); 525 if (eio != NULL && i >= mreq && i - mreq < runlen) 526 *eio = TRUE; 527 break; 528 case VM_PAGER_AGAIN: 529 if (i >= mreq && i - mreq < runlen) 530 runlen = i - mreq; 531 break; 532 } 533 534 /* 535 * If the operation is still going, leave the page busy to 536 * block all other accesses. Also, leave the paging in 537 * progress indicator set so that we don't attempt an object 538 * collapse. 539 */ 540 if (pageout_status[i] != VM_PAGER_PEND) { 541 vm_object_pip_wakeup(object); 542 vm_page_sunbusy(mt); 543 } 544 } 545 if (prunlen != NULL) 546 *prunlen = runlen; 547 return (numpagedout); 548 } 549 550 static void 551 vm_pageout_swapon(void *arg __unused, struct swdevt *sp __unused) 552 { 553 554 atomic_store_rel_int(&swapdev_enabled, 1); 555 } 556 557 static void 558 vm_pageout_swapoff(void *arg __unused, struct swdevt *sp __unused) 559 { 560 561 if (swap_pager_nswapdev() == 1) 562 atomic_store_rel_int(&swapdev_enabled, 0); 563 } 564 565 /* 566 * Attempt to acquire all of the necessary locks to launder a page and 567 * then call through the clustering layer to PUTPAGES. Wait a short 568 * time for a vnode lock. 569 * 570 * Requires the page and object lock on entry, releases both before return. 571 * Returns 0 on success and an errno otherwise. 572 */ 573 static int 574 vm_pageout_clean(vm_page_t m, int *numpagedout) 575 { 576 struct vnode *vp; 577 struct mount *mp; 578 vm_object_t object; 579 vm_pindex_t pindex; 580 int error, lockmode; 581 582 vm_page_assert_locked(m); 583 object = m->object; 584 VM_OBJECT_ASSERT_WLOCKED(object); 585 error = 0; 586 vp = NULL; 587 mp = NULL; 588 589 /* 590 * The object is already known NOT to be dead. It 591 * is possible for the vget() to block the whole 592 * pageout daemon, but the new low-memory handling 593 * code should prevent it. 594 * 595 * We can't wait forever for the vnode lock, we might 596 * deadlock due to a vn_read() getting stuck in 597 * vm_wait while holding this vnode. We skip the 598 * vnode if we can't get it in a reasonable amount 599 * of time. 600 */ 601 if (object->type == OBJT_VNODE) { 602 vm_page_unlock(m); 603 vp = object->handle; 604 if (vp->v_type == VREG && 605 vn_start_write(vp, &mp, V_NOWAIT) != 0) { 606 mp = NULL; 607 error = EDEADLK; 608 goto unlock_all; 609 } 610 KASSERT(mp != NULL, 611 ("vp %p with NULL v_mount", vp)); 612 vm_object_reference_locked(object); 613 pindex = m->pindex; 614 VM_OBJECT_WUNLOCK(object); 615 lockmode = MNT_SHARED_WRITES(vp->v_mount) ? 616 LK_SHARED : LK_EXCLUSIVE; 617 if (vget(vp, lockmode | LK_TIMELOCK, curthread)) { 618 vp = NULL; 619 error = EDEADLK; 620 goto unlock_mp; 621 } 622 VM_OBJECT_WLOCK(object); 623 624 /* 625 * Ensure that the object and vnode were not disassociated 626 * while locks were dropped. 627 */ 628 if (vp->v_object != object) { 629 error = ENOENT; 630 goto unlock_all; 631 } 632 vm_page_lock(m); 633 634 /* 635 * While the object and page were unlocked, the page 636 * may have been: 637 * (1) moved to a different queue, 638 * (2) reallocated to a different object, 639 * (3) reallocated to a different offset, or 640 * (4) cleaned. 641 */ 642 if (!vm_page_in_laundry(m) || m->object != object || 643 m->pindex != pindex || m->dirty == 0) { 644 vm_page_unlock(m); 645 error = ENXIO; 646 goto unlock_all; 647 } 648 649 /* 650 * The page may have been busied or referenced while the object 651 * and page locks were released. 652 */ 653 if (vm_page_busied(m) || vm_page_held(m)) { 654 vm_page_unlock(m); 655 error = EBUSY; 656 goto unlock_all; 657 } 658 } 659 660 /* 661 * If a page is dirty, then it is either being washed 662 * (but not yet cleaned) or it is still in the 663 * laundry. If it is still in the laundry, then we 664 * start the cleaning operation. 665 */ 666 if ((*numpagedout = vm_pageout_cluster(m)) == 0) 667 error = EIO; 668 669 unlock_all: 670 VM_OBJECT_WUNLOCK(object); 671 672 unlock_mp: 673 vm_page_lock_assert(m, MA_NOTOWNED); 674 if (mp != NULL) { 675 if (vp != NULL) 676 vput(vp); 677 vm_object_deallocate(object); 678 vn_finished_write(mp); 679 } 680 681 return (error); 682 } 683 684 /* 685 * Attempt to launder the specified number of pages. 686 * 687 * Returns the number of pages successfully laundered. 688 */ 689 static int 690 vm_pageout_launder(struct vm_domain *vmd, int launder, bool in_shortfall) 691 { 692 struct scan_state ss; 693 struct vm_pagequeue *pq; 694 struct mtx *mtx; 695 vm_object_t object; 696 vm_page_t m, marker; 697 int act_delta, error, numpagedout, queue, starting_target; 698 int vnodes_skipped; 699 bool obj_locked, pageout_ok; 700 701 mtx = NULL; 702 obj_locked = false; 703 object = NULL; 704 starting_target = launder; 705 vnodes_skipped = 0; 706 707 /* 708 * Scan the laundry queues for pages eligible to be laundered. We stop 709 * once the target number of dirty pages have been laundered, or once 710 * we've reached the end of the queue. A single iteration of this loop 711 * may cause more than one page to be laundered because of clustering. 712 * 713 * As an optimization, we avoid laundering from PQ_UNSWAPPABLE when no 714 * swap devices are configured. 715 */ 716 if (atomic_load_acq_int(&swapdev_enabled)) 717 queue = PQ_UNSWAPPABLE; 718 else 719 queue = PQ_LAUNDRY; 720 721 scan: 722 marker = &vmd->vmd_markers[queue]; 723 pq = &vmd->vmd_pagequeues[queue]; 724 vm_pagequeue_lock(pq); 725 vm_pageout_init_scan(&ss, pq, marker, NULL, pq->pq_cnt); 726 while (launder > 0 && (m = vm_pageout_next(&ss, false)) != NULL) { 727 if (__predict_false((m->flags & PG_MARKER) != 0)) 728 continue; 729 730 vm_page_change_lock(m, &mtx); 731 732 recheck: 733 /* 734 * The page may have been disassociated from the queue 735 * while locks were dropped. 736 */ 737 if (vm_page_queue(m) != queue) 738 continue; 739 740 /* 741 * A requeue was requested, so this page gets a second 742 * chance. 743 */ 744 if ((m->aflags & PGA_REQUEUE) != 0) { 745 vm_page_requeue(m); 746 continue; 747 } 748 749 /* 750 * Held pages are essentially stuck in the queue. 751 * 752 * Wired pages may not be freed. Complete their removal 753 * from the queue now to avoid needless revisits during 754 * future scans. 755 */ 756 if (m->hold_count != 0) 757 continue; 758 if (m->wire_count != 0) { 759 vm_page_dequeue_deferred(m); 760 continue; 761 } 762 763 if (object != m->object) { 764 if (obj_locked) { 765 VM_OBJECT_WUNLOCK(object); 766 obj_locked = false; 767 } 768 object = m->object; 769 } 770 if (!obj_locked) { 771 if (!VM_OBJECT_TRYWLOCK(object)) { 772 mtx_unlock(mtx); 773 /* Depends on type-stability. */ 774 VM_OBJECT_WLOCK(object); 775 obj_locked = true; 776 mtx_lock(mtx); 777 goto recheck; 778 } else 779 obj_locked = true; 780 } 781 782 if (vm_page_busied(m)) 783 continue; 784 785 /* 786 * Invalid pages can be easily freed. They cannot be 787 * mapped; vm_page_free() asserts this. 788 */ 789 if (m->valid == 0) 790 goto free_page; 791 792 /* 793 * If the page has been referenced and the object is not dead, 794 * reactivate or requeue the page depending on whether the 795 * object is mapped. 796 * 797 * Test PGA_REFERENCED after calling pmap_ts_referenced() so 798 * that a reference from a concurrently destroyed mapping is 799 * observed here and now. 800 */ 801 if (object->ref_count != 0) 802 act_delta = pmap_ts_referenced(m); 803 else { 804 KASSERT(!pmap_page_is_mapped(m), 805 ("page %p is mapped", m)); 806 act_delta = 0; 807 } 808 if ((m->aflags & PGA_REFERENCED) != 0) { 809 vm_page_aflag_clear(m, PGA_REFERENCED); 810 act_delta++; 811 } 812 if (act_delta != 0) { 813 if (object->ref_count != 0) { 814 VM_CNT_INC(v_reactivated); 815 vm_page_activate(m); 816 817 /* 818 * Increase the activation count if the page 819 * was referenced while in the laundry queue. 820 * This makes it less likely that the page will 821 * be returned prematurely to the inactive 822 * queue. 823 */ 824 m->act_count += act_delta + ACT_ADVANCE; 825 826 /* 827 * If this was a background laundering, count 828 * activated pages towards our target. The 829 * purpose of background laundering is to ensure 830 * that pages are eventually cycled through the 831 * laundry queue, and an activation is a valid 832 * way out. 833 */ 834 if (!in_shortfall) 835 launder--; 836 continue; 837 } else if ((object->flags & OBJ_DEAD) == 0) { 838 vm_page_requeue(m); 839 continue; 840 } 841 } 842 843 /* 844 * If the page appears to be clean at the machine-independent 845 * layer, then remove all of its mappings from the pmap in 846 * anticipation of freeing it. If, however, any of the page's 847 * mappings allow write access, then the page may still be 848 * modified until the last of those mappings are removed. 849 */ 850 if (object->ref_count != 0) { 851 vm_page_test_dirty(m); 852 if (m->dirty == 0) 853 pmap_remove_all(m); 854 } 855 856 /* 857 * Clean pages are freed, and dirty pages are paged out unless 858 * they belong to a dead object. Requeueing dirty pages from 859 * dead objects is pointless, as they are being paged out and 860 * freed by the thread that destroyed the object. 861 */ 862 if (m->dirty == 0) { 863 free_page: 864 vm_page_free(m); 865 VM_CNT_INC(v_dfree); 866 } else if ((object->flags & OBJ_DEAD) == 0) { 867 if (object->type != OBJT_SWAP && 868 object->type != OBJT_DEFAULT) 869 pageout_ok = true; 870 else if (disable_swap_pageouts) 871 pageout_ok = false; 872 else 873 pageout_ok = true; 874 if (!pageout_ok) { 875 vm_page_requeue(m); 876 continue; 877 } 878 879 /* 880 * Form a cluster with adjacent, dirty pages from the 881 * same object, and page out that entire cluster. 882 * 883 * The adjacent, dirty pages must also be in the 884 * laundry. However, their mappings are not checked 885 * for new references. Consequently, a recently 886 * referenced page may be paged out. However, that 887 * page will not be prematurely reclaimed. After page 888 * out, the page will be placed in the inactive queue, 889 * where any new references will be detected and the 890 * page reactivated. 891 */ 892 error = vm_pageout_clean(m, &numpagedout); 893 if (error == 0) { 894 launder -= numpagedout; 895 ss.scanned += numpagedout; 896 } else if (error == EDEADLK) { 897 pageout_lock_miss++; 898 vnodes_skipped++; 899 } 900 mtx = NULL; 901 obj_locked = false; 902 } 903 } 904 if (mtx != NULL) { 905 mtx_unlock(mtx); 906 mtx = NULL; 907 } 908 if (obj_locked) { 909 VM_OBJECT_WUNLOCK(object); 910 obj_locked = false; 911 } 912 vm_pagequeue_lock(pq); 913 vm_pageout_end_scan(&ss); 914 vm_pagequeue_unlock(pq); 915 916 if (launder > 0 && queue == PQ_UNSWAPPABLE) { 917 queue = PQ_LAUNDRY; 918 goto scan; 919 } 920 921 /* 922 * Wakeup the sync daemon if we skipped a vnode in a writeable object 923 * and we didn't launder enough pages. 924 */ 925 if (vnodes_skipped > 0 && launder > 0) 926 (void)speedup_syncer(); 927 928 return (starting_target - launder); 929 } 930 931 /* 932 * Compute the integer square root. 933 */ 934 static u_int 935 isqrt(u_int num) 936 { 937 u_int bit, root, tmp; 938 939 bit = 1u << ((NBBY * sizeof(u_int)) - 2); 940 while (bit > num) 941 bit >>= 2; 942 root = 0; 943 while (bit != 0) { 944 tmp = root + bit; 945 root >>= 1; 946 if (num >= tmp) { 947 num -= tmp; 948 root += bit; 949 } 950 bit >>= 2; 951 } 952 return (root); 953 } 954 955 /* 956 * Perform the work of the laundry thread: periodically wake up and determine 957 * whether any pages need to be laundered. If so, determine the number of pages 958 * that need to be laundered, and launder them. 959 */ 960 static void 961 vm_pageout_laundry_worker(void *arg) 962 { 963 struct vm_domain *vmd; 964 struct vm_pagequeue *pq; 965 uint64_t nclean, ndirty, nfreed; 966 int domain, last_target, launder, shortfall, shortfall_cycle, target; 967 bool in_shortfall; 968 969 domain = (uintptr_t)arg; 970 vmd = VM_DOMAIN(domain); 971 pq = &vmd->vmd_pagequeues[PQ_LAUNDRY]; 972 KASSERT(vmd->vmd_segs != 0, ("domain without segments")); 973 974 shortfall = 0; 975 in_shortfall = false; 976 shortfall_cycle = 0; 977 target = 0; 978 nfreed = 0; 979 980 /* 981 * Calls to these handlers are serialized by the swap syscall lock. 982 */ 983 (void)EVENTHANDLER_REGISTER(swapon, vm_pageout_swapon, vmd, 984 EVENTHANDLER_PRI_ANY); 985 (void)EVENTHANDLER_REGISTER(swapoff, vm_pageout_swapoff, vmd, 986 EVENTHANDLER_PRI_ANY); 987 988 /* 989 * The pageout laundry worker is never done, so loop forever. 990 */ 991 for (;;) { 992 KASSERT(target >= 0, ("negative target %d", target)); 993 KASSERT(shortfall_cycle >= 0, 994 ("negative cycle %d", shortfall_cycle)); 995 launder = 0; 996 997 /* 998 * First determine whether we need to launder pages to meet a 999 * shortage of free pages. 1000 */ 1001 if (shortfall > 0) { 1002 in_shortfall = true; 1003 shortfall_cycle = VM_LAUNDER_RATE / VM_INACT_SCAN_RATE; 1004 target = shortfall; 1005 } else if (!in_shortfall) 1006 goto trybackground; 1007 else if (shortfall_cycle == 0 || vm_laundry_target(vmd) <= 0) { 1008 /* 1009 * We recently entered shortfall and began laundering 1010 * pages. If we have completed that laundering run 1011 * (and we are no longer in shortfall) or we have met 1012 * our laundry target through other activity, then we 1013 * can stop laundering pages. 1014 */ 1015 in_shortfall = false; 1016 target = 0; 1017 goto trybackground; 1018 } 1019 launder = target / shortfall_cycle--; 1020 goto dolaundry; 1021 1022 /* 1023 * There's no immediate need to launder any pages; see if we 1024 * meet the conditions to perform background laundering: 1025 * 1026 * 1. The ratio of dirty to clean inactive pages exceeds the 1027 * background laundering threshold, or 1028 * 2. we haven't yet reached the target of the current 1029 * background laundering run. 1030 * 1031 * The background laundering threshold is not a constant. 1032 * Instead, it is a slowly growing function of the number of 1033 * clean pages freed by the page daemon since the last 1034 * background laundering. Thus, as the ratio of dirty to 1035 * clean inactive pages grows, the amount of memory pressure 1036 * required to trigger laundering decreases. We ensure 1037 * that the threshold is non-zero after an inactive queue 1038 * scan, even if that scan failed to free a single clean page. 1039 */ 1040 trybackground: 1041 nclean = vmd->vmd_free_count + 1042 vmd->vmd_pagequeues[PQ_INACTIVE].pq_cnt; 1043 ndirty = vmd->vmd_pagequeues[PQ_LAUNDRY].pq_cnt; 1044 if (target == 0 && ndirty * isqrt(howmany(nfreed + 1, 1045 vmd->vmd_free_target - vmd->vmd_free_min)) >= nclean) { 1046 target = vmd->vmd_background_launder_target; 1047 } 1048 1049 /* 1050 * We have a non-zero background laundering target. If we've 1051 * laundered up to our maximum without observing a page daemon 1052 * request, just stop. This is a safety belt that ensures we 1053 * don't launder an excessive amount if memory pressure is low 1054 * and the ratio of dirty to clean pages is large. Otherwise, 1055 * proceed at the background laundering rate. 1056 */ 1057 if (target > 0) { 1058 if (nfreed > 0) { 1059 nfreed = 0; 1060 last_target = target; 1061 } else if (last_target - target >= 1062 vm_background_launder_max * PAGE_SIZE / 1024) { 1063 target = 0; 1064 } 1065 launder = vm_background_launder_rate * PAGE_SIZE / 1024; 1066 launder /= VM_LAUNDER_RATE; 1067 if (launder > target) 1068 launder = target; 1069 } 1070 1071 dolaundry: 1072 if (launder > 0) { 1073 /* 1074 * Because of I/O clustering, the number of laundered 1075 * pages could exceed "target" by the maximum size of 1076 * a cluster minus one. 1077 */ 1078 target -= min(vm_pageout_launder(vmd, launder, 1079 in_shortfall), target); 1080 pause("laundp", hz / VM_LAUNDER_RATE); 1081 } 1082 1083 /* 1084 * If we're not currently laundering pages and the page daemon 1085 * hasn't posted a new request, sleep until the page daemon 1086 * kicks us. 1087 */ 1088 vm_pagequeue_lock(pq); 1089 if (target == 0 && vmd->vmd_laundry_request == VM_LAUNDRY_IDLE) 1090 (void)mtx_sleep(&vmd->vmd_laundry_request, 1091 vm_pagequeue_lockptr(pq), PVM, "launds", 0); 1092 1093 /* 1094 * If the pagedaemon has indicated that it's in shortfall, start 1095 * a shortfall laundering unless we're already in the middle of 1096 * one. This may preempt a background laundering. 1097 */ 1098 if (vmd->vmd_laundry_request == VM_LAUNDRY_SHORTFALL && 1099 (!in_shortfall || shortfall_cycle == 0)) { 1100 shortfall = vm_laundry_target(vmd) + 1101 vmd->vmd_pageout_deficit; 1102 target = 0; 1103 } else 1104 shortfall = 0; 1105 1106 if (target == 0) 1107 vmd->vmd_laundry_request = VM_LAUNDRY_IDLE; 1108 nfreed += vmd->vmd_clean_pages_freed; 1109 vmd->vmd_clean_pages_freed = 0; 1110 vm_pagequeue_unlock(pq); 1111 } 1112 } 1113 1114 /* 1115 * Compute the number of pages we want to try to move from the 1116 * active queue to either the inactive or laundry queue. 1117 * 1118 * When scanning active pages during a shortage, we make clean pages 1119 * count more heavily towards the page shortage than dirty pages. 1120 * This is because dirty pages must be laundered before they can be 1121 * reused and thus have less utility when attempting to quickly 1122 * alleviate a free page shortage. However, this weighting also 1123 * causes the scan to deactivate dirty pages more aggressively, 1124 * improving the effectiveness of clustering. 1125 */ 1126 static int 1127 vm_pageout_active_target(struct vm_domain *vmd) 1128 { 1129 int shortage; 1130 1131 shortage = vmd->vmd_inactive_target + vm_paging_target(vmd) - 1132 (vmd->vmd_pagequeues[PQ_INACTIVE].pq_cnt + 1133 vmd->vmd_pagequeues[PQ_LAUNDRY].pq_cnt / act_scan_laundry_weight); 1134 shortage *= act_scan_laundry_weight; 1135 return (shortage); 1136 } 1137 1138 /* 1139 * Scan the active queue. If there is no shortage of inactive pages, scan a 1140 * small portion of the queue in order to maintain quasi-LRU. 1141 */ 1142 static void 1143 vm_pageout_scan_active(struct vm_domain *vmd, int page_shortage) 1144 { 1145 struct scan_state ss; 1146 struct mtx *mtx; 1147 vm_page_t m, marker; 1148 struct vm_pagequeue *pq; 1149 long min_scan; 1150 int act_delta, max_scan, scan_tick; 1151 1152 marker = &vmd->vmd_markers[PQ_ACTIVE]; 1153 pq = &vmd->vmd_pagequeues[PQ_ACTIVE]; 1154 vm_pagequeue_lock(pq); 1155 1156 /* 1157 * If we're just idle polling attempt to visit every 1158 * active page within 'update_period' seconds. 1159 */ 1160 scan_tick = ticks; 1161 if (vm_pageout_update_period != 0) { 1162 min_scan = pq->pq_cnt; 1163 min_scan *= scan_tick - vmd->vmd_last_active_scan; 1164 min_scan /= hz * vm_pageout_update_period; 1165 } else 1166 min_scan = 0; 1167 if (min_scan > 0 || (page_shortage > 0 && pq->pq_cnt > 0)) 1168 vmd->vmd_last_active_scan = scan_tick; 1169 1170 /* 1171 * Scan the active queue for pages that can be deactivated. Update 1172 * the per-page activity counter and use it to identify deactivation 1173 * candidates. Held pages may be deactivated. 1174 * 1175 * To avoid requeuing each page that remains in the active queue, we 1176 * implement the CLOCK algorithm. To keep the implementation of the 1177 * enqueue operation consistent for all page queues, we use two hands, 1178 * represented by marker pages. Scans begin at the first hand, which 1179 * precedes the second hand in the queue. When the two hands meet, 1180 * they are moved back to the head and tail of the queue, respectively, 1181 * and scanning resumes. 1182 */ 1183 max_scan = page_shortage > 0 ? pq->pq_cnt : min_scan; 1184 mtx = NULL; 1185 act_scan: 1186 vm_pageout_init_scan(&ss, pq, marker, &vmd->vmd_clock[0], max_scan); 1187 while ((m = vm_pageout_next(&ss, false)) != NULL) { 1188 if (__predict_false(m == &vmd->vmd_clock[1])) { 1189 vm_pagequeue_lock(pq); 1190 TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_clock[0], plinks.q); 1191 TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_clock[1], plinks.q); 1192 TAILQ_INSERT_HEAD(&pq->pq_pl, &vmd->vmd_clock[0], 1193 plinks.q); 1194 TAILQ_INSERT_TAIL(&pq->pq_pl, &vmd->vmd_clock[1], 1195 plinks.q); 1196 max_scan -= ss.scanned; 1197 vm_pageout_end_scan(&ss); 1198 goto act_scan; 1199 } 1200 if (__predict_false((m->flags & PG_MARKER) != 0)) 1201 continue; 1202 1203 vm_page_change_lock(m, &mtx); 1204 1205 /* 1206 * The page may have been disassociated from the queue 1207 * while locks were dropped. 1208 */ 1209 if (vm_page_queue(m) != PQ_ACTIVE) 1210 continue; 1211 1212 /* 1213 * Wired pages are dequeued lazily. 1214 */ 1215 if (m->wire_count != 0) { 1216 vm_page_dequeue_deferred(m); 1217 continue; 1218 } 1219 1220 /* 1221 * Check to see "how much" the page has been used. 1222 * 1223 * Test PGA_REFERENCED after calling pmap_ts_referenced() so 1224 * that a reference from a concurrently destroyed mapping is 1225 * observed here and now. 1226 * 1227 * Perform an unsynchronized object ref count check. While 1228 * the page lock ensures that the page is not reallocated to 1229 * another object, in particular, one with unmanaged mappings 1230 * that cannot support pmap_ts_referenced(), two races are, 1231 * nonetheless, possible: 1232 * 1) The count was transitioning to zero, but we saw a non- 1233 * zero value. pmap_ts_referenced() will return zero 1234 * because the page is not mapped. 1235 * 2) The count was transitioning to one, but we saw zero. 1236 * This race delays the detection of a new reference. At 1237 * worst, we will deactivate and reactivate the page. 1238 */ 1239 if (m->object->ref_count != 0) 1240 act_delta = pmap_ts_referenced(m); 1241 else 1242 act_delta = 0; 1243 if ((m->aflags & PGA_REFERENCED) != 0) { 1244 vm_page_aflag_clear(m, PGA_REFERENCED); 1245 act_delta++; 1246 } 1247 1248 /* 1249 * Advance or decay the act_count based on recent usage. 1250 */ 1251 if (act_delta != 0) { 1252 m->act_count += ACT_ADVANCE + act_delta; 1253 if (m->act_count > ACT_MAX) 1254 m->act_count = ACT_MAX; 1255 } else 1256 m->act_count -= min(m->act_count, ACT_DECLINE); 1257 1258 if (m->act_count == 0) { 1259 /* 1260 * When not short for inactive pages, let dirty pages go 1261 * through the inactive queue before moving to the 1262 * laundry queues. This gives them some extra time to 1263 * be reactivated, potentially avoiding an expensive 1264 * pageout. However, during a page shortage, the 1265 * inactive queue is necessarily small, and so dirty 1266 * pages would only spend a trivial amount of time in 1267 * the inactive queue. Therefore, we might as well 1268 * place them directly in the laundry queue to reduce 1269 * queuing overhead. 1270 */ 1271 if (page_shortage <= 0) 1272 vm_page_deactivate(m); 1273 else { 1274 /* 1275 * Calling vm_page_test_dirty() here would 1276 * require acquisition of the object's write 1277 * lock. However, during a page shortage, 1278 * directing dirty pages into the laundry 1279 * queue is only an optimization and not a 1280 * requirement. Therefore, we simply rely on 1281 * the opportunistic updates to the page's 1282 * dirty field by the pmap. 1283 */ 1284 if (m->dirty == 0) { 1285 vm_page_deactivate(m); 1286 page_shortage -= 1287 act_scan_laundry_weight; 1288 } else { 1289 vm_page_launder(m); 1290 page_shortage--; 1291 } 1292 } 1293 } 1294 } 1295 if (mtx != NULL) { 1296 mtx_unlock(mtx); 1297 mtx = NULL; 1298 } 1299 vm_pagequeue_lock(pq); 1300 TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_clock[0], plinks.q); 1301 TAILQ_INSERT_AFTER(&pq->pq_pl, marker, &vmd->vmd_clock[0], plinks.q); 1302 vm_pageout_end_scan(&ss); 1303 vm_pagequeue_unlock(pq); 1304 } 1305 1306 static int 1307 vm_pageout_reinsert_inactive_page(struct scan_state *ss, vm_page_t m) 1308 { 1309 struct vm_domain *vmd; 1310 1311 if (m->queue != PQ_INACTIVE || (m->aflags & PGA_ENQUEUED) != 0) 1312 return (0); 1313 vm_page_aflag_set(m, PGA_ENQUEUED); 1314 if ((m->aflags & PGA_REQUEUE_HEAD) != 0) { 1315 vmd = vm_pagequeue_domain(m); 1316 TAILQ_INSERT_BEFORE(&vmd->vmd_inacthead, m, plinks.q); 1317 vm_page_aflag_clear(m, PGA_REQUEUE | PGA_REQUEUE_HEAD); 1318 } else if ((m->aflags & PGA_REQUEUE) != 0) { 1319 TAILQ_INSERT_TAIL(&ss->pq->pq_pl, m, plinks.q); 1320 vm_page_aflag_clear(m, PGA_REQUEUE | PGA_REQUEUE_HEAD); 1321 } else 1322 TAILQ_INSERT_BEFORE(ss->marker, m, plinks.q); 1323 return (1); 1324 } 1325 1326 /* 1327 * Re-add stuck pages to the inactive queue. We will examine them again 1328 * during the next scan. If the queue state of a page has changed since 1329 * it was physically removed from the page queue in 1330 * vm_pageout_collect_batch(), don't do anything with that page. 1331 */ 1332 static void 1333 vm_pageout_reinsert_inactive(struct scan_state *ss, struct vm_batchqueue *bq, 1334 vm_page_t m) 1335 { 1336 struct vm_pagequeue *pq; 1337 int delta; 1338 1339 delta = 0; 1340 pq = ss->pq; 1341 1342 if (m != NULL) { 1343 if (vm_batchqueue_insert(bq, m)) 1344 return; 1345 vm_pagequeue_lock(pq); 1346 delta += vm_pageout_reinsert_inactive_page(ss, m); 1347 } else 1348 vm_pagequeue_lock(pq); 1349 while ((m = vm_batchqueue_pop(bq)) != NULL) 1350 delta += vm_pageout_reinsert_inactive_page(ss, m); 1351 vm_pagequeue_cnt_add(pq, delta); 1352 vm_pagequeue_unlock(pq); 1353 vm_batchqueue_init(bq); 1354 } 1355 1356 /* 1357 * Attempt to reclaim the requested number of pages from the inactive queue. 1358 * Returns true if the shortage was addressed. 1359 */ 1360 static int 1361 vm_pageout_scan_inactive(struct vm_domain *vmd, int shortage, 1362 int *addl_shortage) 1363 { 1364 struct scan_state ss; 1365 struct vm_batchqueue rq; 1366 struct mtx *mtx; 1367 vm_page_t m, marker; 1368 struct vm_pagequeue *pq; 1369 vm_object_t object; 1370 int act_delta, addl_page_shortage, deficit, page_shortage; 1371 int starting_page_shortage; 1372 bool obj_locked; 1373 1374 /* 1375 * The addl_page_shortage is an estimate of the number of temporarily 1376 * stuck pages in the inactive queue. In other words, the 1377 * number of pages from the inactive count that should be 1378 * discounted in setting the target for the active queue scan. 1379 */ 1380 addl_page_shortage = 0; 1381 1382 /* 1383 * vmd_pageout_deficit counts the number of pages requested in 1384 * allocations that failed because of a free page shortage. We assume 1385 * that the allocations will be reattempted and thus include the deficit 1386 * in our scan target. 1387 */ 1388 deficit = atomic_readandclear_int(&vmd->vmd_pageout_deficit); 1389 starting_page_shortage = page_shortage = shortage + deficit; 1390 1391 mtx = NULL; 1392 obj_locked = false; 1393 object = NULL; 1394 vm_batchqueue_init(&rq); 1395 1396 /* 1397 * Start scanning the inactive queue for pages that we can free. The 1398 * scan will stop when we reach the target or we have scanned the 1399 * entire queue. (Note that m->act_count is not used to make 1400 * decisions for the inactive queue, only for the active queue.) 1401 */ 1402 marker = &vmd->vmd_markers[PQ_INACTIVE]; 1403 pq = &vmd->vmd_pagequeues[PQ_INACTIVE]; 1404 vm_pagequeue_lock(pq); 1405 vm_pageout_init_scan(&ss, pq, marker, NULL, pq->pq_cnt); 1406 while (page_shortage > 0 && (m = vm_pageout_next(&ss, true)) != NULL) { 1407 KASSERT((m->flags & PG_MARKER) == 0, 1408 ("marker page %p was dequeued", m)); 1409 1410 vm_page_change_lock(m, &mtx); 1411 1412 recheck: 1413 /* 1414 * The page may have been disassociated from the queue 1415 * while locks were dropped. 1416 */ 1417 if (vm_page_queue(m) != PQ_INACTIVE) { 1418 addl_page_shortage++; 1419 continue; 1420 } 1421 1422 /* 1423 * The page was re-enqueued after the page queue lock was 1424 * dropped, or a requeue was requested. This page gets a second 1425 * chance. 1426 */ 1427 if ((m->aflags & (PGA_ENQUEUED | PGA_REQUEUE | 1428 PGA_REQUEUE_HEAD)) != 0) 1429 goto reinsert; 1430 1431 /* 1432 * Held pages are essentially stuck in the queue. So, 1433 * they ought to be discounted from the inactive count. 1434 * See the description of addl_page_shortage above. 1435 * 1436 * Wired pages may not be freed. Complete their removal 1437 * from the queue now to avoid needless revisits during 1438 * future scans. 1439 */ 1440 if (m->hold_count != 0) { 1441 addl_page_shortage++; 1442 goto reinsert; 1443 } 1444 if (m->wire_count != 0) { 1445 vm_page_dequeue_deferred(m); 1446 continue; 1447 } 1448 1449 if (object != m->object) { 1450 if (obj_locked) { 1451 VM_OBJECT_WUNLOCK(object); 1452 obj_locked = false; 1453 } 1454 object = m->object; 1455 } 1456 if (!obj_locked) { 1457 if (!VM_OBJECT_TRYWLOCK(object)) { 1458 mtx_unlock(mtx); 1459 /* Depends on type-stability. */ 1460 VM_OBJECT_WLOCK(object); 1461 obj_locked = true; 1462 mtx_lock(mtx); 1463 goto recheck; 1464 } else 1465 obj_locked = true; 1466 } 1467 1468 if (vm_page_busied(m)) { 1469 /* 1470 * Don't mess with busy pages. Leave them at 1471 * the front of the queue. Most likely, they 1472 * are being paged out and will leave the 1473 * queue shortly after the scan finishes. So, 1474 * they ought to be discounted from the 1475 * inactive count. 1476 */ 1477 addl_page_shortage++; 1478 goto reinsert; 1479 } 1480 1481 /* 1482 * Invalid pages can be easily freed. They cannot be 1483 * mapped, vm_page_free() asserts this. 1484 */ 1485 if (m->valid == 0) 1486 goto free_page; 1487 1488 /* 1489 * If the page has been referenced and the object is not dead, 1490 * reactivate or requeue the page depending on whether the 1491 * object is mapped. 1492 * 1493 * Test PGA_REFERENCED after calling pmap_ts_referenced() so 1494 * that a reference from a concurrently destroyed mapping is 1495 * observed here and now. 1496 */ 1497 if (object->ref_count != 0) 1498 act_delta = pmap_ts_referenced(m); 1499 else { 1500 KASSERT(!pmap_page_is_mapped(m), 1501 ("page %p is mapped", m)); 1502 act_delta = 0; 1503 } 1504 if ((m->aflags & PGA_REFERENCED) != 0) { 1505 vm_page_aflag_clear(m, PGA_REFERENCED); 1506 act_delta++; 1507 } 1508 if (act_delta != 0) { 1509 if (object->ref_count != 0) { 1510 VM_CNT_INC(v_reactivated); 1511 vm_page_activate(m); 1512 1513 /* 1514 * Increase the activation count if the page 1515 * was referenced while in the inactive queue. 1516 * This makes it less likely that the page will 1517 * be returned prematurely to the inactive 1518 * queue. 1519 */ 1520 m->act_count += act_delta + ACT_ADVANCE; 1521 continue; 1522 } else if ((object->flags & OBJ_DEAD) == 0) { 1523 vm_page_aflag_set(m, PGA_REQUEUE); 1524 goto reinsert; 1525 } 1526 } 1527 1528 /* 1529 * If the page appears to be clean at the machine-independent 1530 * layer, then remove all of its mappings from the pmap in 1531 * anticipation of freeing it. If, however, any of the page's 1532 * mappings allow write access, then the page may still be 1533 * modified until the last of those mappings are removed. 1534 */ 1535 if (object->ref_count != 0) { 1536 vm_page_test_dirty(m); 1537 if (m->dirty == 0) 1538 pmap_remove_all(m); 1539 } 1540 1541 /* 1542 * Clean pages can be freed, but dirty pages must be sent back 1543 * to the laundry, unless they belong to a dead object. 1544 * Requeueing dirty pages from dead objects is pointless, as 1545 * they are being paged out and freed by the thread that 1546 * destroyed the object. 1547 */ 1548 if (m->dirty == 0) { 1549 free_page: 1550 /* 1551 * Because we dequeued the page and have already 1552 * checked for concurrent dequeue and enqueue 1553 * requests, we can safely disassociate the page 1554 * from the inactive queue. 1555 */ 1556 KASSERT((m->aflags & PGA_QUEUE_STATE_MASK) == 0, 1557 ("page %p has queue state", m)); 1558 m->queue = PQ_NONE; 1559 vm_page_free(m); 1560 page_shortage--; 1561 } else if ((object->flags & OBJ_DEAD) == 0) 1562 vm_page_launder(m); 1563 continue; 1564 reinsert: 1565 vm_pageout_reinsert_inactive(&ss, &rq, m); 1566 } 1567 if (mtx != NULL) { 1568 mtx_unlock(mtx); 1569 mtx = NULL; 1570 } 1571 if (obj_locked) { 1572 VM_OBJECT_WUNLOCK(object); 1573 obj_locked = false; 1574 } 1575 vm_pageout_reinsert_inactive(&ss, &rq, NULL); 1576 vm_pageout_reinsert_inactive(&ss, &ss.bq, NULL); 1577 vm_pagequeue_lock(pq); 1578 vm_pageout_end_scan(&ss); 1579 vm_pagequeue_unlock(pq); 1580 1581 VM_CNT_ADD(v_dfree, starting_page_shortage - page_shortage); 1582 1583 /* 1584 * Wake up the laundry thread so that it can perform any needed 1585 * laundering. If we didn't meet our target, we're in shortfall and 1586 * need to launder more aggressively. If PQ_LAUNDRY is empty and no 1587 * swap devices are configured, the laundry thread has no work to do, so 1588 * don't bother waking it up. 1589 * 1590 * The laundry thread uses the number of inactive queue scans elapsed 1591 * since the last laundering to determine whether to launder again, so 1592 * keep count. 1593 */ 1594 if (starting_page_shortage > 0) { 1595 pq = &vmd->vmd_pagequeues[PQ_LAUNDRY]; 1596 vm_pagequeue_lock(pq); 1597 if (vmd->vmd_laundry_request == VM_LAUNDRY_IDLE && 1598 (pq->pq_cnt > 0 || atomic_load_acq_int(&swapdev_enabled))) { 1599 if (page_shortage > 0) { 1600 vmd->vmd_laundry_request = VM_LAUNDRY_SHORTFALL; 1601 VM_CNT_INC(v_pdshortfalls); 1602 } else if (vmd->vmd_laundry_request != 1603 VM_LAUNDRY_SHORTFALL) 1604 vmd->vmd_laundry_request = 1605 VM_LAUNDRY_BACKGROUND; 1606 wakeup(&vmd->vmd_laundry_request); 1607 } 1608 vmd->vmd_clean_pages_freed += 1609 starting_page_shortage - page_shortage; 1610 vm_pagequeue_unlock(pq); 1611 } 1612 1613 /* 1614 * Wakeup the swapout daemon if we didn't free the targeted number of 1615 * pages. 1616 */ 1617 if (page_shortage > 0) 1618 vm_swapout_run(); 1619 1620 /* 1621 * If the inactive queue scan fails repeatedly to meet its 1622 * target, kill the largest process. 1623 */ 1624 vm_pageout_mightbe_oom(vmd, page_shortage, starting_page_shortage); 1625 1626 /* 1627 * Reclaim pages by swapping out idle processes, if configured to do so. 1628 */ 1629 vm_swapout_run_idle(); 1630 1631 /* 1632 * See the description of addl_page_shortage above. 1633 */ 1634 *addl_shortage = addl_page_shortage + deficit; 1635 1636 return (page_shortage <= 0); 1637 } 1638 1639 static int vm_pageout_oom_vote; 1640 1641 /* 1642 * The pagedaemon threads randlomly select one to perform the 1643 * OOM. Trying to kill processes before all pagedaemons 1644 * failed to reach free target is premature. 1645 */ 1646 static void 1647 vm_pageout_mightbe_oom(struct vm_domain *vmd, int page_shortage, 1648 int starting_page_shortage) 1649 { 1650 int old_vote; 1651 1652 if (starting_page_shortage <= 0 || starting_page_shortage != 1653 page_shortage) 1654 vmd->vmd_oom_seq = 0; 1655 else 1656 vmd->vmd_oom_seq++; 1657 if (vmd->vmd_oom_seq < vm_pageout_oom_seq) { 1658 if (vmd->vmd_oom) { 1659 vmd->vmd_oom = FALSE; 1660 atomic_subtract_int(&vm_pageout_oom_vote, 1); 1661 } 1662 return; 1663 } 1664 1665 /* 1666 * Do not follow the call sequence until OOM condition is 1667 * cleared. 1668 */ 1669 vmd->vmd_oom_seq = 0; 1670 1671 if (vmd->vmd_oom) 1672 return; 1673 1674 vmd->vmd_oom = TRUE; 1675 old_vote = atomic_fetchadd_int(&vm_pageout_oom_vote, 1); 1676 if (old_vote != vm_ndomains - 1) 1677 return; 1678 1679 /* 1680 * The current pagedaemon thread is the last in the quorum to 1681 * start OOM. Initiate the selection and signaling of the 1682 * victim. 1683 */ 1684 vm_pageout_oom(VM_OOM_MEM); 1685 1686 /* 1687 * After one round of OOM terror, recall our vote. On the 1688 * next pass, current pagedaemon would vote again if the low 1689 * memory condition is still there, due to vmd_oom being 1690 * false. 1691 */ 1692 vmd->vmd_oom = FALSE; 1693 atomic_subtract_int(&vm_pageout_oom_vote, 1); 1694 } 1695 1696 /* 1697 * The OOM killer is the page daemon's action of last resort when 1698 * memory allocation requests have been stalled for a prolonged period 1699 * of time because it cannot reclaim memory. This function computes 1700 * the approximate number of physical pages that could be reclaimed if 1701 * the specified address space is destroyed. 1702 * 1703 * Private, anonymous memory owned by the address space is the 1704 * principal resource that we expect to recover after an OOM kill. 1705 * Since the physical pages mapped by the address space's COW entries 1706 * are typically shared pages, they are unlikely to be released and so 1707 * they are not counted. 1708 * 1709 * To get to the point where the page daemon runs the OOM killer, its 1710 * efforts to write-back vnode-backed pages may have stalled. This 1711 * could be caused by a memory allocation deadlock in the write path 1712 * that might be resolved by an OOM kill. Therefore, physical pages 1713 * belonging to vnode-backed objects are counted, because they might 1714 * be freed without being written out first if the address space holds 1715 * the last reference to an unlinked vnode. 1716 * 1717 * Similarly, physical pages belonging to OBJT_PHYS objects are 1718 * counted because the address space might hold the last reference to 1719 * the object. 1720 */ 1721 static long 1722 vm_pageout_oom_pagecount(struct vmspace *vmspace) 1723 { 1724 vm_map_t map; 1725 vm_map_entry_t entry; 1726 vm_object_t obj; 1727 long res; 1728 1729 map = &vmspace->vm_map; 1730 KASSERT(!map->system_map, ("system map")); 1731 sx_assert(&map->lock, SA_LOCKED); 1732 res = 0; 1733 for (entry = map->header.next; entry != &map->header; 1734 entry = entry->next) { 1735 if ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 1736 continue; 1737 obj = entry->object.vm_object; 1738 if (obj == NULL) 1739 continue; 1740 if ((entry->eflags & MAP_ENTRY_NEEDS_COPY) != 0 && 1741 obj->ref_count != 1) 1742 continue; 1743 switch (obj->type) { 1744 case OBJT_DEFAULT: 1745 case OBJT_SWAP: 1746 case OBJT_PHYS: 1747 case OBJT_VNODE: 1748 res += obj->resident_page_count; 1749 break; 1750 } 1751 } 1752 return (res); 1753 } 1754 1755 void 1756 vm_pageout_oom(int shortage) 1757 { 1758 struct proc *p, *bigproc; 1759 vm_offset_t size, bigsize; 1760 struct thread *td; 1761 struct vmspace *vm; 1762 bool breakout; 1763 1764 /* 1765 * We keep the process bigproc locked once we find it to keep anyone 1766 * from messing with it; however, there is a possibility of 1767 * deadlock if process B is bigproc and one of its child processes 1768 * attempts to propagate a signal to B while we are waiting for A's 1769 * lock while walking this list. To avoid this, we don't block on 1770 * the process lock but just skip a process if it is already locked. 1771 */ 1772 bigproc = NULL; 1773 bigsize = 0; 1774 sx_slock(&allproc_lock); 1775 FOREACH_PROC_IN_SYSTEM(p) { 1776 PROC_LOCK(p); 1777 1778 /* 1779 * If this is a system, protected or killed process, skip it. 1780 */ 1781 if (p->p_state != PRS_NORMAL || (p->p_flag & (P_INEXEC | 1782 P_PROTECTED | P_SYSTEM | P_WEXIT)) != 0 || 1783 p->p_pid == 1 || P_KILLED(p) || 1784 (p->p_pid < 48 && swap_pager_avail != 0)) { 1785 PROC_UNLOCK(p); 1786 continue; 1787 } 1788 /* 1789 * If the process is in a non-running type state, 1790 * don't touch it. Check all the threads individually. 1791 */ 1792 breakout = false; 1793 FOREACH_THREAD_IN_PROC(p, td) { 1794 thread_lock(td); 1795 if (!TD_ON_RUNQ(td) && 1796 !TD_IS_RUNNING(td) && 1797 !TD_IS_SLEEPING(td) && 1798 !TD_IS_SUSPENDED(td) && 1799 !TD_IS_SWAPPED(td)) { 1800 thread_unlock(td); 1801 breakout = true; 1802 break; 1803 } 1804 thread_unlock(td); 1805 } 1806 if (breakout) { 1807 PROC_UNLOCK(p); 1808 continue; 1809 } 1810 /* 1811 * get the process size 1812 */ 1813 vm = vmspace_acquire_ref(p); 1814 if (vm == NULL) { 1815 PROC_UNLOCK(p); 1816 continue; 1817 } 1818 _PHOLD_LITE(p); 1819 PROC_UNLOCK(p); 1820 sx_sunlock(&allproc_lock); 1821 if (!vm_map_trylock_read(&vm->vm_map)) { 1822 vmspace_free(vm); 1823 sx_slock(&allproc_lock); 1824 PRELE(p); 1825 continue; 1826 } 1827 size = vmspace_swap_count(vm); 1828 if (shortage == VM_OOM_MEM) 1829 size += vm_pageout_oom_pagecount(vm); 1830 vm_map_unlock_read(&vm->vm_map); 1831 vmspace_free(vm); 1832 sx_slock(&allproc_lock); 1833 1834 /* 1835 * If this process is bigger than the biggest one, 1836 * remember it. 1837 */ 1838 if (size > bigsize) { 1839 if (bigproc != NULL) 1840 PRELE(bigproc); 1841 bigproc = p; 1842 bigsize = size; 1843 } else { 1844 PRELE(p); 1845 } 1846 } 1847 sx_sunlock(&allproc_lock); 1848 if (bigproc != NULL) { 1849 if (vm_panic_on_oom != 0) 1850 panic("out of swap space"); 1851 PROC_LOCK(bigproc); 1852 killproc(bigproc, "out of swap space"); 1853 sched_nice(bigproc, PRIO_MIN); 1854 _PRELE(bigproc); 1855 PROC_UNLOCK(bigproc); 1856 } 1857 } 1858 1859 static void 1860 vm_pageout_lowmem(struct vm_domain *vmd) 1861 { 1862 1863 if (vmd == VM_DOMAIN(0) && 1864 time_uptime - lowmem_uptime >= lowmem_period) { 1865 /* 1866 * Decrease registered cache sizes. 1867 */ 1868 SDT_PROBE0(vm, , , vm__lowmem_scan); 1869 EVENTHANDLER_INVOKE(vm_lowmem, VM_LOW_PAGES); 1870 1871 /* 1872 * We do this explicitly after the caches have been 1873 * drained above. 1874 */ 1875 uma_reclaim(); 1876 lowmem_uptime = time_uptime; 1877 } 1878 } 1879 1880 static void 1881 vm_pageout_worker(void *arg) 1882 { 1883 struct vm_domain *vmd; 1884 int addl_shortage, domain, shortage; 1885 bool target_met; 1886 1887 domain = (uintptr_t)arg; 1888 vmd = VM_DOMAIN(domain); 1889 shortage = 0; 1890 target_met = true; 1891 1892 /* 1893 * XXXKIB It could be useful to bind pageout daemon threads to 1894 * the cores belonging to the domain, from which vm_page_array 1895 * is allocated. 1896 */ 1897 1898 KASSERT(vmd->vmd_segs != 0, ("domain without segments")); 1899 vmd->vmd_last_active_scan = ticks; 1900 1901 /* 1902 * The pageout daemon worker is never done, so loop forever. 1903 */ 1904 while (TRUE) { 1905 vm_domain_pageout_lock(vmd); 1906 1907 /* 1908 * We need to clear wanted before we check the limits. This 1909 * prevents races with wakers who will check wanted after they 1910 * reach the limit. 1911 */ 1912 atomic_store_int(&vmd->vmd_pageout_wanted, 0); 1913 1914 /* 1915 * Might the page daemon need to run again? 1916 */ 1917 if (vm_paging_needed(vmd, vmd->vmd_free_count)) { 1918 /* 1919 * Yes. If the scan failed to produce enough free 1920 * pages, sleep uninterruptibly for some time in the 1921 * hope that the laundry thread will clean some pages. 1922 */ 1923 vm_domain_pageout_unlock(vmd); 1924 if (!target_met) 1925 pause("pwait", hz / VM_INACT_SCAN_RATE); 1926 } else { 1927 /* 1928 * No, sleep until the next wakeup or until pages 1929 * need to have their reference stats updated. 1930 */ 1931 if (mtx_sleep(&vmd->vmd_pageout_wanted, 1932 vm_domain_pageout_lockptr(vmd), PDROP | PVM, 1933 "psleep", hz / VM_INACT_SCAN_RATE) == 0) 1934 VM_CNT_INC(v_pdwakeups); 1935 } 1936 1937 /* Prevent spurious wakeups by ensuring that wanted is set. */ 1938 atomic_store_int(&vmd->vmd_pageout_wanted, 1); 1939 1940 /* 1941 * Use the controller to calculate how many pages to free in 1942 * this interval, and scan the inactive queue. 1943 */ 1944 shortage = pidctrl_daemon(&vmd->vmd_pid, vmd->vmd_free_count); 1945 if (shortage > 0) { 1946 vm_pageout_lowmem(vmd); 1947 target_met = vm_pageout_scan_inactive(vmd, shortage, 1948 &addl_shortage); 1949 } else 1950 addl_shortage = 0; 1951 1952 /* 1953 * Scan the active queue. A positive value for shortage 1954 * indicates that we must aggressively deactivate pages to avoid 1955 * a shortfall. 1956 */ 1957 shortage = vm_pageout_active_target(vmd) + addl_shortage; 1958 vm_pageout_scan_active(vmd, shortage); 1959 } 1960 } 1961 1962 /* 1963 * vm_pageout_init initialises basic pageout daemon settings. 1964 */ 1965 static void 1966 vm_pageout_init_domain(int domain) 1967 { 1968 struct vm_domain *vmd; 1969 struct sysctl_oid *oid; 1970 1971 vmd = VM_DOMAIN(domain); 1972 vmd->vmd_interrupt_free_min = 2; 1973 1974 /* 1975 * v_free_reserved needs to include enough for the largest 1976 * swap pager structures plus enough for any pv_entry structs 1977 * when paging. 1978 */ 1979 if (vmd->vmd_page_count > 1024) 1980 vmd->vmd_free_min = 4 + (vmd->vmd_page_count - 1024) / 200; 1981 else 1982 vmd->vmd_free_min = 4; 1983 vmd->vmd_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1984 vmd->vmd_interrupt_free_min; 1985 vmd->vmd_free_reserved = vm_pageout_page_count + 1986 vmd->vmd_pageout_free_min + (vmd->vmd_page_count / 768); 1987 vmd->vmd_free_severe = vmd->vmd_free_min / 2; 1988 vmd->vmd_free_target = 4 * vmd->vmd_free_min + vmd->vmd_free_reserved; 1989 vmd->vmd_free_min += vmd->vmd_free_reserved; 1990 vmd->vmd_free_severe += vmd->vmd_free_reserved; 1991 vmd->vmd_inactive_target = (3 * vmd->vmd_free_target) / 2; 1992 if (vmd->vmd_inactive_target > vmd->vmd_free_count / 3) 1993 vmd->vmd_inactive_target = vmd->vmd_free_count / 3; 1994 1995 /* 1996 * Set the default wakeup threshold to be 10% below the paging 1997 * target. This keeps the steady state out of shortfall. 1998 */ 1999 vmd->vmd_pageout_wakeup_thresh = (vmd->vmd_free_target / 10) * 9; 2000 2001 /* 2002 * Target amount of memory to move out of the laundry queue during a 2003 * background laundering. This is proportional to the amount of system 2004 * memory. 2005 */ 2006 vmd->vmd_background_launder_target = (vmd->vmd_free_target - 2007 vmd->vmd_free_min) / 10; 2008 2009 /* Initialize the pageout daemon pid controller. */ 2010 pidctrl_init(&vmd->vmd_pid, hz / VM_INACT_SCAN_RATE, 2011 vmd->vmd_free_target, PIDCTRL_BOUND, 2012 PIDCTRL_KPD, PIDCTRL_KID, PIDCTRL_KDD); 2013 oid = SYSCTL_ADD_NODE(NULL, SYSCTL_CHILDREN(vmd->vmd_oid), OID_AUTO, 2014 "pidctrl", CTLFLAG_RD, NULL, ""); 2015 pidctrl_init_sysctl(&vmd->vmd_pid, SYSCTL_CHILDREN(oid)); 2016 } 2017 2018 static void 2019 vm_pageout_init(void) 2020 { 2021 u_int freecount; 2022 int i; 2023 2024 /* 2025 * Initialize some paging parameters. 2026 */ 2027 if (vm_cnt.v_page_count < 2000) 2028 vm_pageout_page_count = 8; 2029 2030 freecount = 0; 2031 for (i = 0; i < vm_ndomains; i++) { 2032 struct vm_domain *vmd; 2033 2034 vm_pageout_init_domain(i); 2035 vmd = VM_DOMAIN(i); 2036 vm_cnt.v_free_reserved += vmd->vmd_free_reserved; 2037 vm_cnt.v_free_target += vmd->vmd_free_target; 2038 vm_cnt.v_free_min += vmd->vmd_free_min; 2039 vm_cnt.v_inactive_target += vmd->vmd_inactive_target; 2040 vm_cnt.v_pageout_free_min += vmd->vmd_pageout_free_min; 2041 vm_cnt.v_interrupt_free_min += vmd->vmd_interrupt_free_min; 2042 vm_cnt.v_free_severe += vmd->vmd_free_severe; 2043 freecount += vmd->vmd_free_count; 2044 } 2045 2046 /* 2047 * Set interval in seconds for active scan. We want to visit each 2048 * page at least once every ten minutes. This is to prevent worst 2049 * case paging behaviors with stale active LRU. 2050 */ 2051 if (vm_pageout_update_period == 0) 2052 vm_pageout_update_period = 600; 2053 2054 if (vm_page_max_wired == 0) 2055 vm_page_max_wired = freecount / 3; 2056 } 2057 2058 /* 2059 * vm_pageout is the high level pageout daemon. 2060 */ 2061 static void 2062 vm_pageout(void) 2063 { 2064 int error; 2065 int i; 2066 2067 swap_pager_swap_init(); 2068 snprintf(curthread->td_name, sizeof(curthread->td_name), "dom0"); 2069 error = kthread_add(vm_pageout_laundry_worker, NULL, curproc, NULL, 2070 0, 0, "laundry: dom0"); 2071 if (error != 0) 2072 panic("starting laundry for domain 0, error %d", error); 2073 for (i = 1; i < vm_ndomains; i++) { 2074 error = kthread_add(vm_pageout_worker, (void *)(uintptr_t)i, 2075 curproc, NULL, 0, 0, "dom%d", i); 2076 if (error != 0) { 2077 panic("starting pageout for domain %d, error %d\n", 2078 i, error); 2079 } 2080 error = kthread_add(vm_pageout_laundry_worker, 2081 (void *)(uintptr_t)i, curproc, NULL, 0, 0, 2082 "laundry: dom%d", i); 2083 if (error != 0) 2084 panic("starting laundry for domain %d, error %d", 2085 i, error); 2086 } 2087 error = kthread_add(uma_reclaim_worker, NULL, curproc, NULL, 2088 0, 0, "uma"); 2089 if (error != 0) 2090 panic("starting uma_reclaim helper, error %d\n", error); 2091 vm_pageout_worker((void *)(uintptr_t)0); 2092 } 2093 2094 /* 2095 * Perform an advisory wakeup of the page daemon. 2096 */ 2097 void 2098 pagedaemon_wakeup(int domain) 2099 { 2100 struct vm_domain *vmd; 2101 2102 vmd = VM_DOMAIN(domain); 2103 vm_domain_pageout_assert_unlocked(vmd); 2104 if (curproc == pageproc) 2105 return; 2106 2107 if (atomic_fetchadd_int(&vmd->vmd_pageout_wanted, 1) == 0) { 2108 vm_domain_pageout_lock(vmd); 2109 atomic_store_int(&vmd->vmd_pageout_wanted, 1); 2110 wakeup(&vmd->vmd_pageout_wanted); 2111 vm_domain_pageout_unlock(vmd); 2112 } 2113 } 2114