1 /*- 2 * Copyright (c) 1991 Regents of the University of California. 3 * All rights reserved. 4 * Copyright (c) 1994 John S. Dyson 5 * All rights reserved. 6 * Copyright (c) 1994 David Greenman 7 * All rights reserved. 8 * Copyright (c) 2005 Yahoo! Technologies Norway AS 9 * All rights reserved. 10 * 11 * This code is derived from software contributed to Berkeley by 12 * The Mach Operating System project at Carnegie-Mellon University. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the University of 25 * California, Berkeley and its contributors. 26 * 4. Neither the name of the University nor the names of its contributors 27 * may be used to endorse or promote products derived from this software 28 * without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 * 42 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 43 * 44 * 45 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 46 * All rights reserved. 47 * 48 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 49 * 50 * Permission to use, copy, modify and distribute this software and 51 * its documentation is hereby granted, provided that both the copyright 52 * notice and this permission notice appear in all copies of the 53 * software, derivative works or modified versions, and any portions 54 * thereof, and that both notices appear in supporting documentation. 55 * 56 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 57 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 58 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 59 * 60 * Carnegie Mellon requests users of this software to return to 61 * 62 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 63 * School of Computer Science 64 * Carnegie Mellon University 65 * Pittsburgh PA 15213-3890 66 * 67 * any improvements or extensions that they make and grant Carnegie the 68 * rights to redistribute these changes. 69 */ 70 71 /* 72 * The proverbial page-out daemon. 73 */ 74 75 #include <sys/cdefs.h> 76 __FBSDID("$FreeBSD$"); 77 78 #include "opt_vm.h" 79 #include <sys/param.h> 80 #include <sys/systm.h> 81 #include <sys/kernel.h> 82 #include <sys/eventhandler.h> 83 #include <sys/lock.h> 84 #include <sys/mutex.h> 85 #include <sys/proc.h> 86 #include <sys/kthread.h> 87 #include <sys/ktr.h> 88 #include <sys/mount.h> 89 #include <sys/racct.h> 90 #include <sys/resourcevar.h> 91 #include <sys/sched.h> 92 #include <sys/signalvar.h> 93 #include <sys/vnode.h> 94 #include <sys/vmmeter.h> 95 #include <sys/sx.h> 96 #include <sys/sysctl.h> 97 98 #include <vm/vm.h> 99 #include <vm/vm_param.h> 100 #include <vm/vm_object.h> 101 #include <vm/vm_page.h> 102 #include <vm/vm_map.h> 103 #include <vm/vm_pageout.h> 104 #include <vm/vm_pager.h> 105 #include <vm/swap_pager.h> 106 #include <vm/vm_extern.h> 107 #include <vm/uma.h> 108 109 /* 110 * System initialization 111 */ 112 113 /* the kernel process "vm_pageout"*/ 114 static void vm_pageout(void); 115 static int vm_pageout_clean(vm_page_t); 116 static void vm_pageout_scan(int pass); 117 118 struct proc *pageproc; 119 120 static struct kproc_desc page_kp = { 121 "pagedaemon", 122 vm_pageout, 123 &pageproc 124 }; 125 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, 126 &page_kp); 127 128 #if !defined(NO_SWAPPING) 129 /* the kernel process "vm_daemon"*/ 130 static void vm_daemon(void); 131 static struct proc *vmproc; 132 133 static struct kproc_desc vm_kp = { 134 "vmdaemon", 135 vm_daemon, 136 &vmproc 137 }; 138 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp); 139 #endif 140 141 142 int vm_pages_needed; /* Event on which pageout daemon sleeps */ 143 int vm_pageout_deficit; /* Estimated number of pages deficit */ 144 int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 145 146 #if !defined(NO_SWAPPING) 147 static int vm_pageout_req_swapout; /* XXX */ 148 static int vm_daemon_needed; 149 static struct mtx vm_daemon_mtx; 150 /* Allow for use by vm_pageout before vm_daemon is initialized. */ 151 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); 152 #endif 153 static int vm_max_launder = 32; 154 static int vm_pageout_stats_max; 155 static int vm_pageout_stats; 156 static int vm_pageout_stats_interval; 157 static int vm_pageout_full_stats; 158 static int vm_pageout_full_stats_interval; 159 static int vm_pageout_algorithm; 160 static int defer_swap_pageouts; 161 static int disable_swap_pageouts; 162 163 #if defined(NO_SWAPPING) 164 static int vm_swap_enabled = 0; 165 static int vm_swap_idle_enabled = 0; 166 #else 167 static int vm_swap_enabled = 1; 168 static int vm_swap_idle_enabled = 0; 169 #endif 170 171 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 172 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 173 174 SYSCTL_INT(_vm, OID_AUTO, max_launder, 175 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 176 177 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 178 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 179 180 SYSCTL_INT(_vm, OID_AUTO, pageout_stats, 181 CTLFLAG_RD, &vm_pageout_stats, 0, "Number of partial stats scans"); 182 183 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 184 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 185 186 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats, 187 CTLFLAG_RD, &vm_pageout_full_stats, 0, "Number of full stats scans"); 188 189 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 190 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 191 192 #if defined(NO_SWAPPING) 193 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 194 CTLFLAG_RD, &vm_swap_enabled, 0, "Enable entire process swapout"); 195 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 196 CTLFLAG_RD, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 197 #else 198 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 199 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 200 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 201 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 202 #endif 203 204 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 205 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 206 207 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 208 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 209 210 static int pageout_lock_miss; 211 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 212 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 213 214 #define VM_PAGEOUT_PAGE_COUNT 16 215 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 216 217 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 218 SYSCTL_INT(_vm, OID_AUTO, max_wired, 219 CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count"); 220 221 static boolean_t vm_pageout_fallback_object_lock(vm_page_t, vm_page_t *); 222 static boolean_t vm_pageout_launder(int, int, vm_paddr_t, vm_paddr_t); 223 #if !defined(NO_SWAPPING) 224 static void vm_pageout_map_deactivate_pages(vm_map_t, long); 225 static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long); 226 static void vm_req_vmdaemon(int req); 227 #endif 228 static boolean_t vm_pageout_page_lock(vm_page_t, vm_page_t *); 229 static void vm_pageout_page_stats(void); 230 231 /* 232 * Initialize a dummy page for marking the caller's place in the specified 233 * paging queue. In principle, this function only needs to set the flag 234 * PG_MARKER. Nonetheless, it sets the flag VPO_BUSY and initializes the hold 235 * count to one as safety precautions. 236 */ 237 static void 238 vm_pageout_init_marker(vm_page_t marker, u_short queue) 239 { 240 241 bzero(marker, sizeof(*marker)); 242 marker->flags = PG_MARKER; 243 marker->oflags = VPO_BUSY; 244 marker->queue = queue; 245 marker->hold_count = 1; 246 } 247 248 /* 249 * vm_pageout_fallback_object_lock: 250 * 251 * Lock vm object currently associated with `m'. VM_OBJECT_TRYLOCK is 252 * known to have failed and page queue must be either PQ_ACTIVE or 253 * PQ_INACTIVE. To avoid lock order violation, unlock the page queues 254 * while locking the vm object. Use marker page to detect page queue 255 * changes and maintain notion of next page on page queue. Return 256 * TRUE if no changes were detected, FALSE otherwise. vm object is 257 * locked on return. 258 * 259 * This function depends on both the lock portion of struct vm_object 260 * and normal struct vm_page being type stable. 261 */ 262 static boolean_t 263 vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next) 264 { 265 struct vm_page marker; 266 struct vm_pagequeue *pq; 267 boolean_t unchanged; 268 u_short queue; 269 vm_object_t object; 270 271 queue = m->queue; 272 vm_pageout_init_marker(&marker, queue); 273 pq = &vm_pagequeues[queue]; 274 object = m->object; 275 276 TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, pageq); 277 vm_pagequeue_unlock(pq); 278 vm_page_unlock(m); 279 VM_OBJECT_LOCK(object); 280 vm_page_lock(m); 281 vm_pagequeue_lock(pq); 282 283 /* Page queue might have changed. */ 284 *next = TAILQ_NEXT(&marker, pageq); 285 unchanged = (m->queue == queue && 286 m->object == object && 287 &marker == TAILQ_NEXT(m, pageq)); 288 TAILQ_REMOVE(&pq->pq_pl, &marker, pageq); 289 return (unchanged); 290 } 291 292 /* 293 * Lock the page while holding the page queue lock. Use marker page 294 * to detect page queue changes and maintain notion of next page on 295 * page queue. Return TRUE if no changes were detected, FALSE 296 * otherwise. The page is locked on return. The page queue lock might 297 * be dropped and reacquired. 298 * 299 * This function depends on normal struct vm_page being type stable. 300 */ 301 static boolean_t 302 vm_pageout_page_lock(vm_page_t m, vm_page_t *next) 303 { 304 struct vm_page marker; 305 struct vm_pagequeue *pq; 306 boolean_t unchanged; 307 u_short queue; 308 309 vm_page_lock_assert(m, MA_NOTOWNED); 310 if (vm_page_trylock(m)) 311 return (TRUE); 312 313 queue = m->queue; 314 vm_pageout_init_marker(&marker, queue); 315 pq = &vm_pagequeues[queue]; 316 317 TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, pageq); 318 vm_pagequeue_unlock(pq); 319 vm_page_lock(m); 320 vm_pagequeue_lock(pq); 321 322 /* Page queue might have changed. */ 323 *next = TAILQ_NEXT(&marker, pageq); 324 unchanged = (m->queue == queue && &marker == TAILQ_NEXT(m, pageq)); 325 TAILQ_REMOVE(&pq->pq_pl, &marker, pageq); 326 return (unchanged); 327 } 328 329 /* 330 * vm_pageout_clean: 331 * 332 * Clean the page and remove it from the laundry. 333 * 334 * We set the busy bit to cause potential page faults on this page to 335 * block. Note the careful timing, however, the busy bit isn't set till 336 * late and we cannot do anything that will mess with the page. 337 */ 338 static int 339 vm_pageout_clean(vm_page_t m) 340 { 341 vm_object_t object; 342 vm_page_t mc[2*vm_pageout_page_count], pb, ps; 343 int pageout_count; 344 int ib, is, page_base; 345 vm_pindex_t pindex = m->pindex; 346 347 vm_page_lock_assert(m, MA_OWNED); 348 object = m->object; 349 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 350 351 /* 352 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 353 * with the new swapper, but we could have serious problems paging 354 * out other object types if there is insufficient memory. 355 * 356 * Unfortunately, checking free memory here is far too late, so the 357 * check has been moved up a procedural level. 358 */ 359 360 /* 361 * Can't clean the page if it's busy or held. 362 */ 363 KASSERT(m->busy == 0 && (m->oflags & VPO_BUSY) == 0, 364 ("vm_pageout_clean: page %p is busy", m)); 365 KASSERT(m->hold_count == 0, ("vm_pageout_clean: page %p is held", m)); 366 vm_page_unlock(m); 367 368 mc[vm_pageout_page_count] = pb = ps = m; 369 pageout_count = 1; 370 page_base = vm_pageout_page_count; 371 ib = 1; 372 is = 1; 373 374 /* 375 * Scan object for clusterable pages. 376 * 377 * We can cluster ONLY if: ->> the page is NOT 378 * clean, wired, busy, held, or mapped into a 379 * buffer, and one of the following: 380 * 1) The page is inactive, or a seldom used 381 * active page. 382 * -or- 383 * 2) we force the issue. 384 * 385 * During heavy mmap/modification loads the pageout 386 * daemon can really fragment the underlying file 387 * due to flushing pages out of order and not trying 388 * align the clusters (which leave sporatic out-of-order 389 * holes). To solve this problem we do the reverse scan 390 * first and attempt to align our cluster, then do a 391 * forward scan if room remains. 392 */ 393 more: 394 while (ib && pageout_count < vm_pageout_page_count) { 395 vm_page_t p; 396 397 if (ib > pindex) { 398 ib = 0; 399 break; 400 } 401 402 if ((p = vm_page_prev(pb)) == NULL || 403 (p->oflags & VPO_BUSY) != 0 || p->busy != 0) { 404 ib = 0; 405 break; 406 } 407 vm_page_lock(p); 408 vm_page_test_dirty(p); 409 if (p->dirty == 0 || 410 p->queue != PQ_INACTIVE || 411 p->hold_count != 0) { /* may be undergoing I/O */ 412 vm_page_unlock(p); 413 ib = 0; 414 break; 415 } 416 vm_page_unlock(p); 417 mc[--page_base] = pb = p; 418 ++pageout_count; 419 ++ib; 420 /* 421 * alignment boundry, stop here and switch directions. Do 422 * not clear ib. 423 */ 424 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 425 break; 426 } 427 428 while (pageout_count < vm_pageout_page_count && 429 pindex + is < object->size) { 430 vm_page_t p; 431 432 if ((p = vm_page_next(ps)) == NULL || 433 (p->oflags & VPO_BUSY) != 0 || p->busy != 0) 434 break; 435 vm_page_lock(p); 436 vm_page_test_dirty(p); 437 if (p->dirty == 0 || 438 p->queue != PQ_INACTIVE || 439 p->hold_count != 0) { /* may be undergoing I/O */ 440 vm_page_unlock(p); 441 break; 442 } 443 vm_page_unlock(p); 444 mc[page_base + pageout_count] = ps = p; 445 ++pageout_count; 446 ++is; 447 } 448 449 /* 450 * If we exhausted our forward scan, continue with the reverse scan 451 * when possible, even past a page boundry. This catches boundry 452 * conditions. 453 */ 454 if (ib && pageout_count < vm_pageout_page_count) 455 goto more; 456 457 /* 458 * we allow reads during pageouts... 459 */ 460 return (vm_pageout_flush(&mc[page_base], pageout_count, 0, 0, NULL, 461 NULL)); 462 } 463 464 /* 465 * vm_pageout_flush() - launder the given pages 466 * 467 * The given pages are laundered. Note that we setup for the start of 468 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 469 * reference count all in here rather then in the parent. If we want 470 * the parent to do more sophisticated things we may have to change 471 * the ordering. 472 * 473 * Returned runlen is the count of pages between mreq and first 474 * page after mreq with status VM_PAGER_AGAIN. 475 * *eio is set to TRUE if pager returned VM_PAGER_ERROR or VM_PAGER_FAIL 476 * for any page in runlen set. 477 */ 478 int 479 vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen, 480 boolean_t *eio) 481 { 482 vm_object_t object = mc[0]->object; 483 int pageout_status[count]; 484 int numpagedout = 0; 485 int i, runlen; 486 487 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 488 489 /* 490 * Initiate I/O. Bump the vm_page_t->busy counter and 491 * mark the pages read-only. 492 * 493 * We do not have to fixup the clean/dirty bits here... we can 494 * allow the pager to do it after the I/O completes. 495 * 496 * NOTE! mc[i]->dirty may be partial or fragmented due to an 497 * edge case with file fragments. 498 */ 499 for (i = 0; i < count; i++) { 500 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 501 ("vm_pageout_flush: partially invalid page %p index %d/%d", 502 mc[i], i, count)); 503 vm_page_io_start(mc[i]); 504 pmap_remove_write(mc[i]); 505 } 506 vm_object_pip_add(object, count); 507 508 vm_pager_put_pages(object, mc, count, flags, pageout_status); 509 510 runlen = count - mreq; 511 if (eio != NULL) 512 *eio = FALSE; 513 for (i = 0; i < count; i++) { 514 vm_page_t mt = mc[i]; 515 516 KASSERT(pageout_status[i] == VM_PAGER_PEND || 517 !pmap_page_is_write_mapped(mt), 518 ("vm_pageout_flush: page %p is not write protected", mt)); 519 switch (pageout_status[i]) { 520 case VM_PAGER_OK: 521 case VM_PAGER_PEND: 522 numpagedout++; 523 break; 524 case VM_PAGER_BAD: 525 /* 526 * Page outside of range of object. Right now we 527 * essentially lose the changes by pretending it 528 * worked. 529 */ 530 vm_page_undirty(mt); 531 break; 532 case VM_PAGER_ERROR: 533 case VM_PAGER_FAIL: 534 /* 535 * If page couldn't be paged out, then reactivate the 536 * page so it doesn't clog the inactive list. (We 537 * will try paging out it again later). 538 */ 539 vm_page_lock(mt); 540 vm_page_activate(mt); 541 vm_page_unlock(mt); 542 if (eio != NULL && i >= mreq && i - mreq < runlen) 543 *eio = TRUE; 544 break; 545 case VM_PAGER_AGAIN: 546 if (i >= mreq && i - mreq < runlen) 547 runlen = i - mreq; 548 break; 549 } 550 551 /* 552 * If the operation is still going, leave the page busy to 553 * block all other accesses. Also, leave the paging in 554 * progress indicator set so that we don't attempt an object 555 * collapse. 556 */ 557 if (pageout_status[i] != VM_PAGER_PEND) { 558 vm_object_pip_wakeup(object); 559 vm_page_io_finish(mt); 560 if (vm_page_count_severe()) { 561 vm_page_lock(mt); 562 vm_page_try_to_cache(mt); 563 vm_page_unlock(mt); 564 } 565 } 566 } 567 if (prunlen != NULL) 568 *prunlen = runlen; 569 return (numpagedout); 570 } 571 572 static boolean_t 573 vm_pageout_launder(int queue, int tries, vm_paddr_t low, vm_paddr_t high) 574 { 575 struct mount *mp; 576 struct vm_pagequeue *pq; 577 struct vnode *vp; 578 vm_object_t object; 579 vm_paddr_t pa; 580 vm_page_t m, m_tmp, next; 581 582 pq = &vm_pagequeues[queue]; 583 vm_pagequeue_lock(pq); 584 TAILQ_FOREACH_SAFE(m, &pq->pq_pl, pageq, next) { 585 KASSERT(m->queue == queue, 586 ("vm_pageout_launder: page %p's queue is not %d", m, 587 queue)); 588 if ((m->flags & PG_MARKER) != 0) 589 continue; 590 pa = VM_PAGE_TO_PHYS(m); 591 if (pa < low || pa + PAGE_SIZE > high) 592 continue; 593 if (!vm_pageout_page_lock(m, &next) || m->hold_count != 0) { 594 vm_page_unlock(m); 595 continue; 596 } 597 object = m->object; 598 if ((!VM_OBJECT_TRYLOCK(object) && 599 (!vm_pageout_fallback_object_lock(m, &next) || 600 m->hold_count != 0)) || (m->oflags & VPO_BUSY) != 0 || 601 m->busy != 0) { 602 vm_page_unlock(m); 603 VM_OBJECT_UNLOCK(object); 604 continue; 605 } 606 vm_page_test_dirty(m); 607 if (m->dirty == 0 && object->ref_count != 0) 608 pmap_remove_all(m); 609 if (m->dirty != 0) { 610 vm_page_unlock(m); 611 if (tries == 0 || (object->flags & OBJ_DEAD) != 0) { 612 VM_OBJECT_UNLOCK(object); 613 continue; 614 } 615 if (object->type == OBJT_VNODE) { 616 vm_pagequeue_unlock(pq); 617 vp = object->handle; 618 vm_object_reference_locked(object); 619 VM_OBJECT_UNLOCK(object); 620 (void)vn_start_write(vp, &mp, V_WAIT); 621 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 622 VM_OBJECT_LOCK(object); 623 vm_object_page_clean(object, 0, 0, OBJPC_SYNC); 624 VM_OBJECT_UNLOCK(object); 625 VOP_UNLOCK(vp, 0); 626 vm_object_deallocate(object); 627 vn_finished_write(mp); 628 return (TRUE); 629 } else if (object->type == OBJT_SWAP || 630 object->type == OBJT_DEFAULT) { 631 vm_pagequeue_unlock(pq); 632 m_tmp = m; 633 vm_pageout_flush(&m_tmp, 1, VM_PAGER_PUT_SYNC, 634 0, NULL, NULL); 635 VM_OBJECT_UNLOCK(object); 636 return (TRUE); 637 } 638 } else { 639 /* 640 * Dequeue here to prevent lock recursion in 641 * vm_page_cache(). 642 */ 643 vm_page_dequeue_locked(m); 644 vm_page_cache(m); 645 vm_page_unlock(m); 646 } 647 VM_OBJECT_UNLOCK(object); 648 } 649 vm_pagequeue_unlock(pq); 650 return (FALSE); 651 } 652 653 /* 654 * Increase the number of cached pages. The specified value, "tries", 655 * determines which categories of pages are cached: 656 * 657 * 0: All clean, inactive pages within the specified physical address range 658 * are cached. Will not sleep. 659 * 1: The vm_lowmem handlers are called. All inactive pages within 660 * the specified physical address range are cached. May sleep. 661 * 2: The vm_lowmem handlers are called. All inactive and active pages 662 * within the specified physical address range are cached. May sleep. 663 */ 664 void 665 vm_pageout_grow_cache(int tries, vm_paddr_t low, vm_paddr_t high) 666 { 667 int actl, actmax, inactl, inactmax; 668 669 if (tries > 0) { 670 /* 671 * Decrease registered cache sizes. The vm_lowmem handlers 672 * may acquire locks and/or sleep, so they can only be invoked 673 * when "tries" is greater than zero. 674 */ 675 EVENTHANDLER_INVOKE(vm_lowmem, 0); 676 677 /* 678 * We do this explicitly after the caches have been drained 679 * above. 680 */ 681 uma_reclaim(); 682 } 683 inactl = 0; 684 inactmax = cnt.v_inactive_count; 685 actl = 0; 686 actmax = tries < 2 ? 0 : cnt.v_active_count; 687 again: 688 if (inactl < inactmax && vm_pageout_launder(PQ_INACTIVE, tries, low, 689 high)) { 690 inactl++; 691 goto again; 692 } 693 if (actl < actmax && vm_pageout_launder(PQ_ACTIVE, tries, low, high)) { 694 actl++; 695 goto again; 696 } 697 } 698 699 #if !defined(NO_SWAPPING) 700 /* 701 * vm_pageout_object_deactivate_pages 702 * 703 * Deactivate enough pages to satisfy the inactive target 704 * requirements. 705 * 706 * The object and map must be locked. 707 */ 708 static void 709 vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object, 710 long desired) 711 { 712 vm_object_t backing_object, object; 713 vm_page_t p; 714 int actcount, remove_mode; 715 716 VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED); 717 if ((first_object->flags & OBJ_FICTITIOUS) != 0) 718 return; 719 for (object = first_object;; object = backing_object) { 720 if (pmap_resident_count(pmap) <= desired) 721 goto unlock_return; 722 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 723 if ((object->flags & OBJ_UNMANAGED) != 0 || 724 object->paging_in_progress != 0) 725 goto unlock_return; 726 727 remove_mode = 0; 728 if (object->shadow_count > 1) 729 remove_mode = 1; 730 /* 731 * Scan the object's entire memory queue. 732 */ 733 TAILQ_FOREACH(p, &object->memq, listq) { 734 if (pmap_resident_count(pmap) <= desired) 735 goto unlock_return; 736 if ((p->oflags & VPO_BUSY) != 0 || p->busy != 0) 737 continue; 738 PCPU_INC(cnt.v_pdpages); 739 vm_page_lock(p); 740 if (p->wire_count != 0 || p->hold_count != 0 || 741 !pmap_page_exists_quick(pmap, p)) { 742 vm_page_unlock(p); 743 continue; 744 } 745 actcount = pmap_ts_referenced(p); 746 if ((p->aflags & PGA_REFERENCED) != 0) { 747 if (actcount == 0) 748 actcount = 1; 749 vm_page_aflag_clear(p, PGA_REFERENCED); 750 } 751 if (p->queue != PQ_ACTIVE && actcount != 0) { 752 vm_page_activate(p); 753 p->act_count += actcount; 754 } else if (p->queue == PQ_ACTIVE) { 755 if (actcount == 0) { 756 p->act_count -= min(p->act_count, 757 ACT_DECLINE); 758 if (!remove_mode && 759 (vm_pageout_algorithm || 760 p->act_count == 0)) { 761 pmap_remove_all(p); 762 vm_page_deactivate(p); 763 } else 764 vm_page_requeue(p); 765 } else { 766 vm_page_activate(p); 767 if (p->act_count < ACT_MAX - 768 ACT_ADVANCE) 769 p->act_count += ACT_ADVANCE; 770 vm_page_requeue(p); 771 } 772 } else if (p->queue == PQ_INACTIVE) 773 pmap_remove_all(p); 774 vm_page_unlock(p); 775 } 776 if ((backing_object = object->backing_object) == NULL) 777 goto unlock_return; 778 VM_OBJECT_LOCK(backing_object); 779 if (object != first_object) 780 VM_OBJECT_UNLOCK(object); 781 } 782 unlock_return: 783 if (object != first_object) 784 VM_OBJECT_UNLOCK(object); 785 } 786 787 /* 788 * deactivate some number of pages in a map, try to do it fairly, but 789 * that is really hard to do. 790 */ 791 static void 792 vm_pageout_map_deactivate_pages(map, desired) 793 vm_map_t map; 794 long desired; 795 { 796 vm_map_entry_t tmpe; 797 vm_object_t obj, bigobj; 798 int nothingwired; 799 800 if (!vm_map_trylock(map)) 801 return; 802 803 bigobj = NULL; 804 nothingwired = TRUE; 805 806 /* 807 * first, search out the biggest object, and try to free pages from 808 * that. 809 */ 810 tmpe = map->header.next; 811 while (tmpe != &map->header) { 812 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 813 obj = tmpe->object.vm_object; 814 if (obj != NULL && VM_OBJECT_TRYLOCK(obj)) { 815 if (obj->shadow_count <= 1 && 816 (bigobj == NULL || 817 bigobj->resident_page_count < obj->resident_page_count)) { 818 if (bigobj != NULL) 819 VM_OBJECT_UNLOCK(bigobj); 820 bigobj = obj; 821 } else 822 VM_OBJECT_UNLOCK(obj); 823 } 824 } 825 if (tmpe->wired_count > 0) 826 nothingwired = FALSE; 827 tmpe = tmpe->next; 828 } 829 830 if (bigobj != NULL) { 831 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); 832 VM_OBJECT_UNLOCK(bigobj); 833 } 834 /* 835 * Next, hunt around for other pages to deactivate. We actually 836 * do this search sort of wrong -- .text first is not the best idea. 837 */ 838 tmpe = map->header.next; 839 while (tmpe != &map->header) { 840 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 841 break; 842 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 843 obj = tmpe->object.vm_object; 844 if (obj != NULL) { 845 VM_OBJECT_LOCK(obj); 846 vm_pageout_object_deactivate_pages(map->pmap, obj, desired); 847 VM_OBJECT_UNLOCK(obj); 848 } 849 } 850 tmpe = tmpe->next; 851 } 852 853 /* 854 * Remove all mappings if a process is swapped out, this will free page 855 * table pages. 856 */ 857 if (desired == 0 && nothingwired) { 858 pmap_remove(vm_map_pmap(map), vm_map_min(map), 859 vm_map_max(map)); 860 } 861 vm_map_unlock(map); 862 } 863 #endif /* !defined(NO_SWAPPING) */ 864 865 /* 866 * vm_pageout_scan does the dirty work for the pageout daemon. 867 */ 868 static void 869 vm_pageout_scan(int pass) 870 { 871 vm_page_t m, next; 872 struct vm_page marker; 873 struct vm_pagequeue *pq; 874 int page_shortage, maxscan, pcount; 875 int addl_page_shortage; 876 vm_object_t object; 877 int actcount; 878 int vnodes_skipped = 0; 879 int maxlaunder; 880 boolean_t queues_locked; 881 882 vm_pageout_init_marker(&marker, PQ_INACTIVE); 883 884 /* 885 * Decrease registered cache sizes. 886 */ 887 EVENTHANDLER_INVOKE(vm_lowmem, 0); 888 /* 889 * We do this explicitly after the caches have been drained above. 890 */ 891 uma_reclaim(); 892 893 /* 894 * The addl_page_shortage is the number of temporarily 895 * stuck pages in the inactive queue. In other words, the 896 * number of pages from cnt.v_inactive_count that should be 897 * discounted in setting the target for the active queue scan. 898 */ 899 addl_page_shortage = atomic_readandclear_int(&vm_pageout_deficit); 900 901 /* 902 * Calculate the number of pages we want to either free or move 903 * to the cache. 904 */ 905 page_shortage = vm_paging_target() + addl_page_shortage; 906 907 /* 908 * maxlaunder limits the number of dirty pages we flush per scan. 909 * For most systems a smaller value (16 or 32) is more robust under 910 * extreme memory and disk pressure because any unnecessary writes 911 * to disk can result in extreme performance degredation. However, 912 * systems with excessive dirty pages (especially when MAP_NOSYNC is 913 * used) will die horribly with limited laundering. If the pageout 914 * daemon cannot clean enough pages in the first pass, we let it go 915 * all out in succeeding passes. 916 */ 917 if ((maxlaunder = vm_max_launder) <= 1) 918 maxlaunder = 1; 919 if (pass) 920 maxlaunder = 10000; 921 922 maxscan = cnt.v_inactive_count; 923 924 /* 925 * Start scanning the inactive queue for pages we can move to the 926 * cache or free. The scan will stop when the target is reached or 927 * we have scanned the entire inactive queue. Note that m->act_count 928 * is not used to form decisions for the inactive queue, only for the 929 * active queue. 930 */ 931 pq = &vm_pagequeues[PQ_INACTIVE]; 932 vm_pagequeue_lock(pq); 933 queues_locked = TRUE; 934 for (m = TAILQ_FIRST(&pq->pq_pl); 935 m != NULL && maxscan-- > 0 && page_shortage > 0; 936 m = next) { 937 vm_pagequeue_assert_locked(pq); 938 KASSERT(queues_locked, ("unlocked queues")); 939 KASSERT(m->queue == PQ_INACTIVE, ("Inactive queue %p", m)); 940 941 PCPU_INC(cnt.v_pdpages); 942 next = TAILQ_NEXT(m, pageq); 943 944 /* 945 * skip marker pages 946 */ 947 if (m->flags & PG_MARKER) 948 continue; 949 950 KASSERT((m->flags & PG_FICTITIOUS) == 0, 951 ("Fictitious page %p cannot be in inactive queue", m)); 952 KASSERT((m->oflags & VPO_UNMANAGED) == 0, 953 ("Unmanaged page %p cannot be in inactive queue", m)); 954 955 /* 956 * The page or object lock acquisitions fail if the 957 * page was removed from the queue or moved to a 958 * different position within the queue. In either 959 * case, addl_page_shortage should not be incremented. 960 */ 961 if (!vm_pageout_page_lock(m, &next)) { 962 vm_page_unlock(m); 963 continue; 964 } 965 object = m->object; 966 if (!VM_OBJECT_TRYLOCK(object) && 967 !vm_pageout_fallback_object_lock(m, &next)) { 968 vm_page_unlock(m); 969 VM_OBJECT_UNLOCK(object); 970 continue; 971 } 972 973 /* 974 * Don't mess with busy pages, keep them at at the 975 * front of the queue, most likely they are being 976 * paged out. Increment addl_page_shortage for busy 977 * pages, because they may leave the inactive queue 978 * shortly after page scan is finished. 979 */ 980 if (m->busy != 0 || (m->oflags & VPO_BUSY) != 0) { 981 vm_page_unlock(m); 982 VM_OBJECT_UNLOCK(object); 983 addl_page_shortage++; 984 continue; 985 } 986 987 /* 988 * We unlock the inactive page queue, invalidating the 989 * 'next' pointer. Use our marker to remember our 990 * place. 991 */ 992 TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, pageq); 993 vm_pagequeue_unlock(pq); 994 queues_locked = FALSE; 995 996 /* 997 * If the object is not being used, we ignore previous 998 * references. 999 */ 1000 if (object->ref_count == 0) { 1001 vm_page_aflag_clear(m, PGA_REFERENCED); 1002 KASSERT(!pmap_page_is_mapped(m), 1003 ("vm_pageout_scan: page %p is mapped", m)); 1004 1005 /* 1006 * Otherwise, if the page has been referenced while in the 1007 * inactive queue, we bump the "activation count" upwards, 1008 * making it less likely that the page will be added back to 1009 * the inactive queue prematurely again. Here we check the 1010 * page tables (or emulated bits, if any), given the upper 1011 * level VM system not knowing anything about existing 1012 * references. 1013 */ 1014 } else if ((m->aflags & PGA_REFERENCED) == 0 && 1015 (actcount = pmap_ts_referenced(m)) != 0) { 1016 vm_page_activate(m); 1017 vm_page_unlock(m); 1018 m->act_count += actcount + ACT_ADVANCE; 1019 VM_OBJECT_UNLOCK(object); 1020 goto relock_queues; 1021 } 1022 1023 /* 1024 * If the upper level VM system knows about any page 1025 * references, we activate the page. We also set the 1026 * "activation count" higher than normal so that we will less 1027 * likely place pages back onto the inactive queue again. 1028 */ 1029 if ((m->aflags & PGA_REFERENCED) != 0) { 1030 vm_page_aflag_clear(m, PGA_REFERENCED); 1031 actcount = pmap_ts_referenced(m); 1032 vm_page_activate(m); 1033 vm_page_unlock(m); 1034 m->act_count += actcount + ACT_ADVANCE + 1; 1035 VM_OBJECT_UNLOCK(object); 1036 goto relock_queues; 1037 } 1038 1039 if (m->hold_count != 0) { 1040 vm_page_unlock(m); 1041 VM_OBJECT_UNLOCK(object); 1042 1043 /* 1044 * Held pages are essentially stuck in the 1045 * queue. So, they ought to be discounted 1046 * from cnt.v_inactive_count. See the 1047 * calculation of the page_shortage for the 1048 * loop over the active queue below. 1049 */ 1050 addl_page_shortage++; 1051 goto relock_queues; 1052 } 1053 1054 /* 1055 * If the page appears to be clean at the machine-independent 1056 * layer, then remove all of its mappings from the pmap in 1057 * anticipation of placing it onto the cache queue. If, 1058 * however, any of the page's mappings allow write access, 1059 * then the page may still be modified until the last of those 1060 * mappings are removed. 1061 */ 1062 vm_page_test_dirty(m); 1063 if (m->dirty == 0 && object->ref_count != 0) 1064 pmap_remove_all(m); 1065 1066 if (m->valid == 0) { 1067 /* 1068 * Invalid pages can be easily freed 1069 */ 1070 vm_page_free(m); 1071 PCPU_INC(cnt.v_dfree); 1072 --page_shortage; 1073 } else if (m->dirty == 0) { 1074 /* 1075 * Clean pages can be placed onto the cache queue. 1076 * This effectively frees them. 1077 */ 1078 vm_page_cache(m); 1079 --page_shortage; 1080 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 1081 /* 1082 * Dirty pages need to be paged out, but flushing 1083 * a page is extremely expensive verses freeing 1084 * a clean page. Rather then artificially limiting 1085 * the number of pages we can flush, we instead give 1086 * dirty pages extra priority on the inactive queue 1087 * by forcing them to be cycled through the queue 1088 * twice before being flushed, after which the 1089 * (now clean) page will cycle through once more 1090 * before being freed. This significantly extends 1091 * the thrash point for a heavily loaded machine. 1092 */ 1093 m->flags |= PG_WINATCFLS; 1094 vm_pagequeue_lock(pq); 1095 queues_locked = TRUE; 1096 vm_page_requeue_locked(m); 1097 } else if (maxlaunder > 0) { 1098 /* 1099 * We always want to try to flush some dirty pages if 1100 * we encounter them, to keep the system stable. 1101 * Normally this number is small, but under extreme 1102 * pressure where there are insufficient clean pages 1103 * on the inactive queue, we may have to go all out. 1104 */ 1105 int swap_pageouts_ok; 1106 struct vnode *vp = NULL; 1107 struct mount *mp = NULL; 1108 1109 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 1110 swap_pageouts_ok = 1; 1111 } else { 1112 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 1113 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 1114 vm_page_count_min()); 1115 1116 } 1117 1118 /* 1119 * We don't bother paging objects that are "dead". 1120 * Those objects are in a "rundown" state. 1121 */ 1122 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 1123 vm_pagequeue_lock(pq); 1124 vm_page_unlock(m); 1125 VM_OBJECT_UNLOCK(object); 1126 queues_locked = TRUE; 1127 vm_page_requeue_locked(m); 1128 goto relock_queues; 1129 } 1130 1131 /* 1132 * The object is already known NOT to be dead. It 1133 * is possible for the vget() to block the whole 1134 * pageout daemon, but the new low-memory handling 1135 * code should prevent it. 1136 * 1137 * The previous code skipped locked vnodes and, worse, 1138 * reordered pages in the queue. This results in 1139 * completely non-deterministic operation and, on a 1140 * busy system, can lead to extremely non-optimal 1141 * pageouts. For example, it can cause clean pages 1142 * to be freed and dirty pages to be moved to the end 1143 * of the queue. Since dirty pages are also moved to 1144 * the end of the queue once-cleaned, this gives 1145 * way too large a weighting to defering the freeing 1146 * of dirty pages. 1147 * 1148 * We can't wait forever for the vnode lock, we might 1149 * deadlock due to a vn_read() getting stuck in 1150 * vm_wait while holding this vnode. We skip the 1151 * vnode if we can't get it in a reasonable amount 1152 * of time. 1153 */ 1154 if (object->type == OBJT_VNODE) { 1155 vm_page_unlock(m); 1156 vp = object->handle; 1157 if (vp->v_type == VREG && 1158 vn_start_write(vp, &mp, V_NOWAIT) != 0) { 1159 mp = NULL; 1160 ++pageout_lock_miss; 1161 if (object->flags & OBJ_MIGHTBEDIRTY) 1162 vnodes_skipped++; 1163 goto unlock_and_continue; 1164 } 1165 KASSERT(mp != NULL, 1166 ("vp %p with NULL v_mount", vp)); 1167 vm_object_reference_locked(object); 1168 VM_OBJECT_UNLOCK(object); 1169 if (vget(vp, LK_EXCLUSIVE | LK_TIMELOCK, 1170 curthread)) { 1171 VM_OBJECT_LOCK(object); 1172 ++pageout_lock_miss; 1173 if (object->flags & OBJ_MIGHTBEDIRTY) 1174 vnodes_skipped++; 1175 vp = NULL; 1176 goto unlock_and_continue; 1177 } 1178 VM_OBJECT_LOCK(object); 1179 vm_page_lock(m); 1180 vm_pagequeue_lock(pq); 1181 queues_locked = TRUE; 1182 /* 1183 * The page might have been moved to another 1184 * queue during potential blocking in vget() 1185 * above. The page might have been freed and 1186 * reused for another vnode. 1187 */ 1188 if (m->queue != PQ_INACTIVE || 1189 m->object != object || 1190 TAILQ_NEXT(m, pageq) != &marker) { 1191 vm_page_unlock(m); 1192 if (object->flags & OBJ_MIGHTBEDIRTY) 1193 vnodes_skipped++; 1194 goto unlock_and_continue; 1195 } 1196 1197 /* 1198 * The page may have been busied during the 1199 * blocking in vget(). We don't move the 1200 * page back onto the end of the queue so that 1201 * statistics are more correct if we don't. 1202 */ 1203 if (m->busy || (m->oflags & VPO_BUSY)) { 1204 vm_page_unlock(m); 1205 goto unlock_and_continue; 1206 } 1207 1208 /* 1209 * If the page has become held it might 1210 * be undergoing I/O, so skip it 1211 */ 1212 if (m->hold_count) { 1213 vm_page_unlock(m); 1214 vm_page_requeue_locked(m); 1215 if (object->flags & OBJ_MIGHTBEDIRTY) 1216 vnodes_skipped++; 1217 goto unlock_and_continue; 1218 } 1219 vm_pagequeue_unlock(pq); 1220 queues_locked = FALSE; 1221 } 1222 1223 /* 1224 * If a page is dirty, then it is either being washed 1225 * (but not yet cleaned) or it is still in the 1226 * laundry. If it is still in the laundry, then we 1227 * start the cleaning operation. 1228 * 1229 * decrement page_shortage on success to account for 1230 * the (future) cleaned page. Otherwise we could wind 1231 * up laundering or cleaning too many pages. 1232 */ 1233 if (vm_pageout_clean(m) != 0) { 1234 --page_shortage; 1235 --maxlaunder; 1236 } 1237 unlock_and_continue: 1238 vm_page_lock_assert(m, MA_NOTOWNED); 1239 VM_OBJECT_UNLOCK(object); 1240 if (mp != NULL) { 1241 if (queues_locked) { 1242 vm_pagequeue_unlock(pq); 1243 queues_locked = FALSE; 1244 } 1245 if (vp != NULL) 1246 vput(vp); 1247 vm_object_deallocate(object); 1248 vn_finished_write(mp); 1249 } 1250 vm_page_lock_assert(m, MA_NOTOWNED); 1251 goto relock_queues; 1252 } 1253 vm_page_unlock(m); 1254 VM_OBJECT_UNLOCK(object); 1255 relock_queues: 1256 if (!queues_locked) { 1257 vm_pagequeue_lock(pq); 1258 queues_locked = TRUE; 1259 } 1260 next = TAILQ_NEXT(&marker, pageq); 1261 TAILQ_REMOVE(&pq->pq_pl, &marker, pageq); 1262 } 1263 vm_pagequeue_unlock(pq); 1264 1265 /* 1266 * Compute the number of pages we want to try to move from the 1267 * active queue to the inactive queue. 1268 */ 1269 page_shortage = vm_paging_target() + 1270 cnt.v_inactive_target - cnt.v_inactive_count; 1271 page_shortage += addl_page_shortage; 1272 1273 /* 1274 * Scan the active queue for things we can deactivate. We nominally 1275 * track the per-page activity counter and use it to locate 1276 * deactivation candidates. 1277 */ 1278 pcount = cnt.v_active_count; 1279 pq = &vm_pagequeues[PQ_ACTIVE]; 1280 vm_pagequeue_lock(pq); 1281 m = TAILQ_FIRST(&pq->pq_pl); 1282 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 1283 1284 KASSERT(m->queue == PQ_ACTIVE, 1285 ("vm_pageout_scan: page %p isn't active", m)); 1286 1287 next = TAILQ_NEXT(m, pageq); 1288 if ((m->flags & PG_MARKER) != 0) { 1289 m = next; 1290 continue; 1291 } 1292 KASSERT((m->flags & PG_FICTITIOUS) == 0, 1293 ("Fictitious page %p cannot be in active queue", m)); 1294 KASSERT((m->oflags & VPO_UNMANAGED) == 0, 1295 ("Unmanaged page %p cannot be in active queue", m)); 1296 if (!vm_pageout_page_lock(m, &next)) { 1297 vm_page_unlock(m); 1298 m = next; 1299 continue; 1300 } 1301 object = m->object; 1302 if (!VM_OBJECT_TRYLOCK(object) && 1303 !vm_pageout_fallback_object_lock(m, &next)) { 1304 VM_OBJECT_UNLOCK(object); 1305 vm_page_unlock(m); 1306 m = next; 1307 continue; 1308 } 1309 1310 /* 1311 * Don't deactivate pages that are busy. 1312 */ 1313 if ((m->busy != 0) || 1314 (m->oflags & VPO_BUSY) || 1315 (m->hold_count != 0)) { 1316 vm_page_unlock(m); 1317 VM_OBJECT_UNLOCK(object); 1318 vm_page_requeue_locked(m); 1319 m = next; 1320 continue; 1321 } 1322 1323 /* 1324 * The count for pagedaemon pages is done after checking the 1325 * page for eligibility... 1326 */ 1327 PCPU_INC(cnt.v_pdpages); 1328 1329 /* 1330 * Check to see "how much" the page has been used. 1331 */ 1332 actcount = 0; 1333 if (object->ref_count != 0) { 1334 if (m->aflags & PGA_REFERENCED) { 1335 actcount += 1; 1336 } 1337 actcount += pmap_ts_referenced(m); 1338 if (actcount) { 1339 m->act_count += ACT_ADVANCE + actcount; 1340 if (m->act_count > ACT_MAX) 1341 m->act_count = ACT_MAX; 1342 } 1343 } 1344 1345 /* 1346 * Since we have "tested" this bit, we need to clear it now. 1347 */ 1348 vm_page_aflag_clear(m, PGA_REFERENCED); 1349 1350 /* 1351 * Only if an object is currently being used, do we use the 1352 * page activation count stats. 1353 */ 1354 if (actcount != 0 && object->ref_count != 0) 1355 vm_page_requeue_locked(m); 1356 else { 1357 m->act_count -= min(m->act_count, ACT_DECLINE); 1358 if (vm_pageout_algorithm || 1359 object->ref_count == 0 || 1360 m->act_count == 0) { 1361 page_shortage--; 1362 /* Dequeue to avoid later lock recursion. */ 1363 vm_page_dequeue_locked(m); 1364 if (object->ref_count == 0) { 1365 KASSERT(!pmap_page_is_mapped(m), 1366 ("vm_pageout_scan: page %p is mapped", m)); 1367 if (m->dirty == 0) 1368 vm_page_cache(m); 1369 else 1370 vm_page_deactivate(m); 1371 } else { 1372 vm_page_deactivate(m); 1373 } 1374 } else 1375 vm_page_requeue_locked(m); 1376 } 1377 vm_page_unlock(m); 1378 VM_OBJECT_UNLOCK(object); 1379 m = next; 1380 } 1381 vm_pagequeue_unlock(pq); 1382 #if !defined(NO_SWAPPING) 1383 /* 1384 * Idle process swapout -- run once per second. 1385 */ 1386 if (vm_swap_idle_enabled) { 1387 static long lsec; 1388 if (time_second != lsec) { 1389 vm_req_vmdaemon(VM_SWAP_IDLE); 1390 lsec = time_second; 1391 } 1392 } 1393 #endif 1394 1395 /* 1396 * If we didn't get enough free pages, and we have skipped a vnode 1397 * in a writeable object, wakeup the sync daemon. And kick swapout 1398 * if we did not get enough free pages. 1399 */ 1400 if (vm_paging_target() > 0) { 1401 if (vnodes_skipped && vm_page_count_min()) 1402 (void) speedup_syncer(); 1403 #if !defined(NO_SWAPPING) 1404 if (vm_swap_enabled && vm_page_count_target()) 1405 vm_req_vmdaemon(VM_SWAP_NORMAL); 1406 #endif 1407 } 1408 1409 /* 1410 * If we are critically low on one of RAM or swap and low on 1411 * the other, kill the largest process. However, we avoid 1412 * doing this on the first pass in order to give ourselves a 1413 * chance to flush out dirty vnode-backed pages and to allow 1414 * active pages to be moved to the inactive queue and reclaimed. 1415 */ 1416 if (pass != 0 && 1417 ((swap_pager_avail < 64 && vm_page_count_min()) || 1418 (swap_pager_full && vm_paging_target() > 0))) 1419 vm_pageout_oom(VM_OOM_MEM); 1420 } 1421 1422 1423 void 1424 vm_pageout_oom(int shortage) 1425 { 1426 struct proc *p, *bigproc; 1427 vm_offset_t size, bigsize; 1428 struct thread *td; 1429 struct vmspace *vm; 1430 1431 /* 1432 * We keep the process bigproc locked once we find it to keep anyone 1433 * from messing with it; however, there is a possibility of 1434 * deadlock if process B is bigproc and one of it's child processes 1435 * attempts to propagate a signal to B while we are waiting for A's 1436 * lock while walking this list. To avoid this, we don't block on 1437 * the process lock but just skip a process if it is already locked. 1438 */ 1439 bigproc = NULL; 1440 bigsize = 0; 1441 sx_slock(&allproc_lock); 1442 FOREACH_PROC_IN_SYSTEM(p) { 1443 int breakout; 1444 1445 if (PROC_TRYLOCK(p) == 0) 1446 continue; 1447 /* 1448 * If this is a system, protected or killed process, skip it. 1449 */ 1450 if (p->p_state != PRS_NORMAL || 1451 (p->p_flag & (P_INEXEC | P_PROTECTED | P_SYSTEM)) || 1452 (p->p_pid == 1) || P_KILLED(p) || 1453 ((p->p_pid < 48) && (swap_pager_avail != 0))) { 1454 PROC_UNLOCK(p); 1455 continue; 1456 } 1457 /* 1458 * If the process is in a non-running type state, 1459 * don't touch it. Check all the threads individually. 1460 */ 1461 breakout = 0; 1462 FOREACH_THREAD_IN_PROC(p, td) { 1463 thread_lock(td); 1464 if (!TD_ON_RUNQ(td) && 1465 !TD_IS_RUNNING(td) && 1466 !TD_IS_SLEEPING(td) && 1467 !TD_IS_SUSPENDED(td)) { 1468 thread_unlock(td); 1469 breakout = 1; 1470 break; 1471 } 1472 thread_unlock(td); 1473 } 1474 if (breakout) { 1475 PROC_UNLOCK(p); 1476 continue; 1477 } 1478 /* 1479 * get the process size 1480 */ 1481 vm = vmspace_acquire_ref(p); 1482 if (vm == NULL) { 1483 PROC_UNLOCK(p); 1484 continue; 1485 } 1486 if (!vm_map_trylock_read(&vm->vm_map)) { 1487 vmspace_free(vm); 1488 PROC_UNLOCK(p); 1489 continue; 1490 } 1491 size = vmspace_swap_count(vm); 1492 vm_map_unlock_read(&vm->vm_map); 1493 if (shortage == VM_OOM_MEM) 1494 size += vmspace_resident_count(vm); 1495 vmspace_free(vm); 1496 /* 1497 * if the this process is bigger than the biggest one 1498 * remember it. 1499 */ 1500 if (size > bigsize) { 1501 if (bigproc != NULL) 1502 PROC_UNLOCK(bigproc); 1503 bigproc = p; 1504 bigsize = size; 1505 } else 1506 PROC_UNLOCK(p); 1507 } 1508 sx_sunlock(&allproc_lock); 1509 if (bigproc != NULL) { 1510 killproc(bigproc, "out of swap space"); 1511 sched_nice(bigproc, PRIO_MIN); 1512 PROC_UNLOCK(bigproc); 1513 wakeup(&cnt.v_free_count); 1514 } 1515 } 1516 1517 /* 1518 * This routine tries to maintain the pseudo LRU active queue, 1519 * so that during long periods of time where there is no paging, 1520 * that some statistic accumulation still occurs. This code 1521 * helps the situation where paging just starts to occur. 1522 */ 1523 static void 1524 vm_pageout_page_stats(void) 1525 { 1526 struct vm_pagequeue *pq; 1527 vm_object_t object; 1528 vm_page_t m, next; 1529 int pcount, tpcount; /* Number of pages to check */ 1530 static int fullintervalcount = 0; 1531 int page_shortage; 1532 1533 page_shortage = 1534 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1535 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1536 1537 if (page_shortage <= 0) 1538 return; 1539 1540 pcount = cnt.v_active_count; 1541 fullintervalcount += vm_pageout_stats_interval; 1542 if (fullintervalcount < vm_pageout_full_stats_interval) { 1543 vm_pageout_stats++; 1544 tpcount = (int64_t)vm_pageout_stats_max * cnt.v_active_count / 1545 cnt.v_page_count; 1546 if (pcount > tpcount) 1547 pcount = tpcount; 1548 } else { 1549 vm_pageout_full_stats++; 1550 fullintervalcount = 0; 1551 } 1552 1553 pq = &vm_pagequeues[PQ_ACTIVE]; 1554 vm_pagequeue_lock(pq); 1555 m = TAILQ_FIRST(&pq->pq_pl); 1556 while ((m != NULL) && (pcount-- > 0)) { 1557 int actcount; 1558 1559 KASSERT(m->queue == PQ_ACTIVE, 1560 ("vm_pageout_page_stats: page %p isn't active", m)); 1561 1562 next = TAILQ_NEXT(m, pageq); 1563 if ((m->flags & PG_MARKER) != 0) { 1564 m = next; 1565 continue; 1566 } 1567 vm_page_lock_assert(m, MA_NOTOWNED); 1568 if (!vm_pageout_page_lock(m, &next)) { 1569 vm_page_unlock(m); 1570 m = next; 1571 continue; 1572 } 1573 object = m->object; 1574 if (!VM_OBJECT_TRYLOCK(object) && 1575 !vm_pageout_fallback_object_lock(m, &next)) { 1576 VM_OBJECT_UNLOCK(object); 1577 vm_page_unlock(m); 1578 m = next; 1579 continue; 1580 } 1581 1582 /* 1583 * Don't deactivate pages that are busy. 1584 */ 1585 if ((m->busy != 0) || 1586 (m->oflags & VPO_BUSY) || 1587 (m->hold_count != 0)) { 1588 vm_page_unlock(m); 1589 VM_OBJECT_UNLOCK(object); 1590 vm_page_requeue_locked(m); 1591 m = next; 1592 continue; 1593 } 1594 1595 actcount = 0; 1596 if (m->aflags & PGA_REFERENCED) { 1597 vm_page_aflag_clear(m, PGA_REFERENCED); 1598 actcount += 1; 1599 } 1600 1601 actcount += pmap_ts_referenced(m); 1602 if (actcount) { 1603 m->act_count += ACT_ADVANCE + actcount; 1604 if (m->act_count > ACT_MAX) 1605 m->act_count = ACT_MAX; 1606 vm_page_requeue_locked(m); 1607 } else { 1608 if (m->act_count == 0) { 1609 /* 1610 * We turn off page access, so that we have 1611 * more accurate RSS stats. We don't do this 1612 * in the normal page deactivation when the 1613 * system is loaded VM wise, because the 1614 * cost of the large number of page protect 1615 * operations would be higher than the value 1616 * of doing the operation. 1617 */ 1618 pmap_remove_all(m); 1619 /* Dequeue to avoid later lock recursion. */ 1620 vm_page_dequeue_locked(m); 1621 vm_page_deactivate(m); 1622 } else { 1623 m->act_count -= min(m->act_count, ACT_DECLINE); 1624 vm_page_requeue_locked(m); 1625 } 1626 } 1627 vm_page_unlock(m); 1628 VM_OBJECT_UNLOCK(object); 1629 m = next; 1630 } 1631 vm_pagequeue_unlock(pq); 1632 } 1633 1634 /* 1635 * vm_pageout is the high level pageout daemon. 1636 */ 1637 static void 1638 vm_pageout(void) 1639 { 1640 int error, pass; 1641 1642 /* 1643 * Initialize some paging parameters. 1644 */ 1645 cnt.v_interrupt_free_min = 2; 1646 if (cnt.v_page_count < 2000) 1647 vm_pageout_page_count = 8; 1648 1649 /* 1650 * v_free_reserved needs to include enough for the largest 1651 * swap pager structures plus enough for any pv_entry structs 1652 * when paging. 1653 */ 1654 if (cnt.v_page_count > 1024) 1655 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1656 else 1657 cnt.v_free_min = 4; 1658 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1659 cnt.v_interrupt_free_min; 1660 cnt.v_free_reserved = vm_pageout_page_count + 1661 cnt.v_pageout_free_min + (cnt.v_page_count / 768); 1662 cnt.v_free_severe = cnt.v_free_min / 2; 1663 cnt.v_free_min += cnt.v_free_reserved; 1664 cnt.v_free_severe += cnt.v_free_reserved; 1665 1666 /* 1667 * v_free_target and v_cache_min control pageout hysteresis. Note 1668 * that these are more a measure of the VM cache queue hysteresis 1669 * then the VM free queue. Specifically, v_free_target is the 1670 * high water mark (free+cache pages). 1671 * 1672 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1673 * low water mark, while v_free_min is the stop. v_cache_min must 1674 * be big enough to handle memory needs while the pageout daemon 1675 * is signalled and run to free more pages. 1676 */ 1677 if (cnt.v_free_count > 6144) 1678 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1679 else 1680 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1681 1682 if (cnt.v_free_count > 2048) { 1683 cnt.v_cache_min = cnt.v_free_target; 1684 cnt.v_cache_max = 2 * cnt.v_cache_min; 1685 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1686 } else { 1687 cnt.v_cache_min = 0; 1688 cnt.v_cache_max = 0; 1689 cnt.v_inactive_target = cnt.v_free_count / 4; 1690 } 1691 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1692 cnt.v_inactive_target = cnt.v_free_count / 3; 1693 1694 /* XXX does not really belong here */ 1695 if (vm_page_max_wired == 0) 1696 vm_page_max_wired = cnt.v_free_count / 3; 1697 1698 if (vm_pageout_stats_max == 0) 1699 vm_pageout_stats_max = cnt.v_free_target; 1700 1701 /* 1702 * Set interval in seconds for stats scan. 1703 */ 1704 if (vm_pageout_stats_interval == 0) 1705 vm_pageout_stats_interval = 5; 1706 if (vm_pageout_full_stats_interval == 0) 1707 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1708 1709 swap_pager_swap_init(); 1710 pass = 0; 1711 /* 1712 * The pageout daemon is never done, so loop forever. 1713 */ 1714 while (TRUE) { 1715 /* 1716 * If we have enough free memory, wakeup waiters. Do 1717 * not clear vm_pages_needed until we reach our target, 1718 * otherwise we may be woken up over and over again and 1719 * waste a lot of cpu. 1720 */ 1721 mtx_lock(&vm_page_queue_free_mtx); 1722 if (vm_pages_needed && !vm_page_count_min()) { 1723 if (!vm_paging_needed()) 1724 vm_pages_needed = 0; 1725 wakeup(&cnt.v_free_count); 1726 } 1727 if (vm_pages_needed) { 1728 /* 1729 * Still not done, take a second pass without waiting 1730 * (unlimited dirty cleaning), otherwise sleep a bit 1731 * and try again. 1732 */ 1733 ++pass; 1734 if (pass > 1) 1735 msleep(&vm_pages_needed, 1736 &vm_page_queue_free_mtx, PVM, "psleep", 1737 hz / 2); 1738 } else { 1739 /* 1740 * Good enough, sleep & handle stats. Prime the pass 1741 * for the next run. 1742 */ 1743 if (pass > 1) 1744 pass = 1; 1745 else 1746 pass = 0; 1747 error = msleep(&vm_pages_needed, 1748 &vm_page_queue_free_mtx, PVM, "psleep", 1749 vm_pageout_stats_interval * hz); 1750 if (error && !vm_pages_needed) { 1751 mtx_unlock(&vm_page_queue_free_mtx); 1752 pass = 0; 1753 vm_pageout_page_stats(); 1754 continue; 1755 } 1756 } 1757 if (vm_pages_needed) 1758 cnt.v_pdwakeups++; 1759 mtx_unlock(&vm_page_queue_free_mtx); 1760 vm_pageout_scan(pass); 1761 } 1762 } 1763 1764 /* 1765 * Unless the free page queue lock is held by the caller, this function 1766 * should be regarded as advisory. Specifically, the caller should 1767 * not msleep() on &cnt.v_free_count following this function unless 1768 * the free page queue lock is held until the msleep() is performed. 1769 */ 1770 void 1771 pagedaemon_wakeup(void) 1772 { 1773 1774 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1775 vm_pages_needed = 1; 1776 wakeup(&vm_pages_needed); 1777 } 1778 } 1779 1780 #if !defined(NO_SWAPPING) 1781 static void 1782 vm_req_vmdaemon(int req) 1783 { 1784 static int lastrun = 0; 1785 1786 mtx_lock(&vm_daemon_mtx); 1787 vm_pageout_req_swapout |= req; 1788 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1789 wakeup(&vm_daemon_needed); 1790 lastrun = ticks; 1791 } 1792 mtx_unlock(&vm_daemon_mtx); 1793 } 1794 1795 static void 1796 vm_daemon(void) 1797 { 1798 struct rlimit rsslim; 1799 struct proc *p; 1800 struct thread *td; 1801 struct vmspace *vm; 1802 int breakout, swapout_flags, tryagain, attempts; 1803 #ifdef RACCT 1804 uint64_t rsize, ravailable; 1805 #endif 1806 1807 while (TRUE) { 1808 mtx_lock(&vm_daemon_mtx); 1809 #ifdef RACCT 1810 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", hz); 1811 #else 1812 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0); 1813 #endif 1814 swapout_flags = vm_pageout_req_swapout; 1815 vm_pageout_req_swapout = 0; 1816 mtx_unlock(&vm_daemon_mtx); 1817 if (swapout_flags) 1818 swapout_procs(swapout_flags); 1819 1820 /* 1821 * scan the processes for exceeding their rlimits or if 1822 * process is swapped out -- deactivate pages 1823 */ 1824 tryagain = 0; 1825 attempts = 0; 1826 again: 1827 attempts++; 1828 sx_slock(&allproc_lock); 1829 FOREACH_PROC_IN_SYSTEM(p) { 1830 vm_pindex_t limit, size; 1831 1832 /* 1833 * if this is a system process or if we have already 1834 * looked at this process, skip it. 1835 */ 1836 PROC_LOCK(p); 1837 if (p->p_state != PRS_NORMAL || 1838 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 1839 PROC_UNLOCK(p); 1840 continue; 1841 } 1842 /* 1843 * if the process is in a non-running type state, 1844 * don't touch it. 1845 */ 1846 breakout = 0; 1847 FOREACH_THREAD_IN_PROC(p, td) { 1848 thread_lock(td); 1849 if (!TD_ON_RUNQ(td) && 1850 !TD_IS_RUNNING(td) && 1851 !TD_IS_SLEEPING(td) && 1852 !TD_IS_SUSPENDED(td)) { 1853 thread_unlock(td); 1854 breakout = 1; 1855 break; 1856 } 1857 thread_unlock(td); 1858 } 1859 if (breakout) { 1860 PROC_UNLOCK(p); 1861 continue; 1862 } 1863 /* 1864 * get a limit 1865 */ 1866 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1867 limit = OFF_TO_IDX( 1868 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1869 1870 /* 1871 * let processes that are swapped out really be 1872 * swapped out set the limit to nothing (will force a 1873 * swap-out.) 1874 */ 1875 if ((p->p_flag & P_INMEM) == 0) 1876 limit = 0; /* XXX */ 1877 vm = vmspace_acquire_ref(p); 1878 PROC_UNLOCK(p); 1879 if (vm == NULL) 1880 continue; 1881 1882 size = vmspace_resident_count(vm); 1883 if (size >= limit) { 1884 vm_pageout_map_deactivate_pages( 1885 &vm->vm_map, limit); 1886 } 1887 #ifdef RACCT 1888 rsize = IDX_TO_OFF(size); 1889 PROC_LOCK(p); 1890 racct_set(p, RACCT_RSS, rsize); 1891 ravailable = racct_get_available(p, RACCT_RSS); 1892 PROC_UNLOCK(p); 1893 if (rsize > ravailable) { 1894 /* 1895 * Don't be overly aggressive; this might be 1896 * an innocent process, and the limit could've 1897 * been exceeded by some memory hog. Don't 1898 * try to deactivate more than 1/4th of process' 1899 * resident set size. 1900 */ 1901 if (attempts <= 8) { 1902 if (ravailable < rsize - (rsize / 4)) 1903 ravailable = rsize - (rsize / 4); 1904 } 1905 vm_pageout_map_deactivate_pages( 1906 &vm->vm_map, OFF_TO_IDX(ravailable)); 1907 /* Update RSS usage after paging out. */ 1908 size = vmspace_resident_count(vm); 1909 rsize = IDX_TO_OFF(size); 1910 PROC_LOCK(p); 1911 racct_set(p, RACCT_RSS, rsize); 1912 PROC_UNLOCK(p); 1913 if (rsize > ravailable) 1914 tryagain = 1; 1915 } 1916 #endif 1917 vmspace_free(vm); 1918 } 1919 sx_sunlock(&allproc_lock); 1920 if (tryagain != 0 && attempts <= 10) 1921 goto again; 1922 } 1923 } 1924 #endif /* !defined(NO_SWAPPING) */ 1925