Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]
FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_pageout.c
Version:
- FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10
SearchContext: - none - 3 - 10
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: releng/10.1/sys/vm/vm_pageout.c 272221 2014-09-27 18:20:45Z smh $"); 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/smp.h> 94 #include <sys/vnode.h> 95 #include <sys/vmmeter.h> 96 #include <sys/rwlock.h> 97 #include <sys/sx.h> 98 #include <sys/sysctl.h> 99 100 #include <vm/vm.h> 101 #include <vm/vm_param.h> 102 #include <vm/vm_object.h> 103 #include <vm/vm_page.h> 104 #include <vm/vm_map.h> 105 #include <vm/vm_pageout.h> 106 #include <vm/vm_pager.h> 107 #include <vm/vm_phys.h> 108 #include <vm/swap_pager.h> 109 #include <vm/vm_extern.h> 110 #include <vm/uma.h> 111 112 /* 113 * System initialization 114 */ 115 116 /* the kernel process "vm_pageout"*/ 117 static void vm_pageout(void); 118 static int vm_pageout_clean(vm_page_t); 119 static void vm_pageout_scan(struct vm_domain *vmd, int pass); 120 static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass); 121 122 struct proc *pageproc; 123 124 static struct kproc_desc page_kp = { 125 "pagedaemon", 126 vm_pageout, 127 &pageproc 128 }; 129 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, 130 &page_kp); 131 132 #if !defined(NO_SWAPPING) 133 /* the kernel process "vm_daemon"*/ 134 static void vm_daemon(void); 135 static struct proc *vmproc; 136 137 static struct kproc_desc vm_kp = { 138 "vmdaemon", 139 vm_daemon, 140 &vmproc 141 }; 142 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp); 143 #endif 144 145 146 int vm_pages_needed; /* Event on which pageout daemon sleeps */ 147 int vm_pageout_deficit; /* Estimated number of pages deficit */ 148 int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 149 int vm_pageout_wakeup_thresh; 150 151 #if !defined(NO_SWAPPING) 152 static int vm_pageout_req_swapout; /* XXX */ 153 static int vm_daemon_needed; 154 static struct mtx vm_daemon_mtx; 155 /* Allow for use by vm_pageout before vm_daemon is initialized. */ 156 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); 157 #endif 158 static int vm_max_launder = 32; 159 static int vm_pageout_update_period; 160 static int defer_swap_pageouts; 161 static int disable_swap_pageouts; 162 static int lowmem_period = 10; 163 static int lowmem_ticks; 164 165 #if defined(NO_SWAPPING) 166 static int vm_swap_enabled = 0; 167 static int vm_swap_idle_enabled = 0; 168 #else 169 static int vm_swap_enabled = 1; 170 static int vm_swap_idle_enabled = 0; 171 #endif 172 173 SYSCTL_INT(_vm, OID_AUTO, pageout_wakeup_thresh, 174 CTLFLAG_RW, &vm_pageout_wakeup_thresh, 0, 175 "free page threshold for waking up the pageout daemon"); 176 177 SYSCTL_INT(_vm, OID_AUTO, max_launder, 178 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 179 180 SYSCTL_INT(_vm, OID_AUTO, pageout_update_period, 181 CTLFLAG_RW, &vm_pageout_update_period, 0, 182 "Maximum active LRU update period"); 183 184 SYSCTL_INT(_vm, OID_AUTO, lowmem_period, CTLFLAG_RW, &lowmem_period, 0, 185 "Low memory callback period"); 186 187 #if defined(NO_SWAPPING) 188 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 189 CTLFLAG_RD, &vm_swap_enabled, 0, "Enable entire process swapout"); 190 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 191 CTLFLAG_RD, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 192 #else 193 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 194 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 195 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 196 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 197 #endif 198 199 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 200 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 201 202 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 203 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 204 205 static int pageout_lock_miss; 206 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 207 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 208 209 #define VM_PAGEOUT_PAGE_COUNT 16 210 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 211 212 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 213 SYSCTL_INT(_vm, OID_AUTO, max_wired, 214 CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count"); 215 216 static boolean_t vm_pageout_fallback_object_lock(vm_page_t, vm_page_t *); 217 static boolean_t vm_pageout_launder(struct vm_pagequeue *pq, int, vm_paddr_t, 218 vm_paddr_t); 219 #if !defined(NO_SWAPPING) 220 static void vm_pageout_map_deactivate_pages(vm_map_t, long); 221 static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long); 222 static void vm_req_vmdaemon(int req); 223 #endif 224 static boolean_t vm_pageout_page_lock(vm_page_t, vm_page_t *); 225 226 /* 227 * Initialize a dummy page for marking the caller's place in the specified 228 * paging queue. In principle, this function only needs to set the flag 229 * PG_MARKER. Nonetheless, it wirte busies and initializes the hold count 230 * to one as safety precautions. 231 */ 232 static void 233 vm_pageout_init_marker(vm_page_t marker, u_short queue) 234 { 235 236 bzero(marker, sizeof(*marker)); 237 marker->flags = PG_MARKER; 238 marker->busy_lock = VPB_SINGLE_EXCLUSIVER; 239 marker->queue = queue; 240 marker->hold_count = 1; 241 } 242 243 /* 244 * vm_pageout_fallback_object_lock: 245 * 246 * Lock vm object currently associated with `m'. VM_OBJECT_TRYWLOCK is 247 * known to have failed and page queue must be either PQ_ACTIVE or 248 * PQ_INACTIVE. To avoid lock order violation, unlock the page queues 249 * while locking the vm object. Use marker page to detect page queue 250 * changes and maintain notion of next page on page queue. Return 251 * TRUE if no changes were detected, FALSE otherwise. vm object is 252 * locked on return. 253 * 254 * This function depends on both the lock portion of struct vm_object 255 * and normal struct vm_page being type stable. 256 */ 257 static boolean_t 258 vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next) 259 { 260 struct vm_page marker; 261 struct vm_pagequeue *pq; 262 boolean_t unchanged; 263 u_short queue; 264 vm_object_t object; 265 266 queue = m->queue; 267 vm_pageout_init_marker(&marker, queue); 268 pq = vm_page_pagequeue(m); 269 object = m->object; 270 271 TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q); 272 vm_pagequeue_unlock(pq); 273 vm_page_unlock(m); 274 VM_OBJECT_WLOCK(object); 275 vm_page_lock(m); 276 vm_pagequeue_lock(pq); 277 278 /* Page queue might have changed. */ 279 *next = TAILQ_NEXT(&marker, plinks.q); 280 unchanged = (m->queue == queue && 281 m->object == object && 282 &marker == TAILQ_NEXT(m, plinks.q)); 283 TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q); 284 return (unchanged); 285 } 286 287 /* 288 * Lock the page while holding the page queue lock. Use marker page 289 * to detect page queue changes and maintain notion of next page on 290 * page queue. Return TRUE if no changes were detected, FALSE 291 * otherwise. The page is locked on return. The page queue lock might 292 * be dropped and reacquired. 293 * 294 * This function depends on normal struct vm_page being type stable. 295 */ 296 static boolean_t 297 vm_pageout_page_lock(vm_page_t m, vm_page_t *next) 298 { 299 struct vm_page marker; 300 struct vm_pagequeue *pq; 301 boolean_t unchanged; 302 u_short queue; 303 304 vm_page_lock_assert(m, MA_NOTOWNED); 305 if (vm_page_trylock(m)) 306 return (TRUE); 307 308 queue = m->queue; 309 vm_pageout_init_marker(&marker, queue); 310 pq = vm_page_pagequeue(m); 311 312 TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q); 313 vm_pagequeue_unlock(pq); 314 vm_page_lock(m); 315 vm_pagequeue_lock(pq); 316 317 /* Page queue might have changed. */ 318 *next = TAILQ_NEXT(&marker, plinks.q); 319 unchanged = (m->queue == queue && &marker == TAILQ_NEXT(m, plinks.q)); 320 TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q); 321 return (unchanged); 322 } 323 324 /* 325 * vm_pageout_clean: 326 * 327 * Clean the page and remove it from the laundry. 328 * 329 * We set the busy bit to cause potential page faults on this page to 330 * block. Note the careful timing, however, the busy bit isn't set till 331 * late and we cannot do anything that will mess with the page. 332 */ 333 static int 334 vm_pageout_clean(vm_page_t m) 335 { 336 vm_object_t object; 337 vm_page_t mc[2*vm_pageout_page_count], pb, ps; 338 int pageout_count; 339 int ib, is, page_base; 340 vm_pindex_t pindex = m->pindex; 341 342 vm_page_lock_assert(m, MA_OWNED); 343 object = m->object; 344 VM_OBJECT_ASSERT_WLOCKED(object); 345 346 /* 347 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 348 * with the new swapper, but we could have serious problems paging 349 * out other object types if there is insufficient memory. 350 * 351 * Unfortunately, checking free memory here is far too late, so the 352 * check has been moved up a procedural level. 353 */ 354 355 /* 356 * Can't clean the page if it's busy or held. 357 */ 358 vm_page_assert_unbusied(m); 359 KASSERT(m->hold_count == 0, ("vm_pageout_clean: page %p is held", m)); 360 vm_page_unlock(m); 361 362 mc[vm_pageout_page_count] = pb = ps = m; 363 pageout_count = 1; 364 page_base = vm_pageout_page_count; 365 ib = 1; 366 is = 1; 367 368 /* 369 * Scan object for clusterable pages. 370 * 371 * We can cluster ONLY if: ->> the page is NOT 372 * clean, wired, busy, held, or mapped into a 373 * buffer, and one of the following: 374 * 1) The page is inactive, or a seldom used 375 * active page. 376 * -or- 377 * 2) we force the issue. 378 * 379 * During heavy mmap/modification loads the pageout 380 * daemon can really fragment the underlying file 381 * due to flushing pages out of order and not trying 382 * align the clusters (which leave sporatic out-of-order 383 * holes). To solve this problem we do the reverse scan 384 * first and attempt to align our cluster, then do a 385 * forward scan if room remains. 386 */ 387 more: 388 while (ib && pageout_count < vm_pageout_page_count) { 389 vm_page_t p; 390 391 if (ib > pindex) { 392 ib = 0; 393 break; 394 } 395 396 if ((p = vm_page_prev(pb)) == NULL || vm_page_busied(p)) { 397 ib = 0; 398 break; 399 } 400 vm_page_lock(p); 401 vm_page_test_dirty(p); 402 if (p->dirty == 0 || 403 p->queue != PQ_INACTIVE || 404 p->hold_count != 0) { /* may be undergoing I/O */ 405 vm_page_unlock(p); 406 ib = 0; 407 break; 408 } 409 vm_page_unlock(p); 410 mc[--page_base] = pb = p; 411 ++pageout_count; 412 ++ib; 413 /* 414 * alignment boundry, stop here and switch directions. Do 415 * not clear ib. 416 */ 417 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 418 break; 419 } 420 421 while (pageout_count < vm_pageout_page_count && 422 pindex + is < object->size) { 423 vm_page_t p; 424 425 if ((p = vm_page_next(ps)) == NULL || vm_page_busied(p)) 426 break; 427 vm_page_lock(p); 428 vm_page_test_dirty(p); 429 if (p->dirty == 0 || 430 p->queue != PQ_INACTIVE || 431 p->hold_count != 0) { /* may be undergoing I/O */ 432 vm_page_unlock(p); 433 break; 434 } 435 vm_page_unlock(p); 436 mc[page_base + pageout_count] = ps = p; 437 ++pageout_count; 438 ++is; 439 } 440 441 /* 442 * If we exhausted our forward scan, continue with the reverse scan 443 * when possible, even past a page boundry. This catches boundry 444 * conditions. 445 */ 446 if (ib && pageout_count < vm_pageout_page_count) 447 goto more; 448 449 /* 450 * we allow reads during pageouts... 451 */ 452 return (vm_pageout_flush(&mc[page_base], pageout_count, 0, 0, NULL, 453 NULL)); 454 } 455 456 /* 457 * vm_pageout_flush() - launder the given pages 458 * 459 * The given pages are laundered. Note that we setup for the start of 460 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 461 * reference count all in here rather then in the parent. If we want 462 * the parent to do more sophisticated things we may have to change 463 * the ordering. 464 * 465 * Returned runlen is the count of pages between mreq and first 466 * page after mreq with status VM_PAGER_AGAIN. 467 * *eio is set to TRUE if pager returned VM_PAGER_ERROR or VM_PAGER_FAIL 468 * for any page in runlen set. 469 */ 470 int 471 vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen, 472 boolean_t *eio) 473 { 474 vm_object_t object = mc[0]->object; 475 int pageout_status[count]; 476 int numpagedout = 0; 477 int i, runlen; 478 479 VM_OBJECT_ASSERT_WLOCKED(object); 480 481 /* 482 * Initiate I/O. Bump the vm_page_t->busy counter and 483 * mark the pages read-only. 484 * 485 * We do not have to fixup the clean/dirty bits here... we can 486 * allow the pager to do it after the I/O completes. 487 * 488 * NOTE! mc[i]->dirty may be partial or fragmented due to an 489 * edge case with file fragments. 490 */ 491 for (i = 0; i < count; i++) { 492 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 493 ("vm_pageout_flush: partially invalid page %p index %d/%d", 494 mc[i], i, count)); 495 vm_page_sbusy(mc[i]); 496 pmap_remove_write(mc[i]); 497 } 498 vm_object_pip_add(object, count); 499 500 vm_pager_put_pages(object, mc, count, flags, pageout_status); 501 502 runlen = count - mreq; 503 if (eio != NULL) 504 *eio = FALSE; 505 for (i = 0; i < count; i++) { 506 vm_page_t mt = mc[i]; 507 508 KASSERT(pageout_status[i] == VM_PAGER_PEND || 509 !pmap_page_is_write_mapped(mt), 510 ("vm_pageout_flush: page %p is not write protected", mt)); 511 switch (pageout_status[i]) { 512 case VM_PAGER_OK: 513 case VM_PAGER_PEND: 514 numpagedout++; 515 break; 516 case VM_PAGER_BAD: 517 /* 518 * Page outside of range of object. Right now we 519 * essentially lose the changes by pretending it 520 * worked. 521 */ 522 vm_page_undirty(mt); 523 break; 524 case VM_PAGER_ERROR: 525 case VM_PAGER_FAIL: 526 /* 527 * If page couldn't be paged out, then reactivate the 528 * page so it doesn't clog the inactive list. (We 529 * will try paging out it again later). 530 */ 531 vm_page_lock(mt); 532 vm_page_activate(mt); 533 vm_page_unlock(mt); 534 if (eio != NULL && i >= mreq && i - mreq < runlen) 535 *eio = TRUE; 536 break; 537 case VM_PAGER_AGAIN: 538 if (i >= mreq && i - mreq < runlen) 539 runlen = i - mreq; 540 break; 541 } 542 543 /* 544 * If the operation is still going, leave the page busy to 545 * block all other accesses. Also, leave the paging in 546 * progress indicator set so that we don't attempt an object 547 * collapse. 548 */ 549 if (pageout_status[i] != VM_PAGER_PEND) { 550 vm_object_pip_wakeup(object); 551 vm_page_sunbusy(mt); 552 if (vm_page_count_severe()) { 553 vm_page_lock(mt); 554 vm_page_try_to_cache(mt); 555 vm_page_unlock(mt); 556 } 557 } 558 } 559 if (prunlen != NULL) 560 *prunlen = runlen; 561 return (numpagedout); 562 } 563 564 static boolean_t 565 vm_pageout_launder(struct vm_pagequeue *pq, int tries, vm_paddr_t low, 566 vm_paddr_t high) 567 { 568 struct mount *mp; 569 struct vnode *vp; 570 vm_object_t object; 571 vm_paddr_t pa; 572 vm_page_t m, m_tmp, next; 573 int lockmode; 574 575 vm_pagequeue_lock(pq); 576 TAILQ_FOREACH_SAFE(m, &pq->pq_pl, plinks.q, next) { 577 if ((m->flags & PG_MARKER) != 0) 578 continue; 579 pa = VM_PAGE_TO_PHYS(m); 580 if (pa < low || pa + PAGE_SIZE > high) 581 continue; 582 if (!vm_pageout_page_lock(m, &next) || m->hold_count != 0) { 583 vm_page_unlock(m); 584 continue; 585 } 586 object = m->object; 587 if ((!VM_OBJECT_TRYWLOCK(object) && 588 (!vm_pageout_fallback_object_lock(m, &next) || 589 m->hold_count != 0)) || vm_page_busied(m)) { 590 vm_page_unlock(m); 591 VM_OBJECT_WUNLOCK(object); 592 continue; 593 } 594 vm_page_test_dirty(m); 595 if (m->dirty == 0 && object->ref_count != 0) 596 pmap_remove_all(m); 597 if (m->dirty != 0) { 598 vm_page_unlock(m); 599 if (tries == 0 || (object->flags & OBJ_DEAD) != 0) { 600 VM_OBJECT_WUNLOCK(object); 601 continue; 602 } 603 if (object->type == OBJT_VNODE) { 604 vm_pagequeue_unlock(pq); 605 vp = object->handle; 606 vm_object_reference_locked(object); 607 VM_OBJECT_WUNLOCK(object); 608 (void)vn_start_write(vp, &mp, V_WAIT); 609 lockmode = MNT_SHARED_WRITES(vp->v_mount) ? 610 LK_SHARED : LK_EXCLUSIVE; 611 vn_lock(vp, lockmode | LK_RETRY); 612 VM_OBJECT_WLOCK(object); 613 vm_object_page_clean(object, 0, 0, OBJPC_SYNC); 614 VM_OBJECT_WUNLOCK(object); 615 VOP_UNLOCK(vp, 0); 616 vm_object_deallocate(object); 617 vn_finished_write(mp); 618 return (TRUE); 619 } else if (object->type == OBJT_SWAP || 620 object->type == OBJT_DEFAULT) { 621 vm_pagequeue_unlock(pq); 622 m_tmp = m; 623 vm_pageout_flush(&m_tmp, 1, VM_PAGER_PUT_SYNC, 624 0, NULL, NULL); 625 VM_OBJECT_WUNLOCK(object); 626 return (TRUE); 627 } 628 } else { 629 /* 630 * Dequeue here to prevent lock recursion in 631 * vm_page_cache(). 632 */ 633 vm_page_dequeue_locked(m); 634 vm_page_cache(m); 635 vm_page_unlock(m); 636 } 637 VM_OBJECT_WUNLOCK(object); 638 } 639 vm_pagequeue_unlock(pq); 640 return (FALSE); 641 } 642 643 /* 644 * Increase the number of cached pages. The specified value, "tries", 645 * determines which categories of pages are cached: 646 * 647 * 0: All clean, inactive pages within the specified physical address range 648 * are cached. Will not sleep. 649 * 1: The vm_lowmem handlers are called. All inactive pages within 650 * the specified physical address range are cached. May sleep. 651 * 2: The vm_lowmem handlers are called. All inactive and active pages 652 * within the specified physical address range are cached. May sleep. 653 */ 654 void 655 vm_pageout_grow_cache(int tries, vm_paddr_t low, vm_paddr_t high) 656 { 657 int actl, actmax, inactl, inactmax, dom, initial_dom; 658 static int start_dom = 0; 659 660 if (tries > 0) { 661 /* 662 * Decrease registered cache sizes. The vm_lowmem handlers 663 * may acquire locks and/or sleep, so they can only be invoked 664 * when "tries" is greater than zero. 665 */ 666 EVENTHANDLER_INVOKE(vm_lowmem, 0); 667 668 /* 669 * We do this explicitly after the caches have been drained 670 * above. 671 */ 672 uma_reclaim(); 673 } 674 675 /* 676 * Make the next scan start on the next domain. 677 */ 678 initial_dom = atomic_fetchadd_int(&start_dom, 1) % vm_ndomains; 679 680 inactl = 0; 681 inactmax = cnt.v_inactive_count; 682 actl = 0; 683 actmax = tries < 2 ? 0 : cnt.v_active_count; 684 dom = initial_dom; 685 686 /* 687 * Scan domains in round-robin order, first inactive queues, 688 * then active. Since domain usually owns large physically 689 * contiguous chunk of memory, it makes sense to completely 690 * exhaust one domain before switching to next, while growing 691 * the pool of contiguous physical pages. 692 * 693 * Do not even start launder a domain which cannot contain 694 * the specified address range, as indicated by segments 695 * constituting the domain. 696 */ 697 again: 698 if (inactl < inactmax) { 699 if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs, 700 low, high) && 701 vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_INACTIVE], 702 tries, low, high)) { 703 inactl++; 704 goto again; 705 } 706 if (++dom == vm_ndomains) 707 dom = 0; 708 if (dom != initial_dom) 709 goto again; 710 } 711 if (actl < actmax) { 712 if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs, 713 low, high) && 714 vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_ACTIVE], 715 tries, low, high)) { 716 actl++; 717 goto again; 718 } 719 if (++dom == vm_ndomains) 720 dom = 0; 721 if (dom != initial_dom) 722 goto again; 723 } 724 } 725 726 #if !defined(NO_SWAPPING) 727 /* 728 * vm_pageout_object_deactivate_pages 729 * 730 * Deactivate enough pages to satisfy the inactive target 731 * requirements. 732 * 733 * The object and map must be locked. 734 */ 735 static void 736 vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object, 737 long desired) 738 { 739 vm_object_t backing_object, object; 740 vm_page_t p; 741 int act_delta, remove_mode; 742 743 VM_OBJECT_ASSERT_LOCKED(first_object); 744 if ((first_object->flags & OBJ_FICTITIOUS) != 0) 745 return; 746 for (object = first_object;; object = backing_object) { 747 if (pmap_resident_count(pmap) <= desired) 748 goto unlock_return; 749 VM_OBJECT_ASSERT_LOCKED(object); 750 if ((object->flags & OBJ_UNMANAGED) != 0 || 751 object->paging_in_progress != 0) 752 goto unlock_return; 753 754 remove_mode = 0; 755 if (object->shadow_count > 1) 756 remove_mode = 1; 757 /* 758 * Scan the object's entire memory queue. 759 */ 760 TAILQ_FOREACH(p, &object->memq, listq) { 761 if (pmap_resident_count(pmap) <= desired) 762 goto unlock_return; 763 if (vm_page_busied(p)) 764 continue; 765 PCPU_INC(cnt.v_pdpages); 766 vm_page_lock(p); 767 if (p->wire_count != 0 || p->hold_count != 0 || 768 !pmap_page_exists_quick(pmap, p)) { 769 vm_page_unlock(p); 770 continue; 771 } 772 act_delta = pmap_ts_referenced(p); 773 if ((p->aflags & PGA_REFERENCED) != 0) { 774 if (act_delta == 0) 775 act_delta = 1; 776 vm_page_aflag_clear(p, PGA_REFERENCED); 777 } 778 if (p->queue != PQ_ACTIVE && act_delta != 0) { 779 vm_page_activate(p); 780 p->act_count += act_delta; 781 } else if (p->queue == PQ_ACTIVE) { 782 if (act_delta == 0) { 783 p->act_count -= min(p->act_count, 784 ACT_DECLINE); 785 if (!remove_mode && p->act_count == 0) { 786 pmap_remove_all(p); 787 vm_page_deactivate(p); 788 } else 789 vm_page_requeue(p); 790 } else { 791 vm_page_activate(p); 792 if (p->act_count < ACT_MAX - 793 ACT_ADVANCE) 794 p->act_count += ACT_ADVANCE; 795 vm_page_requeue(p); 796 } 797 } else if (p->queue == PQ_INACTIVE) 798 pmap_remove_all(p); 799 vm_page_unlock(p); 800 } 801 if ((backing_object = object->backing_object) == NULL) 802 goto unlock_return; 803 VM_OBJECT_RLOCK(backing_object); 804 if (object != first_object) 805 VM_OBJECT_RUNLOCK(object); 806 } 807 unlock_return: 808 if (object != first_object) 809 VM_OBJECT_RUNLOCK(object); 810 } 811 812 /* 813 * deactivate some number of pages in a map, try to do it fairly, but 814 * that is really hard to do. 815 */ 816 static void 817 vm_pageout_map_deactivate_pages(map, desired) 818 vm_map_t map; 819 long desired; 820 { 821 vm_map_entry_t tmpe; 822 vm_object_t obj, bigobj; 823 int nothingwired; 824 825 if (!vm_map_trylock(map)) 826 return; 827 828 bigobj = NULL; 829 nothingwired = TRUE; 830 831 /* 832 * first, search out the biggest object, and try to free pages from 833 * that. 834 */ 835 tmpe = map->header.next; 836 while (tmpe != &map->header) { 837 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 838 obj = tmpe->object.vm_object; 839 if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) { 840 if (obj->shadow_count <= 1 && 841 (bigobj == NULL || 842 bigobj->resident_page_count < obj->resident_page_count)) { 843 if (bigobj != NULL) 844 VM_OBJECT_RUNLOCK(bigobj); 845 bigobj = obj; 846 } else 847 VM_OBJECT_RUNLOCK(obj); 848 } 849 } 850 if (tmpe->wired_count > 0) 851 nothingwired = FALSE; 852 tmpe = tmpe->next; 853 } 854 855 if (bigobj != NULL) { 856 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); 857 VM_OBJECT_RUNLOCK(bigobj); 858 } 859 /* 860 * Next, hunt around for other pages to deactivate. We actually 861 * do this search sort of wrong -- .text first is not the best idea. 862 */ 863 tmpe = map->header.next; 864 while (tmpe != &map->header) { 865 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 866 break; 867 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 868 obj = tmpe->object.vm_object; 869 if (obj != NULL) { 870 VM_OBJECT_RLOCK(obj); 871 vm_pageout_object_deactivate_pages(map->pmap, obj, desired); 872 VM_OBJECT_RUNLOCK(obj); 873 } 874 } 875 tmpe = tmpe->next; 876 } 877 878 #ifdef __ia64__ 879 /* 880 * Remove all non-wired, managed mappings if a process is swapped out. 881 * This will free page table pages. 882 */ 883 if (desired == 0) 884 pmap_remove_pages(map->pmap); 885 #else 886 /* 887 * Remove all mappings if a process is swapped out, this will free page 888 * table pages. 889 */ 890 if (desired == 0 && nothingwired) { 891 pmap_remove(vm_map_pmap(map), vm_map_min(map), 892 vm_map_max(map)); 893 } 894 #endif 895 896 vm_map_unlock(map); 897 } 898 #endif /* !defined(NO_SWAPPING) */ 899 900 /* 901 * vm_pageout_scan does the dirty work for the pageout daemon. 902 * 903 * pass 0 - Update active LRU/deactivate pages 904 * pass 1 - Move inactive to cache or free 905 * pass 2 - Launder dirty pages 906 */ 907 static void 908 vm_pageout_scan(struct vm_domain *vmd, int pass) 909 { 910 vm_page_t m, next; 911 struct vm_pagequeue *pq; 912 vm_object_t object; 913 int act_delta, addl_page_shortage, deficit, maxscan, page_shortage; 914 int vnodes_skipped = 0; 915 int maxlaunder; 916 int lockmode; 917 boolean_t queues_locked; 918 919 /* 920 * If we need to reclaim memory ask kernel caches to return 921 * some. We rate limit to avoid thrashing. 922 */ 923 if (vmd == &vm_dom[0] && pass > 0 && 924 (ticks - lowmem_ticks) / hz >= lowmem_period) { 925 /* 926 * Decrease registered cache sizes. 927 */ 928 EVENTHANDLER_INVOKE(vm_lowmem, 0); 929 /* 930 * We do this explicitly after the caches have been 931 * drained above. 932 */ 933 uma_reclaim(); 934 lowmem_ticks = ticks; 935 } 936 937 /* 938 * The addl_page_shortage is the number of temporarily 939 * stuck pages in the inactive queue. In other words, the 940 * number of pages from the inactive count that should be 941 * discounted in setting the target for the active queue scan. 942 */ 943 addl_page_shortage = 0; 944 945 /* 946 * Calculate the number of pages we want to either free or move 947 * to the cache. 948 */ 949 if (pass > 0) { 950 deficit = atomic_readandclear_int(&vm_pageout_deficit); 951 page_shortage = vm_paging_target() + deficit; 952 } else 953 page_shortage = deficit = 0; 954 955 /* 956 * maxlaunder limits the number of dirty pages we flush per scan. 957 * For most systems a smaller value (16 or 32) is more robust under 958 * extreme memory and disk pressure because any unnecessary writes 959 * to disk can result in extreme performance degredation. However, 960 * systems with excessive dirty pages (especially when MAP_NOSYNC is 961 * used) will die horribly with limited laundering. If the pageout 962 * daemon cannot clean enough pages in the first pass, we let it go 963 * all out in succeeding passes. 964 */ 965 if ((maxlaunder = vm_max_launder) <= 1) 966 maxlaunder = 1; 967 if (pass > 1) 968 maxlaunder = 10000; 969 970 /* 971 * Start scanning the inactive queue for pages we can move to the 972 * cache or free. The scan will stop when the target is reached or 973 * we have scanned the entire inactive queue. Note that m->act_count 974 * is not used to form decisions for the inactive queue, only for the 975 * active queue. 976 */ 977 pq = &vmd->vmd_pagequeues[PQ_INACTIVE]; 978 maxscan = pq->pq_cnt; 979 vm_pagequeue_lock(pq); 980 queues_locked = TRUE; 981 for (m = TAILQ_FIRST(&pq->pq_pl); 982 m != NULL && maxscan-- > 0 && page_shortage > 0; 983 m = next) { 984 vm_pagequeue_assert_locked(pq); 985 KASSERT(queues_locked, ("unlocked queues")); 986 KASSERT(m->queue == PQ_INACTIVE, ("Inactive queue %p", m)); 987 988 PCPU_INC(cnt.v_pdpages); 989 next = TAILQ_NEXT(m, plinks.q); 990 991 /* 992 * skip marker pages 993 */ 994 if (m->flags & PG_MARKER) 995 continue; 996 997 KASSERT((m->flags & PG_FICTITIOUS) == 0, 998 ("Fictitious page %p cannot be in inactive queue", m)); 999 KASSERT((m->oflags & VPO_UNMANAGED) == 0, 1000 ("Unmanaged page %p cannot be in inactive queue", m)); 1001 1002 /* 1003 * The page or object lock acquisitions fail if the 1004 * page was removed from the queue or moved to a 1005 * different position within the queue. In either 1006 * case, addl_page_shortage should not be incremented. 1007 */ 1008 if (!vm_pageout_page_lock(m, &next)) { 1009 vm_page_unlock(m); 1010 continue; 1011 } 1012 object = m->object; 1013 if (!VM_OBJECT_TRYWLOCK(object) && 1014 !vm_pageout_fallback_object_lock(m, &next)) { 1015 vm_page_unlock(m); 1016 VM_OBJECT_WUNLOCK(object); 1017 continue; 1018 } 1019 1020 /* 1021 * Don't mess with busy pages, keep them at at the 1022 * front of the queue, most likely they are being 1023 * paged out. Increment addl_page_shortage for busy 1024 * pages, because they may leave the inactive queue 1025 * shortly after page scan is finished. 1026 */ 1027 if (vm_page_busied(m)) { 1028 vm_page_unlock(m); 1029 VM_OBJECT_WUNLOCK(object); 1030 addl_page_shortage++; 1031 continue; 1032 } 1033 1034 /* 1035 * We unlock the inactive page queue, invalidating the 1036 * 'next' pointer. Use our marker to remember our 1037 * place. 1038 */ 1039 TAILQ_INSERT_AFTER(&pq->pq_pl, m, &vmd->vmd_marker, plinks.q); 1040 vm_pagequeue_unlock(pq); 1041 queues_locked = FALSE; 1042 1043 /* 1044 * We bump the activation count if the page has been 1045 * referenced while in the inactive queue. This makes 1046 * it less likely that the page will be added back to the 1047 * inactive queue prematurely again. Here we check the 1048 * page tables (or emulated bits, if any), given the upper 1049 * level VM system not knowing anything about existing 1050 * references. 1051 */ 1052 act_delta = 0; 1053 if ((m->aflags & PGA_REFERENCED) != 0) { 1054 vm_page_aflag_clear(m, PGA_REFERENCED); 1055 act_delta = 1; 1056 } 1057 if (object->ref_count != 0) { 1058 act_delta += pmap_ts_referenced(m); 1059 } else { 1060 KASSERT(!pmap_page_is_mapped(m), 1061 ("vm_pageout_scan: page %p is mapped", m)); 1062 } 1063 1064 /* 1065 * If the upper level VM system knows about any page 1066 * references, we reactivate the page or requeue it. 1067 */ 1068 if (act_delta != 0) { 1069 if (object->ref_count) { 1070 vm_page_activate(m); 1071 m->act_count += act_delta + ACT_ADVANCE; 1072 } else { 1073 vm_pagequeue_lock(pq); 1074 queues_locked = TRUE; 1075 vm_page_requeue_locked(m); 1076 } 1077 VM_OBJECT_WUNLOCK(object); 1078 vm_page_unlock(m); 1079 goto relock_queues; 1080 } 1081 1082 if (m->hold_count != 0) { 1083 vm_page_unlock(m); 1084 VM_OBJECT_WUNLOCK(object); 1085 1086 /* 1087 * Held pages are essentially stuck in the 1088 * queue. So, they ought to be discounted 1089 * from the inactive count. See the 1090 * calculation of the page_shortage for the 1091 * loop over the active queue below. 1092 */ 1093 addl_page_shortage++; 1094 goto relock_queues; 1095 } 1096 1097 /* 1098 * If the page appears to be clean at the machine-independent 1099 * layer, then remove all of its mappings from the pmap in 1100 * anticipation of placing it onto the cache queue. If, 1101 * however, any of the page's mappings allow write access, 1102 * then the page may still be modified until the last of those 1103 * mappings are removed. 1104 */ 1105 vm_page_test_dirty(m); 1106 if (m->dirty == 0 && object->ref_count != 0) 1107 pmap_remove_all(m); 1108 1109 if (m->valid == 0) { 1110 /* 1111 * Invalid pages can be easily freed 1112 */ 1113 vm_page_free(m); 1114 PCPU_INC(cnt.v_dfree); 1115 --page_shortage; 1116 } else if (m->dirty == 0) { 1117 /* 1118 * Clean pages can be placed onto the cache queue. 1119 * This effectively frees them. 1120 */ 1121 vm_page_cache(m); 1122 --page_shortage; 1123 } else if ((m->flags & PG_WINATCFLS) == 0 && pass < 2) { 1124 /* 1125 * Dirty pages need to be paged out, but flushing 1126 * a page is extremely expensive verses freeing 1127 * a clean page. Rather then artificially limiting 1128 * the number of pages we can flush, we instead give 1129 * dirty pages extra priority on the inactive queue 1130 * by forcing them to be cycled through the queue 1131 * twice before being flushed, after which the 1132 * (now clean) page will cycle through once more 1133 * before being freed. This significantly extends 1134 * the thrash point for a heavily loaded machine. 1135 */ 1136 m->flags |= PG_WINATCFLS; 1137 vm_pagequeue_lock(pq); 1138 queues_locked = TRUE; 1139 vm_page_requeue_locked(m); 1140 } else if (maxlaunder > 0) { 1141 /* 1142 * We always want to try to flush some dirty pages if 1143 * we encounter them, to keep the system stable. 1144 * Normally this number is small, but under extreme 1145 * pressure where there are insufficient clean pages 1146 * on the inactive queue, we may have to go all out. 1147 */ 1148 int swap_pageouts_ok; 1149 struct vnode *vp = NULL; 1150 struct mount *mp = NULL; 1151 1152 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 1153 swap_pageouts_ok = 1; 1154 } else { 1155 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 1156 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 1157 vm_page_count_min()); 1158 1159 } 1160 1161 /* 1162 * We don't bother paging objects that are "dead". 1163 * Those objects are in a "rundown" state. 1164 */ 1165 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 1166 vm_pagequeue_lock(pq); 1167 vm_page_unlock(m); 1168 VM_OBJECT_WUNLOCK(object); 1169 queues_locked = TRUE; 1170 vm_page_requeue_locked(m); 1171 goto relock_queues; 1172 } 1173 1174 /* 1175 * The object is already known NOT to be dead. It 1176 * is possible for the vget() to block the whole 1177 * pageout daemon, but the new low-memory handling 1178 * code should prevent it. 1179 * 1180 * The previous code skipped locked vnodes and, worse, 1181 * reordered pages in the queue. This results in 1182 * completely non-deterministic operation and, on a 1183 * busy system, can lead to extremely non-optimal 1184 * pageouts. For example, it can cause clean pages 1185 * to be freed and dirty pages to be moved to the end 1186 * of the queue. Since dirty pages are also moved to 1187 * the end of the queue once-cleaned, this gives 1188 * way too large a weighting to defering the freeing 1189 * of dirty pages. 1190 * 1191 * We can't wait forever for the vnode lock, we might 1192 * deadlock due to a vn_read() getting stuck in 1193 * vm_wait while holding this vnode. We skip the 1194 * vnode if we can't get it in a reasonable amount 1195 * of time. 1196 */ 1197 if (object->type == OBJT_VNODE) { 1198 vm_page_unlock(m); 1199 vp = object->handle; 1200 if (vp->v_type == VREG && 1201 vn_start_write(vp, &mp, V_NOWAIT) != 0) { 1202 mp = NULL; 1203 ++pageout_lock_miss; 1204 if (object->flags & OBJ_MIGHTBEDIRTY) 1205 vnodes_skipped++; 1206 goto unlock_and_continue; 1207 } 1208 KASSERT(mp != NULL, 1209 ("vp %p with NULL v_mount", vp)); 1210 vm_object_reference_locked(object); 1211 VM_OBJECT_WUNLOCK(object); 1212 lockmode = MNT_SHARED_WRITES(vp->v_mount) ? 1213 LK_SHARED : LK_EXCLUSIVE; 1214 if (vget(vp, lockmode | LK_TIMELOCK, 1215 curthread)) { 1216 VM_OBJECT_WLOCK(object); 1217 ++pageout_lock_miss; 1218 if (object->flags & OBJ_MIGHTBEDIRTY) 1219 vnodes_skipped++; 1220 vp = NULL; 1221 goto unlock_and_continue; 1222 } 1223 VM_OBJECT_WLOCK(object); 1224 vm_page_lock(m); 1225 vm_pagequeue_lock(pq); 1226 queues_locked = TRUE; 1227 /* 1228 * The page might have been moved to another 1229 * queue during potential blocking in vget() 1230 * above. The page might have been freed and 1231 * reused for another vnode. 1232 */ 1233 if (m->queue != PQ_INACTIVE || 1234 m->object != object || 1235 TAILQ_NEXT(m, plinks.q) != &vmd->vmd_marker) { 1236 vm_page_unlock(m); 1237 if (object->flags & OBJ_MIGHTBEDIRTY) 1238 vnodes_skipped++; 1239 goto unlock_and_continue; 1240 } 1241 1242 /* 1243 * The page may have been busied during the 1244 * blocking in vget(). We don't move the 1245 * page back onto the end of the queue so that 1246 * statistics are more correct if we don't. 1247 */ 1248 if (vm_page_busied(m)) { 1249 vm_page_unlock(m); 1250 addl_page_shortage++; 1251 goto unlock_and_continue; 1252 } 1253 1254 /* 1255 * If the page has become held it might 1256 * be undergoing I/O, so skip it 1257 */ 1258 if (m->hold_count != 0) { 1259 vm_page_unlock(m); 1260 addl_page_shortage++; 1261 if (object->flags & OBJ_MIGHTBEDIRTY) 1262 vnodes_skipped++; 1263 goto unlock_and_continue; 1264 } 1265 vm_pagequeue_unlock(pq); 1266 queues_locked = FALSE; 1267 } 1268 1269 /* 1270 * If a page is dirty, then it is either being washed 1271 * (but not yet cleaned) or it is still in the 1272 * laundry. If it is still in the laundry, then we 1273 * start the cleaning operation. 1274 * 1275 * decrement page_shortage on success to account for 1276 * the (future) cleaned page. Otherwise we could wind 1277 * up laundering or cleaning too many pages. 1278 */ 1279 if (vm_pageout_clean(m) != 0) { 1280 --page_shortage; 1281 --maxlaunder; 1282 } 1283 unlock_and_continue: 1284 vm_page_lock_assert(m, MA_NOTOWNED); 1285 VM_OBJECT_WUNLOCK(object); 1286 if (mp != NULL) { 1287 if (queues_locked) { 1288 vm_pagequeue_unlock(pq); 1289 queues_locked = FALSE; 1290 } 1291 if (vp != NULL) 1292 vput(vp); 1293 vm_object_deallocate(object); 1294 vn_finished_write(mp); 1295 } 1296 vm_page_lock_assert(m, MA_NOTOWNED); 1297 goto relock_queues; 1298 } 1299 vm_page_unlock(m); 1300 VM_OBJECT_WUNLOCK(object); 1301 relock_queues: 1302 if (!queues_locked) { 1303 vm_pagequeue_lock(pq); 1304 queues_locked = TRUE; 1305 } 1306 next = TAILQ_NEXT(&vmd->vmd_marker, plinks.q); 1307 TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_marker, plinks.q); 1308 } 1309 vm_pagequeue_unlock(pq); 1310 1311 #if !defined(NO_SWAPPING) 1312 /* 1313 * Wakeup the swapout daemon if we didn't cache or free the targeted 1314 * number of pages. 1315 */ 1316 if (vm_swap_enabled && page_shortage > 0) 1317 vm_req_vmdaemon(VM_SWAP_NORMAL); 1318 #endif 1319 1320 /* 1321 * Wakeup the sync daemon if we skipped a vnode in a writeable object 1322 * and we didn't cache or free enough pages. 1323 */ 1324 if (vnodes_skipped > 0 && page_shortage > cnt.v_free_target - 1325 cnt.v_free_min) 1326 (void)speedup_syncer(); 1327 1328 /* 1329 * Compute the number of pages we want to try to move from the 1330 * active queue to the inactive queue. 1331 */ 1332 page_shortage = cnt.v_inactive_target - cnt.v_inactive_count + 1333 vm_paging_target() + deficit + addl_page_shortage; 1334 1335 pq = &vmd->vmd_pagequeues[PQ_ACTIVE]; 1336 vm_pagequeue_lock(pq); 1337 maxscan = pq->pq_cnt; 1338 1339 /* 1340 * If we're just idle polling attempt to visit every 1341 * active page within 'update_period' seconds. 1342 */ 1343 if (pass == 0 && vm_pageout_update_period != 0) { 1344 maxscan /= vm_pageout_update_period; 1345 page_shortage = maxscan; 1346 } 1347 1348 /* 1349 * Scan the active queue for things we can deactivate. We nominally 1350 * track the per-page activity counter and use it to locate 1351 * deactivation candidates. 1352 */ 1353 m = TAILQ_FIRST(&pq->pq_pl); 1354 while (m != NULL && maxscan-- > 0 && page_shortage > 0) { 1355 1356 KASSERT(m->queue == PQ_ACTIVE, 1357 ("vm_pageout_scan: page %p isn't active", m)); 1358 1359 next = TAILQ_NEXT(m, plinks.q); 1360 if ((m->flags & PG_MARKER) != 0) { 1361 m = next; 1362 continue; 1363 } 1364 KASSERT((m->flags & PG_FICTITIOUS) == 0, 1365 ("Fictitious page %p cannot be in active queue", m)); 1366 KASSERT((m->oflags & VPO_UNMANAGED) == 0, 1367 ("Unmanaged page %p cannot be in active queue", m)); 1368 if (!vm_pageout_page_lock(m, &next)) { 1369 vm_page_unlock(m); 1370 m = next; 1371 continue; 1372 } 1373 1374 /* 1375 * The count for pagedaemon pages is done after checking the 1376 * page for eligibility... 1377 */ 1378 PCPU_INC(cnt.v_pdpages); 1379 1380 /* 1381 * Check to see "how much" the page has been used. 1382 */ 1383 act_delta = 0; 1384 if (m->aflags & PGA_REFERENCED) { 1385 vm_page_aflag_clear(m, PGA_REFERENCED); 1386 act_delta += 1; 1387 } 1388 /* 1389 * Unlocked object ref count check. Two races are possible. 1390 * 1) The ref was transitioning to zero and we saw non-zero, 1391 * the pmap bits will be checked unnecessarily. 1392 * 2) The ref was transitioning to one and we saw zero. 1393 * The page lock prevents a new reference to this page so 1394 * we need not check the reference bits. 1395 */ 1396 if (m->object->ref_count != 0) 1397 act_delta += pmap_ts_referenced(m); 1398 1399 /* 1400 * Advance or decay the act_count based on recent usage. 1401 */ 1402 if (act_delta) { 1403 m->act_count += ACT_ADVANCE + act_delta; 1404 if (m->act_count > ACT_MAX) 1405 m->act_count = ACT_MAX; 1406 } else { 1407 m->act_count -= min(m->act_count, ACT_DECLINE); 1408 act_delta = m->act_count; 1409 } 1410 1411 /* 1412 * Move this page to the tail of the active or inactive 1413 * queue depending on usage. 1414 */ 1415 if (act_delta == 0) { 1416 /* Dequeue to avoid later lock recursion. */ 1417 vm_page_dequeue_locked(m); 1418 vm_page_deactivate(m); 1419 page_shortage--; 1420 } else 1421 vm_page_requeue_locked(m); 1422 vm_page_unlock(m); 1423 m = next; 1424 } 1425 vm_pagequeue_unlock(pq); 1426 #if !defined(NO_SWAPPING) 1427 /* 1428 * Idle process swapout -- run once per second. 1429 */ 1430 if (vm_swap_idle_enabled) { 1431 static long lsec; 1432 if (time_second != lsec) { 1433 vm_req_vmdaemon(VM_SWAP_IDLE); 1434 lsec = time_second; 1435 } 1436 } 1437 #endif 1438 1439 /* 1440 * If we are critically low on one of RAM or swap and low on 1441 * the other, kill the largest process. However, we avoid 1442 * doing this on the first pass in order to give ourselves a 1443 * chance to flush out dirty vnode-backed pages and to allow 1444 * active pages to be moved to the inactive queue and reclaimed. 1445 */ 1446 vm_pageout_mightbe_oom(vmd, pass); 1447 } 1448 1449 static int vm_pageout_oom_vote; 1450 1451 /* 1452 * The pagedaemon threads randlomly select one to perform the 1453 * OOM. Trying to kill processes before all pagedaemons 1454 * failed to reach free target is premature. 1455 */ 1456 static void 1457 vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass) 1458 { 1459 int old_vote; 1460 1461 if (pass <= 1 || !((swap_pager_avail < 64 && vm_page_count_min()) || 1462 (swap_pager_full && vm_paging_target() > 0))) { 1463 if (vmd->vmd_oom) { 1464 vmd->vmd_oom = FALSE; 1465 atomic_subtract_int(&vm_pageout_oom_vote, 1); 1466 } 1467 return; 1468 } 1469 1470 if (vmd->vmd_oom) 1471 return; 1472 1473 vmd->vmd_oom = TRUE; 1474 old_vote = atomic_fetchadd_int(&vm_pageout_oom_vote, 1); 1475 if (old_vote != vm_ndomains - 1) 1476 return; 1477 1478 /* 1479 * The current pagedaemon thread is the last in the quorum to 1480 * start OOM. Initiate the selection and signaling of the 1481 * victim. 1482 */ 1483 vm_pageout_oom(VM_OOM_MEM); 1484 1485 /* 1486 * After one round of OOM terror, recall our vote. On the 1487 * next pass, current pagedaemon would vote again if the low 1488 * memory condition is still there, due to vmd_oom being 1489 * false. 1490 */ 1491 vmd->vmd_oom = FALSE; 1492 atomic_subtract_int(&vm_pageout_oom_vote, 1); 1493 } 1494 1495 void 1496 vm_pageout_oom(int shortage) 1497 { 1498 struct proc *p, *bigproc; 1499 vm_offset_t size, bigsize; 1500 struct thread *td; 1501 struct vmspace *vm; 1502 1503 /* 1504 * We keep the process bigproc locked once we find it to keep anyone 1505 * from messing with it; however, there is a possibility of 1506 * deadlock if process B is bigproc and one of it's child processes 1507 * attempts to propagate a signal to B while we are waiting for A's 1508 * lock while walking this list. To avoid this, we don't block on 1509 * the process lock but just skip a process if it is already locked. 1510 */ 1511 bigproc = NULL; 1512 bigsize = 0; 1513 sx_slock(&allproc_lock); 1514 FOREACH_PROC_IN_SYSTEM(p) { 1515 int breakout; 1516 1517 if (PROC_TRYLOCK(p) == 0) 1518 continue; 1519 /* 1520 * If this is a system, protected or killed process, skip it. 1521 */ 1522 if (p->p_state != PRS_NORMAL || 1523 (p->p_flag & (P_INEXEC | P_PROTECTED | P_SYSTEM)) || 1524 (p->p_pid == 1) || P_KILLED(p) || 1525 ((p->p_pid < 48) && (swap_pager_avail != 0))) { 1526 PROC_UNLOCK(p); 1527 continue; 1528 } 1529 /* 1530 * If the process is in a non-running type state, 1531 * don't touch it. Check all the threads individually. 1532 */ 1533 breakout = 0; 1534 FOREACH_THREAD_IN_PROC(p, td) { 1535 thread_lock(td); 1536 if (!TD_ON_RUNQ(td) && 1537 !TD_IS_RUNNING(td) && 1538 !TD_IS_SLEEPING(td) && 1539 !TD_IS_SUSPENDED(td)) { 1540 thread_unlock(td); 1541 breakout = 1; 1542 break; 1543 } 1544 thread_unlock(td); 1545 } 1546 if (breakout) { 1547 PROC_UNLOCK(p); 1548 continue; 1549 } 1550 /* 1551 * get the process size 1552 */ 1553 vm = vmspace_acquire_ref(p); 1554 if (vm == NULL) { 1555 PROC_UNLOCK(p); 1556 continue; 1557 } 1558 if (!vm_map_trylock_read(&vm->vm_map)) { 1559 vmspace_free(vm); 1560 PROC_UNLOCK(p); 1561 continue; 1562 } 1563 size = vmspace_swap_count(vm); 1564 vm_map_unlock_read(&vm->vm_map); 1565 if (shortage == VM_OOM_MEM) 1566 size += vmspace_resident_count(vm); 1567 vmspace_free(vm); 1568 /* 1569 * if the this process is bigger than the biggest one 1570 * remember it. 1571 */ 1572 if (size > bigsize) { 1573 if (bigproc != NULL) 1574 PROC_UNLOCK(bigproc); 1575 bigproc = p; 1576 bigsize = size; 1577 } else 1578 PROC_UNLOCK(p); 1579 } 1580 sx_sunlock(&allproc_lock); 1581 if (bigproc != NULL) { 1582 killproc(bigproc, "out of swap space"); 1583 sched_nice(bigproc, PRIO_MIN); 1584 PROC_UNLOCK(bigproc); 1585 wakeup(&cnt.v_free_count); 1586 } 1587 } 1588 1589 static void 1590 vm_pageout_worker(void *arg) 1591 { 1592 struct vm_domain *domain; 1593 int domidx; 1594 1595 domidx = (uintptr_t)arg; 1596 domain = &vm_dom[domidx]; 1597 1598 /* 1599 * XXXKIB It could be useful to bind pageout daemon threads to 1600 * the cores belonging to the domain, from which vm_page_array 1601 * is allocated. 1602 */ 1603 1604 KASSERT(domain->vmd_segs != 0, ("domain without segments")); 1605 vm_pageout_init_marker(&domain->vmd_marker, PQ_INACTIVE); 1606 1607 /* 1608 * The pageout daemon worker is never done, so loop forever. 1609 */ 1610 while (TRUE) { 1611 /* 1612 * If we have enough free memory, wakeup waiters. Do 1613 * not clear vm_pages_needed until we reach our target, 1614 * otherwise we may be woken up over and over again and 1615 * waste a lot of cpu. 1616 */ 1617 mtx_lock(&vm_page_queue_free_mtx); 1618 if (vm_pages_needed && !vm_page_count_min()) { 1619 if (!vm_paging_needed()) 1620 vm_pages_needed = 0; 1621 wakeup(&cnt.v_free_count); 1622 } 1623 if (vm_pages_needed) { 1624 /* 1625 * Still not done, take a second pass without waiting 1626 * (unlimited dirty cleaning), otherwise sleep a bit 1627 * and try again. 1628 */ 1629 if (domain->vmd_pass > 1) 1630 msleep(&vm_pages_needed, 1631 &vm_page_queue_free_mtx, PVM, "psleep", 1632 hz / 2); 1633 } else { 1634 /* 1635 * Good enough, sleep until required to refresh 1636 * stats. 1637 */ 1638 domain->vmd_pass = 0; 1639 msleep(&vm_pages_needed, &vm_page_queue_free_mtx, 1640 PVM, "psleep", hz); 1641 1642 } 1643 if (vm_pages_needed) { 1644 cnt.v_pdwakeups++; 1645 domain->vmd_pass++; 1646 } 1647 mtx_unlock(&vm_page_queue_free_mtx); 1648 vm_pageout_scan(domain, domain->vmd_pass); 1649 } 1650 } 1651 1652 /* 1653 * vm_pageout is the high level pageout daemon. 1654 */ 1655 static void 1656 vm_pageout(void) 1657 { 1658 #if MAXMEMDOM > 1 1659 int error, i; 1660 #endif 1661 1662 /* 1663 * Initialize some paging parameters. 1664 */ 1665 cnt.v_interrupt_free_min = 2; 1666 if (cnt.v_page_count < 2000) 1667 vm_pageout_page_count = 8; 1668 1669 /* 1670 * v_free_reserved needs to include enough for the largest 1671 * swap pager structures plus enough for any pv_entry structs 1672 * when paging. 1673 */ 1674 if (cnt.v_page_count > 1024) 1675 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1676 else 1677 cnt.v_free_min = 4; 1678 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1679 cnt.v_interrupt_free_min; 1680 cnt.v_free_reserved = vm_pageout_page_count + 1681 cnt.v_pageout_free_min + (cnt.v_page_count / 768); 1682 cnt.v_free_severe = cnt.v_free_min / 2; 1683 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1684 cnt.v_free_min += cnt.v_free_reserved; 1685 cnt.v_free_severe += cnt.v_free_reserved; 1686 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1687 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1688 cnt.v_inactive_target = cnt.v_free_count / 3; 1689 1690 /* 1691 * Set the default wakeup threshold to be 10% above the minimum 1692 * page limit. This keeps the steady state out of shortfall. 1693 */ 1694 vm_pageout_wakeup_thresh = (cnt.v_free_min / 10) * 11; 1695 1696 /* 1697 * Set interval in seconds for active scan. We want to visit each 1698 * page at least once every ten minutes. This is to prevent worst 1699 * case paging behaviors with stale active LRU. 1700 */ 1701 if (vm_pageout_update_period == 0) 1702 vm_pageout_update_period = 600; 1703 1704 /* XXX does not really belong here */ 1705 if (vm_page_max_wired == 0) 1706 vm_page_max_wired = cnt.v_free_count / 3; 1707 1708 swap_pager_swap_init(); 1709 #if MAXMEMDOM > 1 1710 for (i = 1; i < vm_ndomains; i++) { 1711 error = kthread_add(vm_pageout_worker, (void *)(uintptr_t)i, 1712 curproc, NULL, 0, 0, "dom%d", i); 1713 if (error != 0) { 1714 panic("starting pageout for domain %d, error %d\n", 1715 i, error); 1716 } 1717 } 1718 #endif 1719 vm_pageout_worker((void *)(uintptr_t)0); 1720 } 1721 1722 /* 1723 * Unless the free page queue lock is held by the caller, this function 1724 * should be regarded as advisory. Specifically, the caller should 1725 * not msleep() on &cnt.v_free_count following this function unless 1726 * the free page queue lock is held until the msleep() is performed. 1727 */ 1728 void 1729 pagedaemon_wakeup(void) 1730 { 1731 1732 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1733 vm_pages_needed = 1; 1734 wakeup(&vm_pages_needed); 1735 } 1736 } 1737 1738 #if !defined(NO_SWAPPING) 1739 static void 1740 vm_req_vmdaemon(int req) 1741 { 1742 static int lastrun = 0; 1743 1744 mtx_lock(&vm_daemon_mtx); 1745 vm_pageout_req_swapout |= req; 1746 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1747 wakeup(&vm_daemon_needed); 1748 lastrun = ticks; 1749 } 1750 mtx_unlock(&vm_daemon_mtx); 1751 } 1752 1753 static void 1754 vm_daemon(void) 1755 { 1756 struct rlimit rsslim; 1757 struct proc *p; 1758 struct thread *td; 1759 struct vmspace *vm; 1760 int breakout, swapout_flags, tryagain, attempts; 1761 #ifdef RACCT 1762 uint64_t rsize, ravailable; 1763 #endif 1764 1765 while (TRUE) { 1766 mtx_lock(&vm_daemon_mtx); 1767 #ifdef RACCT 1768 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", hz); 1769 #else 1770 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0); 1771 #endif 1772 swapout_flags = vm_pageout_req_swapout; 1773 vm_pageout_req_swapout = 0; 1774 mtx_unlock(&vm_daemon_mtx); 1775 if (swapout_flags) 1776 swapout_procs(swapout_flags); 1777 1778 /* 1779 * scan the processes for exceeding their rlimits or if 1780 * process is swapped out -- deactivate pages 1781 */ 1782 tryagain = 0; 1783 attempts = 0; 1784 again: 1785 attempts++; 1786 sx_slock(&allproc_lock); 1787 FOREACH_PROC_IN_SYSTEM(p) { 1788 vm_pindex_t limit, size; 1789 1790 /* 1791 * if this is a system process or if we have already 1792 * looked at this process, skip it. 1793 */ 1794 PROC_LOCK(p); 1795 if (p->p_state != PRS_NORMAL || 1796 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 1797 PROC_UNLOCK(p); 1798 continue; 1799 } 1800 /* 1801 * if the process is in a non-running type state, 1802 * don't touch it. 1803 */ 1804 breakout = 0; 1805 FOREACH_THREAD_IN_PROC(p, td) { 1806 thread_lock(td); 1807 if (!TD_ON_RUNQ(td) && 1808 !TD_IS_RUNNING(td) && 1809 !TD_IS_SLEEPING(td) && 1810 !TD_IS_SUSPENDED(td)) { 1811 thread_unlock(td); 1812 breakout = 1; 1813 break; 1814 } 1815 thread_unlock(td); 1816 } 1817 if (breakout) { 1818 PROC_UNLOCK(p); 1819 continue; 1820 } 1821 /* 1822 * get a limit 1823 */ 1824 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1825 limit = OFF_TO_IDX( 1826 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1827 1828 /* 1829 * let processes that are swapped out really be 1830 * swapped out set the limit to nothing (will force a 1831 * swap-out.) 1832 */ 1833 if ((p->p_flag & P_INMEM) == 0) 1834 limit = 0; /* XXX */ 1835 vm = vmspace_acquire_ref(p); 1836 PROC_UNLOCK(p); 1837 if (vm == NULL) 1838 continue; 1839 1840 size = vmspace_resident_count(vm); 1841 if (size >= limit) { 1842 vm_pageout_map_deactivate_pages( 1843 &vm->vm_map, limit); 1844 } 1845 #ifdef RACCT 1846 rsize = IDX_TO_OFF(size); 1847 PROC_LOCK(p); 1848 racct_set(p, RACCT_RSS, rsize); 1849 ravailable = racct_get_available(p, RACCT_RSS); 1850 PROC_UNLOCK(p); 1851 if (rsize > ravailable) { 1852 /* 1853 * Don't be overly aggressive; this might be 1854 * an innocent process, and the limit could've 1855 * been exceeded by some memory hog. Don't 1856 * try to deactivate more than 1/4th of process' 1857 * resident set size. 1858 */ 1859 if (attempts <= 8) { 1860 if (ravailable < rsize - (rsize / 4)) 1861 ravailable = rsize - (rsize / 4); 1862 } 1863 vm_pageout_map_deactivate_pages( 1864 &vm->vm_map, OFF_TO_IDX(ravailable)); 1865 /* Update RSS usage after paging out. */ 1866 size = vmspace_resident_count(vm); 1867 rsize = IDX_TO_OFF(size); 1868 PROC_LOCK(p); 1869 racct_set(p, RACCT_RSS, rsize); 1870 PROC_UNLOCK(p); 1871 if (rsize > ravailable) 1872 tryagain = 1; 1873 } 1874 #endif 1875 vmspace_free(vm); 1876 } 1877 sx_sunlock(&allproc_lock); 1878 if (tryagain != 0 && attempts <= 10) 1879 goto again; 1880 } 1881 } 1882 #endif /* !defined(NO_SWAPPING) */
Cache object: 018b019c3b28c27f242739eba524477a
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]