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/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 int page_shortage, maxscan, pcount; 913 int addl_page_shortage; 914 vm_object_t object; 915 int act_delta; 916 int vnodes_skipped = 0; 917 int maxlaunder; 918 int lockmode; 919 boolean_t queues_locked; 920 921 /* 922 * If we need to reclaim memory ask kernel caches to return 923 * some. We rate limit to avoid thrashing. 924 */ 925 if (vmd == &vm_dom[0] && pass > 0 && 926 lowmem_ticks + (lowmem_period * hz) < ticks) { 927 /* 928 * Decrease registered cache sizes. 929 */ 930 EVENTHANDLER_INVOKE(vm_lowmem, 0); 931 /* 932 * We do this explicitly after the caches have been 933 * drained above. 934 */ 935 uma_reclaim(); 936 lowmem_ticks = ticks; 937 } 938 939 /* 940 * The addl_page_shortage is the number of temporarily 941 * stuck pages in the inactive queue. In other words, the 942 * number of pages from the inactive count that should be 943 * discounted in setting the target for the active queue scan. 944 */ 945 addl_page_shortage = atomic_readandclear_int(&vm_pageout_deficit); 946 947 /* 948 * Calculate the number of pages we want to either free or move 949 * to the cache. 950 */ 951 page_shortage = vm_paging_target() + addl_page_shortage; 952 953 /* 954 * maxlaunder limits the number of dirty pages we flush per scan. 955 * For most systems a smaller value (16 or 32) is more robust under 956 * extreme memory and disk pressure because any unnecessary writes 957 * to disk can result in extreme performance degredation. However, 958 * systems with excessive dirty pages (especially when MAP_NOSYNC is 959 * used) will die horribly with limited laundering. If the pageout 960 * daemon cannot clean enough pages in the first pass, we let it go 961 * all out in succeeding passes. 962 */ 963 if ((maxlaunder = vm_max_launder) <= 1) 964 maxlaunder = 1; 965 if (pass > 1) 966 maxlaunder = 10000; 967 968 /* 969 * Start scanning the inactive queue for pages we can move to the 970 * cache or free. The scan will stop when the target is reached or 971 * we have scanned the entire inactive queue. Note that m->act_count 972 * is not used to form decisions for the inactive queue, only for the 973 * active queue. 974 */ 975 pq = &vmd->vmd_pagequeues[PQ_INACTIVE]; 976 maxscan = pq->pq_cnt; 977 vm_pagequeue_lock(pq); 978 queues_locked = TRUE; 979 for (m = TAILQ_FIRST(&pq->pq_pl); 980 m != NULL && maxscan-- > 0 && page_shortage > 0; 981 m = next) { 982 vm_pagequeue_assert_locked(pq); 983 KASSERT(queues_locked, ("unlocked queues")); 984 KASSERT(m->queue == PQ_INACTIVE, ("Inactive queue %p", m)); 985 986 PCPU_INC(cnt.v_pdpages); 987 next = TAILQ_NEXT(m, plinks.q); 988 989 /* 990 * skip marker pages 991 */ 992 if (m->flags & PG_MARKER) 993 continue; 994 995 KASSERT((m->flags & PG_FICTITIOUS) == 0, 996 ("Fictitious page %p cannot be in inactive queue", m)); 997 KASSERT((m->oflags & VPO_UNMANAGED) == 0, 998 ("Unmanaged page %p cannot be in inactive queue", m)); 999 1000 /* 1001 * The page or object lock acquisitions fail if the 1002 * page was removed from the queue or moved to a 1003 * different position within the queue. In either 1004 * case, addl_page_shortage should not be incremented. 1005 */ 1006 if (!vm_pageout_page_lock(m, &next)) { 1007 vm_page_unlock(m); 1008 continue; 1009 } 1010 object = m->object; 1011 if (!VM_OBJECT_TRYWLOCK(object) && 1012 !vm_pageout_fallback_object_lock(m, &next)) { 1013 vm_page_unlock(m); 1014 VM_OBJECT_WUNLOCK(object); 1015 continue; 1016 } 1017 1018 /* 1019 * Don't mess with busy pages, keep them at at the 1020 * front of the queue, most likely they are being 1021 * paged out. Increment addl_page_shortage for busy 1022 * pages, because they may leave the inactive queue 1023 * shortly after page scan is finished. 1024 */ 1025 if (vm_page_busied(m)) { 1026 vm_page_unlock(m); 1027 VM_OBJECT_WUNLOCK(object); 1028 addl_page_shortage++; 1029 continue; 1030 } 1031 1032 /* 1033 * We unlock the inactive page queue, invalidating the 1034 * 'next' pointer. Use our marker to remember our 1035 * place. 1036 */ 1037 TAILQ_INSERT_AFTER(&pq->pq_pl, m, &vmd->vmd_marker, plinks.q); 1038 vm_pagequeue_unlock(pq); 1039 queues_locked = FALSE; 1040 1041 /* 1042 * We bump the activation count if the page has been 1043 * referenced while in the inactive queue. This makes 1044 * it less likely that the page will be added back to the 1045 * inactive queue prematurely again. Here we check the 1046 * page tables (or emulated bits, if any), given the upper 1047 * level VM system not knowing anything about existing 1048 * references. 1049 */ 1050 act_delta = 0; 1051 if ((m->aflags & PGA_REFERENCED) != 0) { 1052 vm_page_aflag_clear(m, PGA_REFERENCED); 1053 act_delta = 1; 1054 } 1055 if (object->ref_count != 0) { 1056 act_delta += pmap_ts_referenced(m); 1057 } else { 1058 KASSERT(!pmap_page_is_mapped(m), 1059 ("vm_pageout_scan: page %p is mapped", m)); 1060 } 1061 1062 /* 1063 * If the upper level VM system knows about any page 1064 * references, we reactivate the page or requeue it. 1065 */ 1066 if (act_delta != 0) { 1067 if (object->ref_count) { 1068 vm_page_activate(m); 1069 m->act_count += act_delta + ACT_ADVANCE; 1070 } else { 1071 vm_pagequeue_lock(pq); 1072 queues_locked = TRUE; 1073 vm_page_requeue_locked(m); 1074 } 1075 VM_OBJECT_WUNLOCK(object); 1076 vm_page_unlock(m); 1077 goto relock_queues; 1078 } 1079 1080 if (m->hold_count != 0) { 1081 vm_page_unlock(m); 1082 VM_OBJECT_WUNLOCK(object); 1083 1084 /* 1085 * Held pages are essentially stuck in the 1086 * queue. So, they ought to be discounted 1087 * from the inactive count. See the 1088 * calculation of the page_shortage for the 1089 * loop over the active queue below. 1090 */ 1091 addl_page_shortage++; 1092 goto relock_queues; 1093 } 1094 1095 /* 1096 * If the page appears to be clean at the machine-independent 1097 * layer, then remove all of its mappings from the pmap in 1098 * anticipation of placing it onto the cache queue. If, 1099 * however, any of the page's mappings allow write access, 1100 * then the page may still be modified until the last of those 1101 * mappings are removed. 1102 */ 1103 vm_page_test_dirty(m); 1104 if (m->dirty == 0 && object->ref_count != 0) 1105 pmap_remove_all(m); 1106 1107 if (m->valid == 0) { 1108 /* 1109 * Invalid pages can be easily freed 1110 */ 1111 vm_page_free(m); 1112 PCPU_INC(cnt.v_dfree); 1113 --page_shortage; 1114 } else if (m->dirty == 0) { 1115 /* 1116 * Clean pages can be placed onto the cache queue. 1117 * This effectively frees them. 1118 */ 1119 vm_page_cache(m); 1120 --page_shortage; 1121 } else if ((m->flags & PG_WINATCFLS) == 0 && pass < 2) { 1122 /* 1123 * Dirty pages need to be paged out, but flushing 1124 * a page is extremely expensive verses freeing 1125 * a clean page. Rather then artificially limiting 1126 * the number of pages we can flush, we instead give 1127 * dirty pages extra priority on the inactive queue 1128 * by forcing them to be cycled through the queue 1129 * twice before being flushed, after which the 1130 * (now clean) page will cycle through once more 1131 * before being freed. This significantly extends 1132 * the thrash point for a heavily loaded machine. 1133 */ 1134 m->flags |= PG_WINATCFLS; 1135 vm_pagequeue_lock(pq); 1136 queues_locked = TRUE; 1137 vm_page_requeue_locked(m); 1138 } else if (maxlaunder > 0) { 1139 /* 1140 * We always want to try to flush some dirty pages if 1141 * we encounter them, to keep the system stable. 1142 * Normally this number is small, but under extreme 1143 * pressure where there are insufficient clean pages 1144 * on the inactive queue, we may have to go all out. 1145 */ 1146 int swap_pageouts_ok; 1147 struct vnode *vp = NULL; 1148 struct mount *mp = NULL; 1149 1150 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 1151 swap_pageouts_ok = 1; 1152 } else { 1153 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 1154 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 1155 vm_page_count_min()); 1156 1157 } 1158 1159 /* 1160 * We don't bother paging objects that are "dead". 1161 * Those objects are in a "rundown" state. 1162 */ 1163 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 1164 vm_pagequeue_lock(pq); 1165 vm_page_unlock(m); 1166 VM_OBJECT_WUNLOCK(object); 1167 queues_locked = TRUE; 1168 vm_page_requeue_locked(m); 1169 goto relock_queues; 1170 } 1171 1172 /* 1173 * The object is already known NOT to be dead. It 1174 * is possible for the vget() to block the whole 1175 * pageout daemon, but the new low-memory handling 1176 * code should prevent it. 1177 * 1178 * The previous code skipped locked vnodes and, worse, 1179 * reordered pages in the queue. This results in 1180 * completely non-deterministic operation and, on a 1181 * busy system, can lead to extremely non-optimal 1182 * pageouts. For example, it can cause clean pages 1183 * to be freed and dirty pages to be moved to the end 1184 * of the queue. Since dirty pages are also moved to 1185 * the end of the queue once-cleaned, this gives 1186 * way too large a weighting to defering the freeing 1187 * of dirty pages. 1188 * 1189 * We can't wait forever for the vnode lock, we might 1190 * deadlock due to a vn_read() getting stuck in 1191 * vm_wait while holding this vnode. We skip the 1192 * vnode if we can't get it in a reasonable amount 1193 * of time. 1194 */ 1195 if (object->type == OBJT_VNODE) { 1196 vm_page_unlock(m); 1197 vp = object->handle; 1198 if (vp->v_type == VREG && 1199 vn_start_write(vp, &mp, V_NOWAIT) != 0) { 1200 mp = NULL; 1201 ++pageout_lock_miss; 1202 if (object->flags & OBJ_MIGHTBEDIRTY) 1203 vnodes_skipped++; 1204 goto unlock_and_continue; 1205 } 1206 KASSERT(mp != NULL, 1207 ("vp %p with NULL v_mount", vp)); 1208 vm_object_reference_locked(object); 1209 VM_OBJECT_WUNLOCK(object); 1210 lockmode = MNT_SHARED_WRITES(vp->v_mount) ? 1211 LK_SHARED : LK_EXCLUSIVE; 1212 if (vget(vp, lockmode | LK_TIMELOCK, 1213 curthread)) { 1214 VM_OBJECT_WLOCK(object); 1215 ++pageout_lock_miss; 1216 if (object->flags & OBJ_MIGHTBEDIRTY) 1217 vnodes_skipped++; 1218 vp = NULL; 1219 goto unlock_and_continue; 1220 } 1221 VM_OBJECT_WLOCK(object); 1222 vm_page_lock(m); 1223 vm_pagequeue_lock(pq); 1224 queues_locked = TRUE; 1225 /* 1226 * The page might have been moved to another 1227 * queue during potential blocking in vget() 1228 * above. The page might have been freed and 1229 * reused for another vnode. 1230 */ 1231 if (m->queue != PQ_INACTIVE || 1232 m->object != object || 1233 TAILQ_NEXT(m, plinks.q) != &vmd->vmd_marker) { 1234 vm_page_unlock(m); 1235 if (object->flags & OBJ_MIGHTBEDIRTY) 1236 vnodes_skipped++; 1237 goto unlock_and_continue; 1238 } 1239 1240 /* 1241 * The page may have been busied during the 1242 * blocking in vget(). We don't move the 1243 * page back onto the end of the queue so that 1244 * statistics are more correct if we don't. 1245 */ 1246 if (vm_page_busied(m)) { 1247 vm_page_unlock(m); 1248 goto unlock_and_continue; 1249 } 1250 1251 /* 1252 * If the page has become held it might 1253 * be undergoing I/O, so skip it 1254 */ 1255 if (m->hold_count) { 1256 vm_page_unlock(m); 1257 vm_page_requeue_locked(m); 1258 if (object->flags & OBJ_MIGHTBEDIRTY) 1259 vnodes_skipped++; 1260 goto unlock_and_continue; 1261 } 1262 vm_pagequeue_unlock(pq); 1263 queues_locked = FALSE; 1264 } 1265 1266 /* 1267 * If a page is dirty, then it is either being washed 1268 * (but not yet cleaned) or it is still in the 1269 * laundry. If it is still in the laundry, then we 1270 * start the cleaning operation. 1271 * 1272 * decrement page_shortage on success to account for 1273 * the (future) cleaned page. Otherwise we could wind 1274 * up laundering or cleaning too many pages. 1275 */ 1276 if (vm_pageout_clean(m) != 0) { 1277 --page_shortage; 1278 --maxlaunder; 1279 } 1280 unlock_and_continue: 1281 vm_page_lock_assert(m, MA_NOTOWNED); 1282 VM_OBJECT_WUNLOCK(object); 1283 if (mp != NULL) { 1284 if (queues_locked) { 1285 vm_pagequeue_unlock(pq); 1286 queues_locked = FALSE; 1287 } 1288 if (vp != NULL) 1289 vput(vp); 1290 vm_object_deallocate(object); 1291 vn_finished_write(mp); 1292 } 1293 vm_page_lock_assert(m, MA_NOTOWNED); 1294 goto relock_queues; 1295 } 1296 vm_page_unlock(m); 1297 VM_OBJECT_WUNLOCK(object); 1298 relock_queues: 1299 if (!queues_locked) { 1300 vm_pagequeue_lock(pq); 1301 queues_locked = TRUE; 1302 } 1303 next = TAILQ_NEXT(&vmd->vmd_marker, plinks.q); 1304 TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_marker, plinks.q); 1305 } 1306 vm_pagequeue_unlock(pq); 1307 1308 /* 1309 * Compute the number of pages we want to try to move from the 1310 * active queue to the inactive queue. 1311 */ 1312 pq = &vmd->vmd_pagequeues[PQ_ACTIVE]; 1313 vm_pagequeue_lock(pq); 1314 pcount = pq->pq_cnt; 1315 page_shortage = vm_paging_target() + 1316 cnt.v_inactive_target - cnt.v_inactive_count; 1317 page_shortage += addl_page_shortage; 1318 /* 1319 * If we're just idle polling attempt to visit every 1320 * active page within 'update_period' seconds. 1321 */ 1322 if (pass == 0 && vm_pageout_update_period != 0) { 1323 pcount /= vm_pageout_update_period; 1324 page_shortage = pcount; 1325 } 1326 1327 /* 1328 * Scan the active queue for things we can deactivate. We nominally 1329 * track the per-page activity counter and use it to locate 1330 * deactivation candidates. 1331 */ 1332 m = TAILQ_FIRST(&pq->pq_pl); 1333 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 1334 1335 KASSERT(m->queue == PQ_ACTIVE, 1336 ("vm_pageout_scan: page %p isn't active", m)); 1337 1338 next = TAILQ_NEXT(m, plinks.q); 1339 if ((m->flags & PG_MARKER) != 0) { 1340 m = next; 1341 continue; 1342 } 1343 KASSERT((m->flags & PG_FICTITIOUS) == 0, 1344 ("Fictitious page %p cannot be in active queue", m)); 1345 KASSERT((m->oflags & VPO_UNMANAGED) == 0, 1346 ("Unmanaged page %p cannot be in active queue", m)); 1347 if (!vm_pageout_page_lock(m, &next)) { 1348 vm_page_unlock(m); 1349 m = next; 1350 continue; 1351 } 1352 1353 /* 1354 * The count for pagedaemon pages is done after checking the 1355 * page for eligibility... 1356 */ 1357 PCPU_INC(cnt.v_pdpages); 1358 1359 /* 1360 * Check to see "how much" the page has been used. 1361 */ 1362 act_delta = 0; 1363 if (m->aflags & PGA_REFERENCED) { 1364 vm_page_aflag_clear(m, PGA_REFERENCED); 1365 act_delta += 1; 1366 } 1367 /* 1368 * Unlocked object ref count check. Two races are possible. 1369 * 1) The ref was transitioning to zero and we saw non-zero, 1370 * the pmap bits will be checked unnecessarily. 1371 * 2) The ref was transitioning to one and we saw zero. 1372 * The page lock prevents a new reference to this page so 1373 * we need not check the reference bits. 1374 */ 1375 if (m->object->ref_count != 0) 1376 act_delta += pmap_ts_referenced(m); 1377 1378 /* 1379 * Advance or decay the act_count based on recent usage. 1380 */ 1381 if (act_delta) { 1382 m->act_count += ACT_ADVANCE + act_delta; 1383 if (m->act_count > ACT_MAX) 1384 m->act_count = ACT_MAX; 1385 } else { 1386 m->act_count -= min(m->act_count, ACT_DECLINE); 1387 act_delta = m->act_count; 1388 } 1389 1390 /* 1391 * Move this page to the tail of the active or inactive 1392 * queue depending on usage. 1393 */ 1394 if (act_delta == 0) { 1395 /* Dequeue to avoid later lock recursion. */ 1396 vm_page_dequeue_locked(m); 1397 vm_page_deactivate(m); 1398 page_shortage--; 1399 } else 1400 vm_page_requeue_locked(m); 1401 vm_page_unlock(m); 1402 m = next; 1403 } 1404 vm_pagequeue_unlock(pq); 1405 #if !defined(NO_SWAPPING) 1406 /* 1407 * Idle process swapout -- run once per second. 1408 */ 1409 if (vm_swap_idle_enabled) { 1410 static long lsec; 1411 if (time_second != lsec) { 1412 vm_req_vmdaemon(VM_SWAP_IDLE); 1413 lsec = time_second; 1414 } 1415 } 1416 #endif 1417 1418 /* 1419 * If we didn't get enough free pages, and we have skipped a vnode 1420 * in a writeable object, wakeup the sync daemon. And kick swapout 1421 * if we did not get enough free pages. 1422 */ 1423 if (vm_paging_target() > 0) { 1424 if (vnodes_skipped && vm_page_count_min()) 1425 (void) speedup_syncer(); 1426 #if !defined(NO_SWAPPING) 1427 if (vm_swap_enabled && vm_page_count_target()) 1428 vm_req_vmdaemon(VM_SWAP_NORMAL); 1429 #endif 1430 } 1431 1432 /* 1433 * If we are critically low on one of RAM or swap and low on 1434 * the other, kill the largest process. However, we avoid 1435 * doing this on the first pass in order to give ourselves a 1436 * chance to flush out dirty vnode-backed pages and to allow 1437 * active pages to be moved to the inactive queue and reclaimed. 1438 */ 1439 vm_pageout_mightbe_oom(vmd, pass); 1440 } 1441 1442 static int vm_pageout_oom_vote; 1443 1444 /* 1445 * The pagedaemon threads randlomly select one to perform the 1446 * OOM. Trying to kill processes before all pagedaemons 1447 * failed to reach free target is premature. 1448 */ 1449 static void 1450 vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass) 1451 { 1452 int old_vote; 1453 1454 if (pass <= 1 || !((swap_pager_avail < 64 && vm_page_count_min()) || 1455 (swap_pager_full && vm_paging_target() > 0))) { 1456 if (vmd->vmd_oom) { 1457 vmd->vmd_oom = FALSE; 1458 atomic_subtract_int(&vm_pageout_oom_vote, 1); 1459 } 1460 return; 1461 } 1462 1463 if (vmd->vmd_oom) 1464 return; 1465 1466 vmd->vmd_oom = TRUE; 1467 old_vote = atomic_fetchadd_int(&vm_pageout_oom_vote, 1); 1468 if (old_vote != vm_ndomains - 1) 1469 return; 1470 1471 /* 1472 * The current pagedaemon thread is the last in the quorum to 1473 * start OOM. Initiate the selection and signaling of the 1474 * victim. 1475 */ 1476 vm_pageout_oom(VM_OOM_MEM); 1477 1478 /* 1479 * After one round of OOM terror, recall our vote. On the 1480 * next pass, current pagedaemon would vote again if the low 1481 * memory condition is still there, due to vmd_oom being 1482 * false. 1483 */ 1484 vmd->vmd_oom = FALSE; 1485 atomic_subtract_int(&vm_pageout_oom_vote, 1); 1486 } 1487 1488 void 1489 vm_pageout_oom(int shortage) 1490 { 1491 struct proc *p, *bigproc; 1492 vm_offset_t size, bigsize; 1493 struct thread *td; 1494 struct vmspace *vm; 1495 1496 /* 1497 * We keep the process bigproc locked once we find it to keep anyone 1498 * from messing with it; however, there is a possibility of 1499 * deadlock if process B is bigproc and one of it's child processes 1500 * attempts to propagate a signal to B while we are waiting for A's 1501 * lock while walking this list. To avoid this, we don't block on 1502 * the process lock but just skip a process if it is already locked. 1503 */ 1504 bigproc = NULL; 1505 bigsize = 0; 1506 sx_slock(&allproc_lock); 1507 FOREACH_PROC_IN_SYSTEM(p) { 1508 int breakout; 1509 1510 if (PROC_TRYLOCK(p) == 0) 1511 continue; 1512 /* 1513 * If this is a system, protected or killed process, skip it. 1514 */ 1515 if (p->p_state != PRS_NORMAL || 1516 (p->p_flag & (P_INEXEC | P_PROTECTED | P_SYSTEM)) || 1517 (p->p_pid == 1) || P_KILLED(p) || 1518 ((p->p_pid < 48) && (swap_pager_avail != 0))) { 1519 PROC_UNLOCK(p); 1520 continue; 1521 } 1522 /* 1523 * If the process is in a non-running type state, 1524 * don't touch it. Check all the threads individually. 1525 */ 1526 breakout = 0; 1527 FOREACH_THREAD_IN_PROC(p, td) { 1528 thread_lock(td); 1529 if (!TD_ON_RUNQ(td) && 1530 !TD_IS_RUNNING(td) && 1531 !TD_IS_SLEEPING(td) && 1532 !TD_IS_SUSPENDED(td)) { 1533 thread_unlock(td); 1534 breakout = 1; 1535 break; 1536 } 1537 thread_unlock(td); 1538 } 1539 if (breakout) { 1540 PROC_UNLOCK(p); 1541 continue; 1542 } 1543 /* 1544 * get the process size 1545 */ 1546 vm = vmspace_acquire_ref(p); 1547 if (vm == NULL) { 1548 PROC_UNLOCK(p); 1549 continue; 1550 } 1551 if (!vm_map_trylock_read(&vm->vm_map)) { 1552 vmspace_free(vm); 1553 PROC_UNLOCK(p); 1554 continue; 1555 } 1556 size = vmspace_swap_count(vm); 1557 vm_map_unlock_read(&vm->vm_map); 1558 if (shortage == VM_OOM_MEM) 1559 size += vmspace_resident_count(vm); 1560 vmspace_free(vm); 1561 /* 1562 * if the this process is bigger than the biggest one 1563 * remember it. 1564 */ 1565 if (size > bigsize) { 1566 if (bigproc != NULL) 1567 PROC_UNLOCK(bigproc); 1568 bigproc = p; 1569 bigsize = size; 1570 } else 1571 PROC_UNLOCK(p); 1572 } 1573 sx_sunlock(&allproc_lock); 1574 if (bigproc != NULL) { 1575 killproc(bigproc, "out of swap space"); 1576 sched_nice(bigproc, PRIO_MIN); 1577 PROC_UNLOCK(bigproc); 1578 wakeup(&cnt.v_free_count); 1579 } 1580 } 1581 1582 static void 1583 vm_pageout_worker(void *arg) 1584 { 1585 struct vm_domain *domain; 1586 int domidx; 1587 1588 domidx = (uintptr_t)arg; 1589 domain = &vm_dom[domidx]; 1590 1591 /* 1592 * XXXKIB It could be useful to bind pageout daemon threads to 1593 * the cores belonging to the domain, from which vm_page_array 1594 * is allocated. 1595 */ 1596 1597 KASSERT(domain->vmd_segs != 0, ("domain without segments")); 1598 vm_pageout_init_marker(&domain->vmd_marker, PQ_INACTIVE); 1599 1600 /* 1601 * The pageout daemon worker is never done, so loop forever. 1602 */ 1603 while (TRUE) { 1604 /* 1605 * If we have enough free memory, wakeup waiters. Do 1606 * not clear vm_pages_needed until we reach our target, 1607 * otherwise we may be woken up over and over again and 1608 * waste a lot of cpu. 1609 */ 1610 mtx_lock(&vm_page_queue_free_mtx); 1611 if (vm_pages_needed && !vm_page_count_min()) { 1612 if (!vm_paging_needed()) 1613 vm_pages_needed = 0; 1614 wakeup(&cnt.v_free_count); 1615 } 1616 if (vm_pages_needed) { 1617 /* 1618 * Still not done, take a second pass without waiting 1619 * (unlimited dirty cleaning), otherwise sleep a bit 1620 * and try again. 1621 */ 1622 if (domain->vmd_pass > 1) 1623 msleep(&vm_pages_needed, 1624 &vm_page_queue_free_mtx, PVM, "psleep", 1625 hz / 2); 1626 } else { 1627 /* 1628 * Good enough, sleep until required to refresh 1629 * stats. 1630 */ 1631 domain->vmd_pass = 0; 1632 msleep(&vm_pages_needed, &vm_page_queue_free_mtx, 1633 PVM, "psleep", hz); 1634 1635 } 1636 if (vm_pages_needed) { 1637 cnt.v_pdwakeups++; 1638 domain->vmd_pass++; 1639 } 1640 mtx_unlock(&vm_page_queue_free_mtx); 1641 vm_pageout_scan(domain, domain->vmd_pass); 1642 } 1643 } 1644 1645 /* 1646 * vm_pageout is the high level pageout daemon. 1647 */ 1648 static void 1649 vm_pageout(void) 1650 { 1651 #if MAXMEMDOM > 1 1652 int error, i; 1653 #endif 1654 1655 /* 1656 * Initialize some paging parameters. 1657 */ 1658 cnt.v_interrupt_free_min = 2; 1659 if (cnt.v_page_count < 2000) 1660 vm_pageout_page_count = 8; 1661 1662 /* 1663 * v_free_reserved needs to include enough for the largest 1664 * swap pager structures plus enough for any pv_entry structs 1665 * when paging. 1666 */ 1667 if (cnt.v_page_count > 1024) 1668 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1669 else 1670 cnt.v_free_min = 4; 1671 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1672 cnt.v_interrupt_free_min; 1673 cnt.v_free_reserved = vm_pageout_page_count + 1674 cnt.v_pageout_free_min + (cnt.v_page_count / 768); 1675 cnt.v_free_severe = cnt.v_free_min / 2; 1676 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1677 cnt.v_free_min += cnt.v_free_reserved; 1678 cnt.v_free_severe += cnt.v_free_reserved; 1679 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1680 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1681 cnt.v_inactive_target = cnt.v_free_count / 3; 1682 1683 /* 1684 * Set the default wakeup threshold to be 10% above the minimum 1685 * page limit. This keeps the steady state out of shortfall. 1686 */ 1687 vm_pageout_wakeup_thresh = (cnt.v_free_min / 10) * 11; 1688 1689 /* 1690 * Set interval in seconds for active scan. We want to visit each 1691 * page at least once every ten minutes. This is to prevent worst 1692 * case paging behaviors with stale active LRU. 1693 */ 1694 if (vm_pageout_update_period == 0) 1695 vm_pageout_update_period = 600; 1696 1697 /* XXX does not really belong here */ 1698 if (vm_page_max_wired == 0) 1699 vm_page_max_wired = cnt.v_free_count / 3; 1700 1701 swap_pager_swap_init(); 1702 #if MAXMEMDOM > 1 1703 for (i = 1; i < vm_ndomains; i++) { 1704 error = kthread_add(vm_pageout_worker, (void *)(uintptr_t)i, 1705 curproc, NULL, 0, 0, "dom%d", i); 1706 if (error != 0) { 1707 panic("starting pageout for domain %d, error %d\n", 1708 i, error); 1709 } 1710 } 1711 #endif 1712 vm_pageout_worker((void *)(uintptr_t)0); 1713 } 1714 1715 /* 1716 * Unless the free page queue lock is held by the caller, this function 1717 * should be regarded as advisory. Specifically, the caller should 1718 * not msleep() on &cnt.v_free_count following this function unless 1719 * the free page queue lock is held until the msleep() is performed. 1720 */ 1721 void 1722 pagedaemon_wakeup(void) 1723 { 1724 1725 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1726 vm_pages_needed = 1; 1727 wakeup(&vm_pages_needed); 1728 } 1729 } 1730 1731 #if !defined(NO_SWAPPING) 1732 static void 1733 vm_req_vmdaemon(int req) 1734 { 1735 static int lastrun = 0; 1736 1737 mtx_lock(&vm_daemon_mtx); 1738 vm_pageout_req_swapout |= req; 1739 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1740 wakeup(&vm_daemon_needed); 1741 lastrun = ticks; 1742 } 1743 mtx_unlock(&vm_daemon_mtx); 1744 } 1745 1746 static void 1747 vm_daemon(void) 1748 { 1749 struct rlimit rsslim; 1750 struct proc *p; 1751 struct thread *td; 1752 struct vmspace *vm; 1753 int breakout, swapout_flags, tryagain, attempts; 1754 #ifdef RACCT 1755 uint64_t rsize, ravailable; 1756 #endif 1757 1758 while (TRUE) { 1759 mtx_lock(&vm_daemon_mtx); 1760 #ifdef RACCT 1761 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", hz); 1762 #else 1763 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0); 1764 #endif 1765 swapout_flags = vm_pageout_req_swapout; 1766 vm_pageout_req_swapout = 0; 1767 mtx_unlock(&vm_daemon_mtx); 1768 if (swapout_flags) 1769 swapout_procs(swapout_flags); 1770 1771 /* 1772 * scan the processes for exceeding their rlimits or if 1773 * process is swapped out -- deactivate pages 1774 */ 1775 tryagain = 0; 1776 attempts = 0; 1777 again: 1778 attempts++; 1779 sx_slock(&allproc_lock); 1780 FOREACH_PROC_IN_SYSTEM(p) { 1781 vm_pindex_t limit, size; 1782 1783 /* 1784 * if this is a system process or if we have already 1785 * looked at this process, skip it. 1786 */ 1787 PROC_LOCK(p); 1788 if (p->p_state != PRS_NORMAL || 1789 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 1790 PROC_UNLOCK(p); 1791 continue; 1792 } 1793 /* 1794 * if the process is in a non-running type state, 1795 * don't touch it. 1796 */ 1797 breakout = 0; 1798 FOREACH_THREAD_IN_PROC(p, td) { 1799 thread_lock(td); 1800 if (!TD_ON_RUNQ(td) && 1801 !TD_IS_RUNNING(td) && 1802 !TD_IS_SLEEPING(td) && 1803 !TD_IS_SUSPENDED(td)) { 1804 thread_unlock(td); 1805 breakout = 1; 1806 break; 1807 } 1808 thread_unlock(td); 1809 } 1810 if (breakout) { 1811 PROC_UNLOCK(p); 1812 continue; 1813 } 1814 /* 1815 * get a limit 1816 */ 1817 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1818 limit = OFF_TO_IDX( 1819 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1820 1821 /* 1822 * let processes that are swapped out really be 1823 * swapped out set the limit to nothing (will force a 1824 * swap-out.) 1825 */ 1826 if ((p->p_flag & P_INMEM) == 0) 1827 limit = 0; /* XXX */ 1828 vm = vmspace_acquire_ref(p); 1829 PROC_UNLOCK(p); 1830 if (vm == NULL) 1831 continue; 1832 1833 size = vmspace_resident_count(vm); 1834 if (size >= limit) { 1835 vm_pageout_map_deactivate_pages( 1836 &vm->vm_map, limit); 1837 } 1838 #ifdef RACCT 1839 rsize = IDX_TO_OFF(size); 1840 PROC_LOCK(p); 1841 racct_set(p, RACCT_RSS, rsize); 1842 ravailable = racct_get_available(p, RACCT_RSS); 1843 PROC_UNLOCK(p); 1844 if (rsize > ravailable) { 1845 /* 1846 * Don't be overly aggressive; this might be 1847 * an innocent process, and the limit could've 1848 * been exceeded by some memory hog. Don't 1849 * try to deactivate more than 1/4th of process' 1850 * resident set size. 1851 */ 1852 if (attempts <= 8) { 1853 if (ravailable < rsize - (rsize / 4)) 1854 ravailable = rsize - (rsize / 4); 1855 } 1856 vm_pageout_map_deactivate_pages( 1857 &vm->vm_map, OFF_TO_IDX(ravailable)); 1858 /* Update RSS usage after paging out. */ 1859 size = vmspace_resident_count(vm); 1860 rsize = IDX_TO_OFF(size); 1861 PROC_LOCK(p); 1862 racct_set(p, RACCT_RSS, rsize); 1863 PROC_UNLOCK(p); 1864 if (rsize > ravailable) 1865 tryagain = 1; 1866 } 1867 #endif 1868 vmspace_free(vm); 1869 } 1870 sx_sunlock(&allproc_lock); 1871 if (tryagain != 0 && attempts <= 10) 1872 goto again; 1873 } 1874 } 1875 #endif /* !defined(NO_SWAPPING) */ 1876