1 /*- 2 * Copyright (c) 1991 Regents of the University of California. 3 * All rights reserved. 4 * Copyright (c) 1994 John S. Dyson 5 * All rights reserved. 6 * Copyright (c) 1994 David Greenman 7 * All rights reserved. 8 * Copyright (c) 2005 Yahoo! Technologies Norway AS 9 * All rights reserved. 10 * 11 * This code is derived from software contributed to Berkeley by 12 * The Mach Operating System project at Carnegie-Mellon University. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the University of 25 * California, Berkeley and its contributors. 26 * 4. Neither the name of the University nor the names of its contributors 27 * may be used to endorse or promote products derived from this software 28 * without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 * 42 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 43 * 44 * 45 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 46 * All rights reserved. 47 * 48 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 49 * 50 * Permission to use, copy, modify and distribute this software and 51 * its documentation is hereby granted, provided that both the copyright 52 * notice and this permission notice appear in all copies of the 53 * software, derivative works or modified versions, and any portions 54 * thereof, and that both notices appear in supporting documentation. 55 * 56 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 57 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 58 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 59 * 60 * Carnegie Mellon requests users of this software to return to 61 * 62 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 63 * School of Computer Science 64 * Carnegie Mellon University 65 * Pittsburgh PA 15213-3890 66 * 67 * any improvements or extensions that they make and grant Carnegie the 68 * rights to redistribute these changes. 69 */ 70 71 /* 72 * The proverbial page-out daemon. 73 */ 74 75 #include <sys/cdefs.h> 76 __FBSDID("$FreeBSD$"); 77 78 #include "opt_vm.h" 79 #include <sys/param.h> 80 #include <sys/systm.h> 81 #include <sys/kernel.h> 82 #include <sys/eventhandler.h> 83 #include <sys/lock.h> 84 #include <sys/mutex.h> 85 #include <sys/proc.h> 86 #include <sys/kthread.h> 87 #include <sys/ktr.h> 88 #include <sys/mount.h> 89 #include <sys/racct.h> 90 #include <sys/resourcevar.h> 91 #include <sys/sched.h> 92 #include <sys/signalvar.h> 93 #include <sys/vnode.h> 94 #include <sys/vmmeter.h> 95 #include <sys/sx.h> 96 #include <sys/sysctl.h> 97 98 #include <vm/vm.h> 99 #include <vm/vm_param.h> 100 #include <vm/vm_object.h> 101 #include <vm/vm_page.h> 102 #include <vm/vm_map.h> 103 #include <vm/vm_pageout.h> 104 #include <vm/vm_pager.h> 105 #include <vm/swap_pager.h> 106 #include <vm/vm_extern.h> 107 #include <vm/uma.h> 108 109 /* 110 * System initialization 111 */ 112 113 /* the kernel process "vm_pageout"*/ 114 static void vm_pageout(void); 115 static int vm_pageout_clean(vm_page_t); 116 static void vm_pageout_scan(int pass); 117 118 struct proc *pageproc; 119 120 static struct kproc_desc page_kp = { 121 "pagedaemon", 122 vm_pageout, 123 &pageproc 124 }; 125 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, 126 &page_kp); 127 128 #if !defined(NO_SWAPPING) 129 /* the kernel process "vm_daemon"*/ 130 static void vm_daemon(void); 131 static struct proc *vmproc; 132 133 static struct kproc_desc vm_kp = { 134 "vmdaemon", 135 vm_daemon, 136 &vmproc 137 }; 138 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp); 139 #endif 140 141 142 int vm_pages_needed; /* Event on which pageout daemon sleeps */ 143 int vm_pageout_deficit; /* Estimated number of pages deficit */ 144 int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 145 146 #if !defined(NO_SWAPPING) 147 static int vm_pageout_req_swapout; /* XXX */ 148 static int vm_daemon_needed; 149 static struct mtx vm_daemon_mtx; 150 /* Allow for use by vm_pageout before vm_daemon is initialized. */ 151 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); 152 #endif 153 static int vm_max_launder = 32; 154 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 155 static int vm_pageout_full_stats_interval = 0; 156 static int vm_pageout_algorithm=0; 157 static int defer_swap_pageouts=0; 158 static int disable_swap_pageouts=0; 159 160 #if defined(NO_SWAPPING) 161 static int vm_swap_enabled=0; 162 static int vm_swap_idle_enabled=0; 163 #else 164 static int vm_swap_enabled=1; 165 static int vm_swap_idle_enabled=0; 166 #endif 167 168 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 169 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 170 171 SYSCTL_INT(_vm, OID_AUTO, max_launder, 172 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 173 174 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 175 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 176 177 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 178 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 179 180 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 181 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 182 183 #if defined(NO_SWAPPING) 184 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 185 CTLFLAG_RD, &vm_swap_enabled, 0, "Enable entire process swapout"); 186 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 187 CTLFLAG_RD, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 188 #else 189 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 190 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 191 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 192 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 193 #endif 194 195 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 196 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 197 198 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 199 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 200 201 static int pageout_lock_miss; 202 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 203 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 204 205 #define VM_PAGEOUT_PAGE_COUNT 16 206 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 207 208 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 209 SYSCTL_INT(_vm, OID_AUTO, max_wired, 210 CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count"); 211 212 #if !defined(NO_SWAPPING) 213 static void vm_pageout_map_deactivate_pages(vm_map_t, long); 214 static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long); 215 static void vm_req_vmdaemon(int req); 216 #endif 217 static void vm_pageout_page_stats(void); 218 219 /* 220 * Initialize a dummy page for marking the caller's place in the specified 221 * paging queue. In principle, this function only needs to set the flag 222 * PG_MARKER. Nonetheless, it sets the flag VPO_BUSY and initializes the hold 223 * count to one as safety precautions. 224 */ 225 static void 226 vm_pageout_init_marker(vm_page_t marker, u_short queue) 227 { 228 229 bzero(marker, sizeof(*marker)); 230 marker->flags = PG_MARKER; 231 marker->oflags = VPO_BUSY; 232 marker->queue = queue; 233 marker->hold_count = 1; 234 } 235 236 /* 237 * vm_pageout_fallback_object_lock: 238 * 239 * Lock vm object currently associated with `m'. VM_OBJECT_TRYLOCK is 240 * known to have failed and page queue must be either PQ_ACTIVE or 241 * PQ_INACTIVE. To avoid lock order violation, unlock the page queues 242 * while locking the vm object. Use marker page to detect page queue 243 * changes and maintain notion of next page on page queue. Return 244 * TRUE if no changes were detected, FALSE otherwise. vm object is 245 * locked on return. 246 * 247 * This function depends on both the lock portion of struct vm_object 248 * and normal struct vm_page being type stable. 249 */ 250 boolean_t 251 vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next) 252 { 253 struct vm_page marker; 254 boolean_t unchanged; 255 u_short queue; 256 vm_object_t object; 257 258 queue = m->queue; 259 vm_pageout_init_marker(&marker, queue); 260 object = m->object; 261 262 TAILQ_INSERT_AFTER(&vm_page_queues[queue].pl, 263 m, &marker, pageq); 264 vm_page_unlock_queues(); 265 vm_page_unlock(m); 266 VM_OBJECT_LOCK(object); 267 vm_page_lock(m); 268 vm_page_lock_queues(); 269 270 /* Page queue might have changed. */ 271 *next = TAILQ_NEXT(&marker, pageq); 272 unchanged = (m->queue == queue && 273 m->object == object && 274 &marker == TAILQ_NEXT(m, pageq)); 275 TAILQ_REMOVE(&vm_page_queues[queue].pl, 276 &marker, pageq); 277 return (unchanged); 278 } 279 280 /* 281 * Lock the page while holding the page queue lock. Use marker page 282 * to detect page queue changes and maintain notion of next page on 283 * page queue. Return TRUE if no changes were detected, FALSE 284 * otherwise. The page is locked on return. The page queue lock might 285 * be dropped and reacquired. 286 * 287 * This function depends on normal struct vm_page being type stable. 288 */ 289 boolean_t 290 vm_pageout_page_lock(vm_page_t m, vm_page_t *next) 291 { 292 struct vm_page marker; 293 boolean_t unchanged; 294 u_short queue; 295 296 vm_page_lock_assert(m, MA_NOTOWNED); 297 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 298 299 if (vm_page_trylock(m)) 300 return (TRUE); 301 302 queue = m->queue; 303 vm_pageout_init_marker(&marker, queue); 304 305 TAILQ_INSERT_AFTER(&vm_page_queues[queue].pl, m, &marker, pageq); 306 vm_page_unlock_queues(); 307 vm_page_lock(m); 308 vm_page_lock_queues(); 309 310 /* Page queue might have changed. */ 311 *next = TAILQ_NEXT(&marker, pageq); 312 unchanged = (m->queue == queue && &marker == TAILQ_NEXT(m, pageq)); 313 TAILQ_REMOVE(&vm_page_queues[queue].pl, &marker, pageq); 314 return (unchanged); 315 } 316 317 /* 318 * vm_pageout_clean: 319 * 320 * Clean the page and remove it from the laundry. 321 * 322 * We set the busy bit to cause potential page faults on this page to 323 * block. Note the careful timing, however, the busy bit isn't set till 324 * late and we cannot do anything that will mess with the page. 325 */ 326 static int 327 vm_pageout_clean(vm_page_t m) 328 { 329 vm_object_t object; 330 vm_page_t mc[2*vm_pageout_page_count], pb, ps; 331 int pageout_count; 332 int ib, is, page_base; 333 vm_pindex_t pindex = m->pindex; 334 335 vm_page_lock_assert(m, MA_OWNED); 336 object = m->object; 337 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 338 339 /* 340 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 341 * with the new swapper, but we could have serious problems paging 342 * out other object types if there is insufficient memory. 343 * 344 * Unfortunately, checking free memory here is far too late, so the 345 * check has been moved up a procedural level. 346 */ 347 348 /* 349 * Can't clean the page if it's busy or held. 350 */ 351 KASSERT(m->busy == 0 && (m->oflags & VPO_BUSY) == 0, 352 ("vm_pageout_clean: page %p is busy", m)); 353 KASSERT(m->hold_count == 0, ("vm_pageout_clean: page %p is held", m)); 354 vm_page_unlock(m); 355 356 mc[vm_pageout_page_count] = pb = ps = m; 357 pageout_count = 1; 358 page_base = vm_pageout_page_count; 359 ib = 1; 360 is = 1; 361 362 /* 363 * Scan object for clusterable pages. 364 * 365 * We can cluster ONLY if: ->> the page is NOT 366 * clean, wired, busy, held, or mapped into a 367 * buffer, and one of the following: 368 * 1) The page is inactive, or a seldom used 369 * active page. 370 * -or- 371 * 2) we force the issue. 372 * 373 * During heavy mmap/modification loads the pageout 374 * daemon can really fragment the underlying file 375 * due to flushing pages out of order and not trying 376 * align the clusters (which leave sporatic out-of-order 377 * holes). To solve this problem we do the reverse scan 378 * first and attempt to align our cluster, then do a 379 * forward scan if room remains. 380 */ 381 more: 382 while (ib && pageout_count < vm_pageout_page_count) { 383 vm_page_t p; 384 385 if (ib > pindex) { 386 ib = 0; 387 break; 388 } 389 390 if ((p = vm_page_prev(pb)) == NULL || 391 (p->oflags & VPO_BUSY) != 0 || p->busy != 0) { 392 ib = 0; 393 break; 394 } 395 vm_page_lock(p); 396 vm_page_test_dirty(p); 397 if (p->dirty == 0 || 398 p->queue != PQ_INACTIVE || 399 p->hold_count != 0) { /* may be undergoing I/O */ 400 vm_page_unlock(p); 401 ib = 0; 402 break; 403 } 404 vm_page_unlock(p); 405 mc[--page_base] = pb = p; 406 ++pageout_count; 407 ++ib; 408 /* 409 * alignment boundry, stop here and switch directions. Do 410 * not clear ib. 411 */ 412 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 413 break; 414 } 415 416 while (pageout_count < vm_pageout_page_count && 417 pindex + is < object->size) { 418 vm_page_t p; 419 420 if ((p = vm_page_next(ps)) == NULL || 421 (p->oflags & VPO_BUSY) != 0 || p->busy != 0) 422 break; 423 vm_page_lock(p); 424 vm_page_test_dirty(p); 425 if (p->dirty == 0 || 426 p->queue != PQ_INACTIVE || 427 p->hold_count != 0) { /* may be undergoing I/O */ 428 vm_page_unlock(p); 429 break; 430 } 431 vm_page_unlock(p); 432 mc[page_base + pageout_count] = ps = p; 433 ++pageout_count; 434 ++is; 435 } 436 437 /* 438 * If we exhausted our forward scan, continue with the reverse scan 439 * when possible, even past a page boundry. This catches boundry 440 * conditions. 441 */ 442 if (ib && pageout_count < vm_pageout_page_count) 443 goto more; 444 445 /* 446 * we allow reads during pageouts... 447 */ 448 return (vm_pageout_flush(&mc[page_base], pageout_count, 0, 0, NULL, 449 NULL)); 450 } 451 452 /* 453 * vm_pageout_flush() - launder the given pages 454 * 455 * The given pages are laundered. Note that we setup for the start of 456 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 457 * reference count all in here rather then in the parent. If we want 458 * the parent to do more sophisticated things we may have to change 459 * the ordering. 460 * 461 * Returned runlen is the count of pages between mreq and first 462 * page after mreq with status VM_PAGER_AGAIN. 463 * *eio is set to TRUE if pager returned VM_PAGER_ERROR or VM_PAGER_FAIL 464 * for any page in runlen set. 465 */ 466 int 467 vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen, 468 boolean_t *eio) 469 { 470 vm_object_t object = mc[0]->object; 471 int pageout_status[count]; 472 int numpagedout = 0; 473 int i, runlen; 474 475 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 476 mtx_assert(&vm_page_queue_mtx, MA_NOTOWNED); 477 478 /* 479 * Initiate I/O. Bump the vm_page_t->busy counter and 480 * mark the pages read-only. 481 * 482 * We do not have to fixup the clean/dirty bits here... we can 483 * allow the pager to do it after the I/O completes. 484 * 485 * NOTE! mc[i]->dirty may be partial or fragmented due to an 486 * edge case with file fragments. 487 */ 488 for (i = 0; i < count; i++) { 489 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 490 ("vm_pageout_flush: partially invalid page %p index %d/%d", 491 mc[i], i, count)); 492 vm_page_io_start(mc[i]); 493 pmap_remove_write(mc[i]); 494 } 495 vm_object_pip_add(object, count); 496 497 vm_pager_put_pages(object, mc, count, flags, pageout_status); 498 499 runlen = count - mreq; 500 if (eio != NULL) 501 *eio = FALSE; 502 for (i = 0; i < count; i++) { 503 vm_page_t mt = mc[i]; 504 505 KASSERT(pageout_status[i] == VM_PAGER_PEND || 506 (mt->aflags & PGA_WRITEABLE) == 0, 507 ("vm_pageout_flush: page %p is not write protected", mt)); 508 switch (pageout_status[i]) { 509 case VM_PAGER_OK: 510 case VM_PAGER_PEND: 511 numpagedout++; 512 break; 513 case VM_PAGER_BAD: 514 /* 515 * Page outside of range of object. Right now we 516 * essentially lose the changes by pretending it 517 * worked. 518 */ 519 vm_page_undirty(mt); 520 break; 521 case VM_PAGER_ERROR: 522 case VM_PAGER_FAIL: 523 /* 524 * If page couldn't be paged out, then reactivate the 525 * page so it doesn't clog the inactive list. (We 526 * will try paging out it again later). 527 */ 528 vm_page_lock(mt); 529 vm_page_activate(mt); 530 vm_page_unlock(mt); 531 if (eio != NULL && i >= mreq && i - mreq < runlen) 532 *eio = TRUE; 533 break; 534 case VM_PAGER_AGAIN: 535 if (i >= mreq && i - mreq < runlen) 536 runlen = i - mreq; 537 break; 538 } 539 540 /* 541 * If the operation is still going, leave the page busy to 542 * block all other accesses. Also, leave the paging in 543 * progress indicator set so that we don't attempt an object 544 * collapse. 545 */ 546 if (pageout_status[i] != VM_PAGER_PEND) { 547 vm_object_pip_wakeup(object); 548 vm_page_io_finish(mt); 549 if (vm_page_count_severe()) { 550 vm_page_lock(mt); 551 vm_page_try_to_cache(mt); 552 vm_page_unlock(mt); 553 } 554 } 555 } 556 if (prunlen != NULL) 557 *prunlen = runlen; 558 return (numpagedout); 559 } 560 561 #if !defined(NO_SWAPPING) 562 /* 563 * vm_pageout_object_deactivate_pages 564 * 565 * Deactivate enough pages to satisfy the inactive target 566 * requirements. 567 * 568 * The object and map must be locked. 569 */ 570 static void 571 vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object, 572 long desired) 573 { 574 vm_object_t backing_object, object; 575 vm_page_t p; 576 int actcount, remove_mode; 577 578 VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED); 579 if (first_object->type == OBJT_DEVICE || 580 first_object->type == OBJT_SG) 581 return; 582 for (object = first_object;; object = backing_object) { 583 if (pmap_resident_count(pmap) <= desired) 584 goto unlock_return; 585 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 586 if (object->type == OBJT_PHYS || object->paging_in_progress) 587 goto unlock_return; 588 589 remove_mode = 0; 590 if (object->shadow_count > 1) 591 remove_mode = 1; 592 /* 593 * Scan the object's entire memory queue. 594 */ 595 TAILQ_FOREACH(p, &object->memq, listq) { 596 if (pmap_resident_count(pmap) <= desired) 597 goto unlock_return; 598 if ((p->oflags & VPO_BUSY) != 0 || p->busy != 0) 599 continue; 600 PCPU_INC(cnt.v_pdpages); 601 vm_page_lock(p); 602 if (p->wire_count != 0 || p->hold_count != 0 || 603 !pmap_page_exists_quick(pmap, p)) { 604 vm_page_unlock(p); 605 continue; 606 } 607 actcount = pmap_ts_referenced(p); 608 if ((p->aflags & PGA_REFERENCED) != 0) { 609 if (actcount == 0) 610 actcount = 1; 611 vm_page_aflag_clear(p, PGA_REFERENCED); 612 } 613 if (p->queue != PQ_ACTIVE && actcount != 0) { 614 vm_page_activate(p); 615 p->act_count += actcount; 616 } else if (p->queue == PQ_ACTIVE) { 617 if (actcount == 0) { 618 p->act_count -= min(p->act_count, 619 ACT_DECLINE); 620 if (!remove_mode && 621 (vm_pageout_algorithm || 622 p->act_count == 0)) { 623 pmap_remove_all(p); 624 vm_page_deactivate(p); 625 } else { 626 vm_page_lock_queues(); 627 vm_page_requeue(p); 628 vm_page_unlock_queues(); 629 } 630 } else { 631 vm_page_activate(p); 632 if (p->act_count < ACT_MAX - 633 ACT_ADVANCE) 634 p->act_count += ACT_ADVANCE; 635 vm_page_lock_queues(); 636 vm_page_requeue(p); 637 vm_page_unlock_queues(); 638 } 639 } else if (p->queue == PQ_INACTIVE) 640 pmap_remove_all(p); 641 vm_page_unlock(p); 642 } 643 if ((backing_object = object->backing_object) == NULL) 644 goto unlock_return; 645 VM_OBJECT_LOCK(backing_object); 646 if (object != first_object) 647 VM_OBJECT_UNLOCK(object); 648 } 649 unlock_return: 650 if (object != first_object) 651 VM_OBJECT_UNLOCK(object); 652 } 653 654 /* 655 * deactivate some number of pages in a map, try to do it fairly, but 656 * that is really hard to do. 657 */ 658 static void 659 vm_pageout_map_deactivate_pages(map, desired) 660 vm_map_t map; 661 long desired; 662 { 663 vm_map_entry_t tmpe; 664 vm_object_t obj, bigobj; 665 int nothingwired; 666 667 if (!vm_map_trylock(map)) 668 return; 669 670 bigobj = NULL; 671 nothingwired = TRUE; 672 673 /* 674 * first, search out the biggest object, and try to free pages from 675 * that. 676 */ 677 tmpe = map->header.next; 678 while (tmpe != &map->header) { 679 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 680 obj = tmpe->object.vm_object; 681 if (obj != NULL && VM_OBJECT_TRYLOCK(obj)) { 682 if (obj->shadow_count <= 1 && 683 (bigobj == NULL || 684 bigobj->resident_page_count < obj->resident_page_count)) { 685 if (bigobj != NULL) 686 VM_OBJECT_UNLOCK(bigobj); 687 bigobj = obj; 688 } else 689 VM_OBJECT_UNLOCK(obj); 690 } 691 } 692 if (tmpe->wired_count > 0) 693 nothingwired = FALSE; 694 tmpe = tmpe->next; 695 } 696 697 if (bigobj != NULL) { 698 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); 699 VM_OBJECT_UNLOCK(bigobj); 700 } 701 /* 702 * Next, hunt around for other pages to deactivate. We actually 703 * do this search sort of wrong -- .text first is not the best idea. 704 */ 705 tmpe = map->header.next; 706 while (tmpe != &map->header) { 707 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 708 break; 709 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 710 obj = tmpe->object.vm_object; 711 if (obj != NULL) { 712 VM_OBJECT_LOCK(obj); 713 vm_pageout_object_deactivate_pages(map->pmap, obj, desired); 714 VM_OBJECT_UNLOCK(obj); 715 } 716 } 717 tmpe = tmpe->next; 718 } 719 720 /* 721 * Remove all mappings if a process is swapped out, this will free page 722 * table pages. 723 */ 724 if (desired == 0 && nothingwired) { 725 pmap_remove(vm_map_pmap(map), vm_map_min(map), 726 vm_map_max(map)); 727 } 728 vm_map_unlock(map); 729 } 730 #endif /* !defined(NO_SWAPPING) */ 731 732 /* 733 * vm_pageout_scan does the dirty work for the pageout daemon. 734 */ 735 static void 736 vm_pageout_scan(int pass) 737 { 738 vm_page_t m, next; 739 struct vm_page marker; 740 int page_shortage, maxscan, pcount; 741 int addl_page_shortage, addl_page_shortage_init; 742 vm_object_t object; 743 int actcount; 744 int vnodes_skipped = 0; 745 int maxlaunder; 746 747 /* 748 * Decrease registered cache sizes. 749 */ 750 EVENTHANDLER_INVOKE(vm_lowmem, 0); 751 /* 752 * We do this explicitly after the caches have been drained above. 753 */ 754 uma_reclaim(); 755 756 addl_page_shortage_init = atomic_readandclear_int(&vm_pageout_deficit); 757 758 /* 759 * Calculate the number of pages we want to either free or move 760 * to the cache. 761 */ 762 page_shortage = vm_paging_target() + addl_page_shortage_init; 763 764 vm_pageout_init_marker(&marker, PQ_INACTIVE); 765 766 /* 767 * Start scanning the inactive queue for pages we can move to the 768 * cache or free. The scan will stop when the target is reached or 769 * we have scanned the entire inactive queue. Note that m->act_count 770 * is not used to form decisions for the inactive queue, only for the 771 * active queue. 772 * 773 * maxlaunder limits the number of dirty pages we flush per scan. 774 * For most systems a smaller value (16 or 32) is more robust under 775 * extreme memory and disk pressure because any unnecessary writes 776 * to disk can result in extreme performance degredation. However, 777 * systems with excessive dirty pages (especially when MAP_NOSYNC is 778 * used) will die horribly with limited laundering. If the pageout 779 * daemon cannot clean enough pages in the first pass, we let it go 780 * all out in succeeding passes. 781 */ 782 if ((maxlaunder = vm_max_launder) <= 1) 783 maxlaunder = 1; 784 if (pass) 785 maxlaunder = 10000; 786 vm_page_lock_queues(); 787 rescan0: 788 addl_page_shortage = addl_page_shortage_init; 789 maxscan = cnt.v_inactive_count; 790 791 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 792 m != NULL && maxscan-- > 0 && page_shortage > 0; 793 m = next) { 794 795 cnt.v_pdpages++; 796 797 if (m->queue != PQ_INACTIVE) 798 goto rescan0; 799 800 next = TAILQ_NEXT(m, pageq); 801 802 /* 803 * skip marker pages 804 */ 805 if (m->flags & PG_MARKER) 806 continue; 807 808 /* 809 * Lock the page. 810 */ 811 if (!vm_pageout_page_lock(m, &next)) { 812 vm_page_unlock(m); 813 addl_page_shortage++; 814 continue; 815 } 816 817 /* 818 * A held page may be undergoing I/O, so skip it. 819 */ 820 if (m->hold_count) { 821 vm_page_unlock(m); 822 vm_page_requeue(m); 823 addl_page_shortage++; 824 continue; 825 } 826 827 /* 828 * Don't mess with busy pages, keep in the front of the 829 * queue, most likely are being paged out. 830 */ 831 object = m->object; 832 if (!VM_OBJECT_TRYLOCK(object) && 833 (!vm_pageout_fallback_object_lock(m, &next) || 834 m->hold_count != 0)) { 835 VM_OBJECT_UNLOCK(object); 836 vm_page_unlock(m); 837 addl_page_shortage++; 838 continue; 839 } 840 if (m->busy || (m->oflags & VPO_BUSY)) { 841 vm_page_unlock(m); 842 VM_OBJECT_UNLOCK(object); 843 addl_page_shortage++; 844 continue; 845 } 846 847 /* 848 * If the object is not being used, we ignore previous 849 * references. 850 */ 851 if (object->ref_count == 0) { 852 vm_page_aflag_clear(m, PGA_REFERENCED); 853 KASSERT(!pmap_page_is_mapped(m), 854 ("vm_pageout_scan: page %p is mapped", m)); 855 856 /* 857 * Otherwise, if the page has been referenced while in the 858 * inactive queue, we bump the "activation count" upwards, 859 * making it less likely that the page will be added back to 860 * the inactive queue prematurely again. Here we check the 861 * page tables (or emulated bits, if any), given the upper 862 * level VM system not knowing anything about existing 863 * references. 864 */ 865 } else if (((m->aflags & PGA_REFERENCED) == 0) && 866 (actcount = pmap_ts_referenced(m))) { 867 vm_page_activate(m); 868 vm_page_unlock(m); 869 m->act_count += actcount + ACT_ADVANCE; 870 VM_OBJECT_UNLOCK(object); 871 continue; 872 } 873 874 /* 875 * If the upper level VM system knows about any page 876 * references, we activate the page. We also set the 877 * "activation count" higher than normal so that we will less 878 * likely place pages back onto the inactive queue again. 879 */ 880 if ((m->aflags & PGA_REFERENCED) != 0) { 881 vm_page_aflag_clear(m, PGA_REFERENCED); 882 actcount = pmap_ts_referenced(m); 883 vm_page_activate(m); 884 vm_page_unlock(m); 885 m->act_count += actcount + ACT_ADVANCE + 1; 886 VM_OBJECT_UNLOCK(object); 887 continue; 888 } 889 890 /* 891 * If the upper level VM system does not believe that the page 892 * is fully dirty, but it is mapped for write access, then we 893 * consult the pmap to see if the page's dirty status should 894 * be updated. 895 */ 896 if (m->dirty != VM_PAGE_BITS_ALL && 897 (m->aflags & PGA_WRITEABLE) != 0) { 898 /* 899 * Avoid a race condition: Unless write access is 900 * removed from the page, another processor could 901 * modify it before all access is removed by the call 902 * to vm_page_cache() below. If vm_page_cache() finds 903 * that the page has been modified when it removes all 904 * access, it panics because it cannot cache dirty 905 * pages. In principle, we could eliminate just write 906 * access here rather than all access. In the expected 907 * case, when there are no last instant modifications 908 * to the page, removing all access will be cheaper 909 * overall. 910 */ 911 if (pmap_is_modified(m)) 912 vm_page_dirty(m); 913 else if (m->dirty == 0) 914 pmap_remove_all(m); 915 } 916 917 if (m->valid == 0) { 918 /* 919 * Invalid pages can be easily freed 920 */ 921 vm_page_free(m); 922 cnt.v_dfree++; 923 --page_shortage; 924 } else if (m->dirty == 0) { 925 /* 926 * Clean pages can be placed onto the cache queue. 927 * This effectively frees them. 928 */ 929 vm_page_cache(m); 930 --page_shortage; 931 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 932 /* 933 * Dirty pages need to be paged out, but flushing 934 * a page is extremely expensive verses freeing 935 * a clean page. Rather then artificially limiting 936 * the number of pages we can flush, we instead give 937 * dirty pages extra priority on the inactive queue 938 * by forcing them to be cycled through the queue 939 * twice before being flushed, after which the 940 * (now clean) page will cycle through once more 941 * before being freed. This significantly extends 942 * the thrash point for a heavily loaded machine. 943 */ 944 m->flags |= PG_WINATCFLS; 945 vm_page_requeue(m); 946 } else if (maxlaunder > 0) { 947 /* 948 * We always want to try to flush some dirty pages if 949 * we encounter them, to keep the system stable. 950 * Normally this number is small, but under extreme 951 * pressure where there are insufficient clean pages 952 * on the inactive queue, we may have to go all out. 953 */ 954 int swap_pageouts_ok, vfslocked = 0; 955 struct vnode *vp = NULL; 956 struct mount *mp = NULL; 957 958 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 959 swap_pageouts_ok = 1; 960 } else { 961 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 962 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 963 vm_page_count_min()); 964 965 } 966 967 /* 968 * We don't bother paging objects that are "dead". 969 * Those objects are in a "rundown" state. 970 */ 971 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 972 vm_page_unlock(m); 973 VM_OBJECT_UNLOCK(object); 974 vm_page_requeue(m); 975 continue; 976 } 977 978 /* 979 * Following operations may unlock 980 * vm_page_queue_mtx, invalidating the 'next' 981 * pointer. To prevent an inordinate number 982 * of restarts we use our marker to remember 983 * our place. 984 * 985 */ 986 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, 987 m, &marker, pageq); 988 /* 989 * The object is already known NOT to be dead. It 990 * is possible for the vget() to block the whole 991 * pageout daemon, but the new low-memory handling 992 * code should prevent it. 993 * 994 * The previous code skipped locked vnodes and, worse, 995 * reordered pages in the queue. This results in 996 * completely non-deterministic operation and, on a 997 * busy system, can lead to extremely non-optimal 998 * pageouts. For example, it can cause clean pages 999 * to be freed and dirty pages to be moved to the end 1000 * of the queue. Since dirty pages are also moved to 1001 * the end of the queue once-cleaned, this gives 1002 * way too large a weighting to defering the freeing 1003 * of dirty pages. 1004 * 1005 * We can't wait forever for the vnode lock, we might 1006 * deadlock due to a vn_read() getting stuck in 1007 * vm_wait while holding this vnode. We skip the 1008 * vnode if we can't get it in a reasonable amount 1009 * of time. 1010 */ 1011 if (object->type == OBJT_VNODE) { 1012 vm_page_unlock_queues(); 1013 vm_page_unlock(m); 1014 vp = object->handle; 1015 if (vp->v_type == VREG && 1016 vn_start_write(vp, &mp, V_NOWAIT) != 0) { 1017 mp = NULL; 1018 ++pageout_lock_miss; 1019 if (object->flags & OBJ_MIGHTBEDIRTY) 1020 vnodes_skipped++; 1021 vm_page_lock_queues(); 1022 goto unlock_and_continue; 1023 } 1024 KASSERT(mp != NULL, 1025 ("vp %p with NULL v_mount", vp)); 1026 vm_object_reference_locked(object); 1027 VM_OBJECT_UNLOCK(object); 1028 vfslocked = VFS_LOCK_GIANT(vp->v_mount); 1029 if (vget(vp, LK_EXCLUSIVE | LK_TIMELOCK, 1030 curthread)) { 1031 VM_OBJECT_LOCK(object); 1032 vm_page_lock_queues(); 1033 ++pageout_lock_miss; 1034 if (object->flags & OBJ_MIGHTBEDIRTY) 1035 vnodes_skipped++; 1036 vp = NULL; 1037 goto unlock_and_continue; 1038 } 1039 VM_OBJECT_LOCK(object); 1040 vm_page_lock(m); 1041 vm_page_lock_queues(); 1042 /* 1043 * The page might have been moved to another 1044 * queue during potential blocking in vget() 1045 * above. The page might have been freed and 1046 * reused for another vnode. 1047 */ 1048 if (m->queue != PQ_INACTIVE || 1049 m->object != object || 1050 TAILQ_NEXT(m, pageq) != &marker) { 1051 vm_page_unlock(m); 1052 if (object->flags & OBJ_MIGHTBEDIRTY) 1053 vnodes_skipped++; 1054 goto unlock_and_continue; 1055 } 1056 1057 /* 1058 * The page may have been busied during the 1059 * blocking in vget(). We don't move the 1060 * page back onto the end of the queue so that 1061 * statistics are more correct if we don't. 1062 */ 1063 if (m->busy || (m->oflags & VPO_BUSY)) { 1064 vm_page_unlock(m); 1065 goto unlock_and_continue; 1066 } 1067 1068 /* 1069 * If the page has become held it might 1070 * be undergoing I/O, so skip it 1071 */ 1072 if (m->hold_count) { 1073 vm_page_unlock(m); 1074 vm_page_requeue(m); 1075 if (object->flags & OBJ_MIGHTBEDIRTY) 1076 vnodes_skipped++; 1077 goto unlock_and_continue; 1078 } 1079 } 1080 1081 /* 1082 * If a page is dirty, then it is either being washed 1083 * (but not yet cleaned) or it is still in the 1084 * laundry. If it is still in the laundry, then we 1085 * start the cleaning operation. 1086 * 1087 * decrement page_shortage on success to account for 1088 * the (future) cleaned page. Otherwise we could wind 1089 * up laundering or cleaning too many pages. 1090 */ 1091 vm_page_unlock_queues(); 1092 if (vm_pageout_clean(m) != 0) { 1093 --page_shortage; 1094 --maxlaunder; 1095 } 1096 vm_page_lock_queues(); 1097 unlock_and_continue: 1098 vm_page_lock_assert(m, MA_NOTOWNED); 1099 VM_OBJECT_UNLOCK(object); 1100 if (mp != NULL) { 1101 vm_page_unlock_queues(); 1102 if (vp != NULL) 1103 vput(vp); 1104 VFS_UNLOCK_GIANT(vfslocked); 1105 vm_object_deallocate(object); 1106 vn_finished_write(mp); 1107 vm_page_lock_queues(); 1108 } 1109 next = TAILQ_NEXT(&marker, pageq); 1110 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, 1111 &marker, pageq); 1112 vm_page_lock_assert(m, MA_NOTOWNED); 1113 continue; 1114 } 1115 vm_page_unlock(m); 1116 VM_OBJECT_UNLOCK(object); 1117 } 1118 1119 /* 1120 * Compute the number of pages we want to try to move from the 1121 * active queue to the inactive queue. 1122 */ 1123 page_shortage = vm_paging_target() + 1124 cnt.v_inactive_target - cnt.v_inactive_count; 1125 page_shortage += addl_page_shortage; 1126 1127 /* 1128 * Scan the active queue for things we can deactivate. We nominally 1129 * track the per-page activity counter and use it to locate 1130 * deactivation candidates. 1131 */ 1132 pcount = cnt.v_active_count; 1133 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1134 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1135 1136 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 1137 1138 KASSERT(m->queue == PQ_ACTIVE, 1139 ("vm_pageout_scan: page %p isn't active", m)); 1140 1141 next = TAILQ_NEXT(m, pageq); 1142 if ((m->flags & PG_MARKER) != 0) { 1143 m = next; 1144 continue; 1145 } 1146 if (!vm_pageout_page_lock(m, &next)) { 1147 vm_page_unlock(m); 1148 m = next; 1149 continue; 1150 } 1151 object = m->object; 1152 if (!VM_OBJECT_TRYLOCK(object) && 1153 !vm_pageout_fallback_object_lock(m, &next)) { 1154 VM_OBJECT_UNLOCK(object); 1155 vm_page_unlock(m); 1156 m = next; 1157 continue; 1158 } 1159 1160 /* 1161 * Don't deactivate pages that are busy. 1162 */ 1163 if ((m->busy != 0) || 1164 (m->oflags & VPO_BUSY) || 1165 (m->hold_count != 0)) { 1166 vm_page_unlock(m); 1167 VM_OBJECT_UNLOCK(object); 1168 vm_page_requeue(m); 1169 m = next; 1170 continue; 1171 } 1172 1173 /* 1174 * The count for pagedaemon pages is done after checking the 1175 * page for eligibility... 1176 */ 1177 cnt.v_pdpages++; 1178 1179 /* 1180 * Check to see "how much" the page has been used. 1181 */ 1182 actcount = 0; 1183 if (object->ref_count != 0) { 1184 if (m->aflags & PGA_REFERENCED) { 1185 actcount += 1; 1186 } 1187 actcount += pmap_ts_referenced(m); 1188 if (actcount) { 1189 m->act_count += ACT_ADVANCE + actcount; 1190 if (m->act_count > ACT_MAX) 1191 m->act_count = ACT_MAX; 1192 } 1193 } 1194 1195 /* 1196 * Since we have "tested" this bit, we need to clear it now. 1197 */ 1198 vm_page_aflag_clear(m, PGA_REFERENCED); 1199 1200 /* 1201 * Only if an object is currently being used, do we use the 1202 * page activation count stats. 1203 */ 1204 if (actcount && (object->ref_count != 0)) { 1205 vm_page_requeue(m); 1206 } else { 1207 m->act_count -= min(m->act_count, ACT_DECLINE); 1208 if (vm_pageout_algorithm || 1209 object->ref_count == 0 || 1210 m->act_count == 0) { 1211 page_shortage--; 1212 if (object->ref_count == 0) { 1213 KASSERT(!pmap_page_is_mapped(m), 1214 ("vm_pageout_scan: page %p is mapped", m)); 1215 if (m->dirty == 0) 1216 vm_page_cache(m); 1217 else 1218 vm_page_deactivate(m); 1219 } else { 1220 vm_page_deactivate(m); 1221 } 1222 } else { 1223 vm_page_requeue(m); 1224 } 1225 } 1226 vm_page_unlock(m); 1227 VM_OBJECT_UNLOCK(object); 1228 m = next; 1229 } 1230 vm_page_unlock_queues(); 1231 #if !defined(NO_SWAPPING) 1232 /* 1233 * Idle process swapout -- run once per second. 1234 */ 1235 if (vm_swap_idle_enabled) { 1236 static long lsec; 1237 if (time_second != lsec) { 1238 vm_req_vmdaemon(VM_SWAP_IDLE); 1239 lsec = time_second; 1240 } 1241 } 1242 #endif 1243 1244 /* 1245 * If we didn't get enough free pages, and we have skipped a vnode 1246 * in a writeable object, wakeup the sync daemon. And kick swapout 1247 * if we did not get enough free pages. 1248 */ 1249 if (vm_paging_target() > 0) { 1250 if (vnodes_skipped && vm_page_count_min()) 1251 (void) speedup_syncer(); 1252 #if !defined(NO_SWAPPING) 1253 if (vm_swap_enabled && vm_page_count_target()) 1254 vm_req_vmdaemon(VM_SWAP_NORMAL); 1255 #endif 1256 } 1257 1258 /* 1259 * If we are critically low on one of RAM or swap and low on 1260 * the other, kill the largest process. However, we avoid 1261 * doing this on the first pass in order to give ourselves a 1262 * chance to flush out dirty vnode-backed pages and to allow 1263 * active pages to be moved to the inactive queue and reclaimed. 1264 */ 1265 if (pass != 0 && 1266 ((swap_pager_avail < 64 && vm_page_count_min()) || 1267 (swap_pager_full && vm_paging_target() > 0))) 1268 vm_pageout_oom(VM_OOM_MEM); 1269 } 1270 1271 1272 void 1273 vm_pageout_oom(int shortage) 1274 { 1275 struct proc *p, *bigproc; 1276 vm_offset_t size, bigsize; 1277 struct thread *td; 1278 struct vmspace *vm; 1279 1280 /* 1281 * We keep the process bigproc locked once we find it to keep anyone 1282 * from messing with it; however, there is a possibility of 1283 * deadlock if process B is bigproc and one of it's child processes 1284 * attempts to propagate a signal to B while we are waiting for A's 1285 * lock while walking this list. To avoid this, we don't block on 1286 * the process lock but just skip a process if it is already locked. 1287 */ 1288 bigproc = NULL; 1289 bigsize = 0; 1290 sx_slock(&allproc_lock); 1291 FOREACH_PROC_IN_SYSTEM(p) { 1292 int breakout; 1293 1294 if (PROC_TRYLOCK(p) == 0) 1295 continue; 1296 /* 1297 * If this is a system, protected or killed process, skip it. 1298 */ 1299 if (p->p_state != PRS_NORMAL || 1300 (p->p_flag & (P_INEXEC | P_PROTECTED | P_SYSTEM)) || 1301 (p->p_pid == 1) || P_KILLED(p) || 1302 ((p->p_pid < 48) && (swap_pager_avail != 0))) { 1303 PROC_UNLOCK(p); 1304 continue; 1305 } 1306 /* 1307 * If the process is in a non-running type state, 1308 * don't touch it. Check all the threads individually. 1309 */ 1310 breakout = 0; 1311 FOREACH_THREAD_IN_PROC(p, td) { 1312 thread_lock(td); 1313 if (!TD_ON_RUNQ(td) && 1314 !TD_IS_RUNNING(td) && 1315 !TD_IS_SLEEPING(td) && 1316 !TD_IS_SUSPENDED(td)) { 1317 thread_unlock(td); 1318 breakout = 1; 1319 break; 1320 } 1321 thread_unlock(td); 1322 } 1323 if (breakout) { 1324 PROC_UNLOCK(p); 1325 continue; 1326 } 1327 /* 1328 * get the process size 1329 */ 1330 vm = vmspace_acquire_ref(p); 1331 if (vm == NULL) { 1332 PROC_UNLOCK(p); 1333 continue; 1334 } 1335 if (!vm_map_trylock_read(&vm->vm_map)) { 1336 vmspace_free(vm); 1337 PROC_UNLOCK(p); 1338 continue; 1339 } 1340 size = vmspace_swap_count(vm); 1341 vm_map_unlock_read(&vm->vm_map); 1342 if (shortage == VM_OOM_MEM) 1343 size += vmspace_resident_count(vm); 1344 vmspace_free(vm); 1345 /* 1346 * if the this process is bigger than the biggest one 1347 * remember it. 1348 */ 1349 if (size > bigsize) { 1350 if (bigproc != NULL) 1351 PROC_UNLOCK(bigproc); 1352 bigproc = p; 1353 bigsize = size; 1354 } else 1355 PROC_UNLOCK(p); 1356 } 1357 sx_sunlock(&allproc_lock); 1358 if (bigproc != NULL) { 1359 killproc(bigproc, "out of swap space"); 1360 sched_nice(bigproc, PRIO_MIN); 1361 PROC_UNLOCK(bigproc); 1362 wakeup(&cnt.v_free_count); 1363 } 1364 } 1365 1366 /* 1367 * This routine tries to maintain the pseudo LRU active queue, 1368 * so that during long periods of time where there is no paging, 1369 * that some statistic accumulation still occurs. This code 1370 * helps the situation where paging just starts to occur. 1371 */ 1372 static void 1373 vm_pageout_page_stats() 1374 { 1375 vm_object_t object; 1376 vm_page_t m,next; 1377 int pcount,tpcount; /* Number of pages to check */ 1378 static int fullintervalcount = 0; 1379 int page_shortage; 1380 1381 page_shortage = 1382 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1383 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1384 1385 if (page_shortage <= 0) 1386 return; 1387 1388 vm_page_lock_queues(); 1389 pcount = cnt.v_active_count; 1390 fullintervalcount += vm_pageout_stats_interval; 1391 if (fullintervalcount < vm_pageout_full_stats_interval) { 1392 tpcount = (int64_t)vm_pageout_stats_max * cnt.v_active_count / 1393 cnt.v_page_count; 1394 if (pcount > tpcount) 1395 pcount = tpcount; 1396 } else { 1397 fullintervalcount = 0; 1398 } 1399 1400 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1401 while ((m != NULL) && (pcount-- > 0)) { 1402 int actcount; 1403 1404 KASSERT(m->queue == PQ_ACTIVE, 1405 ("vm_pageout_page_stats: page %p isn't active", m)); 1406 1407 next = TAILQ_NEXT(m, pageq); 1408 if ((m->flags & PG_MARKER) != 0) { 1409 m = next; 1410 continue; 1411 } 1412 vm_page_lock_assert(m, MA_NOTOWNED); 1413 if (!vm_pageout_page_lock(m, &next)) { 1414 vm_page_unlock(m); 1415 m = next; 1416 continue; 1417 } 1418 object = m->object; 1419 if (!VM_OBJECT_TRYLOCK(object) && 1420 !vm_pageout_fallback_object_lock(m, &next)) { 1421 VM_OBJECT_UNLOCK(object); 1422 vm_page_unlock(m); 1423 m = next; 1424 continue; 1425 } 1426 1427 /* 1428 * Don't deactivate pages that are busy. 1429 */ 1430 if ((m->busy != 0) || 1431 (m->oflags & VPO_BUSY) || 1432 (m->hold_count != 0)) { 1433 vm_page_unlock(m); 1434 VM_OBJECT_UNLOCK(object); 1435 vm_page_requeue(m); 1436 m = next; 1437 continue; 1438 } 1439 1440 actcount = 0; 1441 if (m->aflags & PGA_REFERENCED) { 1442 vm_page_aflag_clear(m, PGA_REFERENCED); 1443 actcount += 1; 1444 } 1445 1446 actcount += pmap_ts_referenced(m); 1447 if (actcount) { 1448 m->act_count += ACT_ADVANCE + actcount; 1449 if (m->act_count > ACT_MAX) 1450 m->act_count = ACT_MAX; 1451 vm_page_requeue(m); 1452 } else { 1453 if (m->act_count == 0) { 1454 /* 1455 * We turn off page access, so that we have 1456 * more accurate RSS stats. We don't do this 1457 * in the normal page deactivation when the 1458 * system is loaded VM wise, because the 1459 * cost of the large number of page protect 1460 * operations would be higher than the value 1461 * of doing the operation. 1462 */ 1463 pmap_remove_all(m); 1464 vm_page_deactivate(m); 1465 } else { 1466 m->act_count -= min(m->act_count, ACT_DECLINE); 1467 vm_page_requeue(m); 1468 } 1469 } 1470 vm_page_unlock(m); 1471 VM_OBJECT_UNLOCK(object); 1472 m = next; 1473 } 1474 vm_page_unlock_queues(); 1475 } 1476 1477 /* 1478 * vm_pageout is the high level pageout daemon. 1479 */ 1480 static void 1481 vm_pageout() 1482 { 1483 int error, pass; 1484 1485 /* 1486 * Initialize some paging parameters. 1487 */ 1488 cnt.v_interrupt_free_min = 2; 1489 if (cnt.v_page_count < 2000) 1490 vm_pageout_page_count = 8; 1491 1492 /* 1493 * v_free_reserved needs to include enough for the largest 1494 * swap pager structures plus enough for any pv_entry structs 1495 * when paging. 1496 */ 1497 if (cnt.v_page_count > 1024) 1498 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1499 else 1500 cnt.v_free_min = 4; 1501 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1502 cnt.v_interrupt_free_min; 1503 cnt.v_free_reserved = vm_pageout_page_count + 1504 cnt.v_pageout_free_min + (cnt.v_page_count / 768); 1505 cnt.v_free_severe = cnt.v_free_min / 2; 1506 cnt.v_free_min += cnt.v_free_reserved; 1507 cnt.v_free_severe += cnt.v_free_reserved; 1508 1509 /* 1510 * v_free_target and v_cache_min control pageout hysteresis. Note 1511 * that these are more a measure of the VM cache queue hysteresis 1512 * then the VM free queue. Specifically, v_free_target is the 1513 * high water mark (free+cache pages). 1514 * 1515 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1516 * low water mark, while v_free_min is the stop. v_cache_min must 1517 * be big enough to handle memory needs while the pageout daemon 1518 * is signalled and run to free more pages. 1519 */ 1520 if (cnt.v_free_count > 6144) 1521 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1522 else 1523 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1524 1525 if (cnt.v_free_count > 2048) { 1526 cnt.v_cache_min = cnt.v_free_target; 1527 cnt.v_cache_max = 2 * cnt.v_cache_min; 1528 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1529 } else { 1530 cnt.v_cache_min = 0; 1531 cnt.v_cache_max = 0; 1532 cnt.v_inactive_target = cnt.v_free_count / 4; 1533 } 1534 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1535 cnt.v_inactive_target = cnt.v_free_count / 3; 1536 1537 /* XXX does not really belong here */ 1538 if (vm_page_max_wired == 0) 1539 vm_page_max_wired = cnt.v_free_count / 3; 1540 1541 if (vm_pageout_stats_max == 0) 1542 vm_pageout_stats_max = cnt.v_free_target; 1543 1544 /* 1545 * Set interval in seconds for stats scan. 1546 */ 1547 if (vm_pageout_stats_interval == 0) 1548 vm_pageout_stats_interval = 5; 1549 if (vm_pageout_full_stats_interval == 0) 1550 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1551 1552 swap_pager_swap_init(); 1553 pass = 0; 1554 /* 1555 * The pageout daemon is never done, so loop forever. 1556 */ 1557 while (TRUE) { 1558 /* 1559 * If we have enough free memory, wakeup waiters. Do 1560 * not clear vm_pages_needed until we reach our target, 1561 * otherwise we may be woken up over and over again and 1562 * waste a lot of cpu. 1563 */ 1564 mtx_lock(&vm_page_queue_free_mtx); 1565 if (vm_pages_needed && !vm_page_count_min()) { 1566 if (!vm_paging_needed()) 1567 vm_pages_needed = 0; 1568 wakeup(&cnt.v_free_count); 1569 } 1570 if (vm_pages_needed) { 1571 /* 1572 * Still not done, take a second pass without waiting 1573 * (unlimited dirty cleaning), otherwise sleep a bit 1574 * and try again. 1575 */ 1576 ++pass; 1577 if (pass > 1) 1578 msleep(&vm_pages_needed, 1579 &vm_page_queue_free_mtx, PVM, "psleep", 1580 hz / 2); 1581 } else { 1582 /* 1583 * Good enough, sleep & handle stats. Prime the pass 1584 * for the next run. 1585 */ 1586 if (pass > 1) 1587 pass = 1; 1588 else 1589 pass = 0; 1590 error = msleep(&vm_pages_needed, 1591 &vm_page_queue_free_mtx, PVM, "psleep", 1592 vm_pageout_stats_interval * hz); 1593 if (error && !vm_pages_needed) { 1594 mtx_unlock(&vm_page_queue_free_mtx); 1595 pass = 0; 1596 vm_pageout_page_stats(); 1597 continue; 1598 } 1599 } 1600 if (vm_pages_needed) 1601 cnt.v_pdwakeups++; 1602 mtx_unlock(&vm_page_queue_free_mtx); 1603 vm_pageout_scan(pass); 1604 } 1605 } 1606 1607 /* 1608 * Unless the free page queue lock is held by the caller, this function 1609 * should be regarded as advisory. Specifically, the caller should 1610 * not msleep() on &cnt.v_free_count following this function unless 1611 * the free page queue lock is held until the msleep() is performed. 1612 */ 1613 void 1614 pagedaemon_wakeup() 1615 { 1616 1617 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1618 vm_pages_needed = 1; 1619 wakeup(&vm_pages_needed); 1620 } 1621 } 1622 1623 #if !defined(NO_SWAPPING) 1624 static void 1625 vm_req_vmdaemon(int req) 1626 { 1627 static int lastrun = 0; 1628 1629 mtx_lock(&vm_daemon_mtx); 1630 vm_pageout_req_swapout |= req; 1631 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1632 wakeup(&vm_daemon_needed); 1633 lastrun = ticks; 1634 } 1635 mtx_unlock(&vm_daemon_mtx); 1636 } 1637 1638 static void 1639 vm_daemon() 1640 { 1641 struct rlimit rsslim; 1642 struct proc *p; 1643 struct thread *td; 1644 struct vmspace *vm; 1645 int breakout, swapout_flags, tryagain, attempts; 1646 #ifdef RACCT 1647 uint64_t rsize, ravailable; 1648 #endif 1649 1650 while (TRUE) { 1651 mtx_lock(&vm_daemon_mtx); 1652 #ifdef RACCT 1653 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", hz); 1654 #else 1655 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0); 1656 #endif 1657 swapout_flags = vm_pageout_req_swapout; 1658 vm_pageout_req_swapout = 0; 1659 mtx_unlock(&vm_daemon_mtx); 1660 if (swapout_flags) 1661 swapout_procs(swapout_flags); 1662 1663 /* 1664 * scan the processes for exceeding their rlimits or if 1665 * process is swapped out -- deactivate pages 1666 */ 1667 tryagain = 0; 1668 attempts = 0; 1669 again: 1670 attempts++; 1671 sx_slock(&allproc_lock); 1672 FOREACH_PROC_IN_SYSTEM(p) { 1673 vm_pindex_t limit, size; 1674 1675 /* 1676 * if this is a system process or if we have already 1677 * looked at this process, skip it. 1678 */ 1679 PROC_LOCK(p); 1680 if (p->p_state != PRS_NORMAL || 1681 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 1682 PROC_UNLOCK(p); 1683 continue; 1684 } 1685 /* 1686 * if the process is in a non-running type state, 1687 * don't touch it. 1688 */ 1689 breakout = 0; 1690 FOREACH_THREAD_IN_PROC(p, td) { 1691 thread_lock(td); 1692 if (!TD_ON_RUNQ(td) && 1693 !TD_IS_RUNNING(td) && 1694 !TD_IS_SLEEPING(td) && 1695 !TD_IS_SUSPENDED(td)) { 1696 thread_unlock(td); 1697 breakout = 1; 1698 break; 1699 } 1700 thread_unlock(td); 1701 } 1702 if (breakout) { 1703 PROC_UNLOCK(p); 1704 continue; 1705 } 1706 /* 1707 * get a limit 1708 */ 1709 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1710 limit = OFF_TO_IDX( 1711 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1712 1713 /* 1714 * let processes that are swapped out really be 1715 * swapped out set the limit to nothing (will force a 1716 * swap-out.) 1717 */ 1718 if ((p->p_flag & P_INMEM) == 0) 1719 limit = 0; /* XXX */ 1720 vm = vmspace_acquire_ref(p); 1721 PROC_UNLOCK(p); 1722 if (vm == NULL) 1723 continue; 1724 1725 size = vmspace_resident_count(vm); 1726 if (limit >= 0 && size >= limit) { 1727 vm_pageout_map_deactivate_pages( 1728 &vm->vm_map, limit); 1729 } 1730 #ifdef RACCT 1731 rsize = IDX_TO_OFF(size); 1732 PROC_LOCK(p); 1733 racct_set(p, RACCT_RSS, rsize); 1734 ravailable = racct_get_available(p, RACCT_RSS); 1735 PROC_UNLOCK(p); 1736 if (rsize > ravailable) { 1737 /* 1738 * Don't be overly aggressive; this might be 1739 * an innocent process, and the limit could've 1740 * been exceeded by some memory hog. Don't 1741 * try to deactivate more than 1/4th of process' 1742 * resident set size. 1743 */ 1744 if (attempts <= 8) { 1745 if (ravailable < rsize - (rsize / 4)) 1746 ravailable = rsize - (rsize / 4); 1747 } 1748 vm_pageout_map_deactivate_pages( 1749 &vm->vm_map, OFF_TO_IDX(ravailable)); 1750 /* Update RSS usage after paging out. */ 1751 size = vmspace_resident_count(vm); 1752 rsize = IDX_TO_OFF(size); 1753 PROC_LOCK(p); 1754 racct_set(p, RACCT_RSS, rsize); 1755 PROC_UNLOCK(p); 1756 if (rsize > ravailable) 1757 tryagain = 1; 1758 } 1759 #endif 1760 vmspace_free(vm); 1761 } 1762 sx_sunlock(&allproc_lock); 1763 if (tryagain != 0 && attempts <= 10) 1764 goto again; 1765 } 1766 } 1767 #endif /* !defined(NO_SWAPPING) */ 1768