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 } 450 451 /* 452 * vm_pageout_flush() - launder the given pages 453 * 454 * The given pages are laundered. Note that we setup for the start of 455 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 456 * reference count all in here rather then in the parent. If we want 457 * the parent to do more sophisticated things we may have to change 458 * the ordering. 459 * 460 * Returned runlen is the count of pages between mreq and first 461 * page after mreq with status VM_PAGER_AGAIN. 462 */ 463 int 464 vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen) 465 { 466 vm_object_t object = mc[0]->object; 467 int pageout_status[count]; 468 int numpagedout = 0; 469 int i, runlen; 470 471 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 472 mtx_assert(&vm_page_queue_mtx, MA_NOTOWNED); 473 474 /* 475 * Initiate I/O. Bump the vm_page_t->busy counter and 476 * mark the pages read-only. 477 * 478 * We do not have to fixup the clean/dirty bits here... we can 479 * allow the pager to do it after the I/O completes. 480 * 481 * NOTE! mc[i]->dirty may be partial or fragmented due to an 482 * edge case with file fragments. 483 */ 484 for (i = 0; i < count; i++) { 485 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 486 ("vm_pageout_flush: partially invalid page %p index %d/%d", 487 mc[i], i, count)); 488 vm_page_io_start(mc[i]); 489 pmap_remove_write(mc[i]); 490 } 491 vm_object_pip_add(object, count); 492 493 vm_pager_put_pages(object, mc, count, flags, pageout_status); 494 495 runlen = count - mreq; 496 for (i = 0; i < count; i++) { 497 vm_page_t mt = mc[i]; 498 499 KASSERT(pageout_status[i] == VM_PAGER_PEND || 500 (mt->aflags & PGA_WRITEABLE) == 0, 501 ("vm_pageout_flush: page %p is not write protected", mt)); 502 switch (pageout_status[i]) { 503 case VM_PAGER_OK: 504 case VM_PAGER_PEND: 505 numpagedout++; 506 break; 507 case VM_PAGER_BAD: 508 /* 509 * Page outside of range of object. Right now we 510 * essentially lose the changes by pretending it 511 * worked. 512 */ 513 vm_page_undirty(mt); 514 break; 515 case VM_PAGER_ERROR: 516 case VM_PAGER_FAIL: 517 /* 518 * If page couldn't be paged out, then reactivate the 519 * page so it doesn't clog the inactive list. (We 520 * will try paging out it again later). 521 */ 522 vm_page_lock(mt); 523 vm_page_activate(mt); 524 vm_page_unlock(mt); 525 break; 526 case VM_PAGER_AGAIN: 527 if (i >= mreq && i - mreq < runlen) 528 runlen = i - mreq; 529 break; 530 } 531 532 /* 533 * If the operation is still going, leave the page busy to 534 * block all other accesses. Also, leave the paging in 535 * progress indicator set so that we don't attempt an object 536 * collapse. 537 */ 538 if (pageout_status[i] != VM_PAGER_PEND) { 539 vm_object_pip_wakeup(object); 540 vm_page_io_finish(mt); 541 if (vm_page_count_severe()) { 542 vm_page_lock(mt); 543 vm_page_try_to_cache(mt); 544 vm_page_unlock(mt); 545 } 546 } 547 } 548 if (prunlen != NULL) 549 *prunlen = runlen; 550 return (numpagedout); 551 } 552 553 #if !defined(NO_SWAPPING) 554 /* 555 * vm_pageout_object_deactivate_pages 556 * 557 * Deactivate enough pages to satisfy the inactive target 558 * requirements. 559 * 560 * The object and map must be locked. 561 */ 562 static void 563 vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object, 564 long desired) 565 { 566 vm_object_t backing_object, object; 567 vm_page_t p; 568 int actcount, remove_mode; 569 570 VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED); 571 if (first_object->type == OBJT_DEVICE || 572 first_object->type == OBJT_SG) 573 return; 574 for (object = first_object;; object = backing_object) { 575 if (pmap_resident_count(pmap) <= desired) 576 goto unlock_return; 577 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 578 if (object->type == OBJT_PHYS || object->paging_in_progress) 579 goto unlock_return; 580 581 remove_mode = 0; 582 if (object->shadow_count > 1) 583 remove_mode = 1; 584 /* 585 * Scan the object's entire memory queue. 586 */ 587 TAILQ_FOREACH(p, &object->memq, listq) { 588 if (pmap_resident_count(pmap) <= desired) 589 goto unlock_return; 590 if ((p->oflags & VPO_BUSY) != 0 || p->busy != 0) 591 continue; 592 PCPU_INC(cnt.v_pdpages); 593 vm_page_lock(p); 594 if (p->wire_count != 0 || p->hold_count != 0 || 595 !pmap_page_exists_quick(pmap, p)) { 596 vm_page_unlock(p); 597 continue; 598 } 599 actcount = pmap_ts_referenced(p); 600 if ((p->aflags & PGA_REFERENCED) != 0) { 601 if (actcount == 0) 602 actcount = 1; 603 vm_page_aflag_clear(p, PGA_REFERENCED); 604 } 605 if (p->queue != PQ_ACTIVE && actcount != 0) { 606 vm_page_activate(p); 607 p->act_count += actcount; 608 } else if (p->queue == PQ_ACTIVE) { 609 if (actcount == 0) { 610 p->act_count -= min(p->act_count, 611 ACT_DECLINE); 612 if (!remove_mode && 613 (vm_pageout_algorithm || 614 p->act_count == 0)) { 615 pmap_remove_all(p); 616 vm_page_deactivate(p); 617 } else { 618 vm_page_lock_queues(); 619 vm_page_requeue(p); 620 vm_page_unlock_queues(); 621 } 622 } else { 623 vm_page_activate(p); 624 if (p->act_count < ACT_MAX - 625 ACT_ADVANCE) 626 p->act_count += ACT_ADVANCE; 627 vm_page_lock_queues(); 628 vm_page_requeue(p); 629 vm_page_unlock_queues(); 630 } 631 } else if (p->queue == PQ_INACTIVE) 632 pmap_remove_all(p); 633 vm_page_unlock(p); 634 } 635 if ((backing_object = object->backing_object) == NULL) 636 goto unlock_return; 637 VM_OBJECT_LOCK(backing_object); 638 if (object != first_object) 639 VM_OBJECT_UNLOCK(object); 640 } 641 unlock_return: 642 if (object != first_object) 643 VM_OBJECT_UNLOCK(object); 644 } 645 646 /* 647 * deactivate some number of pages in a map, try to do it fairly, but 648 * that is really hard to do. 649 */ 650 static void 651 vm_pageout_map_deactivate_pages(map, desired) 652 vm_map_t map; 653 long desired; 654 { 655 vm_map_entry_t tmpe; 656 vm_object_t obj, bigobj; 657 int nothingwired; 658 659 if (!vm_map_trylock(map)) 660 return; 661 662 bigobj = NULL; 663 nothingwired = TRUE; 664 665 /* 666 * first, search out the biggest object, and try to free pages from 667 * that. 668 */ 669 tmpe = map->header.next; 670 while (tmpe != &map->header) { 671 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 672 obj = tmpe->object.vm_object; 673 if (obj != NULL && VM_OBJECT_TRYLOCK(obj)) { 674 if (obj->shadow_count <= 1 && 675 (bigobj == NULL || 676 bigobj->resident_page_count < obj->resident_page_count)) { 677 if (bigobj != NULL) 678 VM_OBJECT_UNLOCK(bigobj); 679 bigobj = obj; 680 } else 681 VM_OBJECT_UNLOCK(obj); 682 } 683 } 684 if (tmpe->wired_count > 0) 685 nothingwired = FALSE; 686 tmpe = tmpe->next; 687 } 688 689 if (bigobj != NULL) { 690 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); 691 VM_OBJECT_UNLOCK(bigobj); 692 } 693 /* 694 * Next, hunt around for other pages to deactivate. We actually 695 * do this search sort of wrong -- .text first is not the best idea. 696 */ 697 tmpe = map->header.next; 698 while (tmpe != &map->header) { 699 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 700 break; 701 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 702 obj = tmpe->object.vm_object; 703 if (obj != NULL) { 704 VM_OBJECT_LOCK(obj); 705 vm_pageout_object_deactivate_pages(map->pmap, obj, desired); 706 VM_OBJECT_UNLOCK(obj); 707 } 708 } 709 tmpe = tmpe->next; 710 } 711 712 /* 713 * Remove all mappings if a process is swapped out, this will free page 714 * table pages. 715 */ 716 if (desired == 0 && nothingwired) { 717 pmap_remove(vm_map_pmap(map), vm_map_min(map), 718 vm_map_max(map)); 719 } 720 vm_map_unlock(map); 721 } 722 #endif /* !defined(NO_SWAPPING) */ 723 724 /* 725 * vm_pageout_scan does the dirty work for the pageout daemon. 726 */ 727 static void 728 vm_pageout_scan(int pass) 729 { 730 vm_page_t m, next; 731 struct vm_page marker; 732 int page_shortage, maxscan, pcount; 733 int addl_page_shortage, addl_page_shortage_init; 734 vm_object_t object; 735 int actcount; 736 int vnodes_skipped = 0; 737 int maxlaunder; 738 739 /* 740 * Decrease registered cache sizes. 741 */ 742 EVENTHANDLER_INVOKE(vm_lowmem, 0); 743 /* 744 * We do this explicitly after the caches have been drained above. 745 */ 746 uma_reclaim(); 747 748 addl_page_shortage_init = atomic_readandclear_int(&vm_pageout_deficit); 749 750 /* 751 * Calculate the number of pages we want to either free or move 752 * to the cache. 753 */ 754 page_shortage = vm_paging_target() + addl_page_shortage_init; 755 756 vm_pageout_init_marker(&marker, PQ_INACTIVE); 757 758 /* 759 * Start scanning the inactive queue for pages we can move to the 760 * cache or free. The scan will stop when the target is reached or 761 * we have scanned the entire inactive queue. Note that m->act_count 762 * is not used to form decisions for the inactive queue, only for the 763 * active queue. 764 * 765 * maxlaunder limits the number of dirty pages we flush per scan. 766 * For most systems a smaller value (16 or 32) is more robust under 767 * extreme memory and disk pressure because any unnecessary writes 768 * to disk can result in extreme performance degredation. However, 769 * systems with excessive dirty pages (especially when MAP_NOSYNC is 770 * used) will die horribly with limited laundering. If the pageout 771 * daemon cannot clean enough pages in the first pass, we let it go 772 * all out in succeeding passes. 773 */ 774 if ((maxlaunder = vm_max_launder) <= 1) 775 maxlaunder = 1; 776 if (pass) 777 maxlaunder = 10000; 778 vm_page_lock_queues(); 779 rescan0: 780 addl_page_shortage = addl_page_shortage_init; 781 maxscan = cnt.v_inactive_count; 782 783 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 784 m != NULL && maxscan-- > 0 && page_shortage > 0; 785 m = next) { 786 787 cnt.v_pdpages++; 788 789 if (m->queue != PQ_INACTIVE) 790 goto rescan0; 791 792 next = TAILQ_NEXT(m, pageq); 793 794 /* 795 * skip marker pages 796 */ 797 if (m->flags & PG_MARKER) 798 continue; 799 800 /* 801 * Lock the page. 802 */ 803 if (!vm_pageout_page_lock(m, &next)) { 804 vm_page_unlock(m); 805 addl_page_shortage++; 806 continue; 807 } 808 809 /* 810 * A held page may be undergoing I/O, so skip it. 811 */ 812 if (m->hold_count) { 813 vm_page_unlock(m); 814 vm_page_requeue(m); 815 addl_page_shortage++; 816 continue; 817 } 818 819 /* 820 * Don't mess with busy pages, keep in the front of the 821 * queue, most likely are being paged out. 822 */ 823 object = m->object; 824 if (!VM_OBJECT_TRYLOCK(object) && 825 (!vm_pageout_fallback_object_lock(m, &next) || 826 m->hold_count != 0)) { 827 VM_OBJECT_UNLOCK(object); 828 vm_page_unlock(m); 829 addl_page_shortage++; 830 continue; 831 } 832 if (m->busy || (m->oflags & VPO_BUSY)) { 833 vm_page_unlock(m); 834 VM_OBJECT_UNLOCK(object); 835 addl_page_shortage++; 836 continue; 837 } 838 839 /* 840 * If the object is not being used, we ignore previous 841 * references. 842 */ 843 if (object->ref_count == 0) { 844 vm_page_aflag_clear(m, PGA_REFERENCED); 845 KASSERT(!pmap_page_is_mapped(m), 846 ("vm_pageout_scan: page %p is mapped", m)); 847 848 /* 849 * Otherwise, if the page has been referenced while in the 850 * inactive queue, we bump the "activation count" upwards, 851 * making it less likely that the page will be added back to 852 * the inactive queue prematurely again. Here we check the 853 * page tables (or emulated bits, if any), given the upper 854 * level VM system not knowing anything about existing 855 * references. 856 */ 857 } else if (((m->aflags & PGA_REFERENCED) == 0) && 858 (actcount = pmap_ts_referenced(m))) { 859 vm_page_activate(m); 860 vm_page_unlock(m); 861 m->act_count += actcount + ACT_ADVANCE; 862 VM_OBJECT_UNLOCK(object); 863 continue; 864 } 865 866 /* 867 * If the upper level VM system knows about any page 868 * references, we activate the page. We also set the 869 * "activation count" higher than normal so that we will less 870 * likely place pages back onto the inactive queue again. 871 */ 872 if ((m->aflags & PGA_REFERENCED) != 0) { 873 vm_page_aflag_clear(m, PGA_REFERENCED); 874 actcount = pmap_ts_referenced(m); 875 vm_page_activate(m); 876 vm_page_unlock(m); 877 m->act_count += actcount + ACT_ADVANCE + 1; 878 VM_OBJECT_UNLOCK(object); 879 continue; 880 } 881 882 /* 883 * If the upper level VM system does not believe that the page 884 * is fully dirty, but it is mapped for write access, then we 885 * consult the pmap to see if the page's dirty status should 886 * be updated. 887 */ 888 if (m->dirty != VM_PAGE_BITS_ALL && 889 (m->aflags & PGA_WRITEABLE) != 0) { 890 /* 891 * Avoid a race condition: Unless write access is 892 * removed from the page, another processor could 893 * modify it before all access is removed by the call 894 * to vm_page_cache() below. If vm_page_cache() finds 895 * that the page has been modified when it removes all 896 * access, it panics because it cannot cache dirty 897 * pages. In principle, we could eliminate just write 898 * access here rather than all access. In the expected 899 * case, when there are no last instant modifications 900 * to the page, removing all access will be cheaper 901 * overall. 902 */ 903 if (pmap_is_modified(m)) 904 vm_page_dirty(m); 905 else if (m->dirty == 0) 906 pmap_remove_all(m); 907 } 908 909 if (m->valid == 0) { 910 /* 911 * Invalid pages can be easily freed 912 */ 913 vm_page_free(m); 914 cnt.v_dfree++; 915 --page_shortage; 916 } else if (m->dirty == 0) { 917 /* 918 * Clean pages can be placed onto the cache queue. 919 * This effectively frees them. 920 */ 921 vm_page_cache(m); 922 --page_shortage; 923 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 924 /* 925 * Dirty pages need to be paged out, but flushing 926 * a page is extremely expensive verses freeing 927 * a clean page. Rather then artificially limiting 928 * the number of pages we can flush, we instead give 929 * dirty pages extra priority on the inactive queue 930 * by forcing them to be cycled through the queue 931 * twice before being flushed, after which the 932 * (now clean) page will cycle through once more 933 * before being freed. This significantly extends 934 * the thrash point for a heavily loaded machine. 935 */ 936 m->flags |= PG_WINATCFLS; 937 vm_page_requeue(m); 938 } else if (maxlaunder > 0) { 939 /* 940 * We always want to try to flush some dirty pages if 941 * we encounter them, to keep the system stable. 942 * Normally this number is small, but under extreme 943 * pressure where there are insufficient clean pages 944 * on the inactive queue, we may have to go all out. 945 */ 946 int swap_pageouts_ok, vfslocked = 0; 947 struct vnode *vp = NULL; 948 struct mount *mp = NULL; 949 950 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 951 swap_pageouts_ok = 1; 952 } else { 953 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 954 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 955 vm_page_count_min()); 956 957 } 958 959 /* 960 * We don't bother paging objects that are "dead". 961 * Those objects are in a "rundown" state. 962 */ 963 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 964 vm_page_unlock(m); 965 VM_OBJECT_UNLOCK(object); 966 vm_page_requeue(m); 967 continue; 968 } 969 970 /* 971 * Following operations may unlock 972 * vm_page_queue_mtx, invalidating the 'next' 973 * pointer. To prevent an inordinate number 974 * of restarts we use our marker to remember 975 * our place. 976 * 977 */ 978 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, 979 m, &marker, pageq); 980 /* 981 * The object is already known NOT to be dead. It 982 * is possible for the vget() to block the whole 983 * pageout daemon, but the new low-memory handling 984 * code should prevent it. 985 * 986 * The previous code skipped locked vnodes and, worse, 987 * reordered pages in the queue. This results in 988 * completely non-deterministic operation and, on a 989 * busy system, can lead to extremely non-optimal 990 * pageouts. For example, it can cause clean pages 991 * to be freed and dirty pages to be moved to the end 992 * of the queue. Since dirty pages are also moved to 993 * the end of the queue once-cleaned, this gives 994 * way too large a weighting to defering the freeing 995 * of dirty pages. 996 * 997 * We can't wait forever for the vnode lock, we might 998 * deadlock due to a vn_read() getting stuck in 999 * vm_wait while holding this vnode. We skip the 1000 * vnode if we can't get it in a reasonable amount 1001 * of time. 1002 */ 1003 if (object->type == OBJT_VNODE) { 1004 vm_page_unlock_queues(); 1005 vm_page_unlock(m); 1006 vp = object->handle; 1007 if (vp->v_type == VREG && 1008 vn_start_write(vp, &mp, V_NOWAIT) != 0) { 1009 mp = NULL; 1010 ++pageout_lock_miss; 1011 if (object->flags & OBJ_MIGHTBEDIRTY) 1012 vnodes_skipped++; 1013 vm_page_lock_queues(); 1014 goto unlock_and_continue; 1015 } 1016 KASSERT(mp != NULL, 1017 ("vp %p with NULL v_mount", vp)); 1018 vm_object_reference_locked(object); 1019 VM_OBJECT_UNLOCK(object); 1020 vfslocked = VFS_LOCK_GIANT(vp->v_mount); 1021 if (vget(vp, LK_EXCLUSIVE | LK_TIMELOCK, 1022 curthread)) { 1023 VM_OBJECT_LOCK(object); 1024 vm_page_lock_queues(); 1025 ++pageout_lock_miss; 1026 if (object->flags & OBJ_MIGHTBEDIRTY) 1027 vnodes_skipped++; 1028 vp = NULL; 1029 goto unlock_and_continue; 1030 } 1031 VM_OBJECT_LOCK(object); 1032 vm_page_lock(m); 1033 vm_page_lock_queues(); 1034 /* 1035 * The page might have been moved to another 1036 * queue during potential blocking in vget() 1037 * above. The page might have been freed and 1038 * reused for another vnode. 1039 */ 1040 if (m->queue != PQ_INACTIVE || 1041 m->object != object || 1042 TAILQ_NEXT(m, pageq) != &marker) { 1043 vm_page_unlock(m); 1044 if (object->flags & OBJ_MIGHTBEDIRTY) 1045 vnodes_skipped++; 1046 goto unlock_and_continue; 1047 } 1048 1049 /* 1050 * The page may have been busied during the 1051 * blocking in vget(). We don't move the 1052 * page back onto the end of the queue so that 1053 * statistics are more correct if we don't. 1054 */ 1055 if (m->busy || (m->oflags & VPO_BUSY)) { 1056 vm_page_unlock(m); 1057 goto unlock_and_continue; 1058 } 1059 1060 /* 1061 * If the page has become held it might 1062 * be undergoing I/O, so skip it 1063 */ 1064 if (m->hold_count) { 1065 vm_page_unlock(m); 1066 vm_page_requeue(m); 1067 if (object->flags & OBJ_MIGHTBEDIRTY) 1068 vnodes_skipped++; 1069 goto unlock_and_continue; 1070 } 1071 } 1072 1073 /* 1074 * If a page is dirty, then it is either being washed 1075 * (but not yet cleaned) or it is still in the 1076 * laundry. If it is still in the laundry, then we 1077 * start the cleaning operation. 1078 * 1079 * decrement page_shortage on success to account for 1080 * the (future) cleaned page. Otherwise we could wind 1081 * up laundering or cleaning too many pages. 1082 */ 1083 vm_page_unlock_queues(); 1084 if (vm_pageout_clean(m) != 0) { 1085 --page_shortage; 1086 --maxlaunder; 1087 } 1088 vm_page_lock_queues(); 1089 unlock_and_continue: 1090 vm_page_lock_assert(m, MA_NOTOWNED); 1091 VM_OBJECT_UNLOCK(object); 1092 if (mp != NULL) { 1093 vm_page_unlock_queues(); 1094 if (vp != NULL) 1095 vput(vp); 1096 VFS_UNLOCK_GIANT(vfslocked); 1097 vm_object_deallocate(object); 1098 vn_finished_write(mp); 1099 vm_page_lock_queues(); 1100 } 1101 next = TAILQ_NEXT(&marker, pageq); 1102 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, 1103 &marker, pageq); 1104 vm_page_lock_assert(m, MA_NOTOWNED); 1105 continue; 1106 } 1107 vm_page_unlock(m); 1108 VM_OBJECT_UNLOCK(object); 1109 } 1110 1111 /* 1112 * Compute the number of pages we want to try to move from the 1113 * active queue to the inactive queue. 1114 */ 1115 page_shortage = vm_paging_target() + 1116 cnt.v_inactive_target - cnt.v_inactive_count; 1117 page_shortage += addl_page_shortage; 1118 1119 /* 1120 * Scan the active queue for things we can deactivate. We nominally 1121 * track the per-page activity counter and use it to locate 1122 * deactivation candidates. 1123 */ 1124 pcount = cnt.v_active_count; 1125 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1126 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1127 1128 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 1129 1130 KASSERT(m->queue == PQ_ACTIVE, 1131 ("vm_pageout_scan: page %p isn't active", m)); 1132 1133 next = TAILQ_NEXT(m, pageq); 1134 if ((m->flags & PG_MARKER) != 0) { 1135 m = next; 1136 continue; 1137 } 1138 if (!vm_pageout_page_lock(m, &next)) { 1139 vm_page_unlock(m); 1140 m = next; 1141 continue; 1142 } 1143 object = m->object; 1144 if (!VM_OBJECT_TRYLOCK(object) && 1145 !vm_pageout_fallback_object_lock(m, &next)) { 1146 VM_OBJECT_UNLOCK(object); 1147 vm_page_unlock(m); 1148 m = next; 1149 continue; 1150 } 1151 1152 /* 1153 * Don't deactivate pages that are busy. 1154 */ 1155 if ((m->busy != 0) || 1156 (m->oflags & VPO_BUSY) || 1157 (m->hold_count != 0)) { 1158 vm_page_unlock(m); 1159 VM_OBJECT_UNLOCK(object); 1160 vm_page_requeue(m); 1161 m = next; 1162 continue; 1163 } 1164 1165 /* 1166 * The count for pagedaemon pages is done after checking the 1167 * page for eligibility... 1168 */ 1169 cnt.v_pdpages++; 1170 1171 /* 1172 * Check to see "how much" the page has been used. 1173 */ 1174 actcount = 0; 1175 if (object->ref_count != 0) { 1176 if (m->aflags & PGA_REFERENCED) { 1177 actcount += 1; 1178 } 1179 actcount += pmap_ts_referenced(m); 1180 if (actcount) { 1181 m->act_count += ACT_ADVANCE + actcount; 1182 if (m->act_count > ACT_MAX) 1183 m->act_count = ACT_MAX; 1184 } 1185 } 1186 1187 /* 1188 * Since we have "tested" this bit, we need to clear it now. 1189 */ 1190 vm_page_aflag_clear(m, PGA_REFERENCED); 1191 1192 /* 1193 * Only if an object is currently being used, do we use the 1194 * page activation count stats. 1195 */ 1196 if (actcount && (object->ref_count != 0)) { 1197 vm_page_requeue(m); 1198 } else { 1199 m->act_count -= min(m->act_count, ACT_DECLINE); 1200 if (vm_pageout_algorithm || 1201 object->ref_count == 0 || 1202 m->act_count == 0) { 1203 page_shortage--; 1204 if (object->ref_count == 0) { 1205 KASSERT(!pmap_page_is_mapped(m), 1206 ("vm_pageout_scan: page %p is mapped", m)); 1207 if (m->dirty == 0) 1208 vm_page_cache(m); 1209 else 1210 vm_page_deactivate(m); 1211 } else { 1212 vm_page_deactivate(m); 1213 } 1214 } else { 1215 vm_page_requeue(m); 1216 } 1217 } 1218 vm_page_unlock(m); 1219 VM_OBJECT_UNLOCK(object); 1220 m = next; 1221 } 1222 vm_page_unlock_queues(); 1223 #if !defined(NO_SWAPPING) 1224 /* 1225 * Idle process swapout -- run once per second. 1226 */ 1227 if (vm_swap_idle_enabled) { 1228 static long lsec; 1229 if (time_second != lsec) { 1230 vm_req_vmdaemon(VM_SWAP_IDLE); 1231 lsec = time_second; 1232 } 1233 } 1234 #endif 1235 1236 /* 1237 * If we didn't get enough free pages, and we have skipped a vnode 1238 * in a writeable object, wakeup the sync daemon. And kick swapout 1239 * if we did not get enough free pages. 1240 */ 1241 if (vm_paging_target() > 0) { 1242 if (vnodes_skipped && vm_page_count_min()) 1243 (void) speedup_syncer(); 1244 #if !defined(NO_SWAPPING) 1245 if (vm_swap_enabled && vm_page_count_target()) 1246 vm_req_vmdaemon(VM_SWAP_NORMAL); 1247 #endif 1248 } 1249 1250 /* 1251 * If we are critically low on one of RAM or swap and low on 1252 * the other, kill the largest process. However, we avoid 1253 * doing this on the first pass in order to give ourselves a 1254 * chance to flush out dirty vnode-backed pages and to allow 1255 * active pages to be moved to the inactive queue and reclaimed. 1256 */ 1257 if (pass != 0 && 1258 ((swap_pager_avail < 64 && vm_page_count_min()) || 1259 (swap_pager_full && vm_paging_target() > 0))) 1260 vm_pageout_oom(VM_OOM_MEM); 1261 } 1262 1263 1264 void 1265 vm_pageout_oom(int shortage) 1266 { 1267 struct proc *p, *bigproc; 1268 vm_offset_t size, bigsize; 1269 struct thread *td; 1270 struct vmspace *vm; 1271 1272 /* 1273 * We keep the process bigproc locked once we find it to keep anyone 1274 * from messing with it; however, there is a possibility of 1275 * deadlock if process B is bigproc and one of it's child processes 1276 * attempts to propagate a signal to B while we are waiting for A's 1277 * lock while walking this list. To avoid this, we don't block on 1278 * the process lock but just skip a process if it is already locked. 1279 */ 1280 bigproc = NULL; 1281 bigsize = 0; 1282 sx_slock(&allproc_lock); 1283 FOREACH_PROC_IN_SYSTEM(p) { 1284 int breakout; 1285 1286 if (PROC_TRYLOCK(p) == 0) 1287 continue; 1288 /* 1289 * If this is a system, protected or killed process, skip it. 1290 */ 1291 if (p->p_state != PRS_NORMAL || 1292 (p->p_flag & (P_INEXEC | P_PROTECTED | P_SYSTEM)) || 1293 (p->p_pid == 1) || P_KILLED(p) || 1294 ((p->p_pid < 48) && (swap_pager_avail != 0))) { 1295 PROC_UNLOCK(p); 1296 continue; 1297 } 1298 /* 1299 * If the process is in a non-running type state, 1300 * don't touch it. Check all the threads individually. 1301 */ 1302 breakout = 0; 1303 FOREACH_THREAD_IN_PROC(p, td) { 1304 thread_lock(td); 1305 if (!TD_ON_RUNQ(td) && 1306 !TD_IS_RUNNING(td) && 1307 !TD_IS_SLEEPING(td) && 1308 !TD_IS_SUSPENDED(td)) { 1309 thread_unlock(td); 1310 breakout = 1; 1311 break; 1312 } 1313 thread_unlock(td); 1314 } 1315 if (breakout) { 1316 PROC_UNLOCK(p); 1317 continue; 1318 } 1319 /* 1320 * get the process size 1321 */ 1322 vm = vmspace_acquire_ref(p); 1323 if (vm == NULL) { 1324 PROC_UNLOCK(p); 1325 continue; 1326 } 1327 if (!vm_map_trylock_read(&vm->vm_map)) { 1328 vmspace_free(vm); 1329 PROC_UNLOCK(p); 1330 continue; 1331 } 1332 size = vmspace_swap_count(vm); 1333 vm_map_unlock_read(&vm->vm_map); 1334 if (shortage == VM_OOM_MEM) 1335 size += vmspace_resident_count(vm); 1336 vmspace_free(vm); 1337 /* 1338 * if the this process is bigger than the biggest one 1339 * remember it. 1340 */ 1341 if (size > bigsize) { 1342 if (bigproc != NULL) 1343 PROC_UNLOCK(bigproc); 1344 bigproc = p; 1345 bigsize = size; 1346 } else 1347 PROC_UNLOCK(p); 1348 } 1349 sx_sunlock(&allproc_lock); 1350 if (bigproc != NULL) { 1351 killproc(bigproc, "out of swap space"); 1352 sched_nice(bigproc, PRIO_MIN); 1353 PROC_UNLOCK(bigproc); 1354 wakeup(&cnt.v_free_count); 1355 } 1356 } 1357 1358 /* 1359 * This routine tries to maintain the pseudo LRU active queue, 1360 * so that during long periods of time where there is no paging, 1361 * that some statistic accumulation still occurs. This code 1362 * helps the situation where paging just starts to occur. 1363 */ 1364 static void 1365 vm_pageout_page_stats() 1366 { 1367 vm_object_t object; 1368 vm_page_t m,next; 1369 int pcount,tpcount; /* Number of pages to check */ 1370 static int fullintervalcount = 0; 1371 int page_shortage; 1372 1373 page_shortage = 1374 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1375 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1376 1377 if (page_shortage <= 0) 1378 return; 1379 1380 vm_page_lock_queues(); 1381 pcount = cnt.v_active_count; 1382 fullintervalcount += vm_pageout_stats_interval; 1383 if (fullintervalcount < vm_pageout_full_stats_interval) { 1384 tpcount = (int64_t)vm_pageout_stats_max * cnt.v_active_count / 1385 cnt.v_page_count; 1386 if (pcount > tpcount) 1387 pcount = tpcount; 1388 } else { 1389 fullintervalcount = 0; 1390 } 1391 1392 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1393 while ((m != NULL) && (pcount-- > 0)) { 1394 int actcount; 1395 1396 KASSERT(m->queue == PQ_ACTIVE, 1397 ("vm_pageout_page_stats: page %p isn't active", m)); 1398 1399 next = TAILQ_NEXT(m, pageq); 1400 if ((m->flags & PG_MARKER) != 0) { 1401 m = next; 1402 continue; 1403 } 1404 vm_page_lock_assert(m, MA_NOTOWNED); 1405 if (!vm_pageout_page_lock(m, &next)) { 1406 vm_page_unlock(m); 1407 m = next; 1408 continue; 1409 } 1410 object = m->object; 1411 if (!VM_OBJECT_TRYLOCK(object) && 1412 !vm_pageout_fallback_object_lock(m, &next)) { 1413 VM_OBJECT_UNLOCK(object); 1414 vm_page_unlock(m); 1415 m = next; 1416 continue; 1417 } 1418 1419 /* 1420 * Don't deactivate pages that are busy. 1421 */ 1422 if ((m->busy != 0) || 1423 (m->oflags & VPO_BUSY) || 1424 (m->hold_count != 0)) { 1425 vm_page_unlock(m); 1426 VM_OBJECT_UNLOCK(object); 1427 vm_page_requeue(m); 1428 m = next; 1429 continue; 1430 } 1431 1432 actcount = 0; 1433 if (m->aflags & PGA_REFERENCED) { 1434 vm_page_aflag_clear(m, PGA_REFERENCED); 1435 actcount += 1; 1436 } 1437 1438 actcount += pmap_ts_referenced(m); 1439 if (actcount) { 1440 m->act_count += ACT_ADVANCE + actcount; 1441 if (m->act_count > ACT_MAX) 1442 m->act_count = ACT_MAX; 1443 vm_page_requeue(m); 1444 } else { 1445 if (m->act_count == 0) { 1446 /* 1447 * We turn off page access, so that we have 1448 * more accurate RSS stats. We don't do this 1449 * in the normal page deactivation when the 1450 * system is loaded VM wise, because the 1451 * cost of the large number of page protect 1452 * operations would be higher than the value 1453 * of doing the operation. 1454 */ 1455 pmap_remove_all(m); 1456 vm_page_deactivate(m); 1457 } else { 1458 m->act_count -= min(m->act_count, ACT_DECLINE); 1459 vm_page_requeue(m); 1460 } 1461 } 1462 vm_page_unlock(m); 1463 VM_OBJECT_UNLOCK(object); 1464 m = next; 1465 } 1466 vm_page_unlock_queues(); 1467 } 1468 1469 /* 1470 * vm_pageout is the high level pageout daemon. 1471 */ 1472 static void 1473 vm_pageout() 1474 { 1475 int error, pass; 1476 1477 /* 1478 * Initialize some paging parameters. 1479 */ 1480 cnt.v_interrupt_free_min = 2; 1481 if (cnt.v_page_count < 2000) 1482 vm_pageout_page_count = 8; 1483 1484 /* 1485 * v_free_reserved needs to include enough for the largest 1486 * swap pager structures plus enough for any pv_entry structs 1487 * when paging. 1488 */ 1489 if (cnt.v_page_count > 1024) 1490 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1491 else 1492 cnt.v_free_min = 4; 1493 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1494 cnt.v_interrupt_free_min; 1495 cnt.v_free_reserved = vm_pageout_page_count + 1496 cnt.v_pageout_free_min + (cnt.v_page_count / 768); 1497 cnt.v_free_severe = cnt.v_free_min / 2; 1498 cnt.v_free_min += cnt.v_free_reserved; 1499 cnt.v_free_severe += cnt.v_free_reserved; 1500 1501 /* 1502 * v_free_target and v_cache_min control pageout hysteresis. Note 1503 * that these are more a measure of the VM cache queue hysteresis 1504 * then the VM free queue. Specifically, v_free_target is the 1505 * high water mark (free+cache pages). 1506 * 1507 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1508 * low water mark, while v_free_min is the stop. v_cache_min must 1509 * be big enough to handle memory needs while the pageout daemon 1510 * is signalled and run to free more pages. 1511 */ 1512 if (cnt.v_free_count > 6144) 1513 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1514 else 1515 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1516 1517 if (cnt.v_free_count > 2048) { 1518 cnt.v_cache_min = cnt.v_free_target; 1519 cnt.v_cache_max = 2 * cnt.v_cache_min; 1520 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1521 } else { 1522 cnt.v_cache_min = 0; 1523 cnt.v_cache_max = 0; 1524 cnt.v_inactive_target = cnt.v_free_count / 4; 1525 } 1526 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1527 cnt.v_inactive_target = cnt.v_free_count / 3; 1528 1529 /* XXX does not really belong here */ 1530 if (vm_page_max_wired == 0) 1531 vm_page_max_wired = cnt.v_free_count / 3; 1532 1533 if (vm_pageout_stats_max == 0) 1534 vm_pageout_stats_max = cnt.v_free_target; 1535 1536 /* 1537 * Set interval in seconds for stats scan. 1538 */ 1539 if (vm_pageout_stats_interval == 0) 1540 vm_pageout_stats_interval = 5; 1541 if (vm_pageout_full_stats_interval == 0) 1542 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1543 1544 swap_pager_swap_init(); 1545 pass = 0; 1546 /* 1547 * The pageout daemon is never done, so loop forever. 1548 */ 1549 while (TRUE) { 1550 /* 1551 * If we have enough free memory, wakeup waiters. Do 1552 * not clear vm_pages_needed until we reach our target, 1553 * otherwise we may be woken up over and over again and 1554 * waste a lot of cpu. 1555 */ 1556 mtx_lock(&vm_page_queue_free_mtx); 1557 if (vm_pages_needed && !vm_page_count_min()) { 1558 if (!vm_paging_needed()) 1559 vm_pages_needed = 0; 1560 wakeup(&cnt.v_free_count); 1561 } 1562 if (vm_pages_needed) { 1563 /* 1564 * Still not done, take a second pass without waiting 1565 * (unlimited dirty cleaning), otherwise sleep a bit 1566 * and try again. 1567 */ 1568 ++pass; 1569 if (pass > 1) 1570 msleep(&vm_pages_needed, 1571 &vm_page_queue_free_mtx, PVM, "psleep", 1572 hz / 2); 1573 } else { 1574 /* 1575 * Good enough, sleep & handle stats. Prime the pass 1576 * for the next run. 1577 */ 1578 if (pass > 1) 1579 pass = 1; 1580 else 1581 pass = 0; 1582 error = msleep(&vm_pages_needed, 1583 &vm_page_queue_free_mtx, PVM, "psleep", 1584 vm_pageout_stats_interval * hz); 1585 if (error && !vm_pages_needed) { 1586 mtx_unlock(&vm_page_queue_free_mtx); 1587 pass = 0; 1588 vm_pageout_page_stats(); 1589 continue; 1590 } 1591 } 1592 if (vm_pages_needed) 1593 cnt.v_pdwakeups++; 1594 mtx_unlock(&vm_page_queue_free_mtx); 1595 vm_pageout_scan(pass); 1596 } 1597 } 1598 1599 /* 1600 * Unless the free page queue lock is held by the caller, this function 1601 * should be regarded as advisory. Specifically, the caller should 1602 * not msleep() on &cnt.v_free_count following this function unless 1603 * the free page queue lock is held until the msleep() is performed. 1604 */ 1605 void 1606 pagedaemon_wakeup() 1607 { 1608 1609 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1610 vm_pages_needed = 1; 1611 wakeup(&vm_pages_needed); 1612 } 1613 } 1614 1615 #if !defined(NO_SWAPPING) 1616 static void 1617 vm_req_vmdaemon(int req) 1618 { 1619 static int lastrun = 0; 1620 1621 mtx_lock(&vm_daemon_mtx); 1622 vm_pageout_req_swapout |= req; 1623 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1624 wakeup(&vm_daemon_needed); 1625 lastrun = ticks; 1626 } 1627 mtx_unlock(&vm_daemon_mtx); 1628 } 1629 1630 static void 1631 vm_daemon() 1632 { 1633 struct rlimit rsslim; 1634 struct proc *p; 1635 struct thread *td; 1636 struct vmspace *vm; 1637 int breakout, swapout_flags, tryagain, attempts; 1638 #ifdef RACCT 1639 uint64_t rsize, ravailable; 1640 #endif 1641 1642 while (TRUE) { 1643 mtx_lock(&vm_daemon_mtx); 1644 #ifdef RACCT 1645 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", hz); 1646 #else 1647 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0); 1648 #endif 1649 swapout_flags = vm_pageout_req_swapout; 1650 vm_pageout_req_swapout = 0; 1651 mtx_unlock(&vm_daemon_mtx); 1652 if (swapout_flags) 1653 swapout_procs(swapout_flags); 1654 1655 /* 1656 * scan the processes for exceeding their rlimits or if 1657 * process is swapped out -- deactivate pages 1658 */ 1659 tryagain = 0; 1660 attempts = 0; 1661 again: 1662 attempts++; 1663 sx_slock(&allproc_lock); 1664 FOREACH_PROC_IN_SYSTEM(p) { 1665 vm_pindex_t limit, size; 1666 1667 /* 1668 * if this is a system process or if we have already 1669 * looked at this process, skip it. 1670 */ 1671 PROC_LOCK(p); 1672 if (p->p_state != PRS_NORMAL || 1673 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 1674 PROC_UNLOCK(p); 1675 continue; 1676 } 1677 /* 1678 * if the process is in a non-running type state, 1679 * don't touch it. 1680 */ 1681 breakout = 0; 1682 FOREACH_THREAD_IN_PROC(p, td) { 1683 thread_lock(td); 1684 if (!TD_ON_RUNQ(td) && 1685 !TD_IS_RUNNING(td) && 1686 !TD_IS_SLEEPING(td) && 1687 !TD_IS_SUSPENDED(td)) { 1688 thread_unlock(td); 1689 breakout = 1; 1690 break; 1691 } 1692 thread_unlock(td); 1693 } 1694 if (breakout) { 1695 PROC_UNLOCK(p); 1696 continue; 1697 } 1698 /* 1699 * get a limit 1700 */ 1701 lim_rlimit(p, RLIMIT_RSS, &rsslim); 1702 limit = OFF_TO_IDX( 1703 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 1704 1705 /* 1706 * let processes that are swapped out really be 1707 * swapped out set the limit to nothing (will force a 1708 * swap-out.) 1709 */ 1710 if ((p->p_flag & P_INMEM) == 0) 1711 limit = 0; /* XXX */ 1712 vm = vmspace_acquire_ref(p); 1713 PROC_UNLOCK(p); 1714 if (vm == NULL) 1715 continue; 1716 1717 size = vmspace_resident_count(vm); 1718 if (limit >= 0 && size >= limit) { 1719 vm_pageout_map_deactivate_pages( 1720 &vm->vm_map, limit); 1721 } 1722 #ifdef RACCT 1723 rsize = IDX_TO_OFF(size); 1724 PROC_LOCK(p); 1725 racct_set(p, RACCT_RSS, rsize); 1726 ravailable = racct_get_available(p, RACCT_RSS); 1727 PROC_UNLOCK(p); 1728 if (rsize > ravailable) { 1729 /* 1730 * Don't be overly aggressive; this might be 1731 * an innocent process, and the limit could've 1732 * been exceeded by some memory hog. Don't 1733 * try to deactivate more than 1/4th of process' 1734 * resident set size. 1735 */ 1736 if (attempts <= 8) { 1737 if (ravailable < rsize - (rsize / 4)) 1738 ravailable = rsize - (rsize / 4); 1739 } 1740 vm_pageout_map_deactivate_pages( 1741 &vm->vm_map, OFF_TO_IDX(ravailable)); 1742 /* Update RSS usage after paging out. */ 1743 size = vmspace_resident_count(vm); 1744 rsize = IDX_TO_OFF(size); 1745 PROC_LOCK(p); 1746 racct_set(p, RACCT_RSS, rsize); 1747 PROC_UNLOCK(p); 1748 if (rsize > ravailable) 1749 tryagain = 1; 1750 } 1751 #endif 1752 vmspace_free(vm); 1753 } 1754 sx_sunlock(&allproc_lock); 1755 if (tryagain != 0 && attempts <= 10) 1756 goto again; 1757 } 1758 } 1759 #endif /* !defined(NO_SWAPPING) */ 1760