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 * 9 * This code is derived from software contributed to Berkeley by 10 * The Mach Operating System project at Carnegie-Mellon University. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 41 * 42 * 43 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 44 * All rights reserved. 45 * 46 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 47 * 48 * Permission to use, copy, modify and distribute this software and 49 * its documentation is hereby granted, provided that both the copyright 50 * notice and this permission notice appear in all copies of the 51 * software, derivative works or modified versions, and any portions 52 * thereof, and that both notices appear in supporting documentation. 53 * 54 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 55 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 56 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 57 * 58 * Carnegie Mellon requests users of this software to return to 59 * 60 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 61 * School of Computer Science 62 * Carnegie Mellon University 63 * Pittsburgh PA 15213-3890 64 * 65 * any improvements or extensions that they make and grant Carnegie the 66 * rights to redistribute these changes. 67 * 68 * $FreeBSD: src/sys/vm/vm_pageout.c,v 1.151.2.15 2002/12/29 18:21:04 dillon Exp $ 69 * $DragonFly: src/sys/vm/vm_pageout.c,v 1.36 2008/07/01 02:02:56 dillon Exp $ 70 */ 71 72 /* 73 * The proverbial page-out daemon. 74 */ 75 76 #include "opt_vm.h" 77 #include <sys/param.h> 78 #include <sys/systm.h> 79 #include <sys/kernel.h> 80 #include <sys/proc.h> 81 #include <sys/kthread.h> 82 #include <sys/resourcevar.h> 83 #include <sys/signalvar.h> 84 #include <sys/vnode.h> 85 #include <sys/vmmeter.h> 86 #include <sys/sysctl.h> 87 88 #include <vm/vm.h> 89 #include <vm/vm_param.h> 90 #include <sys/lock.h> 91 #include <vm/vm_object.h> 92 #include <vm/vm_page.h> 93 #include <vm/vm_map.h> 94 #include <vm/vm_pageout.h> 95 #include <vm/vm_pager.h> 96 #include <vm/swap_pager.h> 97 #include <vm/vm_extern.h> 98 99 #include <sys/thread2.h> 100 #include <vm/vm_page2.h> 101 102 /* 103 * System initialization 104 */ 105 106 /* the kernel process "vm_pageout"*/ 107 static void vm_pageout (void); 108 static int vm_pageout_clean (vm_page_t); 109 static int vm_pageout_scan (int pass); 110 static int vm_pageout_free_page_calc (vm_size_t count); 111 struct thread *pagethread; 112 113 static struct kproc_desc page_kp = { 114 "pagedaemon", 115 vm_pageout, 116 &pagethread 117 }; 118 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 119 120 #if !defined(NO_SWAPPING) 121 /* the kernel process "vm_daemon"*/ 122 static void vm_daemon (void); 123 static struct thread *vmthread; 124 125 static struct kproc_desc vm_kp = { 126 "vmdaemon", 127 vm_daemon, 128 &vmthread 129 }; 130 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) 131 #endif 132 133 134 int vm_pages_needed=0; /* Event on which pageout daemon sleeps */ 135 int vm_pageout_deficit=0; /* Estimated number of pages deficit */ 136 int vm_pageout_pages_needed=0; /* flag saying that the pageout daemon needs pages */ 137 138 #if !defined(NO_SWAPPING) 139 static int vm_pageout_req_swapout; /* XXX */ 140 static int vm_daemon_needed; 141 #endif 142 extern int vm_swap_size; 143 static int vm_max_launder = 32; 144 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 145 static int vm_pageout_full_stats_interval = 0; 146 static int vm_pageout_stats_free_max=0, vm_pageout_algorithm=0; 147 static int defer_swap_pageouts=0; 148 static int disable_swap_pageouts=0; 149 150 #if defined(NO_SWAPPING) 151 static int vm_swap_enabled=0; 152 static int vm_swap_idle_enabled=0; 153 #else 154 static int vm_swap_enabled=1; 155 static int vm_swap_idle_enabled=0; 156 #endif 157 158 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 159 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 160 161 SYSCTL_INT(_vm, OID_AUTO, max_launder, 162 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 163 164 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 165 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 166 167 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 168 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 169 170 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 171 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 172 173 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max, 174 CTLFLAG_RW, &vm_pageout_stats_free_max, 0, "Not implemented"); 175 176 #if defined(NO_SWAPPING) 177 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 178 CTLFLAG_RD, &vm_swap_enabled, 0, ""); 179 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 180 CTLFLAG_RD, &vm_swap_idle_enabled, 0, ""); 181 #else 182 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 183 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 184 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 185 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 186 #endif 187 188 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 189 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 190 191 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 192 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 193 194 static int pageout_lock_miss; 195 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 196 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 197 198 int vm_load; 199 SYSCTL_INT(_vm, OID_AUTO, vm_load, 200 CTLFLAG_RD, &vm_load, 0, "load on the VM system"); 201 int vm_load_enable = 1; 202 SYSCTL_INT(_vm, OID_AUTO, vm_load_enable, 203 CTLFLAG_RW, &vm_load_enable, 0, "enable vm_load rate limiting"); 204 #ifdef INVARIANTS 205 int vm_load_debug; 206 SYSCTL_INT(_vm, OID_AUTO, vm_load_debug, 207 CTLFLAG_RW, &vm_load_debug, 0, "debug vm_load"); 208 #endif 209 210 #define VM_PAGEOUT_PAGE_COUNT 16 211 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 212 213 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 214 215 #if !defined(NO_SWAPPING) 216 typedef void freeer_fcn_t (vm_map_t, vm_object_t, vm_pindex_t, int); 217 static void vm_pageout_map_deactivate_pages (vm_map_t, vm_pindex_t); 218 static freeer_fcn_t vm_pageout_object_deactivate_pages; 219 static void vm_req_vmdaemon (void); 220 #endif 221 static void vm_pageout_page_stats(void); 222 223 /* 224 * Update vm_load to slow down faulting processes. 225 */ 226 void 227 vm_fault_ratecheck(void) 228 { 229 if (vm_pages_needed) { 230 if (vm_load < 1000) 231 ++vm_load; 232 } else { 233 if (vm_load > 0) 234 --vm_load; 235 } 236 } 237 238 /* 239 * vm_pageout_clean: 240 * 241 * Clean the page and remove it from the laundry. The page must not be 242 * busy on-call. 243 * 244 * We set the busy bit to cause potential page faults on this page to 245 * block. Note the careful timing, however, the busy bit isn't set till 246 * late and we cannot do anything that will mess with the page. 247 */ 248 249 static int 250 vm_pageout_clean(vm_page_t m) 251 { 252 vm_object_t object; 253 vm_page_t mc[2*vm_pageout_page_count]; 254 int pageout_count; 255 int ib, is, page_base; 256 vm_pindex_t pindex = m->pindex; 257 258 object = m->object; 259 260 /* 261 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 262 * with the new swapper, but we could have serious problems paging 263 * out other object types if there is insufficient memory. 264 * 265 * Unfortunately, checking free memory here is far too late, so the 266 * check has been moved up a procedural level. 267 */ 268 269 /* 270 * Don't mess with the page if it's busy, held, or special 271 */ 272 if ((m->hold_count != 0) || 273 ((m->busy != 0) || (m->flags & (PG_BUSY|PG_UNMANAGED)))) { 274 return 0; 275 } 276 277 mc[vm_pageout_page_count] = m; 278 pageout_count = 1; 279 page_base = vm_pageout_page_count; 280 ib = 1; 281 is = 1; 282 283 /* 284 * Scan object for clusterable pages. 285 * 286 * We can cluster ONLY if: ->> the page is NOT 287 * clean, wired, busy, held, or mapped into a 288 * buffer, and one of the following: 289 * 1) The page is inactive, or a seldom used 290 * active page. 291 * -or- 292 * 2) we force the issue. 293 * 294 * During heavy mmap/modification loads the pageout 295 * daemon can really fragment the underlying file 296 * due to flushing pages out of order and not trying 297 * align the clusters (which leave sporatic out-of-order 298 * holes). To solve this problem we do the reverse scan 299 * first and attempt to align our cluster, then do a 300 * forward scan if room remains. 301 */ 302 303 more: 304 while (ib && pageout_count < vm_pageout_page_count) { 305 vm_page_t p; 306 307 if (ib > pindex) { 308 ib = 0; 309 break; 310 } 311 312 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) { 313 ib = 0; 314 break; 315 } 316 if (((p->queue - p->pc) == PQ_CACHE) || 317 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 318 ib = 0; 319 break; 320 } 321 vm_page_test_dirty(p); 322 if ((p->dirty & p->valid) == 0 || 323 p->queue != PQ_INACTIVE || 324 p->wire_count != 0 || /* may be held by buf cache */ 325 p->hold_count != 0) { /* may be undergoing I/O */ 326 ib = 0; 327 break; 328 } 329 mc[--page_base] = p; 330 ++pageout_count; 331 ++ib; 332 /* 333 * alignment boundry, stop here and switch directions. Do 334 * not clear ib. 335 */ 336 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 337 break; 338 } 339 340 while (pageout_count < vm_pageout_page_count && 341 pindex + is < object->size) { 342 vm_page_t p; 343 344 if ((p = vm_page_lookup(object, pindex + is)) == NULL) 345 break; 346 if (((p->queue - p->pc) == PQ_CACHE) || 347 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 348 break; 349 } 350 vm_page_test_dirty(p); 351 if ((p->dirty & p->valid) == 0 || 352 p->queue != PQ_INACTIVE || 353 p->wire_count != 0 || /* may be held by buf cache */ 354 p->hold_count != 0) { /* may be undergoing I/O */ 355 break; 356 } 357 mc[page_base + pageout_count] = p; 358 ++pageout_count; 359 ++is; 360 } 361 362 /* 363 * If we exhausted our forward scan, continue with the reverse scan 364 * when possible, even past a page boundry. This catches boundry 365 * conditions. 366 */ 367 if (ib && pageout_count < vm_pageout_page_count) 368 goto more; 369 370 /* 371 * we allow reads during pageouts... 372 */ 373 return vm_pageout_flush(&mc[page_base], pageout_count, 0); 374 } 375 376 /* 377 * vm_pageout_flush() - launder the given pages 378 * 379 * The given pages are laundered. Note that we setup for the start of 380 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 381 * reference count all in here rather then in the parent. If we want 382 * the parent to do more sophisticated things we may have to change 383 * the ordering. 384 */ 385 int 386 vm_pageout_flush(vm_page_t *mc, int count, int flags) 387 { 388 vm_object_t object; 389 int pageout_status[count]; 390 int numpagedout = 0; 391 int i; 392 393 /* 394 * Initiate I/O. Bump the vm_page_t->busy counter. 395 */ 396 for (i = 0; i < count; i++) { 397 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush page %p index %d/%d: partially invalid page", mc[i], i, count)); 398 vm_page_io_start(mc[i]); 399 } 400 401 /* 402 * We must make the pages read-only. This will also force the 403 * modified bit in the related pmaps to be cleared. The pager 404 * cannot clear the bit for us since the I/O completion code 405 * typically runs from an interrupt. The act of making the page 406 * read-only handles the case for us. 407 */ 408 for (i = 0; i < count; i++) { 409 vm_page_protect(mc[i], VM_PROT_READ); 410 } 411 412 object = mc[0]->object; 413 vm_object_pip_add(object, count); 414 415 vm_pager_put_pages(object, mc, count, 416 (flags | ((object == &kernel_object) ? VM_PAGER_PUT_SYNC : 0)), 417 pageout_status); 418 419 for (i = 0; i < count; i++) { 420 vm_page_t mt = mc[i]; 421 422 switch (pageout_status[i]) { 423 case VM_PAGER_OK: 424 numpagedout++; 425 break; 426 case VM_PAGER_PEND: 427 numpagedout++; 428 break; 429 case VM_PAGER_BAD: 430 /* 431 * Page outside of range of object. Right now we 432 * essentially lose the changes by pretending it 433 * worked. 434 */ 435 pmap_clear_modify(mt); 436 vm_page_undirty(mt); 437 break; 438 case VM_PAGER_ERROR: 439 case VM_PAGER_FAIL: 440 /* 441 * A page typically cannot be paged out when we 442 * have run out of swap. We leave the page 443 * marked inactive and will try to page it out 444 * again later. 445 * 446 * Starvation of the active page list is used to 447 * determine when the system is massively memory 448 * starved. 449 */ 450 break; 451 case VM_PAGER_AGAIN: 452 break; 453 } 454 455 /* 456 * If the operation is still going, leave the page busy to 457 * block all other accesses. Also, leave the paging in 458 * progress indicator set so that we don't attempt an object 459 * collapse. 460 * 461 * For any pages which have completed synchronously, 462 * deactivate the page if we are under a severe deficit. 463 * Do not try to enter them into the cache, though, they 464 * might still be read-heavy. 465 */ 466 if (pageout_status[i] != VM_PAGER_PEND) { 467 vm_object_pip_wakeup(object); 468 vm_page_io_finish(mt); 469 if (vm_page_count_severe()) 470 vm_page_deactivate(mt); 471 #if 0 472 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt)) 473 vm_page_protect(mt, VM_PROT_READ); 474 #endif 475 } 476 } 477 return numpagedout; 478 } 479 480 #if !defined(NO_SWAPPING) 481 /* 482 * vm_pageout_object_deactivate_pages 483 * 484 * deactivate enough pages to satisfy the inactive target 485 * requirements or if vm_page_proc_limit is set, then 486 * deactivate all of the pages in the object and its 487 * backing_objects. 488 * 489 * The object and map must be locked. 490 */ 491 static int vm_pageout_object_deactivate_pages_callback(vm_page_t, void *); 492 493 static void 494 vm_pageout_object_deactivate_pages(vm_map_t map, vm_object_t object, 495 vm_pindex_t desired, int map_remove_only) 496 { 497 struct rb_vm_page_scan_info info; 498 int remove_mode; 499 500 if (object->type == OBJT_DEVICE || object->type == OBJT_PHYS) 501 return; 502 503 while (object) { 504 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 505 return; 506 if (object->paging_in_progress) 507 return; 508 509 remove_mode = map_remove_only; 510 if (object->shadow_count > 1) 511 remove_mode = 1; 512 513 /* 514 * scan the objects entire memory queue. spl protection is 515 * required to avoid an interrupt unbusy/free race against 516 * our busy check. 517 */ 518 crit_enter(); 519 info.limit = remove_mode; 520 info.map = map; 521 info.desired = desired; 522 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL, 523 vm_pageout_object_deactivate_pages_callback, 524 &info 525 ); 526 crit_exit(); 527 object = object->backing_object; 528 } 529 } 530 531 static int 532 vm_pageout_object_deactivate_pages_callback(vm_page_t p, void *data) 533 { 534 struct rb_vm_page_scan_info *info = data; 535 int actcount; 536 537 if (pmap_resident_count(vm_map_pmap(info->map)) <= info->desired) { 538 return(-1); 539 } 540 mycpu->gd_cnt.v_pdpages++; 541 if (p->wire_count != 0 || p->hold_count != 0 || p->busy != 0 || 542 (p->flags & (PG_BUSY|PG_UNMANAGED)) || 543 !pmap_page_exists_quick(vm_map_pmap(info->map), p)) { 544 return(0); 545 } 546 547 actcount = pmap_ts_referenced(p); 548 if (actcount) { 549 vm_page_flag_set(p, PG_REFERENCED); 550 } else if (p->flags & PG_REFERENCED) { 551 actcount = 1; 552 } 553 554 if ((p->queue != PQ_ACTIVE) && 555 (p->flags & PG_REFERENCED)) { 556 vm_page_activate(p); 557 p->act_count += actcount; 558 vm_page_flag_clear(p, PG_REFERENCED); 559 } else if (p->queue == PQ_ACTIVE) { 560 if ((p->flags & PG_REFERENCED) == 0) { 561 p->act_count -= min(p->act_count, ACT_DECLINE); 562 if (!info->limit && (vm_pageout_algorithm || (p->act_count == 0))) { 563 vm_page_busy(p); 564 vm_page_protect(p, VM_PROT_NONE); 565 vm_page_wakeup(p); 566 vm_page_deactivate(p); 567 } else { 568 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 569 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 570 } 571 } else { 572 vm_page_activate(p); 573 vm_page_flag_clear(p, PG_REFERENCED); 574 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 575 p->act_count += ACT_ADVANCE; 576 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 577 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 578 } 579 } else if (p->queue == PQ_INACTIVE) { 580 vm_page_busy(p); 581 vm_page_protect(p, VM_PROT_NONE); 582 vm_page_wakeup(p); 583 } 584 return(0); 585 } 586 587 /* 588 * deactivate some number of pages in a map, try to do it fairly, but 589 * that is really hard to do. 590 */ 591 static void 592 vm_pageout_map_deactivate_pages(vm_map_t map, vm_pindex_t desired) 593 { 594 vm_map_entry_t tmpe; 595 vm_object_t obj, bigobj; 596 int nothingwired; 597 598 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT)) { 599 return; 600 } 601 602 bigobj = NULL; 603 nothingwired = TRUE; 604 605 /* 606 * first, search out the biggest object, and try to free pages from 607 * that. 608 */ 609 tmpe = map->header.next; 610 while (tmpe != &map->header) { 611 switch(tmpe->maptype) { 612 case VM_MAPTYPE_NORMAL: 613 case VM_MAPTYPE_VPAGETABLE: 614 obj = tmpe->object.vm_object; 615 if ((obj != NULL) && (obj->shadow_count <= 1) && 616 ((bigobj == NULL) || 617 (bigobj->resident_page_count < obj->resident_page_count))) { 618 bigobj = obj; 619 } 620 break; 621 default: 622 break; 623 } 624 if (tmpe->wired_count > 0) 625 nothingwired = FALSE; 626 tmpe = tmpe->next; 627 } 628 629 if (bigobj) 630 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 631 632 /* 633 * Next, hunt around for other pages to deactivate. We actually 634 * do this search sort of wrong -- .text first is not the best idea. 635 */ 636 tmpe = map->header.next; 637 while (tmpe != &map->header) { 638 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 639 break; 640 switch(tmpe->maptype) { 641 case VM_MAPTYPE_NORMAL: 642 case VM_MAPTYPE_VPAGETABLE: 643 obj = tmpe->object.vm_object; 644 if (obj) 645 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 646 break; 647 default: 648 break; 649 } 650 tmpe = tmpe->next; 651 }; 652 653 /* 654 * Remove all mappings if a process is swapped out, this will free page 655 * table pages. 656 */ 657 if (desired == 0 && nothingwired) 658 pmap_remove(vm_map_pmap(map), 659 VM_MIN_USER_ADDRESS, VM_MAX_USER_ADDRESS); 660 vm_map_unlock(map); 661 } 662 #endif 663 664 /* 665 * Don't try to be fancy - being fancy can lead to vnode deadlocks. We 666 * only do it for OBJT_DEFAULT and OBJT_SWAP objects which we know can 667 * be trivially freed. 668 */ 669 void 670 vm_pageout_page_free(vm_page_t m) 671 { 672 vm_object_t object = m->object; 673 int type = object->type; 674 675 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 676 vm_object_reference(object); 677 vm_page_busy(m); 678 vm_page_protect(m, VM_PROT_NONE); 679 vm_page_free(m); 680 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 681 vm_object_deallocate(object); 682 } 683 684 /* 685 * vm_pageout_scan does the dirty work for the pageout daemon. 686 */ 687 struct vm_pageout_scan_info { 688 struct proc *bigproc; 689 vm_offset_t bigsize; 690 }; 691 692 static int vm_pageout_scan_callback(struct proc *p, void *data); 693 694 static int 695 vm_pageout_scan(int pass) 696 { 697 struct vm_pageout_scan_info info; 698 vm_page_t m, next; 699 struct vm_page marker; 700 int maxscan, pcount; 701 int recycle_count; 702 int inactive_shortage, active_shortage; 703 int inactive_original_shortage; 704 vm_object_t object; 705 int actcount; 706 int vnodes_skipped = 0; 707 int maxlaunder; 708 709 /* 710 * Do whatever cleanup that the pmap code can. 711 */ 712 pmap_collect(); 713 714 /* 715 * Calculate our target for the number of free+cache pages we 716 * want to get to. This is higher then the number that causes 717 * allocations to stall (severe) in order to provide hysteresis, 718 * and if we don't make it all the way but get to the minimum 719 * we're happy. 720 */ 721 inactive_shortage = vm_paging_target() + vm_pageout_deficit; 722 inactive_original_shortage = inactive_shortage; 723 vm_pageout_deficit = 0; 724 725 /* 726 * Initialize our marker 727 */ 728 bzero(&marker, sizeof(marker)); 729 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 730 marker.queue = PQ_INACTIVE; 731 marker.wire_count = 1; 732 733 /* 734 * Start scanning the inactive queue for pages we can move to the 735 * cache or free. The scan will stop when the target is reached or 736 * we have scanned the entire inactive queue. Note that m->act_count 737 * is not used to form decisions for the inactive queue, only for the 738 * active queue. 739 * 740 * maxlaunder limits the number of dirty pages we flush per scan. 741 * For most systems a smaller value (16 or 32) is more robust under 742 * extreme memory and disk pressure because any unnecessary writes 743 * to disk can result in extreme performance degredation. However, 744 * systems with excessive dirty pages (especially when MAP_NOSYNC is 745 * used) will die horribly with limited laundering. If the pageout 746 * daemon cannot clean enough pages in the first pass, we let it go 747 * all out in succeeding passes. 748 */ 749 if ((maxlaunder = vm_max_launder) <= 1) 750 maxlaunder = 1; 751 if (pass) 752 maxlaunder = 10000; 753 754 /* 755 * We will generally be in a critical section throughout the 756 * scan, but we can release it temporarily when we are sitting on a 757 * non-busy page without fear. this is required to prevent an 758 * interrupt from unbusying or freeing a page prior to our busy 759 * check, leaving us on the wrong queue or checking the wrong 760 * page. 761 */ 762 crit_enter(); 763 rescan0: 764 maxscan = vmstats.v_inactive_count; 765 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 766 m != NULL && maxscan-- > 0 && inactive_shortage > 0; 767 m = next 768 ) { 769 mycpu->gd_cnt.v_pdpages++; 770 771 /* 772 * Give interrupts a chance 773 */ 774 crit_exit(); 775 crit_enter(); 776 777 /* 778 * It's easier for some of the conditions below to just loop 779 * and catch queue changes here rather then check everywhere 780 * else. 781 */ 782 if (m->queue != PQ_INACTIVE) 783 goto rescan0; 784 next = TAILQ_NEXT(m, pageq); 785 786 /* 787 * skip marker pages 788 */ 789 if (m->flags & PG_MARKER) 790 continue; 791 792 /* 793 * A held page may be undergoing I/O, so skip it. 794 */ 795 if (m->hold_count) { 796 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 797 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 798 continue; 799 } 800 801 /* 802 * Dont mess with busy pages, keep in the front of the 803 * queue, most likely are being paged out. 804 */ 805 if (m->busy || (m->flags & PG_BUSY)) { 806 continue; 807 } 808 809 if (m->object->ref_count == 0) { 810 /* 811 * If the object is not being used, we ignore previous 812 * references. 813 */ 814 vm_page_flag_clear(m, PG_REFERENCED); 815 pmap_clear_reference(m); 816 817 } else if (((m->flags & PG_REFERENCED) == 0) && 818 (actcount = pmap_ts_referenced(m))) { 819 /* 820 * Otherwise, if the page has been referenced while 821 * in the inactive queue, we bump the "activation 822 * count" upwards, making it less likely that the 823 * page will be added back to the inactive queue 824 * prematurely again. Here we check the page tables 825 * (or emulated bits, if any), given the upper level 826 * VM system not knowing anything about existing 827 * references. 828 */ 829 vm_page_activate(m); 830 m->act_count += (actcount + ACT_ADVANCE); 831 continue; 832 } 833 834 /* 835 * If the upper level VM system knows about any page 836 * references, we activate the page. We also set the 837 * "activation count" higher than normal so that we will less 838 * likely place pages back onto the inactive queue again. 839 */ 840 if ((m->flags & PG_REFERENCED) != 0) { 841 vm_page_flag_clear(m, PG_REFERENCED); 842 actcount = pmap_ts_referenced(m); 843 vm_page_activate(m); 844 m->act_count += (actcount + ACT_ADVANCE + 1); 845 continue; 846 } 847 848 /* 849 * If the upper level VM system doesn't know anything about 850 * the page being dirty, we have to check for it again. As 851 * far as the VM code knows, any partially dirty pages are 852 * fully dirty. 853 * 854 * Pages marked PG_WRITEABLE may be mapped into the user 855 * address space of a process running on another cpu. A 856 * user process (without holding the MP lock) running on 857 * another cpu may be able to touch the page while we are 858 * trying to remove it. vm_page_cache() will handle this 859 * case for us. 860 */ 861 if (m->dirty == 0) { 862 vm_page_test_dirty(m); 863 } else { 864 vm_page_dirty(m); 865 } 866 867 if (m->valid == 0) { 868 /* 869 * Invalid pages can be easily freed 870 */ 871 vm_pageout_page_free(m); 872 mycpu->gd_cnt.v_dfree++; 873 --inactive_shortage; 874 } else if (m->dirty == 0) { 875 /* 876 * Clean pages can be placed onto the cache queue. 877 * This effectively frees them. 878 */ 879 vm_page_cache(m); 880 --inactive_shortage; 881 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 882 /* 883 * Dirty pages need to be paged out, but flushing 884 * a page is extremely expensive verses freeing 885 * a clean page. Rather then artificially limiting 886 * the number of pages we can flush, we instead give 887 * dirty pages extra priority on the inactive queue 888 * by forcing them to be cycled through the queue 889 * twice before being flushed, after which the 890 * (now clean) page will cycle through once more 891 * before being freed. This significantly extends 892 * the thrash point for a heavily loaded machine. 893 */ 894 vm_page_flag_set(m, PG_WINATCFLS); 895 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 896 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 897 } else if (maxlaunder > 0) { 898 /* 899 * We always want to try to flush some dirty pages if 900 * we encounter them, to keep the system stable. 901 * Normally this number is small, but under extreme 902 * pressure where there are insufficient clean pages 903 * on the inactive queue, we may have to go all out. 904 */ 905 int swap_pageouts_ok; 906 struct vnode *vp = NULL; 907 908 object = m->object; 909 910 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 911 swap_pageouts_ok = 1; 912 } else { 913 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 914 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 915 vm_page_count_min(0)); 916 917 } 918 919 /* 920 * We don't bother paging objects that are "dead". 921 * Those objects are in a "rundown" state. 922 */ 923 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 924 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 925 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 926 continue; 927 } 928 929 /* 930 * The object is already known NOT to be dead. It 931 * is possible for the vget() to block the whole 932 * pageout daemon, but the new low-memory handling 933 * code should prevent it. 934 * 935 * The previous code skipped locked vnodes and, worse, 936 * reordered pages in the queue. This results in 937 * completely non-deterministic operation because, 938 * quite often, a vm_fault has initiated an I/O and 939 * is holding a locked vnode at just the point where 940 * the pageout daemon is woken up. 941 * 942 * We can't wait forever for the vnode lock, we might 943 * deadlock due to a vn_read() getting stuck in 944 * vm_wait while holding this vnode. We skip the 945 * vnode if we can't get it in a reasonable amount 946 * of time. 947 */ 948 949 if (object->type == OBJT_VNODE) { 950 vp = object->handle; 951 952 if (vget(vp, LK_EXCLUSIVE|LK_NOOBJ|LK_TIMELOCK)) { 953 ++pageout_lock_miss; 954 if (object->flags & OBJ_MIGHTBEDIRTY) 955 vnodes_skipped++; 956 continue; 957 } 958 959 /* 960 * The page might have been moved to another 961 * queue during potential blocking in vget() 962 * above. The page might have been freed and 963 * reused for another vnode. The object might 964 * have been reused for another vnode. 965 */ 966 if (m->queue != PQ_INACTIVE || 967 m->object != object || 968 object->handle != vp) { 969 if (object->flags & OBJ_MIGHTBEDIRTY) 970 vnodes_skipped++; 971 vput(vp); 972 continue; 973 } 974 975 /* 976 * The page may have been busied during the 977 * blocking in vput(); We don't move the 978 * page back onto the end of the queue so that 979 * statistics are more correct if we don't. 980 */ 981 if (m->busy || (m->flags & PG_BUSY)) { 982 vput(vp); 983 continue; 984 } 985 986 /* 987 * If the page has become held it might 988 * be undergoing I/O, so skip it 989 */ 990 if (m->hold_count) { 991 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 992 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 993 if (object->flags & OBJ_MIGHTBEDIRTY) 994 vnodes_skipped++; 995 vput(vp); 996 continue; 997 } 998 } 999 1000 /* 1001 * If a page is dirty, then it is either being washed 1002 * (but not yet cleaned) or it is still in the 1003 * laundry. If it is still in the laundry, then we 1004 * start the cleaning operation. 1005 * 1006 * This operation may cluster, invalidating the 'next' 1007 * pointer. To prevent an inordinate number of 1008 * restarts we use our marker to remember our place. 1009 * 1010 * decrement inactive_shortage on success to account 1011 * for the (future) cleaned page. Otherwise we 1012 * could wind up laundering or cleaning too many 1013 * pages. 1014 */ 1015 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq); 1016 if (vm_pageout_clean(m) != 0) { 1017 --inactive_shortage; 1018 --maxlaunder; 1019 } 1020 next = TAILQ_NEXT(&marker, pageq); 1021 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq); 1022 if (vp != NULL) 1023 vput(vp); 1024 } 1025 } 1026 1027 /* 1028 * We want to move pages from the active queue to the inactive 1029 * queue to get the inactive queue to the inactive target. If 1030 * we still have a page shortage from above we try to directly free 1031 * clean pages instead of moving them. 1032 * 1033 * If we do still have a shortage we keep track of the number of 1034 * pages we free or cache (recycle_count) as a measure of thrashing 1035 * between the active and inactive queues. 1036 * 1037 * If we were able to completely satisfy the free+cache targets 1038 * from the inactive pool we limit the number of pages we move 1039 * from the active pool to the inactive pool to 2x the pages we 1040 * had removed from the inactive pool. If we were not able to 1041 * completel satisfy the free+cache targets we go for the whole 1042 * target aggressively. 1043 * 1044 * NOTE: Both variables can end up negative. 1045 * NOTE: We are still in a critical section. 1046 */ 1047 active_shortage = vmstats.v_inactive_target - vmstats.v_inactive_count; 1048 if (inactive_shortage <= 0 && 1049 active_shortage > inactive_original_shortage * 2) { 1050 active_shortage = inactive_original_shortage * 2; 1051 } 1052 1053 pcount = vmstats.v_active_count; 1054 recycle_count = 0; 1055 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1056 1057 while ((m != NULL) && (pcount-- > 0) && 1058 (inactive_shortage > 0 || active_shortage > 0) 1059 ) { 1060 /* 1061 * Give interrupts a chance. 1062 */ 1063 crit_exit(); 1064 crit_enter(); 1065 1066 /* 1067 * If the page was ripped out from under us, just stop. 1068 */ 1069 if (m->queue != PQ_ACTIVE) 1070 break; 1071 next = TAILQ_NEXT(m, pageq); 1072 1073 /* 1074 * Don't deactivate pages that are busy. 1075 */ 1076 if ((m->busy != 0) || 1077 (m->flags & PG_BUSY) || 1078 (m->hold_count != 0)) { 1079 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1080 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1081 m = next; 1082 continue; 1083 } 1084 1085 /* 1086 * The count for pagedaemon pages is done after checking the 1087 * page for eligibility... 1088 */ 1089 mycpu->gd_cnt.v_pdpages++; 1090 1091 /* 1092 * Check to see "how much" the page has been used and clear 1093 * the tracking access bits. If the object has no references 1094 * don't bother paying the expense. 1095 */ 1096 actcount = 0; 1097 if (m->object->ref_count != 0) { 1098 if (m->flags & PG_REFERENCED) 1099 ++actcount; 1100 actcount += pmap_ts_referenced(m); 1101 if (actcount) { 1102 m->act_count += ACT_ADVANCE + actcount; 1103 if (m->act_count > ACT_MAX) 1104 m->act_count = ACT_MAX; 1105 } 1106 } 1107 vm_page_flag_clear(m, PG_REFERENCED); 1108 1109 /* 1110 * actcount is only valid if the object ref_count is non-zero. 1111 */ 1112 if (actcount && m->object->ref_count != 0) { 1113 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1114 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1115 } else { 1116 m->act_count -= min(m->act_count, ACT_DECLINE); 1117 if (vm_pageout_algorithm || 1118 m->object->ref_count == 0 || 1119 m->act_count < pass + 1 1120 ) { 1121 /* 1122 * Deactivate the page. If we had a 1123 * shortage from our inactive scan try to 1124 * free (cache) the page instead. 1125 */ 1126 --active_shortage; 1127 if (inactive_shortage > 0 || 1128 m->object->ref_count == 0) { 1129 if (inactive_shortage > 0) 1130 ++recycle_count; 1131 vm_page_busy(m); 1132 vm_page_protect(m, VM_PROT_NONE); 1133 vm_page_wakeup(m); 1134 if (m->dirty == 0) { 1135 --inactive_shortage; 1136 vm_page_cache(m); 1137 } else { 1138 vm_page_deactivate(m); 1139 } 1140 } else { 1141 vm_page_deactivate(m); 1142 } 1143 } else { 1144 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1145 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1146 } 1147 } 1148 m = next; 1149 } 1150 1151 /* 1152 * We try to maintain some *really* free pages, this allows interrupt 1153 * code to be guaranteed space. Since both cache and free queues 1154 * are considered basically 'free', moving pages from cache to free 1155 * does not effect other calculations. 1156 * 1157 * NOTE: we are still in a critical section. 1158 * 1159 * Pages moved from PQ_CACHE to totally free are not counted in the 1160 * pages_freed counter. 1161 */ 1162 while (vmstats.v_free_count < vmstats.v_free_reserved) { 1163 static int cache_rover = 0; 1164 m = vm_page_list_find(PQ_CACHE, cache_rover, FALSE); 1165 if (m == NULL) 1166 break; 1167 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || 1168 m->busy || 1169 m->hold_count || 1170 m->wire_count) { 1171 #ifdef INVARIANTS 1172 kprintf("Warning: busy page %p found in cache\n", m); 1173 #endif 1174 vm_page_deactivate(m); 1175 continue; 1176 } 1177 KKASSERT((m->flags & PG_MAPPED) == 0); 1178 KKASSERT(m->dirty == 0); 1179 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK; 1180 vm_pageout_page_free(m); 1181 mycpu->gd_cnt.v_dfree++; 1182 } 1183 1184 crit_exit(); 1185 1186 #if !defined(NO_SWAPPING) 1187 /* 1188 * Idle process swapout -- run once per second. 1189 */ 1190 if (vm_swap_idle_enabled) { 1191 static long lsec; 1192 if (time_second != lsec) { 1193 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1194 vm_req_vmdaemon(); 1195 lsec = time_second; 1196 } 1197 } 1198 #endif 1199 1200 /* 1201 * If we didn't get enough free pages, and we have skipped a vnode 1202 * in a writeable object, wakeup the sync daemon. And kick swapout 1203 * if we did not get enough free pages. 1204 */ 1205 if (vm_paging_target() > 0) { 1206 if (vnodes_skipped && vm_page_count_min(0)) 1207 speedup_syncer(); 1208 #if !defined(NO_SWAPPING) 1209 if (vm_swap_enabled && vm_page_count_target()) { 1210 vm_req_vmdaemon(); 1211 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1212 } 1213 #endif 1214 } 1215 1216 /* 1217 * Handle catastrophic conditions. Under good conditions we should 1218 * be at the target, well beyond our minimum. If we could not even 1219 * reach our minimum the system is under heavy stress. 1220 * 1221 * Determine whether we have run out of memory. This occurs when 1222 * swap_pager_full is TRUE and the only pages left in the page 1223 * queues are dirty. We will still likely have page shortages. 1224 * 1225 * - swap_pager_full is set if insufficient swap was 1226 * available to satisfy a requested pageout. 1227 * 1228 * - the inactive queue is bloated (4 x size of active queue), 1229 * meaning it is unable to get rid of dirty pages and. 1230 * 1231 * - vm_page_count_min() without counting pages recycled from the 1232 * active queue (recycle_count) means we could not recover 1233 * enough pages to meet bare minimum needs. This test only 1234 * works if the inactive queue is bloated. 1235 * 1236 * - due to a positive inactive_shortage we shifted the remaining 1237 * dirty pages from the active queue to the inactive queue 1238 * trying to find clean ones to free. 1239 */ 1240 if (swap_pager_full && vm_page_count_min(recycle_count)) 1241 kprintf("Warning: system low on memory+swap!\n"); 1242 if (swap_pager_full && vm_page_count_min(recycle_count) && 1243 vmstats.v_inactive_count > vmstats.v_active_count * 4 && 1244 inactive_shortage > 0) { 1245 /* 1246 * Kill something. 1247 */ 1248 info.bigproc = NULL; 1249 info.bigsize = 0; 1250 allproc_scan(vm_pageout_scan_callback, &info); 1251 if (info.bigproc != NULL) { 1252 killproc(info.bigproc, "out of swap space"); 1253 info.bigproc->p_nice = PRIO_MIN; 1254 info.bigproc->p_usched->resetpriority( 1255 FIRST_LWP_IN_PROC(info.bigproc)); 1256 wakeup(&vmstats.v_free_count); 1257 PRELE(info.bigproc); 1258 } 1259 } 1260 return(inactive_shortage); 1261 } 1262 1263 static int 1264 vm_pageout_scan_callback(struct proc *p, void *data) 1265 { 1266 struct vm_pageout_scan_info *info = data; 1267 vm_offset_t size; 1268 1269 /* 1270 * Never kill system processes or init. If we have configured swap 1271 * then try to avoid killing low-numbered pids. 1272 */ 1273 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1274 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1275 return (0); 1276 } 1277 1278 /* 1279 * if the process is in a non-running type state, 1280 * don't touch it. 1281 */ 1282 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) 1283 return (0); 1284 1285 /* 1286 * Get the approximate process size. Note that anonymous pages 1287 * with backing swap will be counted twice, but there should not 1288 * be too many such pages due to the stress the VM system is 1289 * under at this point. 1290 */ 1291 size = vmspace_anonymous_count(p->p_vmspace) + 1292 vmspace_swap_count(p->p_vmspace); 1293 1294 /* 1295 * If the this process is bigger than the biggest one 1296 * remember it. 1297 */ 1298 if (info->bigsize < size) { 1299 if (info->bigproc) 1300 PRELE(info->bigproc); 1301 PHOLD(p); 1302 info->bigproc = p; 1303 info->bigsize = size; 1304 } 1305 return(0); 1306 } 1307 1308 /* 1309 * This routine tries to maintain the pseudo LRU active queue, 1310 * so that during long periods of time where there is no paging, 1311 * that some statistic accumulation still occurs. This code 1312 * helps the situation where paging just starts to occur. 1313 */ 1314 static void 1315 vm_pageout_page_stats(void) 1316 { 1317 vm_page_t m,next; 1318 int pcount,tpcount; /* Number of pages to check */ 1319 static int fullintervalcount = 0; 1320 int page_shortage; 1321 1322 page_shortage = 1323 (vmstats.v_inactive_target + vmstats.v_cache_max + vmstats.v_free_min) - 1324 (vmstats.v_free_count + vmstats.v_inactive_count + vmstats.v_cache_count); 1325 1326 if (page_shortage <= 0) 1327 return; 1328 1329 crit_enter(); 1330 1331 pcount = vmstats.v_active_count; 1332 fullintervalcount += vm_pageout_stats_interval; 1333 if (fullintervalcount < vm_pageout_full_stats_interval) { 1334 tpcount = (vm_pageout_stats_max * vmstats.v_active_count) / vmstats.v_page_count; 1335 if (pcount > tpcount) 1336 pcount = tpcount; 1337 } else { 1338 fullintervalcount = 0; 1339 } 1340 1341 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1342 while ((m != NULL) && (pcount-- > 0)) { 1343 int actcount; 1344 1345 if (m->queue != PQ_ACTIVE) { 1346 break; 1347 } 1348 1349 next = TAILQ_NEXT(m, pageq); 1350 /* 1351 * Don't deactivate pages that are busy. 1352 */ 1353 if ((m->busy != 0) || 1354 (m->flags & PG_BUSY) || 1355 (m->hold_count != 0)) { 1356 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1357 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1358 m = next; 1359 continue; 1360 } 1361 1362 actcount = 0; 1363 if (m->flags & PG_REFERENCED) { 1364 vm_page_flag_clear(m, PG_REFERENCED); 1365 actcount += 1; 1366 } 1367 1368 actcount += pmap_ts_referenced(m); 1369 if (actcount) { 1370 m->act_count += ACT_ADVANCE + actcount; 1371 if (m->act_count > ACT_MAX) 1372 m->act_count = ACT_MAX; 1373 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1374 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1375 } else { 1376 if (m->act_count == 0) { 1377 /* 1378 * We turn off page access, so that we have 1379 * more accurate RSS stats. We don't do this 1380 * in the normal page deactivation when the 1381 * system is loaded VM wise, because the 1382 * cost of the large number of page protect 1383 * operations would be higher than the value 1384 * of doing the operation. 1385 */ 1386 vm_page_busy(m); 1387 vm_page_protect(m, VM_PROT_NONE); 1388 vm_page_wakeup(m); 1389 vm_page_deactivate(m); 1390 } else { 1391 m->act_count -= min(m->act_count, ACT_DECLINE); 1392 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1393 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1394 } 1395 } 1396 1397 m = next; 1398 } 1399 crit_exit(); 1400 } 1401 1402 static int 1403 vm_pageout_free_page_calc(vm_size_t count) 1404 { 1405 if (count < vmstats.v_page_count) 1406 return 0; 1407 /* 1408 * free_reserved needs to include enough for the largest swap pager 1409 * structures plus enough for any pv_entry structs when paging. 1410 */ 1411 if (vmstats.v_page_count > 1024) 1412 vmstats.v_free_min = 4 + (vmstats.v_page_count - 1024) / 200; 1413 else 1414 vmstats.v_free_min = 4; 1415 vmstats.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1416 vmstats.v_interrupt_free_min; 1417 vmstats.v_free_reserved = vm_pageout_page_count + 1418 vmstats.v_pageout_free_min + (count / 768) + PQ_L2_SIZE; 1419 vmstats.v_free_severe = vmstats.v_free_min / 2; 1420 vmstats.v_free_min += vmstats.v_free_reserved; 1421 vmstats.v_free_severe += vmstats.v_free_reserved; 1422 return 1; 1423 } 1424 1425 1426 /* 1427 * vm_pageout is the high level pageout daemon. 1428 */ 1429 static void 1430 vm_pageout(void) 1431 { 1432 int pass; 1433 int inactive_shortage; 1434 1435 /* 1436 * Initialize some paging parameters. 1437 */ 1438 curthread->td_flags |= TDF_SYSTHREAD; 1439 1440 vmstats.v_interrupt_free_min = 2; 1441 if (vmstats.v_page_count < 2000) 1442 vm_pageout_page_count = 8; 1443 1444 vm_pageout_free_page_calc(vmstats.v_page_count); 1445 1446 /* 1447 * v_free_target and v_cache_min control pageout hysteresis. Note 1448 * that these are more a measure of the VM cache queue hysteresis 1449 * then the VM free queue. Specifically, v_free_target is the 1450 * high water mark (free+cache pages). 1451 * 1452 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1453 * low water mark, while v_free_min is the stop. v_cache_min must 1454 * be big enough to handle memory needs while the pageout daemon 1455 * is signalled and run to free more pages. 1456 */ 1457 if (vmstats.v_free_count > 6144) 1458 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved; 1459 else 1460 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved; 1461 1462 /* 1463 * NOTE: With the new buffer cache b_act_count we want the default 1464 * inactive target to be a percentage of available memory. 1465 * 1466 * The inactive target essentially determines the minimum 1467 * number of 'temporary' pages capable of caching one-time-use 1468 * files when the VM system is otherwise full of pages 1469 * belonging to multi-time-use files or active program data. 1470 * 1471 * NOTE: The inactive target is aggressively persued only if the 1472 * inactive queue becomes too small. If the inactive queue 1473 * is large enough to satisfy page movement to free+cache 1474 * then it is repopulated more slowly from the active queue. 1475 * This allows a generate inactive_target default to be set. 1476 * 1477 * There is an issue here for processes which sit mostly idle 1478 * 'overnight', such as sshd, tcsh, and X. Any movement from 1479 * the active queue will eventually cause such pages to 1480 * recycle eventually causing a lot of paging in the morning. 1481 * To reduce the incidence of this pages cycled out of the 1482 * buffer cache are moved directly to the inactive queue if 1483 * they were only used once or twice. The vfs.vm_cycle_point 1484 * sysctl can be used to adjust this. 1485 */ 1486 if (vmstats.v_free_count > 2048) { 1487 vmstats.v_cache_min = vmstats.v_free_target; 1488 vmstats.v_cache_max = 2 * vmstats.v_cache_min; 1489 } else { 1490 vmstats.v_cache_min = 0; 1491 vmstats.v_cache_max = 0; 1492 } 1493 vmstats.v_inactive_target = vmstats.v_free_count / 2; 1494 1495 /* XXX does not really belong here */ 1496 if (vm_page_max_wired == 0) 1497 vm_page_max_wired = vmstats.v_free_count / 3; 1498 1499 if (vm_pageout_stats_max == 0) 1500 vm_pageout_stats_max = vmstats.v_free_target; 1501 1502 /* 1503 * Set interval in seconds for stats scan. 1504 */ 1505 if (vm_pageout_stats_interval == 0) 1506 vm_pageout_stats_interval = 5; 1507 if (vm_pageout_full_stats_interval == 0) 1508 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1509 1510 1511 /* 1512 * Set maximum free per pass 1513 */ 1514 if (vm_pageout_stats_free_max == 0) 1515 vm_pageout_stats_free_max = 5; 1516 1517 swap_pager_swap_init(); 1518 pass = 0; 1519 1520 /* 1521 * The pageout daemon is never done, so loop forever. 1522 */ 1523 while (TRUE) { 1524 int error; 1525 1526 if (vm_pages_needed == 0) { 1527 /* 1528 * Wait for an action request 1529 */ 1530 error = tsleep(&vm_pages_needed, 1531 0, "psleep", 1532 vm_pageout_stats_interval * hz); 1533 if (error && vm_pages_needed == 0) { 1534 vm_pageout_page_stats(); 1535 continue; 1536 } 1537 vm_pages_needed = 1; 1538 } 1539 1540 /* 1541 * If we have enough free memory, wakeup waiters. 1542 */ 1543 crit_enter(); 1544 if (!vm_page_count_min(0)) 1545 wakeup(&vmstats.v_free_count); 1546 mycpu->gd_cnt.v_pdwakeups++; 1547 crit_exit(); 1548 inactive_shortage = vm_pageout_scan(pass); 1549 1550 /* 1551 * Try to avoid thrashing the system with activity. 1552 */ 1553 if (inactive_shortage > 0) { 1554 ++pass; 1555 if (swap_pager_full) { 1556 /* 1557 * Running out of memory, catastrophic back-off 1558 * to one-second intervals. 1559 */ 1560 tsleep(&vm_pages_needed, 0, "pdelay", hz); 1561 } else if (pass < 10 && vm_pages_needed > 1) { 1562 /* 1563 * Normal operation, additional processes 1564 * have already kicked us. Retry immediately. 1565 */ 1566 } else if (pass < 10) { 1567 /* 1568 * Normal operation, fewer processes. Delay 1569 * a bit but allow wakeups. 1570 */ 1571 vm_pages_needed = 0; 1572 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10); 1573 vm_pages_needed = 1; 1574 } else { 1575 /* 1576 * We've taken too many passes, forced delay. 1577 */ 1578 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10); 1579 } 1580 } else { 1581 pass = 0; 1582 vm_pages_needed = 0; 1583 } 1584 } 1585 } 1586 1587 /* 1588 * Called after allocating a page out of the cache or free queue 1589 * to possibly wake the pagedaemon up to replentish our supply. 1590 * 1591 * We try to generate some hysteresis by waking the pagedaemon up 1592 * when our free+cache pages go below the severe level. The pagedaemon 1593 * tries to get the count back up to at least the minimum, and through 1594 * to the target level if possible. 1595 * 1596 * If the pagedaemon is already active bump vm_pages_needed as a hint 1597 * that there are even more requests pending. 1598 */ 1599 void 1600 pagedaemon_wakeup(void) 1601 { 1602 if (vm_page_count_severe() && curthread != pagethread) { 1603 if (vm_pages_needed == 0) { 1604 vm_pages_needed = 1; 1605 wakeup(&vm_pages_needed); 1606 } else if (vm_page_count_min(0)) { 1607 ++vm_pages_needed; 1608 } 1609 } 1610 } 1611 1612 #if !defined(NO_SWAPPING) 1613 static void 1614 vm_req_vmdaemon(void) 1615 { 1616 static int lastrun = 0; 1617 1618 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1619 wakeup(&vm_daemon_needed); 1620 lastrun = ticks; 1621 } 1622 } 1623 1624 static int vm_daemon_callback(struct proc *p, void *data __unused); 1625 1626 static void 1627 vm_daemon(void) 1628 { 1629 while (TRUE) { 1630 tsleep(&vm_daemon_needed, 0, "psleep", 0); 1631 if (vm_pageout_req_swapout) { 1632 swapout_procs(vm_pageout_req_swapout); 1633 vm_pageout_req_swapout = 0; 1634 } 1635 /* 1636 * scan the processes for exceeding their rlimits or if 1637 * process is swapped out -- deactivate pages 1638 */ 1639 allproc_scan(vm_daemon_callback, NULL); 1640 } 1641 } 1642 1643 static int 1644 vm_daemon_callback(struct proc *p, void *data __unused) 1645 { 1646 vm_pindex_t limit, size; 1647 1648 /* 1649 * if this is a system process or if we have already 1650 * looked at this process, skip it. 1651 */ 1652 if (p->p_flag & (P_SYSTEM | P_WEXIT)) 1653 return (0); 1654 1655 /* 1656 * if the process is in a non-running type state, 1657 * don't touch it. 1658 */ 1659 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) 1660 return (0); 1661 1662 /* 1663 * get a limit 1664 */ 1665 limit = OFF_TO_IDX(qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 1666 p->p_rlimit[RLIMIT_RSS].rlim_max)); 1667 1668 /* 1669 * let processes that are swapped out really be 1670 * swapped out. Set the limit to nothing to get as 1671 * many pages out to swap as possible. 1672 */ 1673 if (p->p_flag & P_SWAPPEDOUT) 1674 limit = 0; 1675 1676 size = vmspace_resident_count(p->p_vmspace); 1677 if (limit >= 0 && size >= limit) { 1678 vm_pageout_map_deactivate_pages( 1679 &p->p_vmspace->vm_map, limit); 1680 } 1681 return (0); 1682 } 1683 1684 #endif 1685