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 */ 385 386 int 387 vm_pageout_flush(vm_page_t *mc, int count, int flags) 388 { 389 vm_object_t object; 390 int pageout_status[count]; 391 int numpagedout = 0; 392 int i; 393 394 /* 395 * Initiate I/O. Bump the vm_page_t->busy counter. 396 */ 397 for (i = 0; i < count; i++) { 398 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush page %p index %d/%d: partially invalid page", mc[i], i, count)); 399 vm_page_io_start(mc[i]); 400 } 401 402 /* 403 * We must make the pages read-only. This will also force the 404 * modified bit in the related pmaps to be cleared. The pager 405 * cannot clear the bit for us since the I/O completion code 406 * typically runs from an interrupt. The act of making the page 407 * read-only handles the case for us. 408 */ 409 for (i = 0; i < count; i++) { 410 vm_page_protect(mc[i], VM_PROT_READ); 411 } 412 413 object = mc[0]->object; 414 vm_object_pip_add(object, count); 415 416 vm_pager_put_pages(object, mc, count, 417 (flags | ((object == &kernel_object) ? VM_PAGER_PUT_SYNC : 0)), 418 pageout_status); 419 420 for (i = 0; i < count; i++) { 421 vm_page_t mt = mc[i]; 422 423 switch (pageout_status[i]) { 424 case VM_PAGER_OK: 425 numpagedout++; 426 break; 427 case VM_PAGER_PEND: 428 numpagedout++; 429 break; 430 case VM_PAGER_BAD: 431 /* 432 * Page outside of range of object. Right now we 433 * essentially lose the changes by pretending it 434 * worked. 435 */ 436 pmap_clear_modify(mt); 437 vm_page_undirty(mt); 438 break; 439 case VM_PAGER_ERROR: 440 case VM_PAGER_FAIL: 441 /* 442 * A page typically cannot be paged out when we 443 * have run out of swap. We leave the page 444 * marked inactive and will try to page it out 445 * again later. 446 * 447 * Starvation of the active page list is used to 448 * determine when the system is massively memory 449 * starved. 450 */ 451 break; 452 case VM_PAGER_AGAIN: 453 break; 454 } 455 456 /* 457 * If the operation is still going, leave the page busy to 458 * block all other accesses. Also, leave the paging in 459 * progress indicator set so that we don't attempt an object 460 * collapse. 461 * 462 * For any pages which have completed synchronously, 463 * deactivate the page if we are under a severe deficit. 464 * Do not try to enter them into the cache, though, they 465 * might still be read-heavy. 466 */ 467 if (pageout_status[i] != VM_PAGER_PEND) { 468 vm_object_pip_wakeup(object); 469 vm_page_io_finish(mt); 470 if (vm_page_count_severe()) 471 vm_page_deactivate(mt); 472 #if 0 473 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt)) 474 vm_page_protect(mt, VM_PROT_READ); 475 #endif 476 } 477 } 478 return numpagedout; 479 } 480 481 #if !defined(NO_SWAPPING) 482 /* 483 * vm_pageout_object_deactivate_pages 484 * 485 * deactivate enough pages to satisfy the inactive target 486 * requirements or if vm_page_proc_limit is set, then 487 * deactivate all of the pages in the object and its 488 * backing_objects. 489 * 490 * The object and map must be locked. 491 */ 492 static int vm_pageout_object_deactivate_pages_callback(vm_page_t, void *); 493 494 static void 495 vm_pageout_object_deactivate_pages(vm_map_t map, vm_object_t object, 496 vm_pindex_t desired, int map_remove_only) 497 { 498 struct rb_vm_page_scan_info info; 499 int remove_mode; 500 501 if (object->type == OBJT_DEVICE || object->type == OBJT_PHYS) 502 return; 503 504 while (object) { 505 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 506 return; 507 if (object->paging_in_progress) 508 return; 509 510 remove_mode = map_remove_only; 511 if (object->shadow_count > 1) 512 remove_mode = 1; 513 514 /* 515 * scan the objects entire memory queue. spl protection is 516 * required to avoid an interrupt unbusy/free race against 517 * our busy check. 518 */ 519 crit_enter(); 520 info.limit = remove_mode; 521 info.map = map; 522 info.desired = desired; 523 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL, 524 vm_pageout_object_deactivate_pages_callback, 525 &info 526 ); 527 crit_exit(); 528 object = object->backing_object; 529 } 530 } 531 532 static int 533 vm_pageout_object_deactivate_pages_callback(vm_page_t p, void *data) 534 { 535 struct rb_vm_page_scan_info *info = data; 536 int actcount; 537 538 if (pmap_resident_count(vm_map_pmap(info->map)) <= info->desired) { 539 return(-1); 540 } 541 mycpu->gd_cnt.v_pdpages++; 542 if (p->wire_count != 0 || p->hold_count != 0 || p->busy != 0 || 543 (p->flags & (PG_BUSY|PG_UNMANAGED)) || 544 !pmap_page_exists_quick(vm_map_pmap(info->map), p)) { 545 return(0); 546 } 547 548 actcount = pmap_ts_referenced(p); 549 if (actcount) { 550 vm_page_flag_set(p, PG_REFERENCED); 551 } else if (p->flags & PG_REFERENCED) { 552 actcount = 1; 553 } 554 555 if ((p->queue != PQ_ACTIVE) && 556 (p->flags & PG_REFERENCED)) { 557 vm_page_activate(p); 558 p->act_count += actcount; 559 vm_page_flag_clear(p, PG_REFERENCED); 560 } else if (p->queue == PQ_ACTIVE) { 561 if ((p->flags & PG_REFERENCED) == 0) { 562 p->act_count -= min(p->act_count, ACT_DECLINE); 563 if (!info->limit && (vm_pageout_algorithm || (p->act_count == 0))) { 564 vm_page_busy(p); 565 vm_page_protect(p, VM_PROT_NONE); 566 vm_page_wakeup(p); 567 vm_page_deactivate(p); 568 } else { 569 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 570 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 571 } 572 } else { 573 vm_page_activate(p); 574 vm_page_flag_clear(p, PG_REFERENCED); 575 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 576 p->act_count += ACT_ADVANCE; 577 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 578 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 579 } 580 } else if (p->queue == PQ_INACTIVE) { 581 vm_page_busy(p); 582 vm_page_protect(p, VM_PROT_NONE); 583 vm_page_wakeup(p); 584 } 585 return(0); 586 } 587 588 /* 589 * deactivate some number of pages in a map, try to do it fairly, but 590 * that is really hard to do. 591 */ 592 static void 593 vm_pageout_map_deactivate_pages(vm_map_t map, vm_pindex_t desired) 594 { 595 vm_map_entry_t tmpe; 596 vm_object_t obj, bigobj; 597 int nothingwired; 598 599 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT)) { 600 return; 601 } 602 603 bigobj = NULL; 604 nothingwired = TRUE; 605 606 /* 607 * first, search out the biggest object, and try to free pages from 608 * that. 609 */ 610 tmpe = map->header.next; 611 while (tmpe != &map->header) { 612 switch(tmpe->maptype) { 613 case VM_MAPTYPE_NORMAL: 614 case VM_MAPTYPE_VPAGETABLE: 615 obj = tmpe->object.vm_object; 616 if ((obj != NULL) && (obj->shadow_count <= 1) && 617 ((bigobj == NULL) || 618 (bigobj->resident_page_count < obj->resident_page_count))) { 619 bigobj = obj; 620 } 621 break; 622 default: 623 break; 624 } 625 if (tmpe->wired_count > 0) 626 nothingwired = FALSE; 627 tmpe = tmpe->next; 628 } 629 630 if (bigobj) 631 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 632 633 /* 634 * Next, hunt around for other pages to deactivate. We actually 635 * do this search sort of wrong -- .text first is not the best idea. 636 */ 637 tmpe = map->header.next; 638 while (tmpe != &map->header) { 639 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 640 break; 641 switch(tmpe->maptype) { 642 case VM_MAPTYPE_NORMAL: 643 case VM_MAPTYPE_VPAGETABLE: 644 obj = tmpe->object.vm_object; 645 if (obj) 646 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 647 break; 648 default: 649 break; 650 } 651 tmpe = tmpe->next; 652 }; 653 654 /* 655 * Remove all mappings if a process is swapped out, this will free page 656 * table pages. 657 */ 658 if (desired == 0 && nothingwired) 659 pmap_remove(vm_map_pmap(map), 660 VM_MIN_USER_ADDRESS, VM_MAX_USER_ADDRESS); 661 vm_map_unlock(map); 662 } 663 #endif 664 665 /* 666 * Don't try to be fancy - being fancy can lead to vnode deadlocks. We 667 * only do it for OBJT_DEFAULT and OBJT_SWAP objects which we know can 668 * be trivially freed. 669 */ 670 void 671 vm_pageout_page_free(vm_page_t m) 672 { 673 vm_object_t object = m->object; 674 int type = object->type; 675 676 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 677 vm_object_reference(object); 678 vm_page_busy(m); 679 vm_page_protect(m, VM_PROT_NONE); 680 vm_page_free(m); 681 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 682 vm_object_deallocate(object); 683 } 684 685 /* 686 * vm_pageout_scan does the dirty work for the pageout daemon. 687 */ 688 struct vm_pageout_scan_info { 689 struct proc *bigproc; 690 vm_offset_t bigsize; 691 }; 692 693 static int vm_pageout_scan_callback(struct proc *p, void *data); 694 695 static int 696 vm_pageout_scan(int pass) 697 { 698 struct vm_pageout_scan_info info; 699 vm_page_t m, next; 700 struct vm_page marker; 701 int maxscan, pcount; 702 int recycle_count; 703 int inactive_shortage, active_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 vm_pageout_deficit = 0; 723 724 /* 725 * Initialize our marker 726 */ 727 bzero(&marker, sizeof(marker)); 728 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 729 marker.queue = PQ_INACTIVE; 730 marker.wire_count = 1; 731 732 /* 733 * Start scanning the inactive queue for pages we can move to the 734 * cache or free. The scan will stop when the target is reached or 735 * we have scanned the entire inactive queue. Note that m->act_count 736 * is not used to form decisions for the inactive queue, only for the 737 * active queue. 738 * 739 * maxlaunder limits the number of dirty pages we flush per scan. 740 * For most systems a smaller value (16 or 32) is more robust under 741 * extreme memory and disk pressure because any unnecessary writes 742 * to disk can result in extreme performance degredation. However, 743 * systems with excessive dirty pages (especially when MAP_NOSYNC is 744 * used) will die horribly with limited laundering. If the pageout 745 * daemon cannot clean enough pages in the first pass, we let it go 746 * all out in succeeding passes. 747 */ 748 if ((maxlaunder = vm_max_launder) <= 1) 749 maxlaunder = 1; 750 if (pass) 751 maxlaunder = 10000; 752 753 /* 754 * We will generally be in a critical section throughout the 755 * scan, but we can release it temporarily when we are sitting on a 756 * non-busy page without fear. this is required to prevent an 757 * interrupt from unbusying or freeing a page prior to our busy 758 * check, leaving us on the wrong queue or checking the wrong 759 * page. 760 */ 761 crit_enter(); 762 rescan0: 763 maxscan = vmstats.v_inactive_count; 764 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 765 m != NULL && maxscan-- > 0 && inactive_shortage > 0; 766 m = next 767 ) { 768 mycpu->gd_cnt.v_pdpages++; 769 770 /* 771 * Give interrupts a chance 772 */ 773 crit_exit(); 774 crit_enter(); 775 776 /* 777 * It's easier for some of the conditions below to just loop 778 * and catch queue changes here rather then check everywhere 779 * else. 780 */ 781 if (m->queue != PQ_INACTIVE) 782 goto rescan0; 783 next = TAILQ_NEXT(m, pageq); 784 785 /* 786 * skip marker pages 787 */ 788 if (m->flags & PG_MARKER) 789 continue; 790 791 /* 792 * A held page may be undergoing I/O, so skip it. 793 */ 794 if (m->hold_count) { 795 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 796 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 797 continue; 798 } 799 800 /* 801 * Dont mess with busy pages, keep in the front of the 802 * queue, most likely are being paged out. 803 */ 804 if (m->busy || (m->flags & PG_BUSY)) { 805 continue; 806 } 807 808 if (m->object->ref_count == 0) { 809 /* 810 * If the object is not being used, we ignore previous 811 * references. 812 */ 813 vm_page_flag_clear(m, PG_REFERENCED); 814 pmap_clear_reference(m); 815 816 } else if (((m->flags & PG_REFERENCED) == 0) && 817 (actcount = pmap_ts_referenced(m))) { 818 /* 819 * Otherwise, if the page has been referenced while 820 * in the inactive queue, we bump the "activation 821 * count" upwards, making it less likely that the 822 * page will be added back to the inactive queue 823 * prematurely again. Here we check the page tables 824 * (or emulated bits, if any), given the upper level 825 * VM system not knowing anything about existing 826 * references. 827 */ 828 vm_page_activate(m); 829 m->act_count += (actcount + ACT_ADVANCE); 830 continue; 831 } 832 833 /* 834 * If the upper level VM system knows about any page 835 * references, we activate the page. We also set the 836 * "activation count" higher than normal so that we will less 837 * likely place pages back onto the inactive queue again. 838 */ 839 if ((m->flags & PG_REFERENCED) != 0) { 840 vm_page_flag_clear(m, PG_REFERENCED); 841 actcount = pmap_ts_referenced(m); 842 vm_page_activate(m); 843 m->act_count += (actcount + ACT_ADVANCE + 1); 844 continue; 845 } 846 847 /* 848 * If the upper level VM system doesn't know anything about 849 * the page being dirty, we have to check for it again. As 850 * far as the VM code knows, any partially dirty pages are 851 * fully dirty. 852 * 853 * Pages marked PG_WRITEABLE may be mapped into the user 854 * address space of a process running on another cpu. A 855 * user process (without holding the MP lock) running on 856 * another cpu may be able to touch the page while we are 857 * trying to remove it. vm_page_cache() will handle this 858 * case for us. 859 */ 860 if (m->dirty == 0) { 861 vm_page_test_dirty(m); 862 } else { 863 vm_page_dirty(m); 864 } 865 866 if (m->valid == 0) { 867 /* 868 * Invalid pages can be easily freed 869 */ 870 vm_pageout_page_free(m); 871 mycpu->gd_cnt.v_dfree++; 872 --inactive_shortage; 873 } else if (m->dirty == 0) { 874 /* 875 * Clean pages can be placed onto the cache queue. 876 * This effectively frees them. 877 */ 878 vm_page_cache(m); 879 --inactive_shortage; 880 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 881 /* 882 * Dirty pages need to be paged out, but flushing 883 * a page is extremely expensive verses freeing 884 * a clean page. Rather then artificially limiting 885 * the number of pages we can flush, we instead give 886 * dirty pages extra priority on the inactive queue 887 * by forcing them to be cycled through the queue 888 * twice before being flushed, after which the 889 * (now clean) page will cycle through once more 890 * before being freed. This significantly extends 891 * the thrash point for a heavily loaded machine. 892 */ 893 vm_page_flag_set(m, PG_WINATCFLS); 894 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 895 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 896 } else if (maxlaunder > 0) { 897 /* 898 * We always want to try to flush some dirty pages if 899 * we encounter them, to keep the system stable. 900 * Normally this number is small, but under extreme 901 * pressure where there are insufficient clean pages 902 * on the inactive queue, we may have to go all out. 903 */ 904 int swap_pageouts_ok; 905 struct vnode *vp = NULL; 906 907 object = m->object; 908 909 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 910 swap_pageouts_ok = 1; 911 } else { 912 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 913 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 914 vm_page_count_min(0)); 915 916 } 917 918 /* 919 * We don't bother paging objects that are "dead". 920 * Those objects are in a "rundown" state. 921 */ 922 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 923 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 924 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 925 continue; 926 } 927 928 /* 929 * The object is already known NOT to be dead. It 930 * is possible for the vget() to block the whole 931 * pageout daemon, but the new low-memory handling 932 * code should prevent it. 933 * 934 * The previous code skipped locked vnodes and, worse, 935 * reordered pages in the queue. This results in 936 * completely non-deterministic operation because, 937 * quite often, a vm_fault has initiated an I/O and 938 * is holding a locked vnode at just the point where 939 * the pageout daemon is woken up. 940 * 941 * We can't wait forever for the vnode lock, we might 942 * deadlock due to a vn_read() getting stuck in 943 * vm_wait while holding this vnode. We skip the 944 * vnode if we can't get it in a reasonable amount 945 * of time. 946 */ 947 948 if (object->type == OBJT_VNODE) { 949 vp = object->handle; 950 951 if (vget(vp, LK_EXCLUSIVE|LK_NOOBJ|LK_TIMELOCK)) { 952 ++pageout_lock_miss; 953 if (object->flags & OBJ_MIGHTBEDIRTY) 954 vnodes_skipped++; 955 continue; 956 } 957 958 /* 959 * The page might have been moved to another 960 * queue during potential blocking in vget() 961 * above. The page might have been freed and 962 * reused for another vnode. The object might 963 * have been reused for another vnode. 964 */ 965 if (m->queue != PQ_INACTIVE || 966 m->object != object || 967 object->handle != vp) { 968 if (object->flags & OBJ_MIGHTBEDIRTY) 969 vnodes_skipped++; 970 vput(vp); 971 continue; 972 } 973 974 /* 975 * The page may have been busied during the 976 * blocking in vput(); We don't move the 977 * page back onto the end of the queue so that 978 * statistics are more correct if we don't. 979 */ 980 if (m->busy || (m->flags & PG_BUSY)) { 981 vput(vp); 982 continue; 983 } 984 985 /* 986 * If the page has become held it might 987 * be undergoing I/O, so skip it 988 */ 989 if (m->hold_count) { 990 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 991 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 992 if (object->flags & OBJ_MIGHTBEDIRTY) 993 vnodes_skipped++; 994 vput(vp); 995 continue; 996 } 997 } 998 999 /* 1000 * If a page is dirty, then it is either being washed 1001 * (but not yet cleaned) or it is still in the 1002 * laundry. If it is still in the laundry, then we 1003 * start the cleaning operation. 1004 * 1005 * This operation may cluster, invalidating the 'next' 1006 * pointer. To prevent an inordinate number of 1007 * restarts we use our marker to remember our place. 1008 * 1009 * decrement inactive_shortage on success to account 1010 * for the (future) cleaned page. Otherwise we 1011 * could wind up laundering or cleaning too many 1012 * pages. 1013 */ 1014 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq); 1015 if (vm_pageout_clean(m) != 0) { 1016 --inactive_shortage; 1017 --maxlaunder; 1018 } 1019 next = TAILQ_NEXT(&marker, pageq); 1020 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq); 1021 if (vp != NULL) 1022 vput(vp); 1023 } 1024 } 1025 1026 /* 1027 * We want to move pages from the active queue to the inactive 1028 * queue to get the inactive queue to the inactive target. If 1029 * we still have a page shortage from above we try to directly free 1030 * clean pages instead of moving them. 1031 * 1032 * If we do still have a shortage we keep track of the number of 1033 * pages we free or cache (recycle_count) as a measure of thrashing 1034 * between the active and inactive queues. 1035 * 1036 * We do not do this if we were able to satisfy the requirement 1037 * entirely from the inactive queue. 1038 * 1039 * NOTE: Both variables can end up negative. 1040 * NOTE: We are still in a critical section. 1041 */ 1042 active_shortage = vmstats.v_inactive_target - vmstats.v_inactive_count; 1043 if (inactive_shortage <= 0) 1044 active_shortage = 0; 1045 1046 pcount = vmstats.v_active_count; 1047 recycle_count = 0; 1048 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1049 1050 while ((m != NULL) && (pcount-- > 0) && 1051 (inactive_shortage > 0 || active_shortage > 0) 1052 ) { 1053 /* 1054 * Give interrupts a chance. 1055 */ 1056 crit_exit(); 1057 crit_enter(); 1058 1059 /* 1060 * If the page was ripped out from under us, just stop. 1061 */ 1062 if (m->queue != PQ_ACTIVE) 1063 break; 1064 next = TAILQ_NEXT(m, pageq); 1065 1066 /* 1067 * Don't deactivate pages that are busy. 1068 */ 1069 if ((m->busy != 0) || 1070 (m->flags & PG_BUSY) || 1071 (m->hold_count != 0)) { 1072 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1073 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1074 m = next; 1075 continue; 1076 } 1077 1078 /* 1079 * The count for pagedaemon pages is done after checking the 1080 * page for eligibility... 1081 */ 1082 mycpu->gd_cnt.v_pdpages++; 1083 1084 /* 1085 * Check to see "how much" the page has been used and clear 1086 * the tracking access bits. If the object has no references 1087 * don't bother paying the expense. 1088 */ 1089 actcount = 0; 1090 if (m->object->ref_count != 0) { 1091 if (m->flags & PG_REFERENCED) 1092 ++actcount; 1093 actcount += pmap_ts_referenced(m); 1094 if (actcount) { 1095 m->act_count += ACT_ADVANCE + actcount; 1096 if (m->act_count > ACT_MAX) 1097 m->act_count = ACT_MAX; 1098 } 1099 } 1100 vm_page_flag_clear(m, PG_REFERENCED); 1101 1102 /* 1103 * actcount is only valid if the object ref_count is non-zero. 1104 */ 1105 if (actcount && m->object->ref_count != 0) { 1106 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1107 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1108 } else { 1109 m->act_count -= min(m->act_count, ACT_DECLINE); 1110 if (vm_pageout_algorithm || 1111 m->object->ref_count == 0 || 1112 m->act_count < pass + 1 1113 ) { 1114 /* 1115 * Deactivate the page. If we had a 1116 * shortage from our inactive scan try to 1117 * free (cache) the page instead. 1118 */ 1119 --active_shortage; 1120 if (inactive_shortage > 0 || 1121 m->object->ref_count == 0) { 1122 if (inactive_shortage > 0) 1123 ++recycle_count; 1124 vm_page_busy(m); 1125 vm_page_protect(m, VM_PROT_NONE); 1126 vm_page_wakeup(m); 1127 if (m->dirty == 0) { 1128 --inactive_shortage; 1129 vm_page_cache(m); 1130 } else { 1131 vm_page_deactivate(m); 1132 } 1133 } else { 1134 vm_page_deactivate(m); 1135 } 1136 } else { 1137 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1138 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1139 } 1140 } 1141 m = next; 1142 } 1143 1144 /* 1145 * We try to maintain some *really* free pages, this allows interrupt 1146 * code to be guaranteed space. Since both cache and free queues 1147 * are considered basically 'free', moving pages from cache to free 1148 * does not effect other calculations. 1149 * 1150 * NOTE: we are still in a critical section. 1151 * 1152 * Pages moved from PQ_CACHE to totally free are not counted in the 1153 * pages_freed counter. 1154 */ 1155 while (vmstats.v_free_count < vmstats.v_free_reserved) { 1156 static int cache_rover = 0; 1157 m = vm_page_list_find(PQ_CACHE, cache_rover, FALSE); 1158 if (m == NULL) 1159 break; 1160 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || 1161 m->busy || 1162 m->hold_count || 1163 m->wire_count) { 1164 #ifdef INVARIANTS 1165 kprintf("Warning: busy page %p found in cache\n", m); 1166 #endif 1167 vm_page_deactivate(m); 1168 continue; 1169 } 1170 KKASSERT((m->flags & PG_MAPPED) == 0); 1171 KKASSERT(m->dirty == 0); 1172 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK; 1173 vm_pageout_page_free(m); 1174 mycpu->gd_cnt.v_dfree++; 1175 } 1176 1177 crit_exit(); 1178 1179 #if !defined(NO_SWAPPING) 1180 /* 1181 * Idle process swapout -- run once per second. 1182 */ 1183 if (vm_swap_idle_enabled) { 1184 static long lsec; 1185 if (time_second != lsec) { 1186 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1187 vm_req_vmdaemon(); 1188 lsec = time_second; 1189 } 1190 } 1191 #endif 1192 1193 /* 1194 * If we didn't get enough free pages, and we have skipped a vnode 1195 * in a writeable object, wakeup the sync daemon. And kick swapout 1196 * if we did not get enough free pages. 1197 */ 1198 if (vm_paging_target() > 0) { 1199 if (vnodes_skipped && vm_page_count_min(0)) 1200 speedup_syncer(); 1201 #if !defined(NO_SWAPPING) 1202 if (vm_swap_enabled && vm_page_count_target()) { 1203 vm_req_vmdaemon(); 1204 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1205 } 1206 #endif 1207 } 1208 1209 /* 1210 * Handle catastrophic conditions. Under good conditions we should 1211 * be at the target, well beyond our minimum. If we could not even 1212 * reach our minimum the system is under heavy stress. 1213 * 1214 * Determine whether we have run out of memory. This occurs when 1215 * swap_pager_full is TRUE and the only pages left in the page 1216 * queues are dirty. We will still likely have page shortages. 1217 * 1218 * - swap_pager_full is set if insufficient swap was 1219 * available to satisfy a requested pageout. 1220 * 1221 * - the inactive queue is bloated (4 x size of active queue), 1222 * meaning it is unable to get rid of dirty pages and. 1223 * 1224 * - vm_page_count_min() without counting pages recycled from the 1225 * active queue (recycle_count) means we could not recover 1226 * enough pages to meet bare minimum needs. This test only 1227 * works if the inactive queue is bloated. 1228 * 1229 * - due to a positive inactive_shortage we shifted the remaining 1230 * dirty pages from the active queue to the inactive queue 1231 * trying to find clean ones to free. 1232 */ 1233 if (swap_pager_full && vm_page_count_min(recycle_count)) 1234 kprintf("Warning: system low on memory+swap!\n"); 1235 if (swap_pager_full && vm_page_count_min(recycle_count) && 1236 vmstats.v_inactive_count > vmstats.v_active_count * 4 && 1237 inactive_shortage > 0) { 1238 /* 1239 * Kill something. 1240 */ 1241 info.bigproc = NULL; 1242 info.bigsize = 0; 1243 allproc_scan(vm_pageout_scan_callback, &info); 1244 if (info.bigproc != NULL) { 1245 killproc(info.bigproc, "out of swap space"); 1246 info.bigproc->p_nice = PRIO_MIN; 1247 info.bigproc->p_usched->resetpriority( 1248 FIRST_LWP_IN_PROC(info.bigproc)); 1249 wakeup(&vmstats.v_free_count); 1250 PRELE(info.bigproc); 1251 } 1252 } 1253 return(inactive_shortage); 1254 } 1255 1256 static int 1257 vm_pageout_scan_callback(struct proc *p, void *data) 1258 { 1259 struct vm_pageout_scan_info *info = data; 1260 vm_offset_t size; 1261 1262 /* 1263 * Never kill system processes or init. If we have configured swap 1264 * then try to avoid killing low-numbered pids. 1265 */ 1266 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1267 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1268 return (0); 1269 } 1270 1271 /* 1272 * if the process is in a non-running type state, 1273 * don't touch it. 1274 */ 1275 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) 1276 return (0); 1277 1278 /* 1279 * Get the approximate process size. Note that anonymous pages 1280 * with backing swap will be counted twice, but there should not 1281 * be too many such pages due to the stress the VM system is 1282 * under at this point. 1283 */ 1284 size = vmspace_anonymous_count(p->p_vmspace) + 1285 vmspace_swap_count(p->p_vmspace); 1286 1287 /* 1288 * If the this process is bigger than the biggest one 1289 * remember it. 1290 */ 1291 if (info->bigsize < size) { 1292 if (info->bigproc) 1293 PRELE(info->bigproc); 1294 PHOLD(p); 1295 info->bigproc = p; 1296 info->bigsize = size; 1297 } 1298 return(0); 1299 } 1300 1301 /* 1302 * This routine tries to maintain the pseudo LRU active queue, 1303 * so that during long periods of time where there is no paging, 1304 * that some statistic accumulation still occurs. This code 1305 * helps the situation where paging just starts to occur. 1306 */ 1307 static void 1308 vm_pageout_page_stats(void) 1309 { 1310 vm_page_t m,next; 1311 int pcount,tpcount; /* Number of pages to check */ 1312 static int fullintervalcount = 0; 1313 int page_shortage; 1314 1315 page_shortage = 1316 (vmstats.v_inactive_target + vmstats.v_cache_max + vmstats.v_free_min) - 1317 (vmstats.v_free_count + vmstats.v_inactive_count + vmstats.v_cache_count); 1318 1319 if (page_shortage <= 0) 1320 return; 1321 1322 crit_enter(); 1323 1324 pcount = vmstats.v_active_count; 1325 fullintervalcount += vm_pageout_stats_interval; 1326 if (fullintervalcount < vm_pageout_full_stats_interval) { 1327 tpcount = (vm_pageout_stats_max * vmstats.v_active_count) / vmstats.v_page_count; 1328 if (pcount > tpcount) 1329 pcount = tpcount; 1330 } else { 1331 fullintervalcount = 0; 1332 } 1333 1334 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1335 while ((m != NULL) && (pcount-- > 0)) { 1336 int actcount; 1337 1338 if (m->queue != PQ_ACTIVE) { 1339 break; 1340 } 1341 1342 next = TAILQ_NEXT(m, pageq); 1343 /* 1344 * Don't deactivate pages that are busy. 1345 */ 1346 if ((m->busy != 0) || 1347 (m->flags & PG_BUSY) || 1348 (m->hold_count != 0)) { 1349 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1350 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1351 m = next; 1352 continue; 1353 } 1354 1355 actcount = 0; 1356 if (m->flags & PG_REFERENCED) { 1357 vm_page_flag_clear(m, PG_REFERENCED); 1358 actcount += 1; 1359 } 1360 1361 actcount += pmap_ts_referenced(m); 1362 if (actcount) { 1363 m->act_count += ACT_ADVANCE + actcount; 1364 if (m->act_count > ACT_MAX) 1365 m->act_count = ACT_MAX; 1366 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1367 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1368 } else { 1369 if (m->act_count == 0) { 1370 /* 1371 * We turn off page access, so that we have 1372 * more accurate RSS stats. We don't do this 1373 * in the normal page deactivation when the 1374 * system is loaded VM wise, because the 1375 * cost of the large number of page protect 1376 * operations would be higher than the value 1377 * of doing the operation. 1378 */ 1379 vm_page_busy(m); 1380 vm_page_protect(m, VM_PROT_NONE); 1381 vm_page_wakeup(m); 1382 vm_page_deactivate(m); 1383 } else { 1384 m->act_count -= min(m->act_count, ACT_DECLINE); 1385 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1386 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1387 } 1388 } 1389 1390 m = next; 1391 } 1392 crit_exit(); 1393 } 1394 1395 static int 1396 vm_pageout_free_page_calc(vm_size_t count) 1397 { 1398 if (count < vmstats.v_page_count) 1399 return 0; 1400 /* 1401 * free_reserved needs to include enough for the largest swap pager 1402 * structures plus enough for any pv_entry structs when paging. 1403 */ 1404 if (vmstats.v_page_count > 1024) 1405 vmstats.v_free_min = 4 + (vmstats.v_page_count - 1024) / 200; 1406 else 1407 vmstats.v_free_min = 4; 1408 vmstats.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1409 vmstats.v_interrupt_free_min; 1410 vmstats.v_free_reserved = vm_pageout_page_count + 1411 vmstats.v_pageout_free_min + (count / 768) + PQ_L2_SIZE; 1412 vmstats.v_free_severe = vmstats.v_free_min / 2; 1413 vmstats.v_free_min += vmstats.v_free_reserved; 1414 vmstats.v_free_severe += vmstats.v_free_reserved; 1415 return 1; 1416 } 1417 1418 1419 /* 1420 * vm_pageout is the high level pageout daemon. 1421 */ 1422 static void 1423 vm_pageout(void) 1424 { 1425 int pass; 1426 int inactive_shortage; 1427 1428 /* 1429 * Initialize some paging parameters. 1430 */ 1431 curthread->td_flags |= TDF_SYSTHREAD; 1432 1433 vmstats.v_interrupt_free_min = 2; 1434 if (vmstats.v_page_count < 2000) 1435 vm_pageout_page_count = 8; 1436 1437 vm_pageout_free_page_calc(vmstats.v_page_count); 1438 1439 /* 1440 * v_free_target and v_cache_min control pageout hysteresis. Note 1441 * that these are more a measure of the VM cache queue hysteresis 1442 * then the VM free queue. Specifically, v_free_target is the 1443 * high water mark (free+cache pages). 1444 * 1445 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1446 * low water mark, while v_free_min is the stop. v_cache_min must 1447 * be big enough to handle memory needs while the pageout daemon 1448 * is signalled and run to free more pages. 1449 */ 1450 if (vmstats.v_free_count > 6144) 1451 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved; 1452 else 1453 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved; 1454 1455 if (vmstats.v_free_count > 2048) { 1456 vmstats.v_cache_min = vmstats.v_free_target; 1457 vmstats.v_cache_max = 2 * vmstats.v_cache_min; 1458 vmstats.v_inactive_target = (3 * vmstats.v_free_target) / 2; 1459 } else { 1460 vmstats.v_cache_min = 0; 1461 vmstats.v_cache_max = 0; 1462 vmstats.v_inactive_target = vmstats.v_free_count / 4; 1463 } 1464 if (vmstats.v_inactive_target > vmstats.v_free_count / 3) 1465 vmstats.v_inactive_target = vmstats.v_free_count / 3; 1466 1467 /* XXX does not really belong here */ 1468 if (vm_page_max_wired == 0) 1469 vm_page_max_wired = vmstats.v_free_count / 3; 1470 1471 if (vm_pageout_stats_max == 0) 1472 vm_pageout_stats_max = vmstats.v_free_target; 1473 1474 /* 1475 * Set interval in seconds for stats scan. 1476 */ 1477 if (vm_pageout_stats_interval == 0) 1478 vm_pageout_stats_interval = 5; 1479 if (vm_pageout_full_stats_interval == 0) 1480 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1481 1482 1483 /* 1484 * Set maximum free per pass 1485 */ 1486 if (vm_pageout_stats_free_max == 0) 1487 vm_pageout_stats_free_max = 5; 1488 1489 swap_pager_swap_init(); 1490 pass = 0; 1491 1492 /* 1493 * The pageout daemon is never done, so loop forever. 1494 */ 1495 while (TRUE) { 1496 int error; 1497 1498 if (vm_pages_needed == 0) { 1499 /* 1500 * Wait for an action request 1501 */ 1502 error = tsleep(&vm_pages_needed, 1503 0, "psleep", 1504 vm_pageout_stats_interval * hz); 1505 if (error && vm_pages_needed == 0) { 1506 vm_pageout_page_stats(); 1507 continue; 1508 } 1509 vm_pages_needed = 1; 1510 } 1511 1512 /* 1513 * If we have enough free memory, wakeup waiters. 1514 */ 1515 crit_enter(); 1516 if (!vm_page_count_min(0)) 1517 wakeup(&vmstats.v_free_count); 1518 mycpu->gd_cnt.v_pdwakeups++; 1519 crit_exit(); 1520 inactive_shortage = vm_pageout_scan(pass); 1521 1522 /* 1523 * Try to avoid thrashing the system with activity. 1524 */ 1525 if (inactive_shortage > 0) { 1526 ++pass; 1527 if (swap_pager_full) { 1528 /* 1529 * Running out of memory, catastrophic back-off 1530 * to one-second intervals. 1531 */ 1532 tsleep(&vm_pages_needed, 0, "pdelay", hz); 1533 } else if (pass < 10 && vm_pages_needed > 1) { 1534 /* 1535 * Normal operation, additional processes 1536 * have already kicked us. Retry immediately. 1537 */ 1538 } else if (pass < 10) { 1539 /* 1540 * Normal operation, fewer processes. Delay 1541 * a bit but allow wakeups. 1542 */ 1543 vm_pages_needed = 0; 1544 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10); 1545 vm_pages_needed = 1; 1546 } else { 1547 /* 1548 * We've taken too many passes, forced delay. 1549 */ 1550 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10); 1551 } 1552 } else { 1553 pass = 0; 1554 vm_pages_needed = 0; 1555 } 1556 } 1557 } 1558 1559 /* 1560 * Called after allocating a page out of the cache or free queue 1561 * to possibly wake the pagedaemon up to replentish our supply. 1562 * 1563 * We try to generate some hysteresis by waking the pagedaemon up 1564 * when our free+cache pages go below the severe level. The pagedaemon 1565 * tries to get the count back up to at least the minimum, and through 1566 * to the target level if possible. 1567 * 1568 * If the pagedaemon is already active bump vm_pages_needed as a hint 1569 * that there are even more requests pending. 1570 */ 1571 void 1572 pagedaemon_wakeup(void) 1573 { 1574 if (vm_page_count_severe() && curthread != pagethread) { 1575 if (vm_pages_needed == 0) { 1576 vm_pages_needed = 1; 1577 wakeup(&vm_pages_needed); 1578 } else if (vm_page_count_min(0)) { 1579 ++vm_pages_needed; 1580 } 1581 } 1582 } 1583 1584 #if !defined(NO_SWAPPING) 1585 static void 1586 vm_req_vmdaemon(void) 1587 { 1588 static int lastrun = 0; 1589 1590 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1591 wakeup(&vm_daemon_needed); 1592 lastrun = ticks; 1593 } 1594 } 1595 1596 static int vm_daemon_callback(struct proc *p, void *data __unused); 1597 1598 static void 1599 vm_daemon(void) 1600 { 1601 while (TRUE) { 1602 tsleep(&vm_daemon_needed, 0, "psleep", 0); 1603 if (vm_pageout_req_swapout) { 1604 swapout_procs(vm_pageout_req_swapout); 1605 vm_pageout_req_swapout = 0; 1606 } 1607 /* 1608 * scan the processes for exceeding their rlimits or if 1609 * process is swapped out -- deactivate pages 1610 */ 1611 allproc_scan(vm_daemon_callback, NULL); 1612 } 1613 } 1614 1615 static int 1616 vm_daemon_callback(struct proc *p, void *data __unused) 1617 { 1618 vm_pindex_t limit, size; 1619 1620 /* 1621 * if this is a system process or if we have already 1622 * looked at this process, skip it. 1623 */ 1624 if (p->p_flag & (P_SYSTEM | P_WEXIT)) 1625 return (0); 1626 1627 /* 1628 * if the process is in a non-running type state, 1629 * don't touch it. 1630 */ 1631 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) 1632 return (0); 1633 1634 /* 1635 * get a limit 1636 */ 1637 limit = OFF_TO_IDX(qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 1638 p->p_rlimit[RLIMIT_RSS].rlim_max)); 1639 1640 /* 1641 * let processes that are swapped out really be 1642 * swapped out. Set the limit to nothing to get as 1643 * many pages out to swap as possible. 1644 */ 1645 if (p->p_flag & P_SWAPPEDOUT) 1646 limit = 0; 1647 1648 size = vmspace_resident_count(p->p_vmspace); 1649 if (limit >= 0 && size >= limit) { 1650 vm_pageout_map_deactivate_pages( 1651 &p->p_vmspace->vm_map, limit); 1652 } 1653 return (0); 1654 } 1655 1656 #endif 1657