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 1.24 2006/08/12 00:26:22 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 void 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 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 and 396 * mark the pages read-only. 397 * 398 * We do not have to fixup the clean/dirty bits here... we can 399 * allow the pager to do it after the I/O completes. 400 */ 401 402 for (i = 0; i < count; i++) { 403 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush page %p index %d/%d: partially invalid page", mc[i], i, count)); 404 vm_page_io_start(mc[i]); 405 vm_page_protect(mc[i], VM_PROT_READ); 406 } 407 408 object = mc[0]->object; 409 vm_object_pip_add(object, count); 410 411 vm_pager_put_pages(object, mc, count, 412 (flags | ((object == kernel_object) ? VM_PAGER_PUT_SYNC : 0)), 413 pageout_status); 414 415 for (i = 0; i < count; i++) { 416 vm_page_t mt = mc[i]; 417 418 switch (pageout_status[i]) { 419 case VM_PAGER_OK: 420 numpagedout++; 421 break; 422 case VM_PAGER_PEND: 423 numpagedout++; 424 break; 425 case VM_PAGER_BAD: 426 /* 427 * Page outside of range of object. Right now we 428 * essentially lose the changes by pretending it 429 * worked. 430 */ 431 pmap_clear_modify(mt); 432 vm_page_undirty(mt); 433 break; 434 case VM_PAGER_ERROR: 435 case VM_PAGER_FAIL: 436 /* 437 * If page couldn't be paged out, then reactivate the 438 * page so it doesn't clog the inactive list. (We 439 * will try paging out it again later). 440 */ 441 vm_page_activate(mt); 442 break; 443 case VM_PAGER_AGAIN: 444 break; 445 } 446 447 /* 448 * If the operation is still going, leave the page busy to 449 * block all other accesses. Also, leave the paging in 450 * progress indicator set so that we don't attempt an object 451 * collapse. 452 */ 453 if (pageout_status[i] != VM_PAGER_PEND) { 454 vm_object_pip_wakeup(object); 455 vm_page_io_finish(mt); 456 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt)) 457 vm_page_protect(mt, VM_PROT_READ); 458 } 459 } 460 return numpagedout; 461 } 462 463 #if !defined(NO_SWAPPING) 464 /* 465 * vm_pageout_object_deactivate_pages 466 * 467 * deactivate enough pages to satisfy the inactive target 468 * requirements or if vm_page_proc_limit is set, then 469 * deactivate all of the pages in the object and its 470 * backing_objects. 471 * 472 * The object and map must be locked. 473 */ 474 static void 475 vm_pageout_object_deactivate_pages(vm_map_t map, vm_object_t object, 476 vm_pindex_t desired, int map_remove_only) 477 { 478 vm_page_t p, next; 479 int rcount; 480 int remove_mode; 481 482 if (object->type == OBJT_DEVICE || object->type == OBJT_PHYS) 483 return; 484 485 while (object) { 486 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 487 return; 488 if (object->paging_in_progress) 489 return; 490 491 remove_mode = map_remove_only; 492 if (object->shadow_count > 1) 493 remove_mode = 1; 494 495 /* 496 * scan the objects entire memory queue. spl protection is 497 * required to avoid an interrupt unbusy/free race against 498 * our busy check. 499 */ 500 crit_enter(); 501 rcount = object->resident_page_count; 502 p = TAILQ_FIRST(&object->memq); 503 504 while (p && (rcount-- > 0)) { 505 int actcount; 506 if (pmap_resident_count(vm_map_pmap(map)) <= desired) { 507 crit_exit(); 508 return; 509 } 510 next = TAILQ_NEXT(p, listq); 511 mycpu->gd_cnt.v_pdpages++; 512 if (p->wire_count != 0 || 513 p->hold_count != 0 || 514 p->busy != 0 || 515 (p->flags & (PG_BUSY|PG_UNMANAGED)) || 516 !pmap_page_exists_quick(vm_map_pmap(map), p)) { 517 p = next; 518 continue; 519 } 520 521 actcount = pmap_ts_referenced(p); 522 if (actcount) { 523 vm_page_flag_set(p, PG_REFERENCED); 524 } else if (p->flags & PG_REFERENCED) { 525 actcount = 1; 526 } 527 528 if ((p->queue != PQ_ACTIVE) && 529 (p->flags & PG_REFERENCED)) { 530 vm_page_activate(p); 531 p->act_count += actcount; 532 vm_page_flag_clear(p, PG_REFERENCED); 533 } else if (p->queue == PQ_ACTIVE) { 534 if ((p->flags & PG_REFERENCED) == 0) { 535 p->act_count -= min(p->act_count, ACT_DECLINE); 536 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) { 537 vm_page_protect(p, VM_PROT_NONE); 538 vm_page_deactivate(p); 539 } else { 540 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 541 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 542 } 543 } else { 544 vm_page_activate(p); 545 vm_page_flag_clear(p, PG_REFERENCED); 546 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 547 p->act_count += ACT_ADVANCE; 548 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 549 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 550 } 551 } else if (p->queue == PQ_INACTIVE) { 552 vm_page_protect(p, VM_PROT_NONE); 553 } 554 p = next; 555 } 556 crit_exit(); 557 object = object->backing_object; 558 } 559 } 560 561 /* 562 * deactivate some number of pages in a map, try to do it fairly, but 563 * that is really hard to do. 564 */ 565 static void 566 vm_pageout_map_deactivate_pages(vm_map_t map, vm_pindex_t desired) 567 { 568 vm_map_entry_t tmpe; 569 vm_object_t obj, bigobj; 570 int nothingwired; 571 572 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT)) { 573 return; 574 } 575 576 bigobj = NULL; 577 nothingwired = TRUE; 578 579 /* 580 * first, search out the biggest object, and try to free pages from 581 * that. 582 */ 583 tmpe = map->header.next; 584 while (tmpe != &map->header) { 585 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 586 obj = tmpe->object.vm_object; 587 if ((obj != NULL) && (obj->shadow_count <= 1) && 588 ((bigobj == NULL) || 589 (bigobj->resident_page_count < obj->resident_page_count))) { 590 bigobj = obj; 591 } 592 } 593 if (tmpe->wired_count > 0) 594 nothingwired = FALSE; 595 tmpe = tmpe->next; 596 } 597 598 if (bigobj) 599 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 600 601 /* 602 * Next, hunt around for other pages to deactivate. We actually 603 * do this search sort of wrong -- .text first is not the best idea. 604 */ 605 tmpe = map->header.next; 606 while (tmpe != &map->header) { 607 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 608 break; 609 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 610 obj = tmpe->object.vm_object; 611 if (obj) 612 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 613 } 614 tmpe = tmpe->next; 615 }; 616 617 /* 618 * Remove all mappings if a process is swapped out, this will free page 619 * table pages. 620 */ 621 if (desired == 0 && nothingwired) 622 pmap_remove(vm_map_pmap(map), 623 VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS); 624 vm_map_unlock(map); 625 } 626 #endif 627 628 /* 629 * Don't try to be fancy - being fancy can lead to vnode deadlocks. We 630 * only do it for OBJT_DEFAULT and OBJT_SWAP objects which we know can 631 * be trivially freed. 632 */ 633 void 634 vm_pageout_page_free(vm_page_t m) { 635 vm_object_t object = m->object; 636 int type = object->type; 637 638 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 639 vm_object_reference(object); 640 vm_page_busy(m); 641 vm_page_protect(m, VM_PROT_NONE); 642 vm_page_free(m); 643 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 644 vm_object_deallocate(object); 645 } 646 647 /* 648 * vm_pageout_scan does the dirty work for the pageout daemon. 649 */ 650 651 struct vm_pageout_scan_info { 652 struct proc *bigproc; 653 vm_offset_t bigsize; 654 }; 655 656 static int vm_pageout_scan_callback(struct proc *p, void *data); 657 658 static void 659 vm_pageout_scan(int pass) 660 { 661 struct vm_pageout_scan_info info; 662 vm_page_t m, next; 663 struct vm_page marker; 664 int page_shortage, maxscan, pcount; 665 int addl_page_shortage, addl_page_shortage_init; 666 vm_object_t object; 667 int actcount; 668 int vnodes_skipped = 0; 669 int maxlaunder; 670 671 /* 672 * Do whatever cleanup that the pmap code can. 673 */ 674 pmap_collect(); 675 676 addl_page_shortage_init = vm_pageout_deficit; 677 vm_pageout_deficit = 0; 678 679 /* 680 * Calculate the number of pages we want to either free or move 681 * to the cache. 682 */ 683 page_shortage = vm_paging_target() + addl_page_shortage_init; 684 685 /* 686 * Initialize our marker 687 */ 688 bzero(&marker, sizeof(marker)); 689 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 690 marker.queue = PQ_INACTIVE; 691 marker.wire_count = 1; 692 693 /* 694 * Start scanning the inactive queue for pages we can move to the 695 * cache or free. The scan will stop when the target is reached or 696 * we have scanned the entire inactive queue. Note that m->act_count 697 * is not used to form decisions for the inactive queue, only for the 698 * active queue. 699 * 700 * maxlaunder limits the number of dirty pages we flush per scan. 701 * For most systems a smaller value (16 or 32) is more robust under 702 * extreme memory and disk pressure because any unnecessary writes 703 * to disk can result in extreme performance degredation. However, 704 * systems with excessive dirty pages (especially when MAP_NOSYNC is 705 * used) will die horribly with limited laundering. If the pageout 706 * daemon cannot clean enough pages in the first pass, we let it go 707 * all out in succeeding passes. 708 */ 709 if ((maxlaunder = vm_max_launder) <= 1) 710 maxlaunder = 1; 711 if (pass) 712 maxlaunder = 10000; 713 714 /* 715 * We will generally be in a critical section throughout the 716 * scan, but we can release it temporarily when we are sitting on a 717 * non-busy page without fear. this is required to prevent an 718 * interrupt from unbusying or freeing a page prior to our busy 719 * check, leaving us on the wrong queue or checking the wrong 720 * page. 721 */ 722 crit_enter(); 723 rescan0: 724 addl_page_shortage = addl_page_shortage_init; 725 maxscan = vmstats.v_inactive_count; 726 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 727 m != NULL && maxscan-- > 0 && page_shortage > 0; 728 m = next 729 ) { 730 mycpu->gd_cnt.v_pdpages++; 731 732 /* 733 * Give interrupts a chance 734 */ 735 crit_exit(); 736 crit_enter(); 737 738 /* 739 * It's easier for some of the conditions below to just loop 740 * and catch queue changes here rather then check everywhere 741 * else. 742 */ 743 if (m->queue != PQ_INACTIVE) 744 goto rescan0; 745 next = TAILQ_NEXT(m, pageq); 746 747 /* 748 * skip marker pages 749 */ 750 if (m->flags & PG_MARKER) 751 continue; 752 753 /* 754 * A held page may be undergoing I/O, so skip it. 755 */ 756 if (m->hold_count) { 757 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 758 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 759 addl_page_shortage++; 760 continue; 761 } 762 763 /* 764 * Dont mess with busy pages, keep in the front of the 765 * queue, most likely are being paged out. 766 */ 767 if (m->busy || (m->flags & PG_BUSY)) { 768 addl_page_shortage++; 769 continue; 770 } 771 772 if (m->object->ref_count == 0) { 773 /* 774 * If the object is not being used, we ignore previous 775 * references. 776 */ 777 vm_page_flag_clear(m, PG_REFERENCED); 778 pmap_clear_reference(m); 779 780 } else if (((m->flags & PG_REFERENCED) == 0) && 781 (actcount = pmap_ts_referenced(m))) { 782 /* 783 * Otherwise, if the page has been referenced while 784 * in the inactive queue, we bump the "activation 785 * count" upwards, making it less likely that the 786 * page will be added back to the inactive queue 787 * prematurely again. Here we check the page tables 788 * (or emulated bits, if any), given the upper level 789 * VM system not knowing anything about existing 790 * references. 791 */ 792 vm_page_activate(m); 793 m->act_count += (actcount + ACT_ADVANCE); 794 continue; 795 } 796 797 /* 798 * If the upper level VM system knows about any page 799 * references, we activate the page. We also set the 800 * "activation count" higher than normal so that we will less 801 * likely place pages back onto the inactive queue again. 802 */ 803 if ((m->flags & PG_REFERENCED) != 0) { 804 vm_page_flag_clear(m, PG_REFERENCED); 805 actcount = pmap_ts_referenced(m); 806 vm_page_activate(m); 807 m->act_count += (actcount + ACT_ADVANCE + 1); 808 continue; 809 } 810 811 /* 812 * If the upper level VM system doesn't know anything about 813 * the page being dirty, we have to check for it again. As 814 * far as the VM code knows, any partially dirty pages are 815 * fully dirty. 816 * 817 * Pages marked PG_WRITEABLE may be mapped into the user 818 * address space of a process running on another cpu. A 819 * user process (without holding the MP lock) running on 820 * another cpu may be able to touch the page while we are 821 * trying to remove it. To prevent this from occuring we 822 * must call pmap_remove_all() or otherwise make the page 823 * read-only. If the race occured pmap_remove_all() is 824 * responsible for setting m->dirty. 825 */ 826 if (m->dirty == 0) { 827 vm_page_test_dirty(m); 828 #if 0 829 if (m->dirty == 0 && (m->flags & PG_WRITEABLE) != 0) 830 pmap_remove_all(m); 831 #endif 832 } else { 833 vm_page_dirty(m); 834 } 835 836 if (m->valid == 0) { 837 /* 838 * Invalid pages can be easily freed 839 */ 840 vm_pageout_page_free(m); 841 mycpu->gd_cnt.v_dfree++; 842 --page_shortage; 843 } else if (m->dirty == 0) { 844 /* 845 * Clean pages can be placed onto the cache queue. 846 * This effectively frees them. 847 */ 848 vm_page_cache(m); 849 --page_shortage; 850 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 851 /* 852 * Dirty pages need to be paged out, but flushing 853 * a page is extremely expensive verses freeing 854 * a clean page. Rather then artificially limiting 855 * the number of pages we can flush, we instead give 856 * dirty pages extra priority on the inactive queue 857 * by forcing them to be cycled through the queue 858 * twice before being flushed, after which the 859 * (now clean) page will cycle through once more 860 * before being freed. This significantly extends 861 * the thrash point for a heavily loaded machine. 862 */ 863 vm_page_flag_set(m, PG_WINATCFLS); 864 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 865 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 866 } else if (maxlaunder > 0) { 867 /* 868 * We always want to try to flush some dirty pages if 869 * we encounter them, to keep the system stable. 870 * Normally this number is small, but under extreme 871 * pressure where there are insufficient clean pages 872 * on the inactive queue, we may have to go all out. 873 */ 874 int swap_pageouts_ok; 875 struct vnode *vp = NULL; 876 877 object = m->object; 878 879 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 880 swap_pageouts_ok = 1; 881 } else { 882 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 883 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 884 vm_page_count_min()); 885 886 } 887 888 /* 889 * We don't bother paging objects that are "dead". 890 * Those objects are in a "rundown" state. 891 */ 892 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 893 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 894 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 895 continue; 896 } 897 898 /* 899 * The object is already known NOT to be dead. It 900 * is possible for the vget() to block the whole 901 * pageout daemon, but the new low-memory handling 902 * code should prevent it. 903 * 904 * The previous code skipped locked vnodes and, worse, 905 * reordered pages in the queue. This results in 906 * completely non-deterministic operation because, 907 * quite often, a vm_fault has initiated an I/O and 908 * is holding a locked vnode at just the point where 909 * the pageout daemon is woken up. 910 * 911 * We can't wait forever for the vnode lock, we might 912 * deadlock due to a vn_read() getting stuck in 913 * vm_wait while holding this vnode. We skip the 914 * vnode if we can't get it in a reasonable amount 915 * of time. 916 */ 917 918 if (object->type == OBJT_VNODE) { 919 vp = object->handle; 920 921 if (vget(vp, LK_EXCLUSIVE|LK_NOOBJ|LK_TIMELOCK)) { 922 ++pageout_lock_miss; 923 if (object->flags & OBJ_MIGHTBEDIRTY) 924 vnodes_skipped++; 925 continue; 926 } 927 928 /* 929 * The page might have been moved to another 930 * queue during potential blocking in vget() 931 * above. The page might have been freed and 932 * reused for another vnode. The object might 933 * have been reused for another vnode. 934 */ 935 if (m->queue != PQ_INACTIVE || 936 m->object != object || 937 object->handle != vp) { 938 if (object->flags & OBJ_MIGHTBEDIRTY) 939 vnodes_skipped++; 940 vput(vp); 941 continue; 942 } 943 944 /* 945 * The page may have been busied during the 946 * blocking in vput(); We don't move the 947 * page back onto the end of the queue so that 948 * statistics are more correct if we don't. 949 */ 950 if (m->busy || (m->flags & PG_BUSY)) { 951 vput(vp); 952 continue; 953 } 954 955 /* 956 * If the page has become held it might 957 * be undergoing I/O, so skip it 958 */ 959 if (m->hold_count) { 960 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 961 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 962 if (object->flags & OBJ_MIGHTBEDIRTY) 963 vnodes_skipped++; 964 vput(vp); 965 continue; 966 } 967 } 968 969 /* 970 * If a page is dirty, then it is either being washed 971 * (but not yet cleaned) or it is still in the 972 * laundry. If it is still in the laundry, then we 973 * start the cleaning operation. 974 * 975 * This operation may cluster, invalidating the 'next' 976 * pointer. To prevent an inordinate number of 977 * restarts we use our marker to remember our place. 978 * 979 * decrement page_shortage on success to account for 980 * the (future) cleaned page. Otherwise we could wind 981 * up laundering or cleaning too many pages. 982 */ 983 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq); 984 if (vm_pageout_clean(m) != 0) { 985 --page_shortage; 986 --maxlaunder; 987 } 988 next = TAILQ_NEXT(&marker, pageq); 989 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq); 990 if (vp != NULL) 991 vput(vp); 992 } 993 } 994 995 /* 996 * Compute the number of pages we want to try to move from the 997 * active queue to the inactive queue. 998 */ 999 page_shortage = vm_paging_target() + 1000 vmstats.v_inactive_target - vmstats.v_inactive_count; 1001 page_shortage += addl_page_shortage; 1002 1003 /* 1004 * Scan the active queue for things we can deactivate. We nominally 1005 * track the per-page activity counter and use it to locate 1006 * deactivation candidates. 1007 * 1008 * NOTE: we are still in a critical section. 1009 */ 1010 pcount = vmstats.v_active_count; 1011 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1012 1013 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 1014 /* 1015 * Give interrupts a chance. 1016 */ 1017 crit_exit(); 1018 crit_enter(); 1019 1020 /* 1021 * If the page was ripped out from under us, just stop. 1022 */ 1023 if (m->queue != PQ_ACTIVE) 1024 break; 1025 next = TAILQ_NEXT(m, pageq); 1026 1027 /* 1028 * Don't deactivate pages that are busy. 1029 */ 1030 if ((m->busy != 0) || 1031 (m->flags & PG_BUSY) || 1032 (m->hold_count != 0)) { 1033 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1034 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1035 m = next; 1036 continue; 1037 } 1038 1039 /* 1040 * The count for pagedaemon pages is done after checking the 1041 * page for eligibility... 1042 */ 1043 mycpu->gd_cnt.v_pdpages++; 1044 1045 /* 1046 * Check to see "how much" the page has been used. 1047 */ 1048 actcount = 0; 1049 if (m->object->ref_count != 0) { 1050 if (m->flags & PG_REFERENCED) { 1051 actcount += 1; 1052 } 1053 actcount += pmap_ts_referenced(m); 1054 if (actcount) { 1055 m->act_count += ACT_ADVANCE + actcount; 1056 if (m->act_count > ACT_MAX) 1057 m->act_count = ACT_MAX; 1058 } 1059 } 1060 1061 /* 1062 * Since we have "tested" this bit, we need to clear it now. 1063 */ 1064 vm_page_flag_clear(m, PG_REFERENCED); 1065 1066 /* 1067 * Only if an object is currently being used, do we use the 1068 * page activation count stats. 1069 */ 1070 if (actcount && (m->object->ref_count != 0)) { 1071 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1072 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1073 } else { 1074 m->act_count -= min(m->act_count, ACT_DECLINE); 1075 if (vm_pageout_algorithm || 1076 m->object->ref_count == 0 || 1077 m->act_count < pass) { 1078 page_shortage--; 1079 if (m->object->ref_count == 0) { 1080 vm_page_protect(m, VM_PROT_NONE); 1081 if (m->dirty == 0) 1082 vm_page_cache(m); 1083 else 1084 vm_page_deactivate(m); 1085 } else { 1086 vm_page_deactivate(m); 1087 } 1088 } else { 1089 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1090 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1091 } 1092 } 1093 m = next; 1094 } 1095 1096 /* 1097 * We try to maintain some *really* free pages, this allows interrupt 1098 * code to be guaranteed space. Since both cache and free queues 1099 * are considered basically 'free', moving pages from cache to free 1100 * does not effect other calculations. 1101 * 1102 * NOTE: we are still in a critical section. 1103 */ 1104 1105 while (vmstats.v_free_count < vmstats.v_free_reserved) { 1106 static int cache_rover = 0; 1107 m = vm_page_list_find(PQ_CACHE, cache_rover, FALSE); 1108 if (!m) 1109 break; 1110 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || 1111 m->busy || 1112 m->hold_count || 1113 m->wire_count) { 1114 #ifdef INVARIANTS 1115 printf("Warning: busy page %p found in cache\n", m); 1116 #endif 1117 vm_page_deactivate(m); 1118 continue; 1119 } 1120 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK; 1121 vm_pageout_page_free(m); 1122 mycpu->gd_cnt.v_dfree++; 1123 } 1124 1125 crit_exit(); 1126 1127 #if !defined(NO_SWAPPING) 1128 /* 1129 * Idle process swapout -- run once per second. 1130 */ 1131 if (vm_swap_idle_enabled) { 1132 static long lsec; 1133 if (time_second != lsec) { 1134 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1135 vm_req_vmdaemon(); 1136 lsec = time_second; 1137 } 1138 } 1139 #endif 1140 1141 /* 1142 * If we didn't get enough free pages, and we have skipped a vnode 1143 * in a writeable object, wakeup the sync daemon. And kick swapout 1144 * if we did not get enough free pages. 1145 */ 1146 if (vm_paging_target() > 0) { 1147 if (vnodes_skipped && vm_page_count_min()) 1148 speedup_syncer(); 1149 #if !defined(NO_SWAPPING) 1150 if (vm_swap_enabled && vm_page_count_target()) { 1151 vm_req_vmdaemon(); 1152 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1153 } 1154 #endif 1155 } 1156 1157 /* 1158 * If we are out of swap and were not able to reach our paging 1159 * target, kill the largest process. 1160 */ 1161 if ((vm_swap_size < 64 && vm_page_count_min()) || 1162 (swap_pager_full && vm_paging_target() > 0)) { 1163 #if 0 1164 if ((vm_swap_size < 64 || swap_pager_full) && vm_page_count_min()) { 1165 #endif 1166 info.bigproc = NULL; 1167 info.bigsize = 0; 1168 allproc_scan(vm_pageout_scan_callback, &info); 1169 if (info.bigproc != NULL) { 1170 killproc(info.bigproc, "out of swap space"); 1171 info.bigproc->p_nice = PRIO_MIN; 1172 info.bigproc->p_usched->resetpriority(&info.bigproc->p_lwp); 1173 wakeup(&vmstats.v_free_count); 1174 PRELE(info.bigproc); 1175 } 1176 } 1177 } 1178 1179 static int 1180 vm_pageout_scan_callback(struct proc *p, void *data) 1181 { 1182 struct vm_pageout_scan_info *info = data; 1183 vm_offset_t size; 1184 1185 /* 1186 * if this is a system process, skip it 1187 */ 1188 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1189 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1190 return (0); 1191 } 1192 1193 /* 1194 * if the process is in a non-running type state, 1195 * don't touch it. 1196 */ 1197 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 1198 return (0); 1199 } 1200 1201 /* 1202 * get the process size 1203 */ 1204 size = vmspace_resident_count(p->p_vmspace) + 1205 vmspace_swap_count(p->p_vmspace); 1206 1207 /* 1208 * If the this process is bigger than the biggest one 1209 * remember it. 1210 */ 1211 if (size > info->bigsize) { 1212 if (info->bigproc) 1213 PRELE(info->bigproc); 1214 PHOLD(p); 1215 info->bigproc = p; 1216 info->bigsize = size; 1217 } 1218 return(0); 1219 } 1220 1221 /* 1222 * This routine tries to maintain the pseudo LRU active queue, 1223 * so that during long periods of time where there is no paging, 1224 * that some statistic accumulation still occurs. This code 1225 * helps the situation where paging just starts to occur. 1226 */ 1227 static void 1228 vm_pageout_page_stats(void) 1229 { 1230 vm_page_t m,next; 1231 int pcount,tpcount; /* Number of pages to check */ 1232 static int fullintervalcount = 0; 1233 int page_shortage; 1234 1235 page_shortage = 1236 (vmstats.v_inactive_target + vmstats.v_cache_max + vmstats.v_free_min) - 1237 (vmstats.v_free_count + vmstats.v_inactive_count + vmstats.v_cache_count); 1238 1239 if (page_shortage <= 0) 1240 return; 1241 1242 crit_enter(); 1243 1244 pcount = vmstats.v_active_count; 1245 fullintervalcount += vm_pageout_stats_interval; 1246 if (fullintervalcount < vm_pageout_full_stats_interval) { 1247 tpcount = (vm_pageout_stats_max * vmstats.v_active_count) / vmstats.v_page_count; 1248 if (pcount > tpcount) 1249 pcount = tpcount; 1250 } else { 1251 fullintervalcount = 0; 1252 } 1253 1254 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1255 while ((m != NULL) && (pcount-- > 0)) { 1256 int actcount; 1257 1258 if (m->queue != PQ_ACTIVE) { 1259 break; 1260 } 1261 1262 next = TAILQ_NEXT(m, pageq); 1263 /* 1264 * Don't deactivate pages that are busy. 1265 */ 1266 if ((m->busy != 0) || 1267 (m->flags & PG_BUSY) || 1268 (m->hold_count != 0)) { 1269 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1270 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1271 m = next; 1272 continue; 1273 } 1274 1275 actcount = 0; 1276 if (m->flags & PG_REFERENCED) { 1277 vm_page_flag_clear(m, PG_REFERENCED); 1278 actcount += 1; 1279 } 1280 1281 actcount += pmap_ts_referenced(m); 1282 if (actcount) { 1283 m->act_count += ACT_ADVANCE + actcount; 1284 if (m->act_count > ACT_MAX) 1285 m->act_count = ACT_MAX; 1286 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1287 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1288 } else { 1289 if (m->act_count == 0) { 1290 /* 1291 * We turn off page access, so that we have 1292 * more accurate RSS stats. We don't do this 1293 * in the normal page deactivation when the 1294 * system is loaded VM wise, because the 1295 * cost of the large number of page protect 1296 * operations would be higher than the value 1297 * of doing the operation. 1298 */ 1299 vm_page_protect(m, VM_PROT_NONE); 1300 vm_page_deactivate(m); 1301 } else { 1302 m->act_count -= min(m->act_count, ACT_DECLINE); 1303 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1304 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1305 } 1306 } 1307 1308 m = next; 1309 } 1310 crit_exit(); 1311 } 1312 1313 static int 1314 vm_pageout_free_page_calc(vm_size_t count) 1315 { 1316 if (count < vmstats.v_page_count) 1317 return 0; 1318 /* 1319 * free_reserved needs to include enough for the largest swap pager 1320 * structures plus enough for any pv_entry structs when paging. 1321 */ 1322 if (vmstats.v_page_count > 1024) 1323 vmstats.v_free_min = 4 + (vmstats.v_page_count - 1024) / 200; 1324 else 1325 vmstats.v_free_min = 4; 1326 vmstats.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1327 vmstats.v_interrupt_free_min; 1328 vmstats.v_free_reserved = vm_pageout_page_count + 1329 vmstats.v_pageout_free_min + (count / 768) + PQ_L2_SIZE; 1330 vmstats.v_free_severe = vmstats.v_free_min / 2; 1331 vmstats.v_free_min += vmstats.v_free_reserved; 1332 vmstats.v_free_severe += vmstats.v_free_reserved; 1333 return 1; 1334 } 1335 1336 1337 /* 1338 * vm_pageout is the high level pageout daemon. 1339 */ 1340 static void 1341 vm_pageout(void) 1342 { 1343 int pass; 1344 1345 /* 1346 * Initialize some paging parameters. 1347 */ 1348 1349 vmstats.v_interrupt_free_min = 2; 1350 if (vmstats.v_page_count < 2000) 1351 vm_pageout_page_count = 8; 1352 1353 vm_pageout_free_page_calc(vmstats.v_page_count); 1354 /* 1355 * v_free_target and v_cache_min control pageout hysteresis. Note 1356 * that these are more a measure of the VM cache queue hysteresis 1357 * then the VM free queue. Specifically, v_free_target is the 1358 * high water mark (free+cache pages). 1359 * 1360 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1361 * low water mark, while v_free_min is the stop. v_cache_min must 1362 * be big enough to handle memory needs while the pageout daemon 1363 * is signalled and run to free more pages. 1364 */ 1365 if (vmstats.v_free_count > 6144) 1366 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved; 1367 else 1368 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved; 1369 1370 if (vmstats.v_free_count > 2048) { 1371 vmstats.v_cache_min = vmstats.v_free_target; 1372 vmstats.v_cache_max = 2 * vmstats.v_cache_min; 1373 vmstats.v_inactive_target = (3 * vmstats.v_free_target) / 2; 1374 } else { 1375 vmstats.v_cache_min = 0; 1376 vmstats.v_cache_max = 0; 1377 vmstats.v_inactive_target = vmstats.v_free_count / 4; 1378 } 1379 if (vmstats.v_inactive_target > vmstats.v_free_count / 3) 1380 vmstats.v_inactive_target = vmstats.v_free_count / 3; 1381 1382 /* XXX does not really belong here */ 1383 if (vm_page_max_wired == 0) 1384 vm_page_max_wired = vmstats.v_free_count / 3; 1385 1386 if (vm_pageout_stats_max == 0) 1387 vm_pageout_stats_max = vmstats.v_free_target; 1388 1389 /* 1390 * Set interval in seconds for stats scan. 1391 */ 1392 if (vm_pageout_stats_interval == 0) 1393 vm_pageout_stats_interval = 5; 1394 if (vm_pageout_full_stats_interval == 0) 1395 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1396 1397 1398 /* 1399 * Set maximum free per pass 1400 */ 1401 if (vm_pageout_stats_free_max == 0) 1402 vm_pageout_stats_free_max = 5; 1403 1404 swap_pager_swap_init(); 1405 pass = 0; 1406 /* 1407 * The pageout daemon is never done, so loop forever. 1408 */ 1409 while (TRUE) { 1410 int error; 1411 1412 /* 1413 * If we have enough free memory, wakeup waiters. Do 1414 * not clear vm_pages_needed until we reach our target, 1415 * otherwise we may be woken up over and over again and 1416 * waste a lot of cpu. 1417 */ 1418 crit_enter(); 1419 if (vm_pages_needed && !vm_page_count_min()) { 1420 if (vm_paging_needed() <= 0) 1421 vm_pages_needed = 0; 1422 wakeup(&vmstats.v_free_count); 1423 } 1424 if (vm_pages_needed) { 1425 /* 1426 * Still not done, take a second pass without waiting 1427 * (unlimited dirty cleaning), otherwise sleep a bit 1428 * and try again. 1429 */ 1430 ++pass; 1431 if (pass > 1) 1432 tsleep(&vm_pages_needed, 0, "psleep", hz/2); 1433 } else { 1434 /* 1435 * Good enough, sleep & handle stats. Prime the pass 1436 * for the next run. 1437 */ 1438 if (pass > 1) 1439 pass = 1; 1440 else 1441 pass = 0; 1442 error = tsleep(&vm_pages_needed, 1443 0, "psleep", vm_pageout_stats_interval * hz); 1444 if (error && !vm_pages_needed) { 1445 crit_exit(); 1446 pass = 0; 1447 vm_pageout_page_stats(); 1448 continue; 1449 } 1450 } 1451 1452 if (vm_pages_needed) 1453 mycpu->gd_cnt.v_pdwakeups++; 1454 crit_exit(); 1455 vm_pageout_scan(pass); 1456 vm_pageout_deficit = 0; 1457 } 1458 } 1459 1460 void 1461 pagedaemon_wakeup(void) 1462 { 1463 if (!vm_pages_needed && curthread != pagethread) { 1464 vm_pages_needed++; 1465 wakeup(&vm_pages_needed); 1466 } 1467 } 1468 1469 #if !defined(NO_SWAPPING) 1470 static void 1471 vm_req_vmdaemon(void) 1472 { 1473 static int lastrun = 0; 1474 1475 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1476 wakeup(&vm_daemon_needed); 1477 lastrun = ticks; 1478 } 1479 } 1480 1481 static int vm_daemon_callback(struct proc *p, void *data __unused); 1482 1483 static void 1484 vm_daemon(void) 1485 { 1486 while (TRUE) { 1487 tsleep(&vm_daemon_needed, 0, "psleep", 0); 1488 if (vm_pageout_req_swapout) { 1489 swapout_procs(vm_pageout_req_swapout); 1490 vm_pageout_req_swapout = 0; 1491 } 1492 /* 1493 * scan the processes for exceeding their rlimits or if 1494 * process is swapped out -- deactivate pages 1495 */ 1496 allproc_scan(vm_daemon_callback, NULL); 1497 } 1498 } 1499 1500 static int 1501 vm_daemon_callback(struct proc *p, void *data __unused) 1502 { 1503 vm_pindex_t limit, size; 1504 1505 /* 1506 * if this is a system process or if we have already 1507 * looked at this process, skip it. 1508 */ 1509 if (p->p_flag & (P_SYSTEM | P_WEXIT)) 1510 return (0); 1511 1512 /* 1513 * if the process is in a non-running type state, 1514 * don't touch it. 1515 */ 1516 if (p->p_stat != SRUN && p->p_stat != SSLEEP) 1517 return (0); 1518 1519 /* 1520 * get a limit 1521 */ 1522 limit = OFF_TO_IDX(qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 1523 p->p_rlimit[RLIMIT_RSS].rlim_max)); 1524 1525 /* 1526 * let processes that are swapped out really be 1527 * swapped out. Set the limit to nothing to get as 1528 * many pages out to swap as possible. 1529 */ 1530 if (p->p_flag & P_SWAPPEDOUT) 1531 limit = 0; 1532 1533 size = vmspace_resident_count(p->p_vmspace); 1534 if (limit >= 0 && size >= limit) { 1535 vm_pageout_map_deactivate_pages( 1536 &p->p_vmspace->vm_map, limit); 1537 } 1538 return (0); 1539 } 1540 1541 #endif 1542