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 1.32 2007/03/20 00:54:26 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 int vm_pageout_object_deactivate_pages_callback(vm_page_t, void *); 475 476 static void 477 vm_pageout_object_deactivate_pages(vm_map_t map, vm_object_t object, 478 vm_pindex_t desired, int map_remove_only) 479 { 480 struct rb_vm_page_scan_info info; 481 int remove_mode; 482 483 if (object->type == OBJT_DEVICE || object->type == OBJT_PHYS) 484 return; 485 486 while (object) { 487 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 488 return; 489 if (object->paging_in_progress) 490 return; 491 492 remove_mode = map_remove_only; 493 if (object->shadow_count > 1) 494 remove_mode = 1; 495 496 /* 497 * scan the objects entire memory queue. spl protection is 498 * required to avoid an interrupt unbusy/free race against 499 * our busy check. 500 */ 501 crit_enter(); 502 info.limit = remove_mode; 503 info.map = map; 504 info.desired = desired; 505 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL, 506 vm_pageout_object_deactivate_pages_callback, 507 &info 508 ); 509 crit_exit(); 510 object = object->backing_object; 511 } 512 } 513 514 static int 515 vm_pageout_object_deactivate_pages_callback(vm_page_t p, void *data) 516 { 517 struct rb_vm_page_scan_info *info = data; 518 int actcount; 519 520 if (pmap_resident_count(vm_map_pmap(info->map)) <= info->desired) { 521 return(-1); 522 } 523 mycpu->gd_cnt.v_pdpages++; 524 if (p->wire_count != 0 || p->hold_count != 0 || p->busy != 0 || 525 (p->flags & (PG_BUSY|PG_UNMANAGED)) || 526 !pmap_page_exists_quick(vm_map_pmap(info->map), p)) { 527 return(0); 528 } 529 530 actcount = pmap_ts_referenced(p); 531 if (actcount) { 532 vm_page_flag_set(p, PG_REFERENCED); 533 } else if (p->flags & PG_REFERENCED) { 534 actcount = 1; 535 } 536 537 if ((p->queue != PQ_ACTIVE) && 538 (p->flags & PG_REFERENCED)) { 539 vm_page_activate(p); 540 p->act_count += actcount; 541 vm_page_flag_clear(p, PG_REFERENCED); 542 } else if (p->queue == PQ_ACTIVE) { 543 if ((p->flags & PG_REFERENCED) == 0) { 544 p->act_count -= min(p->act_count, ACT_DECLINE); 545 if (!info->limit && (vm_pageout_algorithm || (p->act_count == 0))) { 546 vm_page_protect(p, VM_PROT_NONE); 547 vm_page_deactivate(p); 548 } else { 549 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 550 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 551 } 552 } else { 553 vm_page_activate(p); 554 vm_page_flag_clear(p, PG_REFERENCED); 555 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 556 p->act_count += ACT_ADVANCE; 557 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 558 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq); 559 } 560 } else if (p->queue == PQ_INACTIVE) { 561 vm_page_protect(p, VM_PROT_NONE); 562 } 563 return(0); 564 } 565 566 /* 567 * deactivate some number of pages in a map, try to do it fairly, but 568 * that is really hard to do. 569 */ 570 static void 571 vm_pageout_map_deactivate_pages(vm_map_t map, vm_pindex_t desired) 572 { 573 vm_map_entry_t tmpe; 574 vm_object_t obj, bigobj; 575 int nothingwired; 576 577 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT)) { 578 return; 579 } 580 581 bigobj = NULL; 582 nothingwired = TRUE; 583 584 /* 585 * first, search out the biggest object, and try to free pages from 586 * that. 587 */ 588 tmpe = map->header.next; 589 while (tmpe != &map->header) { 590 switch(tmpe->maptype) { 591 case VM_MAPTYPE_NORMAL: 592 case VM_MAPTYPE_VPAGETABLE: 593 obj = tmpe->object.vm_object; 594 if ((obj != NULL) && (obj->shadow_count <= 1) && 595 ((bigobj == NULL) || 596 (bigobj->resident_page_count < obj->resident_page_count))) { 597 bigobj = obj; 598 } 599 break; 600 default: 601 break; 602 } 603 if (tmpe->wired_count > 0) 604 nothingwired = FALSE; 605 tmpe = tmpe->next; 606 } 607 608 if (bigobj) 609 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 610 611 /* 612 * Next, hunt around for other pages to deactivate. We actually 613 * do this search sort of wrong -- .text first is not the best idea. 614 */ 615 tmpe = map->header.next; 616 while (tmpe != &map->header) { 617 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 618 break; 619 switch(tmpe->maptype) { 620 case VM_MAPTYPE_NORMAL: 621 case VM_MAPTYPE_VPAGETABLE: 622 obj = tmpe->object.vm_object; 623 if (obj) 624 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 625 break; 626 default: 627 break; 628 } 629 tmpe = tmpe->next; 630 }; 631 632 /* 633 * Remove all mappings if a process is swapped out, this will free page 634 * table pages. 635 */ 636 if (desired == 0 && nothingwired) 637 pmap_remove(vm_map_pmap(map), 638 VM_MIN_USER_ADDRESS, VM_MAX_USER_ADDRESS); 639 vm_map_unlock(map); 640 } 641 #endif 642 643 /* 644 * Don't try to be fancy - being fancy can lead to vnode deadlocks. We 645 * only do it for OBJT_DEFAULT and OBJT_SWAP objects which we know can 646 * be trivially freed. 647 */ 648 void 649 vm_pageout_page_free(vm_page_t m) 650 { 651 vm_object_t object = m->object; 652 int type = object->type; 653 654 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 655 vm_object_reference(object); 656 vm_page_busy(m); 657 vm_page_protect(m, VM_PROT_NONE); 658 vm_page_free(m); 659 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 660 vm_object_deallocate(object); 661 } 662 663 /* 664 * vm_pageout_scan does the dirty work for the pageout daemon. 665 */ 666 667 struct vm_pageout_scan_info { 668 struct proc *bigproc; 669 vm_offset_t bigsize; 670 }; 671 672 static int vm_pageout_scan_callback(struct proc *p, void *data); 673 674 static void 675 vm_pageout_scan(int pass) 676 { 677 struct vm_pageout_scan_info info; 678 vm_page_t m, next; 679 struct vm_page marker; 680 int page_shortage, maxscan, pcount; 681 int addl_page_shortage, addl_page_shortage_init; 682 vm_object_t object; 683 int actcount; 684 int vnodes_skipped = 0; 685 int maxlaunder; 686 687 /* 688 * Do whatever cleanup that the pmap code can. 689 */ 690 pmap_collect(); 691 692 addl_page_shortage_init = vm_pageout_deficit; 693 vm_pageout_deficit = 0; 694 695 /* 696 * Calculate the number of pages we want to either free or move 697 * to the cache. 698 */ 699 page_shortage = vm_paging_target() + addl_page_shortage_init; 700 701 /* 702 * Initialize our marker 703 */ 704 bzero(&marker, sizeof(marker)); 705 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 706 marker.queue = PQ_INACTIVE; 707 marker.wire_count = 1; 708 709 /* 710 * Start scanning the inactive queue for pages we can move to the 711 * cache or free. The scan will stop when the target is reached or 712 * we have scanned the entire inactive queue. Note that m->act_count 713 * is not used to form decisions for the inactive queue, only for the 714 * active queue. 715 * 716 * maxlaunder limits the number of dirty pages we flush per scan. 717 * For most systems a smaller value (16 or 32) is more robust under 718 * extreme memory and disk pressure because any unnecessary writes 719 * to disk can result in extreme performance degredation. However, 720 * systems with excessive dirty pages (especially when MAP_NOSYNC is 721 * used) will die horribly with limited laundering. If the pageout 722 * daemon cannot clean enough pages in the first pass, we let it go 723 * all out in succeeding passes. 724 */ 725 if ((maxlaunder = vm_max_launder) <= 1) 726 maxlaunder = 1; 727 if (pass) 728 maxlaunder = 10000; 729 730 /* 731 * We will generally be in a critical section throughout the 732 * scan, but we can release it temporarily when we are sitting on a 733 * non-busy page without fear. this is required to prevent an 734 * interrupt from unbusying or freeing a page prior to our busy 735 * check, leaving us on the wrong queue or checking the wrong 736 * page. 737 */ 738 crit_enter(); 739 rescan0: 740 addl_page_shortage = addl_page_shortage_init; 741 maxscan = vmstats.v_inactive_count; 742 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 743 m != NULL && maxscan-- > 0 && page_shortage > 0; 744 m = next 745 ) { 746 mycpu->gd_cnt.v_pdpages++; 747 748 /* 749 * Give interrupts a chance 750 */ 751 crit_exit(); 752 crit_enter(); 753 754 /* 755 * It's easier for some of the conditions below to just loop 756 * and catch queue changes here rather then check everywhere 757 * else. 758 */ 759 if (m->queue != PQ_INACTIVE) 760 goto rescan0; 761 next = TAILQ_NEXT(m, pageq); 762 763 /* 764 * skip marker pages 765 */ 766 if (m->flags & PG_MARKER) 767 continue; 768 769 /* 770 * A held page may be undergoing I/O, so skip it. 771 */ 772 if (m->hold_count) { 773 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 774 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 775 addl_page_shortage++; 776 continue; 777 } 778 779 /* 780 * Dont mess with busy pages, keep in the front of the 781 * queue, most likely are being paged out. 782 */ 783 if (m->busy || (m->flags & PG_BUSY)) { 784 addl_page_shortage++; 785 continue; 786 } 787 788 if (m->object->ref_count == 0) { 789 /* 790 * If the object is not being used, we ignore previous 791 * references. 792 */ 793 vm_page_flag_clear(m, PG_REFERENCED); 794 pmap_clear_reference(m); 795 796 } else if (((m->flags & PG_REFERENCED) == 0) && 797 (actcount = pmap_ts_referenced(m))) { 798 /* 799 * Otherwise, if the page has been referenced while 800 * in the inactive queue, we bump the "activation 801 * count" upwards, making it less likely that the 802 * page will be added back to the inactive queue 803 * prematurely again. Here we check the page tables 804 * (or emulated bits, if any), given the upper level 805 * VM system not knowing anything about existing 806 * references. 807 */ 808 vm_page_activate(m); 809 m->act_count += (actcount + ACT_ADVANCE); 810 continue; 811 } 812 813 /* 814 * If the upper level VM system knows about any page 815 * references, we activate the page. We also set the 816 * "activation count" higher than normal so that we will less 817 * likely place pages back onto the inactive queue again. 818 */ 819 if ((m->flags & PG_REFERENCED) != 0) { 820 vm_page_flag_clear(m, PG_REFERENCED); 821 actcount = pmap_ts_referenced(m); 822 vm_page_activate(m); 823 m->act_count += (actcount + ACT_ADVANCE + 1); 824 continue; 825 } 826 827 /* 828 * If the upper level VM system doesn't know anything about 829 * the page being dirty, we have to check for it again. As 830 * far as the VM code knows, any partially dirty pages are 831 * fully dirty. 832 * 833 * Pages marked PG_WRITEABLE may be mapped into the user 834 * address space of a process running on another cpu. A 835 * user process (without holding the MP lock) running on 836 * another cpu may be able to touch the page while we are 837 * trying to remove it. To prevent this from occuring we 838 * must call pmap_remove_all() or otherwise make the page 839 * read-only. If the race occured pmap_remove_all() is 840 * responsible for setting m->dirty. 841 */ 842 if (m->dirty == 0) { 843 vm_page_test_dirty(m); 844 #if 0 845 if (m->dirty == 0 && (m->flags & PG_WRITEABLE) != 0) 846 pmap_remove_all(m); 847 #endif 848 } else { 849 vm_page_dirty(m); 850 } 851 852 if (m->valid == 0) { 853 /* 854 * Invalid pages can be easily freed 855 */ 856 vm_pageout_page_free(m); 857 mycpu->gd_cnt.v_dfree++; 858 --page_shortage; 859 } else if (m->dirty == 0) { 860 /* 861 * Clean pages can be placed onto the cache queue. 862 * This effectively frees them. 863 */ 864 vm_page_cache(m); 865 --page_shortage; 866 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 867 /* 868 * Dirty pages need to be paged out, but flushing 869 * a page is extremely expensive verses freeing 870 * a clean page. Rather then artificially limiting 871 * the number of pages we can flush, we instead give 872 * dirty pages extra priority on the inactive queue 873 * by forcing them to be cycled through the queue 874 * twice before being flushed, after which the 875 * (now clean) page will cycle through once more 876 * before being freed. This significantly extends 877 * the thrash point for a heavily loaded machine. 878 */ 879 vm_page_flag_set(m, PG_WINATCFLS); 880 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 881 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 882 } else if (maxlaunder > 0) { 883 /* 884 * We always want to try to flush some dirty pages if 885 * we encounter them, to keep the system stable. 886 * Normally this number is small, but under extreme 887 * pressure where there are insufficient clean pages 888 * on the inactive queue, we may have to go all out. 889 */ 890 int swap_pageouts_ok; 891 struct vnode *vp = NULL; 892 893 object = m->object; 894 895 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 896 swap_pageouts_ok = 1; 897 } else { 898 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 899 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 900 vm_page_count_min()); 901 902 } 903 904 /* 905 * We don't bother paging objects that are "dead". 906 * Those objects are in a "rundown" state. 907 */ 908 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 909 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 910 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 911 continue; 912 } 913 914 /* 915 * The object is already known NOT to be dead. It 916 * is possible for the vget() to block the whole 917 * pageout daemon, but the new low-memory handling 918 * code should prevent it. 919 * 920 * The previous code skipped locked vnodes and, worse, 921 * reordered pages in the queue. This results in 922 * completely non-deterministic operation because, 923 * quite often, a vm_fault has initiated an I/O and 924 * is holding a locked vnode at just the point where 925 * the pageout daemon is woken up. 926 * 927 * We can't wait forever for the vnode lock, we might 928 * deadlock due to a vn_read() getting stuck in 929 * vm_wait while holding this vnode. We skip the 930 * vnode if we can't get it in a reasonable amount 931 * of time. 932 */ 933 934 if (object->type == OBJT_VNODE) { 935 vp = object->handle; 936 937 if (vget(vp, LK_EXCLUSIVE|LK_NOOBJ|LK_TIMELOCK)) { 938 ++pageout_lock_miss; 939 if (object->flags & OBJ_MIGHTBEDIRTY) 940 vnodes_skipped++; 941 continue; 942 } 943 944 /* 945 * The page might have been moved to another 946 * queue during potential blocking in vget() 947 * above. The page might have been freed and 948 * reused for another vnode. The object might 949 * have been reused for another vnode. 950 */ 951 if (m->queue != PQ_INACTIVE || 952 m->object != object || 953 object->handle != vp) { 954 if (object->flags & OBJ_MIGHTBEDIRTY) 955 vnodes_skipped++; 956 vput(vp); 957 continue; 958 } 959 960 /* 961 * The page may have been busied during the 962 * blocking in vput(); We don't move the 963 * page back onto the end of the queue so that 964 * statistics are more correct if we don't. 965 */ 966 if (m->busy || (m->flags & PG_BUSY)) { 967 vput(vp); 968 continue; 969 } 970 971 /* 972 * If the page has become held it might 973 * be undergoing I/O, so skip it 974 */ 975 if (m->hold_count) { 976 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 977 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 978 if (object->flags & OBJ_MIGHTBEDIRTY) 979 vnodes_skipped++; 980 vput(vp); 981 continue; 982 } 983 } 984 985 /* 986 * If a page is dirty, then it is either being washed 987 * (but not yet cleaned) or it is still in the 988 * laundry. If it is still in the laundry, then we 989 * start the cleaning operation. 990 * 991 * This operation may cluster, invalidating the 'next' 992 * pointer. To prevent an inordinate number of 993 * restarts we use our marker to remember our place. 994 * 995 * decrement page_shortage on success to account for 996 * the (future) cleaned page. Otherwise we could wind 997 * up laundering or cleaning too many pages. 998 */ 999 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq); 1000 if (vm_pageout_clean(m) != 0) { 1001 --page_shortage; 1002 --maxlaunder; 1003 } 1004 next = TAILQ_NEXT(&marker, pageq); 1005 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq); 1006 if (vp != NULL) 1007 vput(vp); 1008 } 1009 } 1010 1011 /* 1012 * Compute the number of pages we want to try to move from the 1013 * active queue to the inactive queue. 1014 */ 1015 page_shortage = vm_paging_target() + 1016 vmstats.v_inactive_target - vmstats.v_inactive_count; 1017 page_shortage += addl_page_shortage; 1018 1019 /* 1020 * Scan the active queue for things we can deactivate. We nominally 1021 * track the per-page activity counter and use it to locate 1022 * deactivation candidates. 1023 * 1024 * NOTE: we are still in a critical section. 1025 */ 1026 pcount = vmstats.v_active_count; 1027 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1028 1029 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 1030 /* 1031 * Give interrupts a chance. 1032 */ 1033 crit_exit(); 1034 crit_enter(); 1035 1036 /* 1037 * If the page was ripped out from under us, just stop. 1038 */ 1039 if (m->queue != PQ_ACTIVE) 1040 break; 1041 next = TAILQ_NEXT(m, pageq); 1042 1043 /* 1044 * Don't deactivate pages that are busy. 1045 */ 1046 if ((m->busy != 0) || 1047 (m->flags & PG_BUSY) || 1048 (m->hold_count != 0)) { 1049 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1050 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1051 m = next; 1052 continue; 1053 } 1054 1055 /* 1056 * The count for pagedaemon pages is done after checking the 1057 * page for eligibility... 1058 */ 1059 mycpu->gd_cnt.v_pdpages++; 1060 1061 /* 1062 * Check to see "how much" the page has been used. 1063 */ 1064 actcount = 0; 1065 if (m->object->ref_count != 0) { 1066 if (m->flags & PG_REFERENCED) { 1067 actcount += 1; 1068 } 1069 actcount += pmap_ts_referenced(m); 1070 if (actcount) { 1071 m->act_count += ACT_ADVANCE + actcount; 1072 if (m->act_count > ACT_MAX) 1073 m->act_count = ACT_MAX; 1074 } 1075 } 1076 1077 /* 1078 * Since we have "tested" this bit, we need to clear it now. 1079 */ 1080 vm_page_flag_clear(m, PG_REFERENCED); 1081 1082 /* 1083 * Only if an object is currently being used, do we use the 1084 * page activation count stats. 1085 */ 1086 if (actcount && (m->object->ref_count != 0)) { 1087 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1088 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1089 } else { 1090 m->act_count -= min(m->act_count, ACT_DECLINE); 1091 if (vm_pageout_algorithm || 1092 m->object->ref_count == 0 || 1093 m->act_count < pass) { 1094 page_shortage--; 1095 if (m->object->ref_count == 0) { 1096 vm_page_protect(m, VM_PROT_NONE); 1097 if (m->dirty == 0) 1098 vm_page_cache(m); 1099 else 1100 vm_page_deactivate(m); 1101 } else { 1102 vm_page_deactivate(m); 1103 } 1104 } else { 1105 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1106 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1107 } 1108 } 1109 m = next; 1110 } 1111 1112 /* 1113 * We try to maintain some *really* free pages, this allows interrupt 1114 * code to be guaranteed space. Since both cache and free queues 1115 * are considered basically 'free', moving pages from cache to free 1116 * does not effect other calculations. 1117 * 1118 * NOTE: we are still in a critical section. 1119 */ 1120 1121 while (vmstats.v_free_count < vmstats.v_free_reserved) { 1122 static int cache_rover = 0; 1123 m = vm_page_list_find(PQ_CACHE, cache_rover, FALSE); 1124 if (!m) 1125 break; 1126 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || 1127 m->busy || 1128 m->hold_count || 1129 m->wire_count) { 1130 #ifdef INVARIANTS 1131 kprintf("Warning: busy page %p found in cache\n", m); 1132 #endif 1133 vm_page_deactivate(m); 1134 continue; 1135 } 1136 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK; 1137 vm_pageout_page_free(m); 1138 mycpu->gd_cnt.v_dfree++; 1139 } 1140 1141 crit_exit(); 1142 1143 #if !defined(NO_SWAPPING) 1144 /* 1145 * Idle process swapout -- run once per second. 1146 */ 1147 if (vm_swap_idle_enabled) { 1148 static long lsec; 1149 if (time_second != lsec) { 1150 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1151 vm_req_vmdaemon(); 1152 lsec = time_second; 1153 } 1154 } 1155 #endif 1156 1157 /* 1158 * If we didn't get enough free pages, and we have skipped a vnode 1159 * in a writeable object, wakeup the sync daemon. And kick swapout 1160 * if we did not get enough free pages. 1161 */ 1162 if (vm_paging_target() > 0) { 1163 if (vnodes_skipped && vm_page_count_min()) 1164 speedup_syncer(); 1165 #if !defined(NO_SWAPPING) 1166 if (vm_swap_enabled && vm_page_count_target()) { 1167 vm_req_vmdaemon(); 1168 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1169 } 1170 #endif 1171 } 1172 1173 /* 1174 * If we are out of swap and were not able to reach our paging 1175 * target, kill the largest process. 1176 */ 1177 if ((vm_swap_size < 64 && vm_page_count_min()) || 1178 (swap_pager_full && vm_paging_target() > 0)) { 1179 #if 0 1180 if ((vm_swap_size < 64 || swap_pager_full) && vm_page_count_min()) { 1181 #endif 1182 info.bigproc = NULL; 1183 info.bigsize = 0; 1184 allproc_scan(vm_pageout_scan_callback, &info); 1185 if (info.bigproc != NULL) { 1186 killproc(info.bigproc, "out of swap space"); 1187 info.bigproc->p_nice = PRIO_MIN; 1188 info.bigproc->p_usched->resetpriority( 1189 FIRST_LWP_IN_PROC(info.bigproc)); 1190 wakeup(&vmstats.v_free_count); 1191 PRELE(info.bigproc); 1192 } 1193 } 1194 } 1195 1196 static int 1197 vm_pageout_scan_callback(struct proc *p, void *data) 1198 { 1199 struct vm_pageout_scan_info *info = data; 1200 vm_offset_t size; 1201 1202 /* 1203 * if this is a system process, skip it 1204 */ 1205 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1206 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1207 return (0); 1208 } 1209 1210 /* 1211 * if the process is in a non-running type state, 1212 * don't touch it. 1213 */ 1214 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) { 1215 return (0); 1216 } 1217 1218 /* 1219 * get the process size 1220 */ 1221 size = vmspace_resident_count(p->p_vmspace) + 1222 vmspace_swap_count(p->p_vmspace); 1223 1224 /* 1225 * If the this process is bigger than the biggest one 1226 * remember it. 1227 */ 1228 if (size > info->bigsize) { 1229 if (info->bigproc) 1230 PRELE(info->bigproc); 1231 PHOLD(p); 1232 info->bigproc = p; 1233 info->bigsize = size; 1234 } 1235 return(0); 1236 } 1237 1238 /* 1239 * This routine tries to maintain the pseudo LRU active queue, 1240 * so that during long periods of time where there is no paging, 1241 * that some statistic accumulation still occurs. This code 1242 * helps the situation where paging just starts to occur. 1243 */ 1244 static void 1245 vm_pageout_page_stats(void) 1246 { 1247 vm_page_t m,next; 1248 int pcount,tpcount; /* Number of pages to check */ 1249 static int fullintervalcount = 0; 1250 int page_shortage; 1251 1252 page_shortage = 1253 (vmstats.v_inactive_target + vmstats.v_cache_max + vmstats.v_free_min) - 1254 (vmstats.v_free_count + vmstats.v_inactive_count + vmstats.v_cache_count); 1255 1256 if (page_shortage <= 0) 1257 return; 1258 1259 crit_enter(); 1260 1261 pcount = vmstats.v_active_count; 1262 fullintervalcount += vm_pageout_stats_interval; 1263 if (fullintervalcount < vm_pageout_full_stats_interval) { 1264 tpcount = (vm_pageout_stats_max * vmstats.v_active_count) / vmstats.v_page_count; 1265 if (pcount > tpcount) 1266 pcount = tpcount; 1267 } else { 1268 fullintervalcount = 0; 1269 } 1270 1271 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1272 while ((m != NULL) && (pcount-- > 0)) { 1273 int actcount; 1274 1275 if (m->queue != PQ_ACTIVE) { 1276 break; 1277 } 1278 1279 next = TAILQ_NEXT(m, pageq); 1280 /* 1281 * Don't deactivate pages that are busy. 1282 */ 1283 if ((m->busy != 0) || 1284 (m->flags & PG_BUSY) || 1285 (m->hold_count != 0)) { 1286 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1287 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1288 m = next; 1289 continue; 1290 } 1291 1292 actcount = 0; 1293 if (m->flags & PG_REFERENCED) { 1294 vm_page_flag_clear(m, PG_REFERENCED); 1295 actcount += 1; 1296 } 1297 1298 actcount += pmap_ts_referenced(m); 1299 if (actcount) { 1300 m->act_count += ACT_ADVANCE + actcount; 1301 if (m->act_count > ACT_MAX) 1302 m->act_count = ACT_MAX; 1303 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1304 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1305 } else { 1306 if (m->act_count == 0) { 1307 /* 1308 * We turn off page access, so that we have 1309 * more accurate RSS stats. We don't do this 1310 * in the normal page deactivation when the 1311 * system is loaded VM wise, because the 1312 * cost of the large number of page protect 1313 * operations would be higher than the value 1314 * of doing the operation. 1315 */ 1316 vm_page_protect(m, VM_PROT_NONE); 1317 vm_page_deactivate(m); 1318 } else { 1319 m->act_count -= min(m->act_count, ACT_DECLINE); 1320 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1321 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1322 } 1323 } 1324 1325 m = next; 1326 } 1327 crit_exit(); 1328 } 1329 1330 static int 1331 vm_pageout_free_page_calc(vm_size_t count) 1332 { 1333 if (count < vmstats.v_page_count) 1334 return 0; 1335 /* 1336 * free_reserved needs to include enough for the largest swap pager 1337 * structures plus enough for any pv_entry structs when paging. 1338 */ 1339 if (vmstats.v_page_count > 1024) 1340 vmstats.v_free_min = 4 + (vmstats.v_page_count - 1024) / 200; 1341 else 1342 vmstats.v_free_min = 4; 1343 vmstats.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1344 vmstats.v_interrupt_free_min; 1345 vmstats.v_free_reserved = vm_pageout_page_count + 1346 vmstats.v_pageout_free_min + (count / 768) + PQ_L2_SIZE; 1347 vmstats.v_free_severe = vmstats.v_free_min / 2; 1348 vmstats.v_free_min += vmstats.v_free_reserved; 1349 vmstats.v_free_severe += vmstats.v_free_reserved; 1350 return 1; 1351 } 1352 1353 1354 /* 1355 * vm_pageout is the high level pageout daemon. 1356 */ 1357 static void 1358 vm_pageout(void) 1359 { 1360 int pass; 1361 1362 /* 1363 * Initialize some paging parameters. 1364 */ 1365 1366 vmstats.v_interrupt_free_min = 2; 1367 if (vmstats.v_page_count < 2000) 1368 vm_pageout_page_count = 8; 1369 1370 vm_pageout_free_page_calc(vmstats.v_page_count); 1371 /* 1372 * v_free_target and v_cache_min control pageout hysteresis. Note 1373 * that these are more a measure of the VM cache queue hysteresis 1374 * then the VM free queue. Specifically, v_free_target is the 1375 * high water mark (free+cache pages). 1376 * 1377 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1378 * low water mark, while v_free_min is the stop. v_cache_min must 1379 * be big enough to handle memory needs while the pageout daemon 1380 * is signalled and run to free more pages. 1381 */ 1382 if (vmstats.v_free_count > 6144) 1383 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved; 1384 else 1385 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved; 1386 1387 if (vmstats.v_free_count > 2048) { 1388 vmstats.v_cache_min = vmstats.v_free_target; 1389 vmstats.v_cache_max = 2 * vmstats.v_cache_min; 1390 vmstats.v_inactive_target = (3 * vmstats.v_free_target) / 2; 1391 } else { 1392 vmstats.v_cache_min = 0; 1393 vmstats.v_cache_max = 0; 1394 vmstats.v_inactive_target = vmstats.v_free_count / 4; 1395 } 1396 if (vmstats.v_inactive_target > vmstats.v_free_count / 3) 1397 vmstats.v_inactive_target = vmstats.v_free_count / 3; 1398 1399 /* XXX does not really belong here */ 1400 if (vm_page_max_wired == 0) 1401 vm_page_max_wired = vmstats.v_free_count / 3; 1402 1403 if (vm_pageout_stats_max == 0) 1404 vm_pageout_stats_max = vmstats.v_free_target; 1405 1406 /* 1407 * Set interval in seconds for stats scan. 1408 */ 1409 if (vm_pageout_stats_interval == 0) 1410 vm_pageout_stats_interval = 5; 1411 if (vm_pageout_full_stats_interval == 0) 1412 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1413 1414 1415 /* 1416 * Set maximum free per pass 1417 */ 1418 if (vm_pageout_stats_free_max == 0) 1419 vm_pageout_stats_free_max = 5; 1420 1421 swap_pager_swap_init(); 1422 pass = 0; 1423 /* 1424 * The pageout daemon is never done, so loop forever. 1425 */ 1426 while (TRUE) { 1427 int error; 1428 1429 /* 1430 * If we have enough free memory, wakeup waiters. Do 1431 * not clear vm_pages_needed until we reach our target, 1432 * otherwise we may be woken up over and over again and 1433 * waste a lot of cpu. 1434 */ 1435 crit_enter(); 1436 if (vm_pages_needed && !vm_page_count_min()) { 1437 if (vm_paging_needed() <= 0) 1438 vm_pages_needed = 0; 1439 wakeup(&vmstats.v_free_count); 1440 } 1441 if (vm_pages_needed) { 1442 /* 1443 * Still not done, take a second pass without waiting 1444 * (unlimited dirty cleaning), otherwise sleep a bit 1445 * and try again. 1446 */ 1447 ++pass; 1448 if (pass > 1) 1449 tsleep(&vm_pages_needed, 0, "psleep", hz/2); 1450 } else { 1451 /* 1452 * Good enough, sleep & handle stats. Prime the pass 1453 * for the next run. 1454 */ 1455 if (pass > 1) 1456 pass = 1; 1457 else 1458 pass = 0; 1459 error = tsleep(&vm_pages_needed, 1460 0, "psleep", vm_pageout_stats_interval * hz); 1461 if (error && !vm_pages_needed) { 1462 crit_exit(); 1463 pass = 0; 1464 vm_pageout_page_stats(); 1465 continue; 1466 } 1467 } 1468 1469 if (vm_pages_needed) 1470 mycpu->gd_cnt.v_pdwakeups++; 1471 crit_exit(); 1472 vm_pageout_scan(pass); 1473 vm_pageout_deficit = 0; 1474 } 1475 } 1476 1477 void 1478 pagedaemon_wakeup(void) 1479 { 1480 if (!vm_pages_needed && curthread != pagethread) { 1481 vm_pages_needed++; 1482 wakeup(&vm_pages_needed); 1483 } 1484 } 1485 1486 #if !defined(NO_SWAPPING) 1487 static void 1488 vm_req_vmdaemon(void) 1489 { 1490 static int lastrun = 0; 1491 1492 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1493 wakeup(&vm_daemon_needed); 1494 lastrun = ticks; 1495 } 1496 } 1497 1498 static int vm_daemon_callback(struct proc *p, void *data __unused); 1499 1500 static void 1501 vm_daemon(void) 1502 { 1503 while (TRUE) { 1504 tsleep(&vm_daemon_needed, 0, "psleep", 0); 1505 if (vm_pageout_req_swapout) { 1506 swapout_procs(vm_pageout_req_swapout); 1507 vm_pageout_req_swapout = 0; 1508 } 1509 /* 1510 * scan the processes for exceeding their rlimits or if 1511 * process is swapped out -- deactivate pages 1512 */ 1513 allproc_scan(vm_daemon_callback, NULL); 1514 } 1515 } 1516 1517 static int 1518 vm_daemon_callback(struct proc *p, void *data __unused) 1519 { 1520 vm_pindex_t limit, size; 1521 1522 /* 1523 * if this is a system process or if we have already 1524 * looked at this process, skip it. 1525 */ 1526 if (p->p_flag & (P_SYSTEM | P_WEXIT)) 1527 return (0); 1528 1529 /* 1530 * if the process is in a non-running type state, 1531 * don't touch it. 1532 */ 1533 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) 1534 return (0); 1535 1536 /* 1537 * get a limit 1538 */ 1539 limit = OFF_TO_IDX(qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 1540 p->p_rlimit[RLIMIT_RSS].rlim_max)); 1541 1542 /* 1543 * let processes that are swapped out really be 1544 * swapped out. Set the limit to nothing to get as 1545 * many pages out to swap as possible. 1546 */ 1547 if (p->p_flag & P_SWAPPEDOUT) 1548 limit = 0; 1549 1550 size = vmspace_resident_count(p->p_vmspace); 1551 if (limit >= 0 && size >= limit) { 1552 vm_pageout_map_deactivate_pages( 1553 &p->p_vmspace->vm_map, limit); 1554 } 1555 return (0); 1556 } 1557 1558 #endif 1559