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 69 /* 70 * The proverbial page-out daemon. 71 */ 72 73 #include <sys/cdefs.h> 74 __FBSDID("$FreeBSD$"); 75 76 #include "opt_vm.h" 77 #include <sys/param.h> 78 #include <sys/systm.h> 79 #include <sys/kernel.h> 80 #include <sys/eventhandler.h> 81 #include <sys/lock.h> 82 #include <sys/mutex.h> 83 #include <sys/proc.h> 84 #include <sys/kthread.h> 85 #include <sys/ktr.h> 86 #include <sys/resourcevar.h> 87 #include <sys/sched.h> 88 #include <sys/signalvar.h> 89 #include <sys/vnode.h> 90 #include <sys/vmmeter.h> 91 #include <sys/sx.h> 92 #include <sys/sysctl.h> 93 94 #include <vm/vm.h> 95 #include <vm/vm_param.h> 96 #include <vm/vm_object.h> 97 #include <vm/vm_page.h> 98 #include <vm/vm_map.h> 99 #include <vm/vm_pageout.h> 100 #include <vm/vm_pager.h> 101 #include <vm/swap_pager.h> 102 #include <vm/vm_extern.h> 103 #include <vm/uma.h> 104 105 #include <machine/mutex.h> 106 107 /* 108 * System initialization 109 */ 110 111 /* the kernel process "vm_pageout"*/ 112 static void vm_pageout(void); 113 static int vm_pageout_clean(vm_page_t); 114 static void vm_pageout_page_free(vm_page_t); 115 static void vm_pageout_pmap_collect(void); 116 static void vm_pageout_scan(int pass); 117 static int vm_pageout_free_page_calc(vm_size_t count); 118 struct proc *pageproc; 119 120 static struct kproc_desc page_kp = { 121 "pagedaemon", 122 vm_pageout, 123 &pageproc 124 }; 125 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 126 127 #if !defined(NO_SWAPPING) 128 /* the kernel process "vm_daemon"*/ 129 static void vm_daemon(void); 130 static struct proc *vmproc; 131 132 static struct kproc_desc vm_kp = { 133 "vmdaemon", 134 vm_daemon, 135 &vmproc 136 }; 137 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) 138 #endif 139 140 141 int vm_pages_needed; /* Event on which pageout daemon sleeps */ 142 int vm_pageout_deficit; /* Estimated number of pages deficit */ 143 int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ 144 145 #if !defined(NO_SWAPPING) 146 static int vm_pageout_req_swapout; /* XXX */ 147 static int vm_daemon_needed; 148 #endif 149 static int vm_max_launder = 32; 150 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 151 static int vm_pageout_full_stats_interval = 0; 152 static int vm_pageout_stats_free_max=0, vm_pageout_algorithm=0; 153 static int defer_swap_pageouts=0; 154 static int disable_swap_pageouts=0; 155 156 #if defined(NO_SWAPPING) 157 static int vm_swap_enabled=0; 158 static int vm_swap_idle_enabled=0; 159 #else 160 static int vm_swap_enabled=1; 161 static int vm_swap_idle_enabled=0; 162 #endif 163 164 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 165 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 166 167 SYSCTL_INT(_vm, OID_AUTO, max_launder, 168 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 169 170 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 171 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 172 173 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 174 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 175 176 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 177 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 178 179 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max, 180 CTLFLAG_RW, &vm_pageout_stats_free_max, 0, "Not implemented"); 181 182 #if defined(NO_SWAPPING) 183 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 184 CTLFLAG_RD, &vm_swap_enabled, 0, ""); 185 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 186 CTLFLAG_RD, &vm_swap_idle_enabled, 0, ""); 187 #else 188 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 189 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 190 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 191 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 192 #endif 193 194 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 195 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 196 197 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 198 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 199 200 static int pageout_lock_miss; 201 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 202 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 203 204 #define VM_PAGEOUT_PAGE_COUNT 16 205 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 206 207 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 208 209 #if !defined(NO_SWAPPING) 210 static void vm_pageout_map_deactivate_pages(vm_map_t, long); 211 static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long); 212 static void vm_req_vmdaemon(void); 213 #endif 214 static void vm_pageout_page_stats(void); 215 216 /* 217 * vm_pageout_clean: 218 * 219 * Clean the page and remove it from the laundry. 220 * 221 * We set the busy bit to cause potential page faults on this page to 222 * block. Note the careful timing, however, the busy bit isn't set till 223 * late and we cannot do anything that will mess with the page. 224 */ 225 static int 226 vm_pageout_clean(m) 227 vm_page_t m; 228 { 229 vm_object_t object; 230 vm_page_t mc[2*vm_pageout_page_count]; 231 int numpagedout, pageout_count; 232 int ib, is, page_base; 233 vm_pindex_t pindex = m->pindex; 234 235 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 236 237 /* 238 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 239 * with the new swapper, but we could have serious problems paging 240 * out other object types if there is insufficient memory. 241 * 242 * Unfortunately, checking free memory here is far too late, so the 243 * check has been moved up a procedural level. 244 */ 245 246 /* 247 * Don't mess with the page if it's busy, held, or special 248 */ 249 if ((m->hold_count != 0) || 250 ((m->busy != 0) || (m->flags & (PG_BUSY|PG_UNMANAGED))) || 251 !VM_OBJECT_TRYLOCK(m->object)) { 252 return 0; 253 } 254 255 mc[vm_pageout_page_count] = m; 256 pageout_count = 1; 257 page_base = vm_pageout_page_count; 258 ib = 1; 259 is = 1; 260 261 /* 262 * Scan object for clusterable pages. 263 * 264 * We can cluster ONLY if: ->> the page is NOT 265 * clean, wired, busy, held, or mapped into a 266 * buffer, and one of the following: 267 * 1) The page is inactive, or a seldom used 268 * active page. 269 * -or- 270 * 2) we force the issue. 271 * 272 * During heavy mmap/modification loads the pageout 273 * daemon can really fragment the underlying file 274 * due to flushing pages out of order and not trying 275 * align the clusters (which leave sporatic out-of-order 276 * holes). To solve this problem we do the reverse scan 277 * first and attempt to align our cluster, then do a 278 * forward scan if room remains. 279 */ 280 object = m->object; 281 more: 282 while (ib && pageout_count < vm_pageout_page_count) { 283 vm_page_t p; 284 285 if (ib > pindex) { 286 ib = 0; 287 break; 288 } 289 290 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) { 291 ib = 0; 292 break; 293 } 294 if (((p->queue - p->pc) == PQ_CACHE) || 295 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 296 ib = 0; 297 break; 298 } 299 vm_page_test_dirty(p); 300 if ((p->dirty & p->valid) == 0 || 301 p->queue != PQ_INACTIVE || 302 p->wire_count != 0 || /* may be held by buf cache */ 303 p->hold_count != 0) { /* may be undergoing I/O */ 304 ib = 0; 305 break; 306 } 307 mc[--page_base] = p; 308 ++pageout_count; 309 ++ib; 310 /* 311 * alignment boundry, stop here and switch directions. Do 312 * not clear ib. 313 */ 314 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 315 break; 316 } 317 318 while (pageout_count < vm_pageout_page_count && 319 pindex + is < object->size) { 320 vm_page_t p; 321 322 if ((p = vm_page_lookup(object, pindex + is)) == NULL) 323 break; 324 if (((p->queue - p->pc) == PQ_CACHE) || 325 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 326 break; 327 } 328 vm_page_test_dirty(p); 329 if ((p->dirty & p->valid) == 0 || 330 p->queue != PQ_INACTIVE || 331 p->wire_count != 0 || /* may be held by buf cache */ 332 p->hold_count != 0) { /* may be undergoing I/O */ 333 break; 334 } 335 mc[page_base + pageout_count] = p; 336 ++pageout_count; 337 ++is; 338 } 339 340 /* 341 * If we exhausted our forward scan, continue with the reverse scan 342 * when possible, even past a page boundry. This catches boundry 343 * conditions. 344 */ 345 if (ib && pageout_count < vm_pageout_page_count) 346 goto more; 347 348 /* 349 * we allow reads during pageouts... 350 */ 351 numpagedout = vm_pageout_flush(&mc[page_base], pageout_count, 0, TRUE); 352 VM_OBJECT_UNLOCK(object); 353 return (numpagedout); 354 } 355 356 /* 357 * vm_pageout_flush() - launder the given pages 358 * 359 * The given pages are laundered. Note that we setup for the start of 360 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 361 * reference count all in here rather then in the parent. If we want 362 * the parent to do more sophisticated things we may have to change 363 * the ordering. 364 */ 365 int 366 vm_pageout_flush(mc, count, flags, is_object_locked) 367 vm_page_t *mc; 368 int count; 369 int flags; 370 int is_object_locked; 371 { 372 vm_object_t object; 373 int pageout_status[count]; 374 int numpagedout = 0; 375 int i; 376 377 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 378 /* 379 * Initiate I/O. Bump the vm_page_t->busy counter and 380 * mark the pages read-only. 381 * 382 * We do not have to fixup the clean/dirty bits here... we can 383 * allow the pager to do it after the I/O completes. 384 * 385 * NOTE! mc[i]->dirty may be partial or fragmented due to an 386 * edge case with file fragments. 387 */ 388 for (i = 0; i < count; i++) { 389 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush page %p index %d/%d: partially invalid page", mc[i], i, count)); 390 vm_page_io_start(mc[i]); 391 pmap_page_protect(mc[i], VM_PROT_READ); 392 } 393 object = mc[0]->object; 394 vm_page_unlock_queues(); 395 if (!is_object_locked) 396 VM_OBJECT_LOCK(object); 397 vm_object_pip_add(object, count); 398 VM_OBJECT_UNLOCK(object); 399 400 vm_pager_put_pages(object, mc, count, 401 (flags | ((object == kernel_object) ? VM_PAGER_PUT_SYNC : 0)), 402 pageout_status); 403 404 VM_OBJECT_LOCK(object); 405 vm_page_lock_queues(); 406 for (i = 0; i < count; i++) { 407 vm_page_t mt = mc[i]; 408 409 switch (pageout_status[i]) { 410 case VM_PAGER_OK: 411 case VM_PAGER_PEND: 412 numpagedout++; 413 break; 414 case VM_PAGER_BAD: 415 /* 416 * Page outside of range of object. Right now we 417 * essentially lose the changes by pretending it 418 * worked. 419 */ 420 pmap_clear_modify(mt); 421 vm_page_undirty(mt); 422 break; 423 case VM_PAGER_ERROR: 424 case VM_PAGER_FAIL: 425 /* 426 * If page couldn't be paged out, then reactivate the 427 * page so it doesn't clog the inactive list. (We 428 * will try paging out it again later). 429 */ 430 vm_page_activate(mt); 431 break; 432 case VM_PAGER_AGAIN: 433 break; 434 } 435 436 /* 437 * If the operation is still going, leave the page busy to 438 * block all other accesses. Also, leave the paging in 439 * progress indicator set so that we don't attempt an object 440 * collapse. 441 */ 442 if (pageout_status[i] != VM_PAGER_PEND) { 443 vm_object_pip_wakeup(object); 444 vm_page_io_finish(mt); 445 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt)) 446 pmap_page_protect(mt, VM_PROT_READ); 447 } 448 } 449 if (!is_object_locked) 450 VM_OBJECT_UNLOCK(object); 451 return numpagedout; 452 } 453 454 #if !defined(NO_SWAPPING) 455 /* 456 * vm_pageout_object_deactivate_pages 457 * 458 * deactivate enough pages to satisfy the inactive target 459 * requirements or if vm_page_proc_limit is set, then 460 * deactivate all of the pages in the object and its 461 * backing_objects. 462 * 463 * The object and map must be locked. 464 */ 465 static void 466 vm_pageout_object_deactivate_pages(pmap, first_object, desired) 467 pmap_t pmap; 468 vm_object_t first_object; 469 long desired; 470 { 471 vm_object_t backing_object, object; 472 vm_page_t p, next; 473 int actcount, rcount, remove_mode; 474 475 VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED); 476 if (first_object->type == OBJT_DEVICE || first_object->type == OBJT_PHYS) 477 return; 478 for (object = first_object;; object = backing_object) { 479 if (pmap_resident_count(pmap) <= desired) 480 goto unlock_return; 481 if (object->paging_in_progress) 482 goto unlock_return; 483 484 remove_mode = 0; 485 if (object->shadow_count > 1) 486 remove_mode = 1; 487 /* 488 * scan the objects entire memory queue 489 */ 490 rcount = object->resident_page_count; 491 p = TAILQ_FIRST(&object->memq); 492 vm_page_lock_queues(); 493 while (p && (rcount-- > 0)) { 494 if (pmap_resident_count(pmap) <= desired) { 495 vm_page_unlock_queues(); 496 goto unlock_return; 497 } 498 next = TAILQ_NEXT(p, listq); 499 cnt.v_pdpages++; 500 if (p->wire_count != 0 || 501 p->hold_count != 0 || 502 p->busy != 0 || 503 (p->flags & (PG_BUSY|PG_UNMANAGED)) || 504 !pmap_page_exists_quick(pmap, p)) { 505 p = next; 506 continue; 507 } 508 actcount = pmap_ts_referenced(p); 509 if (actcount) { 510 vm_page_flag_set(p, PG_REFERENCED); 511 } else if (p->flags & PG_REFERENCED) { 512 actcount = 1; 513 } 514 if ((p->queue != PQ_ACTIVE) && 515 (p->flags & PG_REFERENCED)) { 516 vm_page_activate(p); 517 p->act_count += actcount; 518 vm_page_flag_clear(p, PG_REFERENCED); 519 } else if (p->queue == PQ_ACTIVE) { 520 if ((p->flags & PG_REFERENCED) == 0) { 521 p->act_count -= min(p->act_count, ACT_DECLINE); 522 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) { 523 pmap_remove_all(p); 524 vm_page_deactivate(p); 525 } else { 526 vm_pageq_requeue(p); 527 } 528 } else { 529 vm_page_activate(p); 530 vm_page_flag_clear(p, PG_REFERENCED); 531 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 532 p->act_count += ACT_ADVANCE; 533 vm_pageq_requeue(p); 534 } 535 } else if (p->queue == PQ_INACTIVE) { 536 pmap_remove_all(p); 537 } 538 p = next; 539 } 540 vm_page_unlock_queues(); 541 if ((backing_object = object->backing_object) == NULL) 542 goto unlock_return; 543 VM_OBJECT_LOCK(backing_object); 544 if (object != first_object) 545 VM_OBJECT_UNLOCK(object); 546 } 547 unlock_return: 548 if (object != first_object) 549 VM_OBJECT_UNLOCK(object); 550 } 551 552 /* 553 * deactivate some number of pages in a map, try to do it fairly, but 554 * that is really hard to do. 555 */ 556 static void 557 vm_pageout_map_deactivate_pages(map, desired) 558 vm_map_t map; 559 long desired; 560 { 561 vm_map_entry_t tmpe; 562 vm_object_t obj, bigobj; 563 int nothingwired; 564 565 if (!vm_map_trylock(map)) 566 return; 567 568 bigobj = NULL; 569 nothingwired = TRUE; 570 571 /* 572 * first, search out the biggest object, and try to free pages from 573 * that. 574 */ 575 tmpe = map->header.next; 576 while (tmpe != &map->header) { 577 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 578 obj = tmpe->object.vm_object; 579 if (obj != NULL && VM_OBJECT_TRYLOCK(obj)) { 580 if (obj->shadow_count <= 1 && 581 (bigobj == NULL || 582 bigobj->resident_page_count < obj->resident_page_count)) { 583 if (bigobj != NULL) 584 VM_OBJECT_UNLOCK(bigobj); 585 bigobj = obj; 586 } else 587 VM_OBJECT_UNLOCK(obj); 588 } 589 } 590 if (tmpe->wired_count > 0) 591 nothingwired = FALSE; 592 tmpe = tmpe->next; 593 } 594 595 if (bigobj != NULL) { 596 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); 597 VM_OBJECT_UNLOCK(bigobj); 598 } 599 /* 600 * Next, hunt around for other pages to deactivate. We actually 601 * do this search sort of wrong -- .text first is not the best idea. 602 */ 603 tmpe = map->header.next; 604 while (tmpe != &map->header) { 605 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 606 break; 607 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 608 obj = tmpe->object.vm_object; 609 if (obj != NULL) { 610 VM_OBJECT_LOCK(obj); 611 vm_pageout_object_deactivate_pages(map->pmap, obj, desired); 612 VM_OBJECT_UNLOCK(obj); 613 } 614 } 615 tmpe = tmpe->next; 616 } 617 618 /* 619 * Remove all mappings if a process is swapped out, this will free page 620 * table pages. 621 */ 622 if (desired == 0 && nothingwired) { 623 GIANT_REQUIRED; 624 vm_page_lock_queues(); 625 pmap_remove(vm_map_pmap(map), vm_map_min(map), 626 vm_map_max(map)); 627 vm_page_unlock_queues(); 628 } 629 vm_map_unlock(map); 630 } 631 #endif /* !defined(NO_SWAPPING) */ 632 633 /* 634 * Warning! The page queue lock is released and reacquired. 635 */ 636 static void 637 vm_pageout_page_free(vm_page_t m) 638 { 639 vm_object_t object = m->object; 640 641 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 642 vm_page_busy(m); 643 vm_page_unlock_queues(); 644 /* 645 * Avoid a lock order reversal. The page must be busy. 646 */ 647 VM_OBJECT_LOCK(object); 648 vm_page_lock_queues(); 649 pmap_remove_all(m); 650 vm_page_free(m); 651 VM_OBJECT_UNLOCK(object); 652 cnt.v_dfree++; 653 } 654 655 /* 656 * This routine is very drastic, but can save the system 657 * in a pinch. 658 */ 659 static void 660 vm_pageout_pmap_collect(void) 661 { 662 int i; 663 vm_page_t m; 664 static int warningdone; 665 666 if (pmap_pagedaemon_waken == 0) 667 return; 668 if (warningdone < 5) { 669 printf("collecting pv entries -- suggest increasing PMAP_SHPGPERPROC\n"); 670 warningdone++; 671 } 672 vm_page_lock_queues(); 673 for (i = 0; i < vm_page_array_size; i++) { 674 m = &vm_page_array[i]; 675 if (m->wire_count || m->hold_count || m->busy || 676 (m->flags & (PG_BUSY | PG_UNMANAGED))) 677 continue; 678 pmap_remove_all(m); 679 } 680 vm_page_unlock_queues(); 681 pmap_pagedaemon_waken = 0; 682 } 683 684 /* 685 * vm_pageout_scan does the dirty work for the pageout daemon. 686 */ 687 static void 688 vm_pageout_scan(int pass) 689 { 690 vm_page_t m, next; 691 struct vm_page marker; 692 int save_page_shortage; 693 int save_inactive_count; 694 int page_shortage, maxscan, pcount; 695 int addl_page_shortage, addl_page_shortage_init; 696 struct proc *p, *bigproc; 697 vm_offset_t size, bigsize; 698 vm_object_t object; 699 int actcount; 700 int vnodes_skipped = 0; 701 int maxlaunder; 702 int s; 703 struct thread *td; 704 705 GIANT_REQUIRED; 706 /* 707 * Decrease registered cache sizes. 708 */ 709 EVENTHANDLER_INVOKE(vm_lowmem, 0); 710 /* 711 * We do this explicitly after the caches have been drained above. 712 */ 713 uma_reclaim(); 714 /* 715 * Do whatever cleanup that the pmap code can. 716 */ 717 vm_pageout_pmap_collect(); 718 719 addl_page_shortage_init = atomic_readandclear_int(&vm_pageout_deficit); 720 721 /* 722 * Calculate the number of pages we want to either free or move 723 * to the cache. 724 */ 725 page_shortage = vm_paging_target() + addl_page_shortage_init; 726 save_page_shortage = page_shortage; 727 save_inactive_count = cnt.v_inactive_count; 728 729 /* 730 * Initialize our marker 731 */ 732 bzero(&marker, sizeof(marker)); 733 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 734 marker.queue = PQ_INACTIVE; 735 marker.wire_count = 1; 736 737 /* 738 * Start scanning the inactive queue for pages we can move to the 739 * cache or free. The scan will stop when the target is reached or 740 * we have scanned the entire inactive queue. Note that m->act_count 741 * is not used to form decisions for the inactive queue, only for the 742 * active queue. 743 * 744 * maxlaunder limits the number of dirty pages we flush per scan. 745 * For most systems a smaller value (16 or 32) is more robust under 746 * extreme memory and disk pressure because any unnecessary writes 747 * to disk can result in extreme performance degredation. However, 748 * systems with excessive dirty pages (especially when MAP_NOSYNC is 749 * used) will die horribly with limited laundering. If the pageout 750 * daemon cannot clean enough pages in the first pass, we let it go 751 * all out in succeeding passes. 752 */ 753 if ((maxlaunder = vm_max_launder) <= 1) 754 maxlaunder = 1; 755 if (pass) 756 maxlaunder = 10000; 757 rescan0: 758 addl_page_shortage = addl_page_shortage_init; 759 maxscan = cnt.v_inactive_count; 760 761 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 762 m != NULL && maxscan-- > 0 && page_shortage > 0; 763 m = next) { 764 765 cnt.v_pdpages++; 766 767 if (m->queue != PQ_INACTIVE) { 768 goto rescan0; 769 } 770 771 next = TAILQ_NEXT(m, pageq); 772 773 /* 774 * skip marker pages 775 */ 776 if (m->flags & PG_MARKER) 777 continue; 778 779 /* 780 * A held page may be undergoing I/O, so skip it. 781 */ 782 if (m->hold_count) { 783 vm_pageq_requeue(m); 784 addl_page_shortage++; 785 continue; 786 } 787 /* 788 * Don't mess with busy pages, keep in the front of the 789 * queue, most likely are being paged out. 790 */ 791 if (m->busy || (m->flags & PG_BUSY)) { 792 addl_page_shortage++; 793 continue; 794 } 795 796 vm_page_lock_queues(); 797 /* 798 * If the object is not being used, we ignore previous 799 * references. 800 */ 801 if (m->object->ref_count == 0) { 802 vm_page_flag_clear(m, PG_REFERENCED); 803 pmap_clear_reference(m); 804 805 /* 806 * Otherwise, if the page has been referenced while in the 807 * inactive queue, we bump the "activation count" upwards, 808 * making it less likely that the page will be added back to 809 * the inactive queue prematurely again. Here we check the 810 * page tables (or emulated bits, if any), given the upper 811 * level VM system not knowing anything about existing 812 * references. 813 */ 814 } else if (((m->flags & PG_REFERENCED) == 0) && 815 (actcount = pmap_ts_referenced(m))) { 816 vm_page_activate(m); 817 vm_page_unlock_queues(); 818 m->act_count += (actcount + ACT_ADVANCE); 819 continue; 820 } 821 822 /* 823 * If the upper level VM system knows about any page 824 * references, we activate the page. We also set the 825 * "activation count" higher than normal so that we will less 826 * likely place pages back onto the inactive queue again. 827 */ 828 if ((m->flags & PG_REFERENCED) != 0) { 829 vm_page_flag_clear(m, PG_REFERENCED); 830 actcount = pmap_ts_referenced(m); 831 vm_page_activate(m); 832 vm_page_unlock_queues(); 833 m->act_count += (actcount + ACT_ADVANCE + 1); 834 continue; 835 } 836 837 /* 838 * If the upper level VM system doesn't know anything about 839 * the page being dirty, we have to check for it again. As 840 * far as the VM code knows, any partially dirty pages are 841 * fully dirty. 842 */ 843 if (m->dirty == 0) { 844 vm_page_test_dirty(m); 845 } else { 846 vm_page_dirty(m); 847 } 848 vm_page_unlock_queues(); 849 850 /* 851 * Invalid pages can be easily freed 852 */ 853 if (m->valid == 0) { 854 vm_page_lock_queues(); 855 vm_pageout_page_free(m); 856 vm_page_unlock_queues(); 857 --page_shortage; 858 859 /* 860 * Clean pages can be placed onto the cache queue. This 861 * effectively frees them. 862 */ 863 } else if (m->dirty == 0) { 864 vm_page_lock_queues(); 865 vm_page_cache(m); 866 vm_page_unlock_queues(); 867 --page_shortage; 868 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 869 /* 870 * Dirty pages need to be paged out, but flushing 871 * a page is extremely expensive verses freeing 872 * a clean page. Rather then artificially limiting 873 * the number of pages we can flush, we instead give 874 * dirty pages extra priority on the inactive queue 875 * by forcing them to be cycled through the queue 876 * twice before being flushed, after which the 877 * (now clean) page will cycle through once more 878 * before being freed. This significantly extends 879 * the thrash point for a heavily loaded machine. 880 */ 881 vm_page_lock_queues(); 882 vm_page_flag_set(m, PG_WINATCFLS); 883 vm_pageq_requeue(m); 884 vm_page_unlock_queues(); 885 } else if (maxlaunder > 0) { 886 /* 887 * We always want to try to flush some dirty pages if 888 * we encounter them, to keep the system stable. 889 * Normally this number is small, but under extreme 890 * pressure where there are insufficient clean pages 891 * on the inactive queue, we may have to go all out. 892 */ 893 int swap_pageouts_ok; 894 struct vnode *vp = NULL; 895 struct mount *mp; 896 897 object = m->object; 898 899 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 900 swap_pageouts_ok = 1; 901 } else { 902 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 903 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 904 vm_page_count_min()); 905 906 } 907 908 /* 909 * We don't bother paging objects that are "dead". 910 * Those objects are in a "rundown" state. 911 */ 912 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 913 vm_pageq_requeue(m); 914 continue; 915 } 916 917 /* 918 * The object is already known NOT to be dead. It 919 * is possible for the vget() to block the whole 920 * pageout daemon, but the new low-memory handling 921 * code should prevent it. 922 * 923 * The previous code skipped locked vnodes and, worse, 924 * reordered pages in the queue. This results in 925 * completely non-deterministic operation and, on a 926 * busy system, can lead to extremely non-optimal 927 * pageouts. For example, it can cause clean pages 928 * to be freed and dirty pages to be moved to the end 929 * of the queue. Since dirty pages are also moved to 930 * the end of the queue once-cleaned, this gives 931 * way too large a weighting to defering the freeing 932 * of dirty pages. 933 * 934 * We can't wait forever for the vnode lock, we might 935 * deadlock due to a vn_read() getting stuck in 936 * vm_wait while holding this vnode. We skip the 937 * vnode if we can't get it in a reasonable amount 938 * of time. 939 */ 940 if (object->type == OBJT_VNODE) { 941 vp = object->handle; 942 943 mp = NULL; 944 if (vp->v_type == VREG) 945 vn_start_write(vp, &mp, V_NOWAIT); 946 if (vget(vp, LK_EXCLUSIVE|LK_TIMELOCK, curthread)) { 947 ++pageout_lock_miss; 948 vn_finished_write(mp); 949 if (object->flags & OBJ_MIGHTBEDIRTY) 950 vnodes_skipped++; 951 continue; 952 } 953 954 /* 955 * The page might have been moved to another 956 * queue during potential blocking in vget() 957 * above. The page might have been freed and 958 * reused for another vnode. The object might 959 * have been reused for another vnode. 960 */ 961 if (m->queue != PQ_INACTIVE || 962 m->object != object || 963 object->handle != vp) { 964 if (object->flags & OBJ_MIGHTBEDIRTY) 965 vnodes_skipped++; 966 vput(vp); 967 vn_finished_write(mp); 968 continue; 969 } 970 971 /* 972 * The page may have been busied during the 973 * blocking in vput(); We don't move the 974 * page back onto the end of the queue so that 975 * statistics are more correct if we don't. 976 */ 977 if (m->busy || (m->flags & PG_BUSY)) { 978 vput(vp); 979 vn_finished_write(mp); 980 continue; 981 } 982 983 /* 984 * If the page has become held it might 985 * be undergoing I/O, so skip it 986 */ 987 if (m->hold_count) { 988 vm_pageq_requeue(m); 989 if (object->flags & OBJ_MIGHTBEDIRTY) 990 vnodes_skipped++; 991 vput(vp); 992 vn_finished_write(mp); 993 continue; 994 } 995 } 996 997 /* 998 * If a page is dirty, then it is either being washed 999 * (but not yet cleaned) or it is still in the 1000 * laundry. If it is still in the laundry, then we 1001 * start the cleaning operation. 1002 * 1003 * This operation may cluster, invalidating the 'next' 1004 * pointer. To prevent an inordinate number of 1005 * restarts we use our marker to remember our place. 1006 * 1007 * decrement page_shortage on success to account for 1008 * the (future) cleaned page. Otherwise we could wind 1009 * up laundering or cleaning too many pages. 1010 */ 1011 vm_page_lock_queues(); 1012 s = splvm(); 1013 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq); 1014 splx(s); 1015 if (vm_pageout_clean(m) != 0) { 1016 --page_shortage; 1017 --maxlaunder; 1018 } 1019 s = splvm(); 1020 next = TAILQ_NEXT(&marker, pageq); 1021 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq); 1022 splx(s); 1023 vm_page_unlock_queues(); 1024 if (vp) { 1025 vput(vp); 1026 vn_finished_write(mp); 1027 } 1028 } 1029 } 1030 1031 /* 1032 * Compute the number of pages we want to try to move from the 1033 * active queue to the inactive queue. 1034 */ 1035 page_shortage = vm_paging_target() + 1036 cnt.v_inactive_target - cnt.v_inactive_count; 1037 page_shortage += addl_page_shortage; 1038 1039 vm_page_lock_queues(); 1040 /* 1041 * Scan the active queue for things we can deactivate. We nominally 1042 * track the per-page activity counter and use it to locate 1043 * deactivation candidates. 1044 */ 1045 pcount = cnt.v_active_count; 1046 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1047 1048 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 1049 1050 /* 1051 * This is a consistency check, and should likely be a panic 1052 * or warning. 1053 */ 1054 if (m->queue != PQ_ACTIVE) { 1055 break; 1056 } 1057 1058 next = TAILQ_NEXT(m, pageq); 1059 /* 1060 * Don't deactivate pages that are busy. 1061 */ 1062 if ((m->busy != 0) || 1063 (m->flags & PG_BUSY) || 1064 (m->hold_count != 0)) { 1065 vm_pageq_requeue(m); 1066 m = next; 1067 continue; 1068 } 1069 1070 /* 1071 * The count for pagedaemon pages is done after checking the 1072 * page for eligibility... 1073 */ 1074 cnt.v_pdpages++; 1075 1076 /* 1077 * Check to see "how much" the page has been used. 1078 */ 1079 actcount = 0; 1080 if (m->object->ref_count != 0) { 1081 if (m->flags & PG_REFERENCED) { 1082 actcount += 1; 1083 } 1084 actcount += pmap_ts_referenced(m); 1085 if (actcount) { 1086 m->act_count += ACT_ADVANCE + actcount; 1087 if (m->act_count > ACT_MAX) 1088 m->act_count = ACT_MAX; 1089 } 1090 } 1091 1092 /* 1093 * Since we have "tested" this bit, we need to clear it now. 1094 */ 1095 vm_page_flag_clear(m, PG_REFERENCED); 1096 1097 /* 1098 * Only if an object is currently being used, do we use the 1099 * page activation count stats. 1100 */ 1101 if (actcount && (m->object->ref_count != 0)) { 1102 vm_pageq_requeue(m); 1103 } else { 1104 m->act_count -= min(m->act_count, ACT_DECLINE); 1105 if (vm_pageout_algorithm || 1106 m->object->ref_count == 0 || 1107 m->act_count == 0) { 1108 page_shortage--; 1109 if (m->object->ref_count == 0) { 1110 pmap_remove_all(m); 1111 if (m->dirty == 0) 1112 vm_page_cache(m); 1113 else 1114 vm_page_deactivate(m); 1115 } else { 1116 vm_page_deactivate(m); 1117 } 1118 } else { 1119 vm_pageq_requeue(m); 1120 } 1121 } 1122 m = next; 1123 } 1124 s = splvm(); 1125 1126 /* 1127 * We try to maintain some *really* free pages, this allows interrupt 1128 * code to be guaranteed space. Since both cache and free queues 1129 * are considered basically 'free', moving pages from cache to free 1130 * does not effect other calculations. 1131 */ 1132 while (cnt.v_free_count < cnt.v_free_reserved) { 1133 static int cache_rover = 0; 1134 m = vm_pageq_find(PQ_CACHE, cache_rover, FALSE); 1135 if (!m) 1136 break; 1137 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || 1138 m->busy || 1139 m->hold_count || 1140 m->wire_count) { 1141 #ifdef INVARIANTS 1142 printf("Warning: busy page %p found in cache\n", m); 1143 #endif 1144 vm_page_deactivate(m); 1145 continue; 1146 } 1147 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK; 1148 vm_pageout_page_free(m); 1149 } 1150 splx(s); 1151 vm_page_unlock_queues(); 1152 #if !defined(NO_SWAPPING) 1153 /* 1154 * Idle process swapout -- run once per second. 1155 */ 1156 if (vm_swap_idle_enabled) { 1157 static long lsec; 1158 if (time_second != lsec) { 1159 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1160 vm_req_vmdaemon(); 1161 lsec = time_second; 1162 } 1163 } 1164 #endif 1165 1166 /* 1167 * If we didn't get enough free pages, and we have skipped a vnode 1168 * in a writeable object, wakeup the sync daemon. And kick swapout 1169 * if we did not get enough free pages. 1170 */ 1171 if (vm_paging_target() > 0) { 1172 if (vnodes_skipped && vm_page_count_min()) 1173 (void) speedup_syncer(); 1174 #if !defined(NO_SWAPPING) 1175 if (vm_swap_enabled && vm_page_count_target()) { 1176 vm_req_vmdaemon(); 1177 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1178 } 1179 #endif 1180 } 1181 1182 /* 1183 * If we are critically low on one of RAM or swap and low on 1184 * the other, kill the largest process. However, we avoid 1185 * doing this on the first pass in order to give ourselves a 1186 * chance to flush out dirty vnode-backed pages and to allow 1187 * active pages to be moved to the inactive queue and reclaimed. 1188 * 1189 * We keep the process bigproc locked once we find it to keep anyone 1190 * from messing with it; however, there is a possibility of 1191 * deadlock if process B is bigproc and one of it's child processes 1192 * attempts to propagate a signal to B while we are waiting for A's 1193 * lock while walking this list. To avoid this, we don't block on 1194 * the process lock but just skip a process if it is already locked. 1195 */ 1196 if (pass != 0 && 1197 ((vm_swap_size < 64 && vm_page_count_min()) || 1198 (swap_pager_full && vm_paging_target() > 0))) { 1199 bigproc = NULL; 1200 bigsize = 0; 1201 sx_slock(&allproc_lock); 1202 FOREACH_PROC_IN_SYSTEM(p) { 1203 int breakout; 1204 /* 1205 * If this process is already locked, skip it. 1206 */ 1207 if (PROC_TRYLOCK(p) == 0) 1208 continue; 1209 /* 1210 * If this is a system or protected process, skip it. 1211 */ 1212 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || 1213 (p->p_flag & P_PROTECTED) || 1214 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1215 PROC_UNLOCK(p); 1216 continue; 1217 } 1218 /* 1219 * if the process is in a non-running type state, 1220 * don't touch it. Check all the threads individually. 1221 */ 1222 mtx_lock_spin(&sched_lock); 1223 breakout = 0; 1224 FOREACH_THREAD_IN_PROC(p, td) { 1225 if (!TD_ON_RUNQ(td) && 1226 !TD_IS_RUNNING(td) && 1227 !TD_IS_SLEEPING(td)) { 1228 breakout = 1; 1229 break; 1230 } 1231 } 1232 if (breakout) { 1233 mtx_unlock_spin(&sched_lock); 1234 PROC_UNLOCK(p); 1235 continue; 1236 } 1237 mtx_unlock_spin(&sched_lock); 1238 /* 1239 * get the process size 1240 */ 1241 if (!vm_map_trylock_read(&p->p_vmspace->vm_map)) { 1242 PROC_UNLOCK(p); 1243 continue; 1244 } 1245 size = vmspace_swap_count(p->p_vmspace); 1246 vm_map_unlock_read(&p->p_vmspace->vm_map); 1247 size += vmspace_resident_count(p->p_vmspace); 1248 /* 1249 * if the this process is bigger than the biggest one 1250 * remember it. 1251 */ 1252 if (size > bigsize) { 1253 if (bigproc != NULL) 1254 PROC_UNLOCK(bigproc); 1255 bigproc = p; 1256 bigsize = size; 1257 } else 1258 PROC_UNLOCK(p); 1259 } 1260 sx_sunlock(&allproc_lock); 1261 if (bigproc != NULL) { 1262 struct ksegrp *kg; 1263 killproc(bigproc, "out of swap space"); 1264 mtx_lock_spin(&sched_lock); 1265 FOREACH_KSEGRP_IN_PROC(bigproc, kg) { 1266 sched_nice(kg, PRIO_MIN); /* XXXKSE ??? */ 1267 } 1268 mtx_unlock_spin(&sched_lock); 1269 PROC_UNLOCK(bigproc); 1270 wakeup(&cnt.v_free_count); 1271 } 1272 } 1273 } 1274 1275 /* 1276 * This routine tries to maintain the pseudo LRU active queue, 1277 * so that during long periods of time where there is no paging, 1278 * that some statistic accumulation still occurs. This code 1279 * helps the situation where paging just starts to occur. 1280 */ 1281 static void 1282 vm_pageout_page_stats() 1283 { 1284 vm_page_t m,next; 1285 int pcount,tpcount; /* Number of pages to check */ 1286 static int fullintervalcount = 0; 1287 int page_shortage; 1288 int s0; 1289 1290 page_shortage = 1291 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1292 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1293 1294 if (page_shortage <= 0) 1295 return; 1296 1297 s0 = splvm(); 1298 vm_page_lock_queues(); 1299 pcount = cnt.v_active_count; 1300 fullintervalcount += vm_pageout_stats_interval; 1301 if (fullintervalcount < vm_pageout_full_stats_interval) { 1302 tpcount = (vm_pageout_stats_max * cnt.v_active_count) / cnt.v_page_count; 1303 if (pcount > tpcount) 1304 pcount = tpcount; 1305 } else { 1306 fullintervalcount = 0; 1307 } 1308 1309 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1310 while ((m != NULL) && (pcount-- > 0)) { 1311 int actcount; 1312 1313 if (m->queue != PQ_ACTIVE) { 1314 break; 1315 } 1316 1317 next = TAILQ_NEXT(m, pageq); 1318 /* 1319 * Don't deactivate pages that are busy. 1320 */ 1321 if ((m->busy != 0) || 1322 (m->flags & PG_BUSY) || 1323 (m->hold_count != 0)) { 1324 vm_pageq_requeue(m); 1325 m = next; 1326 continue; 1327 } 1328 1329 actcount = 0; 1330 if (m->flags & PG_REFERENCED) { 1331 vm_page_flag_clear(m, PG_REFERENCED); 1332 actcount += 1; 1333 } 1334 1335 actcount += pmap_ts_referenced(m); 1336 if (actcount) { 1337 m->act_count += ACT_ADVANCE + actcount; 1338 if (m->act_count > ACT_MAX) 1339 m->act_count = ACT_MAX; 1340 vm_pageq_requeue(m); 1341 } else { 1342 if (m->act_count == 0) { 1343 /* 1344 * We turn off page access, so that we have 1345 * more accurate RSS stats. We don't do this 1346 * in the normal page deactivation when the 1347 * system is loaded VM wise, because the 1348 * cost of the large number of page protect 1349 * operations would be higher than the value 1350 * of doing the operation. 1351 */ 1352 pmap_remove_all(m); 1353 vm_page_deactivate(m); 1354 } else { 1355 m->act_count -= min(m->act_count, ACT_DECLINE); 1356 vm_pageq_requeue(m); 1357 } 1358 } 1359 1360 m = next; 1361 } 1362 vm_page_unlock_queues(); 1363 splx(s0); 1364 } 1365 1366 static int 1367 vm_pageout_free_page_calc(count) 1368 vm_size_t count; 1369 { 1370 if (count < cnt.v_page_count) 1371 return 0; 1372 /* 1373 * free_reserved needs to include enough for the largest swap pager 1374 * structures plus enough for any pv_entry structs when paging. 1375 */ 1376 if (cnt.v_page_count > 1024) 1377 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1378 else 1379 cnt.v_free_min = 4; 1380 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1381 cnt.v_interrupt_free_min; 1382 cnt.v_free_reserved = vm_pageout_page_count + 1383 cnt.v_pageout_free_min + (count / 768) + PQ_L2_SIZE; 1384 cnt.v_free_severe = cnt.v_free_min / 2; 1385 cnt.v_free_min += cnt.v_free_reserved; 1386 cnt.v_free_severe += cnt.v_free_reserved; 1387 return 1; 1388 } 1389 1390 /* 1391 * vm_pageout is the high level pageout daemon. 1392 */ 1393 static void 1394 vm_pageout() 1395 { 1396 int error, pass, s; 1397 1398 mtx_lock(&Giant); 1399 1400 /* 1401 * Initialize some paging parameters. 1402 */ 1403 cnt.v_interrupt_free_min = 2; 1404 if (cnt.v_page_count < 2000) 1405 vm_pageout_page_count = 8; 1406 1407 vm_pageout_free_page_calc(cnt.v_page_count); 1408 /* 1409 * v_free_target and v_cache_min control pageout hysteresis. Note 1410 * that these are more a measure of the VM cache queue hysteresis 1411 * then the VM free queue. Specifically, v_free_target is the 1412 * high water mark (free+cache pages). 1413 * 1414 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1415 * low water mark, while v_free_min is the stop. v_cache_min must 1416 * be big enough to handle memory needs while the pageout daemon 1417 * is signalled and run to free more pages. 1418 */ 1419 if (cnt.v_free_count > 6144) 1420 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1421 else 1422 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1423 1424 if (cnt.v_free_count > 2048) { 1425 cnt.v_cache_min = cnt.v_free_target; 1426 cnt.v_cache_max = 2 * cnt.v_cache_min; 1427 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1428 } else { 1429 cnt.v_cache_min = 0; 1430 cnt.v_cache_max = 0; 1431 cnt.v_inactive_target = cnt.v_free_count / 4; 1432 } 1433 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1434 cnt.v_inactive_target = cnt.v_free_count / 3; 1435 1436 /* XXX does not really belong here */ 1437 if (vm_page_max_wired == 0) 1438 vm_page_max_wired = cnt.v_free_count / 3; 1439 1440 if (vm_pageout_stats_max == 0) 1441 vm_pageout_stats_max = cnt.v_free_target; 1442 1443 /* 1444 * Set interval in seconds for stats scan. 1445 */ 1446 if (vm_pageout_stats_interval == 0) 1447 vm_pageout_stats_interval = 5; 1448 if (vm_pageout_full_stats_interval == 0) 1449 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1450 1451 /* 1452 * Set maximum free per pass 1453 */ 1454 if (vm_pageout_stats_free_max == 0) 1455 vm_pageout_stats_free_max = 5; 1456 1457 swap_pager_swap_init(); 1458 pass = 0; 1459 /* 1460 * The pageout daemon is never done, so loop forever. 1461 */ 1462 while (TRUE) { 1463 s = splvm(); 1464 vm_page_lock_queues(); 1465 /* 1466 * If we have enough free memory, wakeup waiters. Do 1467 * not clear vm_pages_needed until we reach our target, 1468 * otherwise we may be woken up over and over again and 1469 * waste a lot of cpu. 1470 */ 1471 if (vm_pages_needed && !vm_page_count_min()) { 1472 if (!vm_paging_needed()) 1473 vm_pages_needed = 0; 1474 wakeup(&cnt.v_free_count); 1475 } 1476 if (vm_pages_needed) { 1477 /* 1478 * Still not done, take a second pass without waiting 1479 * (unlimited dirty cleaning), otherwise sleep a bit 1480 * and try again. 1481 */ 1482 ++pass; 1483 if (pass > 1) 1484 msleep(&vm_pages_needed, &vm_page_queue_mtx, PVM, 1485 "psleep", hz/2); 1486 } else { 1487 /* 1488 * Good enough, sleep & handle stats. Prime the pass 1489 * for the next run. 1490 */ 1491 if (pass > 1) 1492 pass = 1; 1493 else 1494 pass = 0; 1495 error = msleep(&vm_pages_needed, &vm_page_queue_mtx, PVM, 1496 "psleep", vm_pageout_stats_interval * hz); 1497 if (error && !vm_pages_needed) { 1498 vm_page_unlock_queues(); 1499 splx(s); 1500 pass = 0; 1501 vm_pageout_page_stats(); 1502 continue; 1503 } 1504 } 1505 if (vm_pages_needed) 1506 cnt.v_pdwakeups++; 1507 vm_page_unlock_queues(); 1508 splx(s); 1509 vm_pageout_scan(pass); 1510 } 1511 } 1512 1513 /* 1514 * Unless the page queue lock is held by the caller, this function 1515 * should be regarded as advisory. Specifically, the caller should 1516 * not msleep() on &cnt.v_free_count following this function unless 1517 * the page queue lock is held until the msleep() is performed. 1518 */ 1519 void 1520 pagedaemon_wakeup() 1521 { 1522 1523 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1524 vm_pages_needed = 1; 1525 wakeup(&vm_pages_needed); 1526 } 1527 } 1528 1529 #if !defined(NO_SWAPPING) 1530 static void 1531 vm_req_vmdaemon() 1532 { 1533 static int lastrun = 0; 1534 1535 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1536 wakeup(&vm_daemon_needed); 1537 lastrun = ticks; 1538 } 1539 } 1540 1541 static void 1542 vm_daemon() 1543 { 1544 struct proc *p; 1545 int breakout; 1546 struct thread *td; 1547 1548 mtx_lock(&Giant); 1549 while (TRUE) { 1550 tsleep(&vm_daemon_needed, PPAUSE, "psleep", 0); 1551 if (vm_pageout_req_swapout) { 1552 swapout_procs(vm_pageout_req_swapout); 1553 vm_pageout_req_swapout = 0; 1554 } 1555 /* 1556 * scan the processes for exceeding their rlimits or if 1557 * process is swapped out -- deactivate pages 1558 */ 1559 sx_slock(&allproc_lock); 1560 LIST_FOREACH(p, &allproc, p_list) { 1561 vm_pindex_t limit, size; 1562 1563 /* 1564 * if this is a system process or if we have already 1565 * looked at this process, skip it. 1566 */ 1567 PROC_LOCK(p); 1568 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 1569 PROC_UNLOCK(p); 1570 continue; 1571 } 1572 /* 1573 * if the process is in a non-running type state, 1574 * don't touch it. 1575 */ 1576 mtx_lock_spin(&sched_lock); 1577 breakout = 0; 1578 FOREACH_THREAD_IN_PROC(p, td) { 1579 if (!TD_ON_RUNQ(td) && 1580 !TD_IS_RUNNING(td) && 1581 !TD_IS_SLEEPING(td)) { 1582 breakout = 1; 1583 break; 1584 } 1585 } 1586 mtx_unlock_spin(&sched_lock); 1587 if (breakout) { 1588 PROC_UNLOCK(p); 1589 continue; 1590 } 1591 /* 1592 * get a limit 1593 */ 1594 limit = OFF_TO_IDX( 1595 qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 1596 p->p_rlimit[RLIMIT_RSS].rlim_max)); 1597 1598 /* 1599 * let processes that are swapped out really be 1600 * swapped out set the limit to nothing (will force a 1601 * swap-out.) 1602 */ 1603 if ((p->p_sflag & PS_INMEM) == 0) 1604 limit = 0; /* XXX */ 1605 PROC_UNLOCK(p); 1606 1607 size = vmspace_resident_count(p->p_vmspace); 1608 if (limit >= 0 && size >= limit) { 1609 vm_pageout_map_deactivate_pages( 1610 &p->p_vmspace->vm_map, limit); 1611 } 1612 } 1613 sx_sunlock(&allproc_lock); 1614 } 1615 } 1616 #endif /* !defined(NO_SWAPPING) */ 1617