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