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