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 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 37 * 38 * 39 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 40 * All rights reserved. 41 * 42 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 43 * 44 * Permission to use, copy, modify and distribute this software and 45 * its documentation is hereby granted, provided that both the copyright 46 * notice and this permission notice appear in all copies of the 47 * software, derivative works or modified versions, and any portions 48 * thereof, and that both notices appear in supporting documentation. 49 * 50 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 51 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 52 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 53 * 54 * Carnegie Mellon requests users of this software to return to 55 * 56 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 57 * School of Computer Science 58 * Carnegie Mellon University 59 * Pittsburgh PA 15213-3890 60 * 61 * any improvements or extensions that they make and grant Carnegie the 62 * rights to redistribute these changes. 63 * 64 * $FreeBSD: src/sys/vm/vm_pageout.c,v 1.151.2.15 2002/12/29 18:21:04 dillon Exp $ 65 */ 66 67 /* 68 * The proverbial page-out daemon. 69 */ 70 71 #include "opt_vm.h" 72 #include <sys/param.h> 73 #include <sys/systm.h> 74 #include <sys/kernel.h> 75 #include <sys/proc.h> 76 #include <sys/kthread.h> 77 #include <sys/resourcevar.h> 78 #include <sys/signalvar.h> 79 #include <sys/vnode.h> 80 #include <sys/vmmeter.h> 81 #include <sys/sysctl.h> 82 83 #include <vm/vm.h> 84 #include <vm/vm_param.h> 85 #include <sys/lock.h> 86 #include <vm/vm_object.h> 87 #include <vm/vm_page.h> 88 #include <vm/vm_map.h> 89 #include <vm/vm_pageout.h> 90 #include <vm/vm_pager.h> 91 #include <vm/swap_pager.h> 92 #include <vm/vm_extern.h> 93 94 #include <sys/thread2.h> 95 #include <sys/spinlock2.h> 96 #include <vm/vm_page2.h> 97 98 /* 99 * System initialization 100 */ 101 102 /* the kernel process "vm_pageout"*/ 103 static int vm_pageout_clean (vm_page_t); 104 static int vm_pageout_free_page_calc (vm_size_t count); 105 struct thread *pagethread; 106 107 #if !defined(NO_SWAPPING) 108 /* the kernel process "vm_daemon"*/ 109 static void vm_daemon (void); 110 static struct thread *vmthread; 111 112 static struct kproc_desc vm_kp = { 113 "vmdaemon", 114 vm_daemon, 115 &vmthread 116 }; 117 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) 118 #endif 119 120 int vm_pages_needed=0; /* Event on which pageout daemon sleeps */ 121 int vm_pageout_deficit=0; /* Estimated number of pages deficit */ 122 int vm_pageout_pages_needed=0; /* flag saying that the pageout daemon needs pages */ 123 124 #if !defined(NO_SWAPPING) 125 static int vm_pageout_req_swapout; /* XXX */ 126 static int vm_daemon_needed; 127 #endif 128 static int vm_max_launder = 32; 129 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 130 static int vm_pageout_full_stats_interval = 0; 131 static int vm_pageout_stats_free_max=0, vm_pageout_algorithm=0; 132 static int defer_swap_pageouts=0; 133 static int disable_swap_pageouts=0; 134 135 #if defined(NO_SWAPPING) 136 static int vm_swap_enabled=0; 137 static int vm_swap_idle_enabled=0; 138 #else 139 static int vm_swap_enabled=1; 140 static int vm_swap_idle_enabled=0; 141 #endif 142 143 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 144 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 145 146 SYSCTL_INT(_vm, OID_AUTO, max_launder, 147 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 148 149 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 150 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 151 152 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 153 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 154 155 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 156 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 157 158 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max, 159 CTLFLAG_RW, &vm_pageout_stats_free_max, 0, "Not implemented"); 160 161 #if defined(NO_SWAPPING) 162 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 163 CTLFLAG_RD, &vm_swap_enabled, 0, ""); 164 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 165 CTLFLAG_RD, &vm_swap_idle_enabled, 0, ""); 166 #else 167 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 168 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 169 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 170 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 171 #endif 172 173 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 174 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 175 176 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 177 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 178 179 static int pageout_lock_miss; 180 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 181 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 182 183 #define VM_PAGEOUT_PAGE_COUNT 16 184 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 185 186 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 187 188 #if !defined(NO_SWAPPING) 189 typedef void freeer_fcn_t (vm_map_t, vm_object_t, vm_pindex_t, int); 190 static void vm_pageout_map_deactivate_pages (vm_map_t, vm_pindex_t); 191 static freeer_fcn_t vm_pageout_object_deactivate_pages; 192 static void vm_req_vmdaemon (void); 193 #endif 194 static void vm_pageout_page_stats(int q); 195 196 static __inline int 197 PQAVERAGE(int n) 198 { 199 if (n >= 0) 200 return((n + (PQ_L2_SIZE - 1)) / PQ_L2_SIZE + 1); 201 else 202 return((n - (PQ_L2_SIZE - 1)) / PQ_L2_SIZE - 1); 203 } 204 205 /* 206 * vm_pageout_clean: 207 * 208 * Clean the page and remove it from the laundry. The page must not be 209 * busy on-call. 210 * 211 * We set the busy bit to cause potential page faults on this page to 212 * block. Note the careful timing, however, the busy bit isn't set till 213 * late and we cannot do anything that will mess with the page. 214 */ 215 static int 216 vm_pageout_clean(vm_page_t m) 217 { 218 vm_object_t object; 219 vm_page_t mc[2*vm_pageout_page_count]; 220 int pageout_count; 221 int error; 222 int ib, is, page_base; 223 vm_pindex_t pindex = m->pindex; 224 225 object = m->object; 226 227 /* 228 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 229 * with the new swapper, but we could have serious problems paging 230 * out other object types if there is insufficient memory. 231 * 232 * Unfortunately, checking free memory here is far too late, so the 233 * check has been moved up a procedural level. 234 */ 235 236 /* 237 * Don't mess with the page if it's busy, held, or special 238 * 239 * XXX do we really need to check hold_count here? hold_count 240 * isn't supposed to mess with vm_page ops except prevent the 241 * page from being reused. 242 */ 243 if (m->hold_count != 0 || (m->flags & PG_UNMANAGED)) { 244 vm_page_wakeup(m); 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 vm_object_hold(object); 275 more: 276 while (ib && pageout_count < vm_pageout_page_count) { 277 vm_page_t p; 278 279 if (ib > pindex) { 280 ib = 0; 281 break; 282 } 283 284 p = vm_page_lookup_busy_try(object, pindex - ib, TRUE, &error); 285 if (error || p == NULL) { 286 ib = 0; 287 break; 288 } 289 if ((p->queue - p->pc) == PQ_CACHE || 290 (p->flags & PG_UNMANAGED)) { 291 vm_page_wakeup(p); 292 ib = 0; 293 break; 294 } 295 vm_page_test_dirty(p); 296 if (((p->dirty & p->valid) == 0 && 297 (p->flags & PG_NEED_COMMIT) == 0) || 298 p->queue - p->pc != PQ_INACTIVE || 299 p->wire_count != 0 || /* may be held by buf cache */ 300 p->hold_count != 0) { /* may be undergoing I/O */ 301 vm_page_wakeup(p); 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 p = vm_page_lookup_busy_try(object, pindex + is, TRUE, &error); 321 if (error || p == NULL) 322 break; 323 if (((p->queue - p->pc) == PQ_CACHE) || 324 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 325 vm_page_wakeup(p); 326 break; 327 } 328 vm_page_test_dirty(p); 329 if (((p->dirty & p->valid) == 0 && 330 (p->flags & PG_NEED_COMMIT) == 0) || 331 p->queue - p->pc != PQ_INACTIVE || 332 p->wire_count != 0 || /* may be held by buf cache */ 333 p->hold_count != 0) { /* may be undergoing I/O */ 334 vm_page_wakeup(p); 335 break; 336 } 337 mc[page_base + pageout_count] = p; 338 ++pageout_count; 339 ++is; 340 } 341 342 /* 343 * If we exhausted our forward scan, continue with the reverse scan 344 * when possible, even past a page boundry. This catches boundry 345 * conditions. 346 */ 347 if (ib && pageout_count < vm_pageout_page_count) 348 goto more; 349 350 vm_object_drop(object); 351 352 /* 353 * we allow reads during pageouts... 354 */ 355 return vm_pageout_flush(&mc[page_base], pageout_count, 0); 356 } 357 358 /* 359 * vm_pageout_flush() - launder the given pages 360 * 361 * The given pages are laundered. Note that we setup for the start of 362 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 363 * reference count all in here rather then in the parent. If we want 364 * the parent to do more sophisticated things we may have to change 365 * the ordering. 366 * 367 * The pages in the array must be busied by the caller and will be 368 * unbusied by this function. 369 */ 370 int 371 vm_pageout_flush(vm_page_t *mc, int count, int flags) 372 { 373 vm_object_t object; 374 int pageout_status[count]; 375 int numpagedout = 0; 376 int i; 377 378 /* 379 * Initiate I/O. Bump the vm_page_t->busy counter. 380 */ 381 for (i = 0; i < count; i++) { 382 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 383 ("vm_pageout_flush page %p index %d/%d: partially " 384 "invalid page", mc[i], i, count)); 385 vm_page_io_start(mc[i]); 386 } 387 388 /* 389 * We must make the pages read-only. This will also force the 390 * modified bit in the related pmaps to be cleared. The pager 391 * cannot clear the bit for us since the I/O completion code 392 * typically runs from an interrupt. The act of making the page 393 * read-only handles the case for us. 394 * 395 * Then we can unbusy the pages, we still hold a reference by virtue 396 * of our soft-busy. 397 */ 398 for (i = 0; i < count; i++) { 399 vm_page_protect(mc[i], VM_PROT_READ); 400 vm_page_wakeup(mc[i]); 401 } 402 403 object = mc[0]->object; 404 vm_object_pip_add(object, count); 405 406 vm_pager_put_pages(object, mc, count, 407 (flags | ((object == &kernel_object) ? VM_PAGER_PUT_SYNC : 0)), 408 pageout_status); 409 410 for (i = 0; i < count; i++) { 411 vm_page_t mt = mc[i]; 412 413 switch (pageout_status[i]) { 414 case VM_PAGER_OK: 415 numpagedout++; 416 break; 417 case VM_PAGER_PEND: 418 numpagedout++; 419 break; 420 case VM_PAGER_BAD: 421 /* 422 * Page outside of range of object. Right now we 423 * essentially lose the changes by pretending it 424 * worked. 425 */ 426 vm_page_busy_wait(mt, FALSE, "pgbad"); 427 pmap_clear_modify(mt); 428 vm_page_undirty(mt); 429 vm_page_wakeup(mt); 430 break; 431 case VM_PAGER_ERROR: 432 case VM_PAGER_FAIL: 433 /* 434 * A page typically cannot be paged out when we 435 * have run out of swap. We leave the page 436 * marked inactive and will try to page it out 437 * again later. 438 * 439 * Starvation of the active page list is used to 440 * determine when the system is massively memory 441 * starved. 442 */ 443 break; 444 case VM_PAGER_AGAIN: 445 break; 446 } 447 448 /* 449 * If the operation is still going, leave the page busy to 450 * block all other accesses. Also, leave the paging in 451 * progress indicator set so that we don't attempt an object 452 * collapse. 453 * 454 * For any pages which have completed synchronously, 455 * deactivate the page if we are under a severe deficit. 456 * Do not try to enter them into the cache, though, they 457 * might still be read-heavy. 458 */ 459 if (pageout_status[i] != VM_PAGER_PEND) { 460 vm_page_busy_wait(mt, FALSE, "pgouw"); 461 if (vm_page_count_severe()) 462 vm_page_deactivate(mt); 463 #if 0 464 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt)) 465 vm_page_protect(mt, VM_PROT_READ); 466 #endif 467 vm_page_io_finish(mt); 468 vm_page_wakeup(mt); 469 vm_object_pip_wakeup(object); 470 } 471 } 472 return numpagedout; 473 } 474 475 #if !defined(NO_SWAPPING) 476 /* 477 * deactivate enough pages to satisfy the inactive target 478 * requirements or if vm_page_proc_limit is set, then 479 * deactivate all of the pages in the object and its 480 * backing_objects. 481 * 482 * The map must be locked. 483 * The caller must hold the vm_object. 484 */ 485 static int vm_pageout_object_deactivate_pages_callback(vm_page_t, void *); 486 487 static void 488 vm_pageout_object_deactivate_pages(vm_map_t map, vm_object_t object, 489 vm_pindex_t desired, int map_remove_only) 490 { 491 struct rb_vm_page_scan_info info; 492 vm_object_t lobject; 493 vm_object_t tobject; 494 int remove_mode; 495 496 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 497 lobject = object; 498 499 while (lobject) { 500 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 501 break; 502 if (lobject->type == OBJT_DEVICE || lobject->type == OBJT_PHYS) 503 break; 504 if (lobject->paging_in_progress) 505 break; 506 507 remove_mode = map_remove_only; 508 if (lobject->shadow_count > 1) 509 remove_mode = 1; 510 511 /* 512 * scan the objects entire memory queue. We hold the 513 * object's token so the scan should not race anything. 514 */ 515 info.limit = remove_mode; 516 info.map = map; 517 info.desired = desired; 518 vm_page_rb_tree_RB_SCAN(&lobject->rb_memq, NULL, 519 vm_pageout_object_deactivate_pages_callback, 520 &info 521 ); 522 while ((tobject = lobject->backing_object) != NULL) { 523 KKASSERT(tobject != object); 524 vm_object_hold(tobject); 525 if (tobject == lobject->backing_object) 526 break; 527 vm_object_drop(tobject); 528 } 529 if (lobject != object) { 530 vm_object_lock_swap(); 531 vm_object_drop(lobject); 532 } 533 lobject = tobject; 534 } 535 if (lobject != object) 536 vm_object_drop(lobject); 537 } 538 539 /* 540 * The caller must hold the vm_object. 541 */ 542 static int 543 vm_pageout_object_deactivate_pages_callback(vm_page_t p, void *data) 544 { 545 struct rb_vm_page_scan_info *info = data; 546 int actcount; 547 548 if (pmap_resident_count(vm_map_pmap(info->map)) <= info->desired) { 549 return(-1); 550 } 551 mycpu->gd_cnt.v_pdpages++; 552 553 if (vm_page_busy_try(p, TRUE)) 554 return(0); 555 if (p->wire_count || p->hold_count || (p->flags & PG_UNMANAGED)) { 556 vm_page_wakeup(p); 557 return(0); 558 } 559 if (!pmap_page_exists_quick(vm_map_pmap(info->map), p)) { 560 vm_page_wakeup(p); 561 return(0); 562 } 563 564 actcount = pmap_ts_referenced(p); 565 if (actcount) { 566 vm_page_flag_set(p, PG_REFERENCED); 567 } else if (p->flags & PG_REFERENCED) { 568 actcount = 1; 569 } 570 571 vm_page_and_queue_spin_lock(p); 572 if (p->queue - p->pc != PQ_ACTIVE && (p->flags & PG_REFERENCED)) { 573 vm_page_and_queue_spin_unlock(p); 574 vm_page_activate(p); 575 p->act_count += actcount; 576 vm_page_flag_clear(p, PG_REFERENCED); 577 } else if (p->queue - p->pc == PQ_ACTIVE) { 578 if ((p->flags & PG_REFERENCED) == 0) { 579 p->act_count -= min(p->act_count, ACT_DECLINE); 580 if (!info->limit && 581 (vm_pageout_algorithm || (p->act_count == 0))) { 582 vm_page_and_queue_spin_unlock(p); 583 vm_page_protect(p, VM_PROT_NONE); 584 vm_page_deactivate(p); 585 } else { 586 TAILQ_REMOVE(&vm_page_queues[p->queue].pl, 587 p, pageq); 588 TAILQ_INSERT_TAIL(&vm_page_queues[p->queue].pl, 589 p, pageq); 590 vm_page_and_queue_spin_unlock(p); 591 } 592 } else { 593 vm_page_and_queue_spin_unlock(p); 594 vm_page_activate(p); 595 vm_page_flag_clear(p, PG_REFERENCED); 596 597 vm_page_and_queue_spin_lock(p); 598 if (p->queue - p->pc == PQ_ACTIVE) { 599 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 600 p->act_count += ACT_ADVANCE; 601 TAILQ_REMOVE(&vm_page_queues[p->queue].pl, 602 p, pageq); 603 TAILQ_INSERT_TAIL(&vm_page_queues[p->queue].pl, 604 p, pageq); 605 } 606 vm_page_and_queue_spin_unlock(p); 607 } 608 } else if (p->queue - p->pc == PQ_INACTIVE) { 609 vm_page_and_queue_spin_unlock(p); 610 vm_page_protect(p, VM_PROT_NONE); 611 } else { 612 vm_page_and_queue_spin_unlock(p); 613 } 614 vm_page_wakeup(p); 615 return(0); 616 } 617 618 /* 619 * Deactivate some number of pages in a map, try to do it fairly, but 620 * that is really hard to do. 621 */ 622 static void 623 vm_pageout_map_deactivate_pages(vm_map_t map, vm_pindex_t desired) 624 { 625 vm_map_entry_t tmpe; 626 vm_object_t obj, bigobj; 627 int nothingwired; 628 629 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT)) { 630 return; 631 } 632 633 bigobj = NULL; 634 nothingwired = TRUE; 635 636 /* 637 * first, search out the biggest object, and try to free pages from 638 * that. 639 */ 640 tmpe = map->header.next; 641 while (tmpe != &map->header) { 642 switch(tmpe->maptype) { 643 case VM_MAPTYPE_NORMAL: 644 case VM_MAPTYPE_VPAGETABLE: 645 obj = tmpe->object.vm_object; 646 if ((obj != NULL) && (obj->shadow_count <= 1) && 647 ((bigobj == NULL) || 648 (bigobj->resident_page_count < obj->resident_page_count))) { 649 bigobj = obj; 650 } 651 break; 652 default: 653 break; 654 } 655 if (tmpe->wired_count > 0) 656 nothingwired = FALSE; 657 tmpe = tmpe->next; 658 } 659 660 if (bigobj) { 661 vm_object_hold(bigobj); 662 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 663 vm_object_drop(bigobj); 664 } 665 666 /* 667 * Next, hunt around for other pages to deactivate. We actually 668 * do this search sort of wrong -- .text first is not the best idea. 669 */ 670 tmpe = map->header.next; 671 while (tmpe != &map->header) { 672 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 673 break; 674 switch(tmpe->maptype) { 675 case VM_MAPTYPE_NORMAL: 676 case VM_MAPTYPE_VPAGETABLE: 677 obj = tmpe->object.vm_object; 678 if (obj) { 679 vm_object_hold(obj); 680 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 681 vm_object_drop(obj); 682 } 683 break; 684 default: 685 break; 686 } 687 tmpe = tmpe->next; 688 }; 689 690 /* 691 * Remove all mappings if a process is swapped out, this will free page 692 * table pages. 693 */ 694 if (desired == 0 && nothingwired) 695 pmap_remove(vm_map_pmap(map), 696 VM_MIN_USER_ADDRESS, VM_MAX_USER_ADDRESS); 697 vm_map_unlock(map); 698 } 699 #endif 700 701 /* 702 * Called when the pageout scan wants to free a page. We no longer 703 * try to cycle the vm_object here with a reference & dealloc, which can 704 * cause a non-trivial object collapse in a critical path. 705 * 706 * It is unclear why we cycled the ref_count in the past, perhaps to try 707 * to optimize shadow chain collapses but I don't quite see why it would 708 * be necessary. An OBJ_DEAD object should terminate any and all vm_pages 709 * synchronously and not have to be kicked-start. 710 */ 711 static void 712 vm_pageout_page_free(vm_page_t m) 713 { 714 vm_page_protect(m, VM_PROT_NONE); 715 vm_page_free(m); 716 } 717 718 /* 719 * vm_pageout_scan does the dirty work for the pageout daemon. 720 */ 721 struct vm_pageout_scan_info { 722 struct proc *bigproc; 723 vm_offset_t bigsize; 724 }; 725 726 static int vm_pageout_scan_callback(struct proc *p, void *data); 727 728 static int 729 vm_pageout_scan_inactive(int pass, int q, int avail_shortage, 730 int *vnodes_skippedp) 731 { 732 vm_page_t m; 733 struct vm_page marker; 734 struct vnode *vpfailed; /* warning, allowed to be stale */ 735 int maxscan; 736 int delta = 0; 737 vm_object_t object; 738 int actcount; 739 int maxlaunder; 740 741 /* 742 * Start scanning the inactive queue for pages we can move to the 743 * cache or free. The scan will stop when the target is reached or 744 * we have scanned the entire inactive queue. Note that m->act_count 745 * is not used to form decisions for the inactive queue, only for the 746 * active queue. 747 * 748 * maxlaunder limits the number of dirty pages we flush per scan. 749 * For most systems a smaller value (16 or 32) is more robust under 750 * extreme memory and disk pressure because any unnecessary writes 751 * to disk can result in extreme performance degredation. However, 752 * systems with excessive dirty pages (especially when MAP_NOSYNC is 753 * used) will die horribly with limited laundering. If the pageout 754 * daemon cannot clean enough pages in the first pass, we let it go 755 * all out in succeeding passes. 756 */ 757 if ((maxlaunder = vm_max_launder) <= 1) 758 maxlaunder = 1; 759 if (pass) 760 maxlaunder = 10000; 761 762 /* 763 * Initialize our marker 764 */ 765 bzero(&marker, sizeof(marker)); 766 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 767 marker.queue = PQ_INACTIVE + q; 768 marker.pc = q; 769 marker.wire_count = 1; 770 771 /* 772 * Inactive queue scan. 773 * 774 * NOTE: The vm_page must be spinlocked before the queue to avoid 775 * deadlocks, so it is easiest to simply iterate the loop 776 * with the queue unlocked at the top. 777 */ 778 vpfailed = NULL; 779 780 vm_page_queues_spin_lock(PQ_INACTIVE + q); 781 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE + q].pl, &marker, pageq); 782 maxscan = vm_page_queues[PQ_INACTIVE + q].lcnt; 783 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 784 785 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL && 786 maxscan-- > 0 && avail_shortage - delta > 0) 787 { 788 vm_page_and_queue_spin_lock(m); 789 if (m != TAILQ_NEXT(&marker, pageq)) { 790 vm_page_and_queue_spin_unlock(m); 791 ++maxscan; 792 continue; 793 } 794 KKASSERT(m->queue - m->pc == PQ_INACTIVE); 795 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl, 796 &marker, pageq); 797 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE + q].pl, m, 798 &marker, pageq); 799 mycpu->gd_cnt.v_pdpages++; 800 801 /* 802 * Skip marker pages 803 */ 804 if (m->flags & PG_MARKER) { 805 vm_page_and_queue_spin_unlock(m); 806 continue; 807 } 808 809 /* 810 * Try to busy the page. Don't mess with pages which are 811 * already busy or reorder them in the queue. 812 */ 813 if (vm_page_busy_try(m, TRUE)) { 814 vm_page_and_queue_spin_unlock(m); 815 continue; 816 } 817 vm_page_and_queue_spin_unlock(m); 818 KKASSERT(m->queue - m->pc == PQ_INACTIVE); 819 820 lwkt_yield(); 821 822 /* 823 * The page has been successfully busied and is now no 824 * longer spinlocked. The queue is no longer spinlocked 825 * either. 826 */ 827 828 /* 829 * It is possible for a page to be busied ad-hoc (e.g. the 830 * pmap_collect() code) and wired and race against the 831 * allocation of a new page. vm_page_alloc() may be forced 832 * to deactivate the wired page in which case it winds up 833 * on the inactive queue and must be handled here. We 834 * correct the problem simply by unqueuing the page. 835 */ 836 if (m->wire_count) { 837 vm_page_unqueue_nowakeup(m); 838 vm_page_wakeup(m); 839 kprintf("WARNING: pagedaemon: wired page on " 840 "inactive queue %p\n", m); 841 continue; 842 } 843 844 /* 845 * A held page may be undergoing I/O, so skip it. 846 */ 847 if (m->hold_count) { 848 vm_page_and_queue_spin_lock(m); 849 if (m->queue - m->pc == PQ_INACTIVE) { 850 TAILQ_REMOVE( 851 &vm_page_queues[PQ_INACTIVE + q].pl, 852 m, pageq); 853 TAILQ_INSERT_TAIL( 854 &vm_page_queues[PQ_INACTIVE + q].pl, 855 m, pageq); 856 ++vm_swapcache_inactive_heuristic; 857 } 858 vm_page_and_queue_spin_unlock(m); 859 vm_page_wakeup(m); 860 continue; 861 } 862 863 if (m->object == NULL || m->object->ref_count == 0) { 864 /* 865 * If the object is not being used, we ignore previous 866 * references. 867 */ 868 vm_page_flag_clear(m, PG_REFERENCED); 869 pmap_clear_reference(m); 870 /* fall through to end */ 871 } else if (((m->flags & PG_REFERENCED) == 0) && 872 (actcount = pmap_ts_referenced(m))) { 873 /* 874 * Otherwise, if the page has been referenced while 875 * in the inactive queue, we bump the "activation 876 * count" upwards, making it less likely that the 877 * page will be added back to the inactive queue 878 * prematurely again. Here we check the page tables 879 * (or emulated bits, if any), given the upper level 880 * VM system not knowing anything about existing 881 * references. 882 */ 883 vm_page_activate(m); 884 m->act_count += (actcount + ACT_ADVANCE); 885 vm_page_wakeup(m); 886 continue; 887 } 888 889 /* 890 * (m) is still busied. 891 * 892 * If the upper level VM system knows about any page 893 * references, we activate the page. We also set the 894 * "activation count" higher than normal so that we will less 895 * likely place pages back onto the inactive queue again. 896 */ 897 if ((m->flags & PG_REFERENCED) != 0) { 898 vm_page_flag_clear(m, PG_REFERENCED); 899 actcount = pmap_ts_referenced(m); 900 vm_page_activate(m); 901 m->act_count += (actcount + ACT_ADVANCE + 1); 902 vm_page_wakeup(m); 903 continue; 904 } 905 906 /* 907 * If the upper level VM system doesn't know anything about 908 * the page being dirty, we have to check for it again. As 909 * far as the VM code knows, any partially dirty pages are 910 * fully dirty. 911 * 912 * Pages marked PG_WRITEABLE may be mapped into the user 913 * address space of a process running on another cpu. A 914 * user process (without holding the MP lock) running on 915 * another cpu may be able to touch the page while we are 916 * trying to remove it. vm_page_cache() will handle this 917 * case for us. 918 */ 919 if (m->dirty == 0) { 920 vm_page_test_dirty(m); 921 } else { 922 vm_page_dirty(m); 923 } 924 925 if (m->valid == 0 && (m->flags & PG_NEED_COMMIT) == 0) { 926 /* 927 * Invalid pages can be easily freed 928 */ 929 vm_pageout_page_free(m); 930 mycpu->gd_cnt.v_dfree++; 931 ++delta; 932 } else if (m->dirty == 0 && (m->flags & PG_NEED_COMMIT) == 0) { 933 /* 934 * Clean pages can be placed onto the cache queue. 935 * This effectively frees them. 936 */ 937 vm_page_cache(m); 938 ++delta; 939 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 940 /* 941 * Dirty pages need to be paged out, but flushing 942 * a page is extremely expensive verses freeing 943 * a clean page. Rather then artificially limiting 944 * the number of pages we can flush, we instead give 945 * dirty pages extra priority on the inactive queue 946 * by forcing them to be cycled through the queue 947 * twice before being flushed, after which the 948 * (now clean) page will cycle through once more 949 * before being freed. This significantly extends 950 * the thrash point for a heavily loaded machine. 951 */ 952 vm_page_flag_set(m, PG_WINATCFLS); 953 vm_page_and_queue_spin_lock(m); 954 if (m->queue - m->pc == PQ_INACTIVE) { 955 TAILQ_REMOVE( 956 &vm_page_queues[PQ_INACTIVE + q].pl, 957 m, pageq); 958 TAILQ_INSERT_TAIL( 959 &vm_page_queues[PQ_INACTIVE + q].pl, 960 m, pageq); 961 ++vm_swapcache_inactive_heuristic; 962 } 963 vm_page_and_queue_spin_unlock(m); 964 vm_page_wakeup(m); 965 } else if (maxlaunder > 0) { 966 /* 967 * We always want to try to flush some dirty pages if 968 * we encounter them, to keep the system stable. 969 * Normally this number is small, but under extreme 970 * pressure where there are insufficient clean pages 971 * on the inactive queue, we may have to go all out. 972 */ 973 int swap_pageouts_ok; 974 struct vnode *vp = NULL; 975 976 swap_pageouts_ok = 0; 977 object = m->object; 978 if (object && 979 (object->type != OBJT_SWAP) && 980 (object->type != OBJT_DEFAULT)) { 981 swap_pageouts_ok = 1; 982 } else { 983 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 984 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 985 vm_page_count_min(0)); 986 987 } 988 989 /* 990 * We don't bother paging objects that are "dead". 991 * Those objects are in a "rundown" state. 992 */ 993 if (!swap_pageouts_ok || 994 (object == NULL) || 995 (object->flags & OBJ_DEAD)) { 996 vm_page_and_queue_spin_lock(m); 997 if (m->queue - m->pc == PQ_INACTIVE) { 998 TAILQ_REMOVE( 999 &vm_page_queues[PQ_INACTIVE + q].pl, 1000 m, pageq); 1001 TAILQ_INSERT_TAIL( 1002 &vm_page_queues[PQ_INACTIVE + q].pl, 1003 m, pageq); 1004 ++vm_swapcache_inactive_heuristic; 1005 } 1006 vm_page_and_queue_spin_unlock(m); 1007 vm_page_wakeup(m); 1008 continue; 1009 } 1010 1011 /* 1012 * (m) is still busied. 1013 * 1014 * The object is already known NOT to be dead. It 1015 * is possible for the vget() to block the whole 1016 * pageout daemon, but the new low-memory handling 1017 * code should prevent it. 1018 * 1019 * The previous code skipped locked vnodes and, worse, 1020 * reordered pages in the queue. This results in 1021 * completely non-deterministic operation because, 1022 * quite often, a vm_fault has initiated an I/O and 1023 * is holding a locked vnode at just the point where 1024 * the pageout daemon is woken up. 1025 * 1026 * We can't wait forever for the vnode lock, we might 1027 * deadlock due to a vn_read() getting stuck in 1028 * vm_wait while holding this vnode. We skip the 1029 * vnode if we can't get it in a reasonable amount 1030 * of time. 1031 * 1032 * vpfailed is used to (try to) avoid the case where 1033 * a large number of pages are associated with a 1034 * locked vnode, which could cause the pageout daemon 1035 * to stall for an excessive amount of time. 1036 */ 1037 if (object->type == OBJT_VNODE) { 1038 int flags; 1039 1040 vp = object->handle; 1041 flags = LK_EXCLUSIVE | LK_NOOBJ; 1042 if (vp == vpfailed) 1043 flags |= LK_NOWAIT; 1044 else 1045 flags |= LK_TIMELOCK; 1046 vm_page_hold(m); 1047 vm_page_wakeup(m); 1048 1049 /* 1050 * We have unbusied (m) temporarily so we can 1051 * acquire the vp lock without deadlocking. 1052 * (m) is held to prevent destruction. 1053 */ 1054 if (vget(vp, flags) != 0) { 1055 vpfailed = vp; 1056 ++pageout_lock_miss; 1057 if (object->flags & OBJ_MIGHTBEDIRTY) 1058 ++*vnodes_skippedp; 1059 vm_page_unhold(m); 1060 continue; 1061 } 1062 1063 /* 1064 * The page might have been moved to another 1065 * queue during potential blocking in vget() 1066 * above. The page might have been freed and 1067 * reused for another vnode. The object might 1068 * have been reused for another vnode. 1069 */ 1070 if (m->queue - m->pc != PQ_INACTIVE || 1071 m->object != object || 1072 object->handle != vp) { 1073 if (object->flags & OBJ_MIGHTBEDIRTY) 1074 ++*vnodes_skippedp; 1075 vput(vp); 1076 vm_page_unhold(m); 1077 continue; 1078 } 1079 1080 /* 1081 * The page may have been busied during the 1082 * blocking in vput(); We don't move the 1083 * page back onto the end of the queue so that 1084 * statistics are more correct if we don't. 1085 */ 1086 if (vm_page_busy_try(m, TRUE)) { 1087 vput(vp); 1088 vm_page_unhold(m); 1089 continue; 1090 } 1091 vm_page_unhold(m); 1092 1093 /* 1094 * (m) is busied again 1095 * 1096 * We own the busy bit and remove our hold 1097 * bit. If the page is still held it 1098 * might be undergoing I/O, so skip it. 1099 */ 1100 if (m->hold_count) { 1101 vm_page_and_queue_spin_lock(m); 1102 if (m->queue - m->pc == PQ_INACTIVE) { 1103 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl, m, pageq); 1104 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE + q].pl, m, pageq); 1105 ++vm_swapcache_inactive_heuristic; 1106 } 1107 vm_page_and_queue_spin_unlock(m); 1108 if (object->flags & OBJ_MIGHTBEDIRTY) 1109 ++*vnodes_skippedp; 1110 vm_page_wakeup(m); 1111 vput(vp); 1112 continue; 1113 } 1114 /* (m) is left busied as we fall through */ 1115 } 1116 1117 /* 1118 * page is busy and not held here. 1119 * 1120 * If a page is dirty, then it is either being washed 1121 * (but not yet cleaned) or it is still in the 1122 * laundry. If it is still in the laundry, then we 1123 * start the cleaning operation. 1124 * 1125 * decrement inactive_shortage on success to account 1126 * for the (future) cleaned page. Otherwise we 1127 * could wind up laundering or cleaning too many 1128 * pages. 1129 */ 1130 if (vm_pageout_clean(m) != 0) { 1131 ++delta; 1132 --maxlaunder; 1133 } 1134 /* clean ate busy, page no longer accessible */ 1135 if (vp != NULL) 1136 vput(vp); 1137 } else { 1138 vm_page_wakeup(m); 1139 } 1140 } 1141 vm_page_queues_spin_lock(PQ_INACTIVE + q); 1142 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl, &marker, pageq); 1143 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 1144 return (delta); 1145 } 1146 1147 static int 1148 vm_pageout_scan_active(int pass, int q, 1149 int avail_shortage, int inactive_shortage, 1150 int *recycle_countp) 1151 { 1152 struct vm_page marker; 1153 vm_page_t m; 1154 int actcount; 1155 int delta = 0; 1156 int maxscan; 1157 1158 /* 1159 * We want to move pages from the active queue to the inactive 1160 * queue to get the inactive queue to the inactive target. If 1161 * we still have a page shortage from above we try to directly free 1162 * clean pages instead of moving them. 1163 * 1164 * If we do still have a shortage we keep track of the number of 1165 * pages we free or cache (recycle_count) as a measure of thrashing 1166 * between the active and inactive queues. 1167 * 1168 * If we were able to completely satisfy the free+cache targets 1169 * from the inactive pool we limit the number of pages we move 1170 * from the active pool to the inactive pool to 2x the pages we 1171 * had removed from the inactive pool (with a minimum of 1/5 the 1172 * inactive target). If we were not able to completely satisfy 1173 * the free+cache targets we go for the whole target aggressively. 1174 * 1175 * NOTE: Both variables can end up negative. 1176 * NOTE: We are still in a critical section. 1177 */ 1178 1179 bzero(&marker, sizeof(marker)); 1180 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 1181 marker.queue = PQ_ACTIVE + q; 1182 marker.pc = q; 1183 marker.wire_count = 1; 1184 1185 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1186 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1187 maxscan = vm_page_queues[PQ_ACTIVE + q].lcnt; 1188 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1189 1190 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL && 1191 maxscan-- > 0 && (avail_shortage - delta > 0 || 1192 inactive_shortage > 0)) 1193 { 1194 vm_page_and_queue_spin_lock(m); 1195 if (m != TAILQ_NEXT(&marker, pageq)) { 1196 vm_page_and_queue_spin_unlock(m); 1197 ++maxscan; 1198 continue; 1199 } 1200 KKASSERT(m->queue - m->pc == PQ_ACTIVE); 1201 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, 1202 &marker, pageq); 1203 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_ACTIVE + q].pl, m, 1204 &marker, pageq); 1205 1206 /* 1207 * Skip marker pages 1208 */ 1209 if (m->flags & PG_MARKER) { 1210 vm_page_and_queue_spin_unlock(m); 1211 continue; 1212 } 1213 1214 /* 1215 * Try to busy the page. Don't mess with pages which are 1216 * already busy or reorder them in the queue. 1217 */ 1218 if (vm_page_busy_try(m, TRUE)) { 1219 vm_page_and_queue_spin_unlock(m); 1220 continue; 1221 } 1222 1223 /* 1224 * Don't deactivate pages that are held, even if we can 1225 * busy them. (XXX why not?) 1226 */ 1227 if (m->hold_count != 0) { 1228 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, 1229 m, pageq); 1230 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE + q].pl, 1231 m, pageq); 1232 vm_page_and_queue_spin_unlock(m); 1233 vm_page_wakeup(m); 1234 continue; 1235 } 1236 vm_page_and_queue_spin_unlock(m); 1237 lwkt_yield(); 1238 1239 /* 1240 * The page has been successfully busied and the page and 1241 * queue are no longer locked. 1242 */ 1243 1244 /* 1245 * The count for pagedaemon pages is done after checking the 1246 * page for eligibility... 1247 */ 1248 mycpu->gd_cnt.v_pdpages++; 1249 1250 /* 1251 * Check to see "how much" the page has been used and clear 1252 * the tracking access bits. If the object has no references 1253 * don't bother paying the expense. 1254 */ 1255 actcount = 0; 1256 if (m->object && m->object->ref_count != 0) { 1257 if (m->flags & PG_REFERENCED) 1258 ++actcount; 1259 actcount += pmap_ts_referenced(m); 1260 if (actcount) { 1261 m->act_count += ACT_ADVANCE + actcount; 1262 if (m->act_count > ACT_MAX) 1263 m->act_count = ACT_MAX; 1264 } 1265 } 1266 vm_page_flag_clear(m, PG_REFERENCED); 1267 1268 /* 1269 * actcount is only valid if the object ref_count is non-zero. 1270 * If the page does not have an object, actcount will be zero. 1271 */ 1272 if (actcount && m->object->ref_count != 0) { 1273 vm_page_and_queue_spin_lock(m); 1274 if (m->queue - m->pc == PQ_ACTIVE) { 1275 TAILQ_REMOVE( 1276 &vm_page_queues[PQ_ACTIVE + q].pl, 1277 m, pageq); 1278 TAILQ_INSERT_TAIL( 1279 &vm_page_queues[PQ_ACTIVE + q].pl, 1280 m, pageq); 1281 } 1282 vm_page_and_queue_spin_unlock(m); 1283 vm_page_wakeup(m); 1284 } else { 1285 m->act_count -= min(m->act_count, ACT_DECLINE); 1286 if (vm_pageout_algorithm || 1287 (m->object == NULL) || 1288 (m->object && (m->object->ref_count == 0)) || 1289 m->act_count < pass + 1 1290 ) { 1291 /* 1292 * Deactivate the page. If we had a 1293 * shortage from our inactive scan try to 1294 * free (cache) the page instead. 1295 * 1296 * Don't just blindly cache the page if 1297 * we do not have a shortage from the 1298 * inactive scan, that could lead to 1299 * gigabytes being moved. 1300 */ 1301 --inactive_shortage; 1302 if (avail_shortage - delta > 0 || 1303 (m->object && (m->object->ref_count == 0))) 1304 { 1305 if (avail_shortage - delta > 0) 1306 ++*recycle_countp; 1307 vm_page_protect(m, VM_PROT_NONE); 1308 if (m->dirty == 0 && 1309 (m->flags & PG_NEED_COMMIT) == 0 && 1310 avail_shortage - delta > 0) { 1311 vm_page_cache(m); 1312 } else { 1313 vm_page_deactivate(m); 1314 vm_page_wakeup(m); 1315 } 1316 } else { 1317 vm_page_deactivate(m); 1318 vm_page_wakeup(m); 1319 } 1320 ++delta; 1321 } else { 1322 vm_page_and_queue_spin_lock(m); 1323 if (m->queue - m->pc == PQ_ACTIVE) { 1324 TAILQ_REMOVE( 1325 &vm_page_queues[PQ_ACTIVE + q].pl, 1326 m, pageq); 1327 TAILQ_INSERT_TAIL( 1328 &vm_page_queues[PQ_ACTIVE + q].pl, 1329 m, pageq); 1330 } 1331 vm_page_and_queue_spin_unlock(m); 1332 vm_page_wakeup(m); 1333 } 1334 } 1335 } 1336 1337 /* 1338 * Clean out our local marker. 1339 */ 1340 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1341 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1342 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1343 1344 return (delta); 1345 } 1346 1347 /* 1348 * The number of actually free pages can drop down to v_free_reserved, 1349 * we try to build the free count back above v_free_min. Note that 1350 * vm_paging_needed() also returns TRUE if v_free_count is not at 1351 * least v_free_min so that is the minimum we must build the free 1352 * count to. 1353 * 1354 * We use a slightly higher target to improve hysteresis, 1355 * ((v_free_target + v_free_min) / 2). Since v_free_target 1356 * is usually the same as v_cache_min this maintains about 1357 * half the pages in the free queue as are in the cache queue, 1358 * providing pretty good pipelining for pageout operation. 1359 * 1360 * The system operator can manipulate vm.v_cache_min and 1361 * vm.v_free_target to tune the pageout demon. Be sure 1362 * to keep vm.v_free_min < vm.v_free_target. 1363 * 1364 * Note that the original paging target is to get at least 1365 * (free_min + cache_min) into (free + cache). The slightly 1366 * higher target will shift additional pages from cache to free 1367 * without effecting the original paging target in order to 1368 * maintain better hysteresis and not have the free count always 1369 * be dead-on v_free_min. 1370 * 1371 * NOTE: we are still in a critical section. 1372 * 1373 * Pages moved from PQ_CACHE to totally free are not counted in the 1374 * pages_freed counter. 1375 */ 1376 static void 1377 vm_pageout_scan_cache(int avail_shortage, int vnodes_skipped, int recycle_count) 1378 { 1379 struct vm_pageout_scan_info info; 1380 vm_page_t m; 1381 1382 while (vmstats.v_free_count < 1383 (vmstats.v_free_min + vmstats.v_free_target) / 2) { 1384 /* 1385 * This steals some code from vm/vm_page.c 1386 */ 1387 static int cache_rover = 0; 1388 1389 m = vm_page_list_find(PQ_CACHE, cache_rover & PQ_L2_MASK, FALSE); 1390 if (m == NULL) 1391 break; 1392 /* page is returned removed from its queue and spinlocked */ 1393 if (vm_page_busy_try(m, TRUE)) { 1394 vm_page_deactivate_locked(m); 1395 vm_page_spin_unlock(m); 1396 #ifdef INVARIANTS 1397 kprintf("Warning: busy page %p found in cache\n", m); 1398 #endif 1399 continue; 1400 } 1401 vm_page_spin_unlock(m); 1402 pagedaemon_wakeup(); 1403 lwkt_yield(); 1404 1405 /* 1406 * Page has been successfully busied and it and its queue 1407 * is no longer spinlocked. 1408 */ 1409 if ((m->flags & (PG_UNMANAGED | PG_NEED_COMMIT)) || 1410 m->hold_count || 1411 m->wire_count) { 1412 vm_page_deactivate(m); 1413 vm_page_wakeup(m); 1414 continue; 1415 } 1416 KKASSERT((m->flags & PG_MAPPED) == 0); 1417 KKASSERT(m->dirty == 0); 1418 cache_rover += PQ_PRIME2; 1419 vm_pageout_page_free(m); 1420 mycpu->gd_cnt.v_dfree++; 1421 } 1422 1423 #if !defined(NO_SWAPPING) 1424 /* 1425 * Idle process swapout -- run once per second. 1426 */ 1427 if (vm_swap_idle_enabled) { 1428 static long lsec; 1429 if (time_second != lsec) { 1430 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1431 vm_req_vmdaemon(); 1432 lsec = time_second; 1433 } 1434 } 1435 #endif 1436 1437 /* 1438 * If we didn't get enough free pages, and we have skipped a vnode 1439 * in a writeable object, wakeup the sync daemon. And kick swapout 1440 * if we did not get enough free pages. 1441 */ 1442 if (vm_paging_target() > 0) { 1443 if (vnodes_skipped && vm_page_count_min(0)) 1444 speedup_syncer(); 1445 #if !defined(NO_SWAPPING) 1446 if (vm_swap_enabled && vm_page_count_target()) { 1447 vm_req_vmdaemon(); 1448 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1449 } 1450 #endif 1451 } 1452 1453 /* 1454 * Handle catastrophic conditions. Under good conditions we should 1455 * be at the target, well beyond our minimum. If we could not even 1456 * reach our minimum the system is under heavy stress. 1457 * 1458 * Determine whether we have run out of memory. This occurs when 1459 * swap_pager_full is TRUE and the only pages left in the page 1460 * queues are dirty. We will still likely have page shortages. 1461 * 1462 * - swap_pager_full is set if insufficient swap was 1463 * available to satisfy a requested pageout. 1464 * 1465 * - the inactive queue is bloated (4 x size of active queue), 1466 * meaning it is unable to get rid of dirty pages and. 1467 * 1468 * - vm_page_count_min() without counting pages recycled from the 1469 * active queue (recycle_count) means we could not recover 1470 * enough pages to meet bare minimum needs. This test only 1471 * works if the inactive queue is bloated. 1472 * 1473 * - due to a positive avail_shortage we shifted the remaining 1474 * dirty pages from the active queue to the inactive queue 1475 * trying to find clean ones to free. 1476 */ 1477 if (swap_pager_full && vm_page_count_min(recycle_count)) 1478 kprintf("Warning: system low on memory+swap!\n"); 1479 if (swap_pager_full && vm_page_count_min(recycle_count) && 1480 vmstats.v_inactive_count > vmstats.v_active_count * 4 && 1481 avail_shortage > 0) { 1482 /* 1483 * Kill something. 1484 */ 1485 info.bigproc = NULL; 1486 info.bigsize = 0; 1487 allproc_scan(vm_pageout_scan_callback, &info); 1488 if (info.bigproc != NULL) { 1489 killproc(info.bigproc, "out of swap space"); 1490 info.bigproc->p_nice = PRIO_MIN; 1491 info.bigproc->p_usched->resetpriority( 1492 FIRST_LWP_IN_PROC(info.bigproc)); 1493 wakeup(&vmstats.v_free_count); 1494 PRELE(info.bigproc); 1495 } 1496 } 1497 } 1498 1499 /* 1500 * The caller must hold proc_token. 1501 */ 1502 static int 1503 vm_pageout_scan_callback(struct proc *p, void *data) 1504 { 1505 struct vm_pageout_scan_info *info = data; 1506 vm_offset_t size; 1507 1508 /* 1509 * Never kill system processes or init. If we have configured swap 1510 * then try to avoid killing low-numbered pids. 1511 */ 1512 if ((p->p_flags & P_SYSTEM) || (p->p_pid == 1) || 1513 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1514 return (0); 1515 } 1516 1517 /* 1518 * if the process is in a non-running type state, 1519 * don't touch it. 1520 */ 1521 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) 1522 return (0); 1523 1524 /* 1525 * Get the approximate process size. Note that anonymous pages 1526 * with backing swap will be counted twice, but there should not 1527 * be too many such pages due to the stress the VM system is 1528 * under at this point. 1529 */ 1530 size = vmspace_anonymous_count(p->p_vmspace) + 1531 vmspace_swap_count(p->p_vmspace); 1532 1533 /* 1534 * If the this process is bigger than the biggest one 1535 * remember it. 1536 */ 1537 if (info->bigsize < size) { 1538 if (info->bigproc) 1539 PRELE(info->bigproc); 1540 PHOLD(p); 1541 info->bigproc = p; 1542 info->bigsize = size; 1543 } 1544 lwkt_yield(); 1545 return(0); 1546 } 1547 1548 /* 1549 * This routine tries to maintain the pseudo LRU active queue, 1550 * so that during long periods of time where there is no paging, 1551 * that some statistic accumulation still occurs. This code 1552 * helps the situation where paging just starts to occur. 1553 */ 1554 static void 1555 vm_pageout_page_stats(int q) 1556 { 1557 static int fullintervalcount = 0; 1558 struct vm_page marker; 1559 vm_page_t m; 1560 int pcount, tpcount; /* Number of pages to check */ 1561 int page_shortage; 1562 1563 page_shortage = (vmstats.v_inactive_target + vmstats.v_cache_max + 1564 vmstats.v_free_min) - 1565 (vmstats.v_free_count + vmstats.v_inactive_count + 1566 vmstats.v_cache_count); 1567 1568 if (page_shortage <= 0) 1569 return; 1570 1571 pcount = vm_page_queues[PQ_ACTIVE + q].lcnt; 1572 fullintervalcount += vm_pageout_stats_interval; 1573 if (fullintervalcount < vm_pageout_full_stats_interval) { 1574 tpcount = (vm_pageout_stats_max * pcount) / 1575 vmstats.v_page_count + 1; 1576 if (pcount > tpcount) 1577 pcount = tpcount; 1578 } else { 1579 fullintervalcount = 0; 1580 } 1581 1582 bzero(&marker, sizeof(marker)); 1583 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 1584 marker.queue = PQ_ACTIVE + q; 1585 marker.pc = q; 1586 marker.wire_count = 1; 1587 1588 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1589 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1590 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1591 1592 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL && 1593 pcount-- > 0) 1594 { 1595 int actcount; 1596 1597 vm_page_and_queue_spin_lock(m); 1598 if (m != TAILQ_NEXT(&marker, pageq)) { 1599 vm_page_and_queue_spin_unlock(m); 1600 ++pcount; 1601 continue; 1602 } 1603 KKASSERT(m->queue - m->pc == PQ_ACTIVE); 1604 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1605 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_ACTIVE + q].pl, m, 1606 &marker, pageq); 1607 1608 /* 1609 * Ignore markers 1610 */ 1611 if (m->flags & PG_MARKER) { 1612 vm_page_and_queue_spin_unlock(m); 1613 continue; 1614 } 1615 1616 /* 1617 * Ignore pages we can't busy 1618 */ 1619 if (vm_page_busy_try(m, TRUE)) { 1620 vm_page_and_queue_spin_unlock(m); 1621 continue; 1622 } 1623 vm_page_and_queue_spin_unlock(m); 1624 KKASSERT(m->queue - m->pc == PQ_ACTIVE); 1625 1626 /* 1627 * We now have a safely busied page, the page and queue 1628 * spinlocks have been released. 1629 * 1630 * Ignore held pages 1631 */ 1632 if (m->hold_count) { 1633 vm_page_wakeup(m); 1634 continue; 1635 } 1636 1637 /* 1638 * Calculate activity 1639 */ 1640 actcount = 0; 1641 if (m->flags & PG_REFERENCED) { 1642 vm_page_flag_clear(m, PG_REFERENCED); 1643 actcount += 1; 1644 } 1645 actcount += pmap_ts_referenced(m); 1646 1647 /* 1648 * Update act_count and move page to end of queue. 1649 */ 1650 if (actcount) { 1651 m->act_count += ACT_ADVANCE + actcount; 1652 if (m->act_count > ACT_MAX) 1653 m->act_count = ACT_MAX; 1654 vm_page_and_queue_spin_lock(m); 1655 if (m->queue - m->pc == PQ_ACTIVE) { 1656 TAILQ_REMOVE( 1657 &vm_page_queues[PQ_ACTIVE + q].pl, 1658 m, pageq); 1659 TAILQ_INSERT_TAIL( 1660 &vm_page_queues[PQ_ACTIVE + q].pl, 1661 m, pageq); 1662 } 1663 vm_page_and_queue_spin_unlock(m); 1664 vm_page_wakeup(m); 1665 continue; 1666 } 1667 1668 if (m->act_count == 0) { 1669 /* 1670 * We turn off page access, so that we have 1671 * more accurate RSS stats. We don't do this 1672 * in the normal page deactivation when the 1673 * system is loaded VM wise, because the 1674 * cost of the large number of page protect 1675 * operations would be higher than the value 1676 * of doing the operation. 1677 * 1678 * We use the marker to save our place so 1679 * we can release the spin lock. both (m) 1680 * and (next) will be invalid. 1681 */ 1682 vm_page_protect(m, VM_PROT_NONE); 1683 vm_page_deactivate(m); 1684 } else { 1685 m->act_count -= min(m->act_count, ACT_DECLINE); 1686 vm_page_and_queue_spin_lock(m); 1687 if (m->queue - m->pc == PQ_ACTIVE) { 1688 TAILQ_REMOVE( 1689 &vm_page_queues[PQ_ACTIVE + q].pl, 1690 m, pageq); 1691 TAILQ_INSERT_TAIL( 1692 &vm_page_queues[PQ_ACTIVE + q].pl, 1693 m, pageq); 1694 } 1695 vm_page_and_queue_spin_unlock(m); 1696 } 1697 vm_page_wakeup(m); 1698 } 1699 1700 /* 1701 * Remove our local marker 1702 */ 1703 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1704 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1705 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1706 } 1707 1708 static int 1709 vm_pageout_free_page_calc(vm_size_t count) 1710 { 1711 if (count < vmstats.v_page_count) 1712 return 0; 1713 /* 1714 * free_reserved needs to include enough for the largest swap pager 1715 * structures plus enough for any pv_entry structs when paging. 1716 * 1717 * v_free_min normal allocations 1718 * v_free_reserved system allocations 1719 * v_pageout_free_min allocations by pageout daemon 1720 * v_interrupt_free_min low level allocations (e.g swap structures) 1721 */ 1722 if (vmstats.v_page_count > 1024) 1723 vmstats.v_free_min = 64 + (vmstats.v_page_count - 1024) / 200; 1724 else 1725 vmstats.v_free_min = 64; 1726 vmstats.v_free_reserved = vmstats.v_free_min * 4 / 8 + 7; 1727 vmstats.v_free_severe = vmstats.v_free_min * 4 / 8 + 0; 1728 vmstats.v_pageout_free_min = vmstats.v_free_min * 2 / 8 + 7; 1729 vmstats.v_interrupt_free_min = vmstats.v_free_min * 1 / 8 + 7; 1730 1731 return 1; 1732 } 1733 1734 1735 /* 1736 * vm_pageout is the high level pageout daemon. 1737 * 1738 * No requirements. 1739 */ 1740 static void 1741 vm_pageout_thread(void) 1742 { 1743 int pass; 1744 int q; 1745 1746 /* 1747 * Initialize some paging parameters. 1748 */ 1749 curthread->td_flags |= TDF_SYSTHREAD; 1750 1751 if (vmstats.v_page_count < 2000) 1752 vm_pageout_page_count = 8; 1753 1754 vm_pageout_free_page_calc(vmstats.v_page_count); 1755 1756 /* 1757 * v_free_target and v_cache_min control pageout hysteresis. Note 1758 * that these are more a measure of the VM cache queue hysteresis 1759 * then the VM free queue. Specifically, v_free_target is the 1760 * high water mark (free+cache pages). 1761 * 1762 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1763 * low water mark, while v_free_min is the stop. v_cache_min must 1764 * be big enough to handle memory needs while the pageout daemon 1765 * is signalled and run to free more pages. 1766 */ 1767 if (vmstats.v_free_count > 6144) 1768 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved; 1769 else 1770 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved; 1771 1772 /* 1773 * NOTE: With the new buffer cache b_act_count we want the default 1774 * inactive target to be a percentage of available memory. 1775 * 1776 * The inactive target essentially determines the minimum 1777 * number of 'temporary' pages capable of caching one-time-use 1778 * files when the VM system is otherwise full of pages 1779 * belonging to multi-time-use files or active program data. 1780 * 1781 * NOTE: The inactive target is aggressively persued only if the 1782 * inactive queue becomes too small. If the inactive queue 1783 * is large enough to satisfy page movement to free+cache 1784 * then it is repopulated more slowly from the active queue. 1785 * This allows a general inactive_target default to be set. 1786 * 1787 * There is an issue here for processes which sit mostly idle 1788 * 'overnight', such as sshd, tcsh, and X. Any movement from 1789 * the active queue will eventually cause such pages to 1790 * recycle eventually causing a lot of paging in the morning. 1791 * To reduce the incidence of this pages cycled out of the 1792 * buffer cache are moved directly to the inactive queue if 1793 * they were only used once or twice. 1794 * 1795 * The vfs.vm_cycle_point sysctl can be used to adjust this. 1796 * Increasing the value (up to 64) increases the number of 1797 * buffer recyclements which go directly to the inactive queue. 1798 */ 1799 if (vmstats.v_free_count > 2048) { 1800 vmstats.v_cache_min = vmstats.v_free_target; 1801 vmstats.v_cache_max = 2 * vmstats.v_cache_min; 1802 } else { 1803 vmstats.v_cache_min = 0; 1804 vmstats.v_cache_max = 0; 1805 } 1806 vmstats.v_inactive_target = vmstats.v_free_count / 4; 1807 1808 /* XXX does not really belong here */ 1809 if (vm_page_max_wired == 0) 1810 vm_page_max_wired = vmstats.v_free_count / 3; 1811 1812 if (vm_pageout_stats_max == 0) 1813 vm_pageout_stats_max = vmstats.v_free_target; 1814 1815 /* 1816 * Set interval in seconds for stats scan. 1817 */ 1818 if (vm_pageout_stats_interval == 0) 1819 vm_pageout_stats_interval = 5; 1820 if (vm_pageout_full_stats_interval == 0) 1821 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1822 1823 1824 /* 1825 * Set maximum free per pass 1826 */ 1827 if (vm_pageout_stats_free_max == 0) 1828 vm_pageout_stats_free_max = 5; 1829 1830 swap_pager_swap_init(); 1831 pass = 0; 1832 1833 /* 1834 * The pageout daemon is never done, so loop forever. 1835 */ 1836 while (TRUE) { 1837 int error; 1838 int delta1; 1839 int delta2; 1840 int avail_shortage; 1841 int inactive_shortage; 1842 int vnodes_skipped = 0; 1843 int recycle_count = 0; 1844 int tmp; 1845 1846 /* 1847 * Wait for an action request. If we timeout check to 1848 * see if paging is needed (in case the normal wakeup 1849 * code raced us). 1850 */ 1851 if (vm_pages_needed == 0) { 1852 error = tsleep(&vm_pages_needed, 1853 0, "psleep", 1854 vm_pageout_stats_interval * hz); 1855 if (error && 1856 vm_paging_needed() == 0 && 1857 vm_pages_needed == 0) { 1858 for (q = 0; q < PQ_L2_SIZE; ++q) 1859 vm_pageout_page_stats(q); 1860 continue; 1861 } 1862 vm_pages_needed = 1; 1863 } 1864 1865 mycpu->gd_cnt.v_pdwakeups++; 1866 1867 /* 1868 * Do whatever cleanup that the pmap code can. 1869 */ 1870 pmap_collect(); 1871 1872 /* 1873 * Scan for pageout. Try to avoid thrashing the system 1874 * with activity. 1875 * 1876 * Calculate our target for the number of free+cache pages we 1877 * want to get to. This is higher then the number that causes 1878 * allocations to stall (severe) in order to provide hysteresis, 1879 * and if we don't make it all the way but get to the minimum 1880 * we're happy. Goose it a bit if there are multipler 1881 * requests for memory. 1882 */ 1883 avail_shortage = vm_paging_target() + vm_pageout_deficit; 1884 vm_pageout_deficit = 0; 1885 delta1 = 0; 1886 if (avail_shortage > 0) { 1887 for (q = 0; q < PQ_L2_SIZE; ++q) { 1888 delta1 += vm_pageout_scan_inactive( 1889 pass, q, 1890 PQAVERAGE(avail_shortage), 1891 &vnodes_skipped); 1892 } 1893 avail_shortage -= delta1; 1894 } 1895 1896 /* 1897 * Figure out how many active pages we must deactivate. If 1898 * we were able to reach our target with just the inactive 1899 * scan above we limit the number of active pages we 1900 * deactivate to reduce unnecessary work. 1901 */ 1902 inactive_shortage = vmstats.v_inactive_target - 1903 vmstats.v_inactive_count; 1904 1905 /* 1906 * If we were unable to free sufficient inactive pages to 1907 * satisfy the free/cache queue requirements then simply 1908 * reaching the inactive target may not be good enough. 1909 * Try to deactivate pages in excess of the target based 1910 * on the shortfall. 1911 * 1912 * However to prevent thrashing the VM system do not 1913 * deactivate more than an additional 1/10 the inactive 1914 * target's worth of active pages. 1915 */ 1916 if (avail_shortage > 0) { 1917 tmp = avail_shortage * 2; 1918 if (tmp > vmstats.v_inactive_target / 10) 1919 tmp = vmstats.v_inactive_target / 10; 1920 inactive_shortage += tmp; 1921 } 1922 1923 if (avail_shortage > 0 || inactive_shortage > 0) { 1924 delta2 = 0; 1925 for (q = 0; q < PQ_L2_SIZE; ++q) { 1926 delta2 += vm_pageout_scan_active( 1927 pass, q, 1928 PQAVERAGE(avail_shortage), 1929 PQAVERAGE(inactive_shortage), 1930 &recycle_count); 1931 } 1932 inactive_shortage -= delta2; 1933 avail_shortage -= delta2; 1934 } 1935 1936 /* 1937 * Finally free enough cache pages to meet our free page 1938 * requirement and take more drastic measures if we are 1939 * still in trouble. 1940 */ 1941 vm_pageout_scan_cache(avail_shortage, vnodes_skipped, 1942 recycle_count); 1943 1944 /* 1945 * Wait for more work. 1946 */ 1947 if (avail_shortage > 0) { 1948 ++pass; 1949 if (swap_pager_full) { 1950 /* 1951 * Running out of memory, catastrophic back-off 1952 * to one-second intervals. 1953 */ 1954 tsleep(&vm_pages_needed, 0, "pdelay", hz); 1955 } else if (pass < 10 && vm_pages_needed > 1) { 1956 /* 1957 * Normal operation, additional processes 1958 * have already kicked us. Retry immediately. 1959 */ 1960 } else if (pass < 10) { 1961 /* 1962 * Normal operation, fewer processes. Delay 1963 * a bit but allow wakeups. 1964 */ 1965 vm_pages_needed = 0; 1966 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10); 1967 vm_pages_needed = 1; 1968 } else { 1969 /* 1970 * We've taken too many passes, forced delay. 1971 */ 1972 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10); 1973 } 1974 } else { 1975 /* 1976 * Interlocked wakeup of waiters (non-optional) 1977 */ 1978 pass = 0; 1979 if (vm_pages_needed && !vm_page_count_min(0)) { 1980 wakeup(&vmstats.v_free_count); 1981 vm_pages_needed = 0; 1982 } 1983 } 1984 } 1985 } 1986 1987 static struct kproc_desc page_kp = { 1988 "pagedaemon", 1989 vm_pageout_thread, 1990 &pagethread 1991 }; 1992 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 1993 1994 1995 /* 1996 * Called after allocating a page out of the cache or free queue 1997 * to possibly wake the pagedaemon up to replentish our supply. 1998 * 1999 * We try to generate some hysteresis by waking the pagedaemon up 2000 * when our free+cache pages go below the free_min+cache_min level. 2001 * The pagedaemon tries to get the count back up to at least the 2002 * minimum, and through to the target level if possible. 2003 * 2004 * If the pagedaemon is already active bump vm_pages_needed as a hint 2005 * that there are even more requests pending. 2006 * 2007 * SMP races ok? 2008 * No requirements. 2009 */ 2010 void 2011 pagedaemon_wakeup(void) 2012 { 2013 if (vm_paging_needed() && curthread != pagethread) { 2014 if (vm_pages_needed == 0) { 2015 vm_pages_needed = 1; /* SMP race ok */ 2016 wakeup(&vm_pages_needed); 2017 } else if (vm_page_count_min(0)) { 2018 ++vm_pages_needed; /* SMP race ok */ 2019 } 2020 } 2021 } 2022 2023 #if !defined(NO_SWAPPING) 2024 2025 /* 2026 * SMP races ok? 2027 * No requirements. 2028 */ 2029 static void 2030 vm_req_vmdaemon(void) 2031 { 2032 static int lastrun = 0; 2033 2034 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 2035 wakeup(&vm_daemon_needed); 2036 lastrun = ticks; 2037 } 2038 } 2039 2040 static int vm_daemon_callback(struct proc *p, void *data __unused); 2041 2042 /* 2043 * No requirements. 2044 */ 2045 static void 2046 vm_daemon(void) 2047 { 2048 /* 2049 * XXX vm_daemon_needed specific token? 2050 */ 2051 while (TRUE) { 2052 tsleep(&vm_daemon_needed, 0, "psleep", 0); 2053 if (vm_pageout_req_swapout) { 2054 swapout_procs(vm_pageout_req_swapout); 2055 vm_pageout_req_swapout = 0; 2056 } 2057 /* 2058 * scan the processes for exceeding their rlimits or if 2059 * process is swapped out -- deactivate pages 2060 */ 2061 allproc_scan(vm_daemon_callback, NULL); 2062 } 2063 } 2064 2065 /* 2066 * Caller must hold proc_token. 2067 */ 2068 static int 2069 vm_daemon_callback(struct proc *p, void *data __unused) 2070 { 2071 vm_pindex_t limit, size; 2072 2073 /* 2074 * if this is a system process or if we have already 2075 * looked at this process, skip it. 2076 */ 2077 if (p->p_flags & (P_SYSTEM | P_WEXIT)) 2078 return (0); 2079 2080 /* 2081 * if the process is in a non-running type state, 2082 * don't touch it. 2083 */ 2084 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) 2085 return (0); 2086 2087 /* 2088 * get a limit 2089 */ 2090 limit = OFF_TO_IDX(qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 2091 p->p_rlimit[RLIMIT_RSS].rlim_max)); 2092 2093 /* 2094 * let processes that are swapped out really be 2095 * swapped out. Set the limit to nothing to get as 2096 * many pages out to swap as possible. 2097 */ 2098 if (p->p_flags & P_SWAPPEDOUT) 2099 limit = 0; 2100 2101 lwkt_gettoken(&p->p_vmspace->vm_map.token); 2102 size = vmspace_resident_count(p->p_vmspace); 2103 if (limit >= 0 && size >= limit) { 2104 vm_pageout_map_deactivate_pages(&p->p_vmspace->vm_map, limit); 2105 } 2106 lwkt_reltoken(&p->p_vmspace->vm_map.token); 2107 return (0); 2108 } 2109 2110 #endif 2111