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. 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; /* pageout daemon needs pages */ 123 int vm_page_free_hysteresis = 16; 124 125 #if !defined(NO_SWAPPING) 126 static int vm_pageout_req_swapout; /* XXX */ 127 static int vm_daemon_needed; 128 #endif 129 static int vm_max_launder = 4096; 130 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 131 static int vm_pageout_full_stats_interval = 0; 132 static int vm_pageout_stats_free_max=0, vm_pageout_algorithm=0; 133 static int defer_swap_pageouts=0; 134 static int disable_swap_pageouts=0; 135 static u_int vm_anonmem_decline = ACT_DECLINE; 136 static u_int vm_filemem_decline = ACT_DECLINE * 2; 137 138 #if defined(NO_SWAPPING) 139 static int vm_swap_enabled=0; 140 static int vm_swap_idle_enabled=0; 141 #else 142 static int vm_swap_enabled=1; 143 static int vm_swap_idle_enabled=0; 144 #endif 145 146 SYSCTL_UINT(_vm, VM_PAGEOUT_ALGORITHM, anonmem_decline, 147 CTLFLAG_RW, &vm_anonmem_decline, 0, "active->inactive anon memory"); 148 149 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, filemem_decline, 150 CTLFLAG_RW, &vm_filemem_decline, 0, "active->inactive file cache"); 151 152 SYSCTL_INT(_vm, OID_AUTO, page_free_hysteresis, 153 CTLFLAG_RW, &vm_page_free_hysteresis, 0, 154 "Free more pages than the minimum required"); 155 156 SYSCTL_INT(_vm, OID_AUTO, max_launder, 157 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 158 159 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 160 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 161 162 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 163 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 164 165 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 166 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 167 168 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max, 169 CTLFLAG_RW, &vm_pageout_stats_free_max, 0, "Not implemented"); 170 171 #if defined(NO_SWAPPING) 172 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 173 CTLFLAG_RD, &vm_swap_enabled, 0, ""); 174 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 175 CTLFLAG_RD, &vm_swap_idle_enabled, 0, ""); 176 #else 177 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 178 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 179 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 180 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 181 #endif 182 183 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 184 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 185 186 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 187 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 188 189 static int pageout_lock_miss; 190 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, 191 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); 192 193 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 194 195 #if !defined(NO_SWAPPING) 196 typedef void freeer_fcn_t (vm_map_t, vm_object_t, vm_pindex_t, int); 197 static void vm_pageout_map_deactivate_pages (vm_map_t, vm_pindex_t); 198 static freeer_fcn_t vm_pageout_object_deactivate_pages; 199 static void vm_req_vmdaemon (void); 200 #endif 201 static void vm_pageout_page_stats(int q); 202 203 static __inline int 204 PQAVERAGE(int n) 205 { 206 if (n >= 0) 207 return((n + (PQ_L2_SIZE - 1)) / PQ_L2_SIZE + 1); 208 else 209 return((n - (PQ_L2_SIZE - 1)) / PQ_L2_SIZE - 1); 210 } 211 212 /* 213 * vm_pageout_clean: 214 * 215 * Clean the page and remove it from the laundry. The page must not be 216 * busy on-call. 217 * 218 * We set the busy bit to cause potential page faults on this page to 219 * block. Note the careful timing, however, the busy bit isn't set till 220 * late and we cannot do anything that will mess with the page. 221 */ 222 static int 223 vm_pageout_clean(vm_page_t m) 224 { 225 vm_object_t object; 226 vm_page_t mc[BLIST_MAX_ALLOC]; 227 int error; 228 int ib, is, page_base; 229 vm_pindex_t pindex = m->pindex; 230 231 object = m->object; 232 233 /* 234 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 235 * with the new swapper, but we could have serious problems paging 236 * out other object types if there is insufficient memory. 237 * 238 * Unfortunately, checking free memory here is far too late, so the 239 * check has been moved up a procedural level. 240 */ 241 242 /* 243 * Don't mess with the page if it's busy, held, or special 244 * 245 * XXX do we really need to check hold_count here? hold_count 246 * isn't supposed to mess with vm_page ops except prevent the 247 * page from being reused. 248 */ 249 if (m->hold_count != 0 || (m->flags & PG_UNMANAGED)) { 250 vm_page_wakeup(m); 251 return 0; 252 } 253 254 /* 255 * Place page in cluster. Align cluster for optimal swap space 256 * allocation (whether it is swap or not). This is typically ~16-32 257 * pages, which also tends to align the cluster to multiples of the 258 * filesystem block size if backed by a filesystem. 259 */ 260 page_base = pindex % BLIST_MAX_ALLOC; 261 mc[page_base] = m; 262 ib = page_base - 1; 263 is = page_base + 1; 264 265 /* 266 * Scan object for clusterable pages. 267 * 268 * We can cluster ONLY if: ->> the page is NOT 269 * clean, wired, busy, held, or mapped into a 270 * buffer, and one of the following: 271 * 1) The page is inactive, or a seldom used 272 * active page. 273 * -or- 274 * 2) we force the issue. 275 * 276 * During heavy mmap/modification loads the pageout 277 * daemon can really fragment the underlying file 278 * due to flushing pages out of order and not trying 279 * align the clusters (which leave sporatic out-of-order 280 * holes). To solve this problem we do the reverse scan 281 * first and attempt to align our cluster, then do a 282 * forward scan if room remains. 283 */ 284 285 vm_object_hold(object); 286 while (ib >= 0) { 287 vm_page_t p; 288 289 p = vm_page_lookup_busy_try(object, pindex - page_base + ib, 290 TRUE, &error); 291 if (error || p == NULL) 292 break; 293 if ((p->queue - p->pc) == PQ_CACHE || 294 (p->flags & PG_UNMANAGED)) { 295 vm_page_wakeup(p); 296 break; 297 } 298 vm_page_test_dirty(p); 299 if (((p->dirty & p->valid) == 0 && 300 (p->flags & PG_NEED_COMMIT) == 0) || 301 p->queue - p->pc != PQ_INACTIVE || 302 p->wire_count != 0 || /* may be held by buf cache */ 303 p->hold_count != 0) { /* may be undergoing I/O */ 304 vm_page_wakeup(p); 305 break; 306 } 307 mc[ib] = p; 308 --ib; 309 } 310 ++ib; /* fixup */ 311 312 while (is < BLIST_MAX_ALLOC && 313 pindex - page_base + is < object->size) { 314 vm_page_t p; 315 316 p = vm_page_lookup_busy_try(object, pindex - page_base + is, 317 TRUE, &error); 318 if (error || p == NULL) 319 break; 320 if (((p->queue - p->pc) == PQ_CACHE) || 321 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 322 vm_page_wakeup(p); 323 break; 324 } 325 vm_page_test_dirty(p); 326 if (((p->dirty & p->valid) == 0 && 327 (p->flags & PG_NEED_COMMIT) == 0) || 328 p->queue - p->pc != PQ_INACTIVE || 329 p->wire_count != 0 || /* may be held by buf cache */ 330 p->hold_count != 0) { /* may be undergoing I/O */ 331 vm_page_wakeup(p); 332 break; 333 } 334 mc[is] = p; 335 ++is; 336 } 337 338 vm_object_drop(object); 339 340 /* 341 * we allow reads during pageouts... 342 */ 343 return vm_pageout_flush(&mc[ib], is - ib, 0); 344 } 345 346 /* 347 * vm_pageout_flush() - launder the given pages 348 * 349 * The given pages are laundered. Note that we setup for the start of 350 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 351 * reference count all in here rather then in the parent. If we want 352 * the parent to do more sophisticated things we may have to change 353 * the ordering. 354 * 355 * The pages in the array must be busied by the caller and will be 356 * unbusied by this function. 357 */ 358 int 359 vm_pageout_flush(vm_page_t *mc, int count, int flags) 360 { 361 vm_object_t object; 362 int pageout_status[count]; 363 int numpagedout = 0; 364 int i; 365 366 /* 367 * Initiate I/O. Bump the vm_page_t->busy counter. 368 */ 369 for (i = 0; i < count; i++) { 370 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 371 ("vm_pageout_flush page %p index %d/%d: partially " 372 "invalid page", mc[i], i, count)); 373 vm_page_io_start(mc[i]); 374 } 375 376 /* 377 * We must make the pages read-only. This will also force the 378 * modified bit in the related pmaps to be cleared. The pager 379 * cannot clear the bit for us since the I/O completion code 380 * typically runs from an interrupt. The act of making the page 381 * read-only handles the case for us. 382 * 383 * Then we can unbusy the pages, we still hold a reference by virtue 384 * of our soft-busy. 385 */ 386 for (i = 0; i < count; i++) { 387 vm_page_protect(mc[i], VM_PROT_READ); 388 vm_page_wakeup(mc[i]); 389 } 390 391 object = mc[0]->object; 392 vm_object_pip_add(object, count); 393 394 vm_pager_put_pages(object, mc, count, 395 (flags | ((object == &kernel_object) ? VM_PAGER_PUT_SYNC : 0)), 396 pageout_status); 397 398 for (i = 0; i < count; i++) { 399 vm_page_t mt = mc[i]; 400 401 switch (pageout_status[i]) { 402 case VM_PAGER_OK: 403 numpagedout++; 404 break; 405 case VM_PAGER_PEND: 406 numpagedout++; 407 break; 408 case VM_PAGER_BAD: 409 /* 410 * Page outside of range of object. Right now we 411 * essentially lose the changes by pretending it 412 * worked. 413 */ 414 vm_page_busy_wait(mt, FALSE, "pgbad"); 415 pmap_clear_modify(mt); 416 vm_page_undirty(mt); 417 vm_page_wakeup(mt); 418 break; 419 case VM_PAGER_ERROR: 420 case VM_PAGER_FAIL: 421 /* 422 * A page typically cannot be paged out when we 423 * have run out of swap. We leave the page 424 * marked inactive and will try to page it out 425 * again later. 426 * 427 * Starvation of the active page list is used to 428 * determine when the system is massively memory 429 * starved. 430 */ 431 break; 432 case VM_PAGER_AGAIN: 433 break; 434 } 435 436 /* 437 * If the operation is still going, leave the page busy to 438 * block all other accesses. Also, leave the paging in 439 * progress indicator set so that we don't attempt an object 440 * collapse. 441 * 442 * For any pages which have completed synchronously, 443 * deactivate the page if we are under a severe deficit. 444 * Do not try to enter them into the cache, though, they 445 * might still be read-heavy. 446 */ 447 if (pageout_status[i] != VM_PAGER_PEND) { 448 vm_page_busy_wait(mt, FALSE, "pgouw"); 449 if (vm_page_count_severe()) 450 vm_page_deactivate(mt); 451 #if 0 452 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt)) 453 vm_page_protect(mt, VM_PROT_READ); 454 #endif 455 vm_page_io_finish(mt); 456 vm_page_wakeup(mt); 457 vm_object_pip_wakeup(object); 458 } 459 } 460 return numpagedout; 461 } 462 463 #if !defined(NO_SWAPPING) 464 /* 465 * deactivate enough pages to satisfy the inactive target 466 * requirements or if vm_page_proc_limit is set, then 467 * deactivate all of the pages in the object and its 468 * backing_objects. 469 * 470 * The map must be locked. 471 * The caller must hold the vm_object. 472 */ 473 static int vm_pageout_object_deactivate_pages_callback(vm_page_t, void *); 474 475 static void 476 vm_pageout_object_deactivate_pages(vm_map_t map, vm_object_t object, 477 vm_pindex_t desired, int map_remove_only) 478 { 479 struct rb_vm_page_scan_info info; 480 vm_object_t lobject; 481 vm_object_t tobject; 482 int remove_mode; 483 484 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 485 lobject = object; 486 487 while (lobject) { 488 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 489 break; 490 if (lobject->type == OBJT_DEVICE || 491 lobject->type == OBJT_MGTDEVICE || 492 lobject->type == OBJT_PHYS) 493 break; 494 if (lobject->paging_in_progress) 495 break; 496 497 remove_mode = map_remove_only; 498 if (lobject->shadow_count > 1) 499 remove_mode = 1; 500 501 /* 502 * scan the objects entire memory queue. We hold the 503 * object's token so the scan should not race anything. 504 */ 505 info.limit = remove_mode; 506 info.map = map; 507 info.desired = desired; 508 vm_page_rb_tree_RB_SCAN(&lobject->rb_memq, NULL, 509 vm_pageout_object_deactivate_pages_callback, 510 &info 511 ); 512 while ((tobject = lobject->backing_object) != NULL) { 513 KKASSERT(tobject != object); 514 vm_object_hold(tobject); 515 if (tobject == lobject->backing_object) 516 break; 517 vm_object_drop(tobject); 518 } 519 if (lobject != object) { 520 if (tobject) 521 vm_object_lock_swap(); 522 vm_object_drop(lobject); 523 /* leaves tobject locked & at top */ 524 } 525 lobject = tobject; 526 } 527 if (lobject != object) 528 vm_object_drop(lobject); /* NULL ok */ 529 } 530 531 /* 532 * The caller must hold the vm_object. 533 */ 534 static int 535 vm_pageout_object_deactivate_pages_callback(vm_page_t p, void *data) 536 { 537 struct rb_vm_page_scan_info *info = data; 538 int actcount; 539 540 if (pmap_resident_count(vm_map_pmap(info->map)) <= info->desired) { 541 return(-1); 542 } 543 mycpu->gd_cnt.v_pdpages++; 544 545 if (vm_page_busy_try(p, TRUE)) 546 return(0); 547 if (p->wire_count || p->hold_count || (p->flags & PG_UNMANAGED)) { 548 vm_page_wakeup(p); 549 return(0); 550 } 551 if (!pmap_page_exists_quick(vm_map_pmap(info->map), p)) { 552 vm_page_wakeup(p); 553 return(0); 554 } 555 556 actcount = pmap_ts_referenced(p); 557 if (actcount) { 558 vm_page_flag_set(p, PG_REFERENCED); 559 } else if (p->flags & PG_REFERENCED) { 560 actcount = 1; 561 } 562 563 vm_page_and_queue_spin_lock(p); 564 if (p->queue - p->pc != PQ_ACTIVE && (p->flags & PG_REFERENCED)) { 565 vm_page_and_queue_spin_unlock(p); 566 vm_page_activate(p); 567 p->act_count += actcount; 568 vm_page_flag_clear(p, PG_REFERENCED); 569 } else if (p->queue - p->pc == PQ_ACTIVE) { 570 if ((p->flags & PG_REFERENCED) == 0) { 571 p->act_count -= min(p->act_count, ACT_DECLINE); 572 if (!info->limit && 573 (vm_pageout_algorithm || (p->act_count == 0))) { 574 vm_page_and_queue_spin_unlock(p); 575 vm_page_protect(p, VM_PROT_NONE); 576 vm_page_deactivate(p); 577 } else { 578 TAILQ_REMOVE(&vm_page_queues[p->queue].pl, 579 p, pageq); 580 TAILQ_INSERT_TAIL(&vm_page_queues[p->queue].pl, 581 p, pageq); 582 vm_page_and_queue_spin_unlock(p); 583 } 584 } else { 585 vm_page_and_queue_spin_unlock(p); 586 vm_page_activate(p); 587 vm_page_flag_clear(p, PG_REFERENCED); 588 589 vm_page_and_queue_spin_lock(p); 590 if (p->queue - p->pc == PQ_ACTIVE) { 591 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 592 p->act_count += ACT_ADVANCE; 593 TAILQ_REMOVE(&vm_page_queues[p->queue].pl, 594 p, pageq); 595 TAILQ_INSERT_TAIL(&vm_page_queues[p->queue].pl, 596 p, pageq); 597 } 598 vm_page_and_queue_spin_unlock(p); 599 } 600 } else if (p->queue - p->pc == PQ_INACTIVE) { 601 vm_page_and_queue_spin_unlock(p); 602 vm_page_protect(p, VM_PROT_NONE); 603 } else { 604 vm_page_and_queue_spin_unlock(p); 605 } 606 vm_page_wakeup(p); 607 return(0); 608 } 609 610 /* 611 * Deactivate some number of pages in a map, try to do it fairly, but 612 * that is really hard to do. 613 */ 614 static void 615 vm_pageout_map_deactivate_pages(vm_map_t map, vm_pindex_t desired) 616 { 617 vm_map_entry_t tmpe; 618 vm_object_t obj, bigobj; 619 int nothingwired; 620 621 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT)) { 622 return; 623 } 624 625 bigobj = NULL; 626 nothingwired = TRUE; 627 628 /* 629 * first, search out the biggest object, and try to free pages from 630 * that. 631 */ 632 tmpe = map->header.next; 633 while (tmpe != &map->header) { 634 switch(tmpe->maptype) { 635 case VM_MAPTYPE_NORMAL: 636 case VM_MAPTYPE_VPAGETABLE: 637 obj = tmpe->object.vm_object; 638 if ((obj != NULL) && (obj->shadow_count <= 1) && 639 ((bigobj == NULL) || 640 (bigobj->resident_page_count < obj->resident_page_count))) { 641 bigobj = obj; 642 } 643 break; 644 default: 645 break; 646 } 647 if (tmpe->wired_count > 0) 648 nothingwired = FALSE; 649 tmpe = tmpe->next; 650 } 651 652 if (bigobj) { 653 vm_object_hold(bigobj); 654 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 655 vm_object_drop(bigobj); 656 } 657 658 /* 659 * Next, hunt around for other pages to deactivate. We actually 660 * do this search sort of wrong -- .text first is not the best idea. 661 */ 662 tmpe = map->header.next; 663 while (tmpe != &map->header) { 664 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 665 break; 666 switch(tmpe->maptype) { 667 case VM_MAPTYPE_NORMAL: 668 case VM_MAPTYPE_VPAGETABLE: 669 obj = tmpe->object.vm_object; 670 if (obj) { 671 vm_object_hold(obj); 672 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 673 vm_object_drop(obj); 674 } 675 break; 676 default: 677 break; 678 } 679 tmpe = tmpe->next; 680 } 681 682 /* 683 * Remove all mappings if a process is swapped out, this will free page 684 * table pages. 685 */ 686 if (desired == 0 && nothingwired) 687 pmap_remove(vm_map_pmap(map), 688 VM_MIN_USER_ADDRESS, VM_MAX_USER_ADDRESS); 689 vm_map_unlock(map); 690 } 691 #endif 692 693 /* 694 * Called when the pageout scan wants to free a page. We no longer 695 * try to cycle the vm_object here with a reference & dealloc, which can 696 * cause a non-trivial object collapse in a critical path. 697 * 698 * It is unclear why we cycled the ref_count in the past, perhaps to try 699 * to optimize shadow chain collapses but I don't quite see why it would 700 * be necessary. An OBJ_DEAD object should terminate any and all vm_pages 701 * synchronously and not have to be kicked-start. 702 */ 703 static void 704 vm_pageout_page_free(vm_page_t m) 705 { 706 vm_page_protect(m, VM_PROT_NONE); 707 vm_page_free(m); 708 } 709 710 /* 711 * vm_pageout_scan does the dirty work for the pageout daemon. 712 */ 713 struct vm_pageout_scan_info { 714 struct proc *bigproc; 715 vm_offset_t bigsize; 716 }; 717 718 static int vm_pageout_scan_callback(struct proc *p, void *data); 719 720 static int 721 vm_pageout_scan_inactive(int pass, int q, int avail_shortage, 722 int *vnodes_skippedp) 723 { 724 vm_page_t m; 725 struct vm_page marker; 726 struct vnode *vpfailed; /* warning, allowed to be stale */ 727 int maxscan; 728 int count; 729 int delta = 0; 730 vm_object_t object; 731 int actcount; 732 int maxlaunder; 733 734 /* 735 * Start scanning the inactive queue for pages we can move to the 736 * cache or free. The scan will stop when the target is reached or 737 * we have scanned the entire inactive queue. Note that m->act_count 738 * is not used to form decisions for the inactive queue, only for the 739 * active queue. 740 * 741 * maxlaunder limits the number of dirty pages we flush per scan. 742 * For most systems a smaller value (16 or 32) is more robust under 743 * extreme memory and disk pressure because any unnecessary writes 744 * to disk can result in extreme performance degredation. However, 745 * systems with excessive dirty pages (especially when MAP_NOSYNC is 746 * used) will die horribly with limited laundering. If the pageout 747 * daemon cannot clean enough pages in the first pass, we let it go 748 * all out in succeeding passes. 749 */ 750 if ((maxlaunder = vm_max_launder) <= 1) 751 maxlaunder = 1; 752 if (pass) 753 maxlaunder = 10000; 754 755 /* 756 * Initialize our marker 757 */ 758 bzero(&marker, sizeof(marker)); 759 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 760 marker.queue = PQ_INACTIVE + q; 761 marker.pc = q; 762 marker.wire_count = 1; 763 764 /* 765 * Inactive queue scan. 766 * 767 * NOTE: The vm_page must be spinlocked before the queue to avoid 768 * deadlocks, so it is easiest to simply iterate the loop 769 * with the queue unlocked at the top. 770 */ 771 vpfailed = NULL; 772 773 vm_page_queues_spin_lock(PQ_INACTIVE + q); 774 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE + q].pl, &marker, pageq); 775 maxscan = vm_page_queues[PQ_INACTIVE + q].lcnt; 776 777 /* 778 * Queue locked at top of loop to avoid stack marker issues. 779 */ 780 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL && 781 maxscan-- > 0 && avail_shortage - delta > 0) 782 { 783 KKASSERT(m->queue - m->pc == PQ_INACTIVE); 784 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl, 785 &marker, pageq); 786 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE + q].pl, m, 787 &marker, pageq); 788 mycpu->gd_cnt.v_pdpages++; 789 790 /* 791 * Skip marker pages (atomic against other markers to avoid 792 * infinite hop-over scans). 793 */ 794 if (m->flags & PG_MARKER) 795 continue; 796 797 /* 798 * Try to busy the page. Don't mess with pages which are 799 * already busy or reorder them in the queue. 800 */ 801 if (vm_page_busy_try(m, TRUE)) 802 continue; 803 804 /* 805 * Remaining operations run with the page busy and neither 806 * the page or the queue will be spin-locked. 807 */ 808 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 809 KKASSERT(m->queue - m->pc == PQ_INACTIVE); 810 lwkt_yield(); 811 812 /* 813 * It is possible for a page to be busied ad-hoc (e.g. the 814 * pmap_collect() code) and wired and race against the 815 * allocation of a new page. vm_page_alloc() may be forced 816 * to deactivate the wired page in which case it winds up 817 * on the inactive queue and must be handled here. We 818 * correct the problem simply by unqueuing the page. 819 */ 820 if (m->wire_count) { 821 vm_page_unqueue_nowakeup(m); 822 vm_page_wakeup(m); 823 kprintf("WARNING: pagedaemon: wired page on " 824 "inactive queue %p\n", m); 825 goto next; 826 } 827 828 /* 829 * A held page may be undergoing I/O, so skip it. 830 */ 831 if (m->hold_count) { 832 vm_page_and_queue_spin_lock(m); 833 if (m->queue - m->pc == PQ_INACTIVE) { 834 TAILQ_REMOVE( 835 &vm_page_queues[PQ_INACTIVE + q].pl, 836 m, pageq); 837 TAILQ_INSERT_TAIL( 838 &vm_page_queues[PQ_INACTIVE + q].pl, 839 m, pageq); 840 ++vm_swapcache_inactive_heuristic; 841 } 842 vm_page_and_queue_spin_unlock(m); 843 vm_page_wakeup(m); 844 goto next; 845 } 846 847 if (m->object == NULL || m->object->ref_count == 0) { 848 /* 849 * If the object is not being used, we ignore previous 850 * references. 851 */ 852 vm_page_flag_clear(m, PG_REFERENCED); 853 pmap_clear_reference(m); 854 /* fall through to end */ 855 } else if (((m->flags & PG_REFERENCED) == 0) && 856 (actcount = pmap_ts_referenced(m))) { 857 /* 858 * Otherwise, if the page has been referenced while 859 * in the inactive queue, we bump the "activation 860 * count" upwards, making it less likely that the 861 * page will be added back to the inactive queue 862 * prematurely again. Here we check the page tables 863 * (or emulated bits, if any), given the upper level 864 * VM system not knowing anything about existing 865 * references. 866 */ 867 vm_page_activate(m); 868 m->act_count += (actcount + ACT_ADVANCE); 869 vm_page_wakeup(m); 870 goto next; 871 } 872 873 /* 874 * (m) is still busied. 875 * 876 * If the upper level VM system knows about any page 877 * references, we activate the page. We also set the 878 * "activation count" higher than normal so that we will less 879 * likely place pages back onto the inactive queue again. 880 */ 881 if ((m->flags & PG_REFERENCED) != 0) { 882 vm_page_flag_clear(m, PG_REFERENCED); 883 actcount = pmap_ts_referenced(m); 884 vm_page_activate(m); 885 m->act_count += (actcount + ACT_ADVANCE + 1); 886 vm_page_wakeup(m); 887 goto next; 888 } 889 890 /* 891 * If the upper level VM system doesn't know anything about 892 * the page being dirty, we have to check for it again. As 893 * far as the VM code knows, any partially dirty pages are 894 * fully dirty. 895 * 896 * Pages marked PG_WRITEABLE may be mapped into the user 897 * address space of a process running on another cpu. A 898 * user process (without holding the MP lock) running on 899 * another cpu may be able to touch the page while we are 900 * trying to remove it. vm_page_cache() will handle this 901 * case for us. 902 */ 903 if (m->dirty == 0) { 904 vm_page_test_dirty(m); 905 } else { 906 vm_page_dirty(m); 907 } 908 909 if (m->valid == 0 && (m->flags & PG_NEED_COMMIT) == 0) { 910 /* 911 * Invalid pages can be easily freed 912 */ 913 vm_pageout_page_free(m); 914 mycpu->gd_cnt.v_dfree++; 915 ++delta; 916 } else if (m->dirty == 0 && (m->flags & PG_NEED_COMMIT) == 0) { 917 /* 918 * Clean pages can be placed onto the cache queue. 919 * This effectively frees them. 920 */ 921 vm_page_cache(m); 922 ++delta; 923 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 924 /* 925 * Dirty pages need to be paged out, but flushing 926 * a page is extremely expensive verses freeing 927 * a clean page. Rather then artificially limiting 928 * the number of pages we can flush, we instead give 929 * dirty pages extra priority on the inactive queue 930 * by forcing them to be cycled through the queue 931 * twice before being flushed, after which the 932 * (now clean) page will cycle through once more 933 * before being freed. This significantly extends 934 * the thrash point for a heavily loaded machine. 935 */ 936 vm_page_flag_set(m, PG_WINATCFLS); 937 vm_page_and_queue_spin_lock(m); 938 if (m->queue - m->pc == PQ_INACTIVE) { 939 TAILQ_REMOVE( 940 &vm_page_queues[PQ_INACTIVE + q].pl, 941 m, pageq); 942 TAILQ_INSERT_TAIL( 943 &vm_page_queues[PQ_INACTIVE + q].pl, 944 m, pageq); 945 ++vm_swapcache_inactive_heuristic; 946 } 947 vm_page_and_queue_spin_unlock(m); 948 vm_page_wakeup(m); 949 } else if (maxlaunder > 0) { 950 /* 951 * We always want to try to flush some dirty pages if 952 * we encounter them, to keep the system stable. 953 * Normally this number is small, but under extreme 954 * pressure where there are insufficient clean pages 955 * on the inactive queue, we may have to go all out. 956 */ 957 int swap_pageouts_ok; 958 struct vnode *vp = NULL; 959 960 swap_pageouts_ok = 0; 961 object = m->object; 962 if (object && 963 (object->type != OBJT_SWAP) && 964 (object->type != OBJT_DEFAULT)) { 965 swap_pageouts_ok = 1; 966 } else { 967 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 968 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 969 vm_page_count_min(0)); 970 971 } 972 973 /* 974 * We don't bother paging objects that are "dead". 975 * Those objects are in a "rundown" state. 976 */ 977 if (!swap_pageouts_ok || 978 (object == NULL) || 979 (object->flags & OBJ_DEAD)) { 980 vm_page_and_queue_spin_lock(m); 981 if (m->queue - m->pc == PQ_INACTIVE) { 982 TAILQ_REMOVE( 983 &vm_page_queues[PQ_INACTIVE + q].pl, 984 m, pageq); 985 TAILQ_INSERT_TAIL( 986 &vm_page_queues[PQ_INACTIVE + q].pl, 987 m, pageq); 988 ++vm_swapcache_inactive_heuristic; 989 } 990 vm_page_and_queue_spin_unlock(m); 991 vm_page_wakeup(m); 992 goto next; 993 } 994 995 /* 996 * (m) is still busied. 997 * 998 * The object is already known NOT to be dead. It 999 * is possible for the vget() to block the whole 1000 * pageout daemon, but the new low-memory handling 1001 * code should prevent it. 1002 * 1003 * The previous code skipped locked vnodes and, worse, 1004 * reordered pages in the queue. This results in 1005 * completely non-deterministic operation because, 1006 * quite often, a vm_fault has initiated an I/O and 1007 * is holding a locked vnode at just the point where 1008 * the pageout daemon is woken up. 1009 * 1010 * We can't wait forever for the vnode lock, we might 1011 * deadlock due to a vn_read() getting stuck in 1012 * vm_wait while holding this vnode. We skip the 1013 * vnode if we can't get it in a reasonable amount 1014 * of time. 1015 * 1016 * vpfailed is used to (try to) avoid the case where 1017 * a large number of pages are associated with a 1018 * locked vnode, which could cause the pageout daemon 1019 * to stall for an excessive amount of time. 1020 */ 1021 if (object->type == OBJT_VNODE) { 1022 int flags; 1023 1024 vp = object->handle; 1025 flags = LK_EXCLUSIVE; 1026 if (vp == vpfailed) 1027 flags |= LK_NOWAIT; 1028 else 1029 flags |= LK_TIMELOCK; 1030 vm_page_hold(m); 1031 vm_page_wakeup(m); 1032 1033 /* 1034 * We have unbusied (m) temporarily so we can 1035 * acquire the vp lock without deadlocking. 1036 * (m) is held to prevent destruction. 1037 */ 1038 if (vget(vp, flags) != 0) { 1039 vpfailed = vp; 1040 ++pageout_lock_miss; 1041 if (object->flags & OBJ_MIGHTBEDIRTY) 1042 ++*vnodes_skippedp; 1043 vm_page_unhold(m); 1044 goto next; 1045 } 1046 1047 /* 1048 * The page might have been moved to another 1049 * queue during potential blocking in vget() 1050 * above. The page might have been freed and 1051 * reused for another vnode. The object might 1052 * have been reused for another vnode. 1053 */ 1054 if (m->queue - m->pc != PQ_INACTIVE || 1055 m->object != object || 1056 object->handle != vp) { 1057 if (object->flags & OBJ_MIGHTBEDIRTY) 1058 ++*vnodes_skippedp; 1059 vput(vp); 1060 vm_page_unhold(m); 1061 goto next; 1062 } 1063 1064 /* 1065 * The page may have been busied during the 1066 * blocking in vput(); We don't move the 1067 * page back onto the end of the queue so that 1068 * statistics are more correct if we don't. 1069 */ 1070 if (vm_page_busy_try(m, TRUE)) { 1071 vput(vp); 1072 vm_page_unhold(m); 1073 goto next; 1074 } 1075 vm_page_unhold(m); 1076 1077 /* 1078 * (m) is busied again 1079 * 1080 * We own the busy bit and remove our hold 1081 * bit. If the page is still held it 1082 * might be undergoing I/O, so skip it. 1083 */ 1084 if (m->hold_count) { 1085 vm_page_and_queue_spin_lock(m); 1086 if (m->queue - m->pc == PQ_INACTIVE) { 1087 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl, m, pageq); 1088 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE + q].pl, m, pageq); 1089 ++vm_swapcache_inactive_heuristic; 1090 } 1091 vm_page_and_queue_spin_unlock(m); 1092 if (object->flags & OBJ_MIGHTBEDIRTY) 1093 ++*vnodes_skippedp; 1094 vm_page_wakeup(m); 1095 vput(vp); 1096 goto next; 1097 } 1098 /* (m) is left busied as we fall through */ 1099 } 1100 1101 /* 1102 * page is busy and not held here. 1103 * 1104 * If a page is dirty, then it is either being washed 1105 * (but not yet cleaned) or it is still in the 1106 * laundry. If it is still in the laundry, then we 1107 * start the cleaning operation. 1108 * 1109 * decrement inactive_shortage on success to account 1110 * for the (future) cleaned page. Otherwise we 1111 * could wind up laundering or cleaning too many 1112 * pages. 1113 */ 1114 count = vm_pageout_clean(m); 1115 delta += count; 1116 maxlaunder -= count; 1117 1118 /* 1119 * Clean ate busy, page no longer accessible 1120 */ 1121 if (vp != NULL) 1122 vput(vp); 1123 } else { 1124 vm_page_wakeup(m); 1125 } 1126 1127 next: 1128 /* 1129 * Systems with a ton of memory can wind up with huge 1130 * deactivation counts. Because the inactive scan is 1131 * doing a lot of flushing, the combination can result 1132 * in excessive paging even in situations where other 1133 * unrelated threads free up sufficient VM. 1134 * 1135 * To deal with this we abort the nominal active->inactive 1136 * scan before we hit the inactive target when free+cache 1137 * levels have already reached their target. 1138 * 1139 * Note that nominally the inactive scan is not freeing or 1140 * caching pages, it is deactivating active pages, so it 1141 * will not by itself cause the abort condition. 1142 */ 1143 vm_page_queues_spin_lock(PQ_INACTIVE + q); 1144 if (vm_paging_target() < 0) 1145 break; 1146 } 1147 1148 /* page queue still spin-locked */ 1149 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl, &marker, pageq); 1150 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 1151 1152 return (delta); 1153 } 1154 1155 static int 1156 vm_pageout_scan_active(int pass, int q, 1157 int avail_shortage, int inactive_shortage, 1158 int *recycle_countp) 1159 { 1160 struct vm_page marker; 1161 vm_page_t m; 1162 int actcount; 1163 int delta = 0; 1164 int maxscan; 1165 1166 /* 1167 * We want to move pages from the active queue to the inactive 1168 * queue to get the inactive queue to the inactive target. If 1169 * we still have a page shortage from above we try to directly free 1170 * clean pages instead of moving them. 1171 * 1172 * If we do still have a shortage we keep track of the number of 1173 * pages we free or cache (recycle_count) as a measure of thrashing 1174 * between the active and inactive queues. 1175 * 1176 * If we were able to completely satisfy the free+cache targets 1177 * from the inactive pool we limit the number of pages we move 1178 * from the active pool to the inactive pool to 2x the pages we 1179 * had removed from the inactive pool (with a minimum of 1/5 the 1180 * inactive target). If we were not able to completely satisfy 1181 * the free+cache targets we go for the whole target aggressively. 1182 * 1183 * NOTE: Both variables can end up negative. 1184 * NOTE: We are still in a critical section. 1185 */ 1186 1187 bzero(&marker, sizeof(marker)); 1188 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 1189 marker.queue = PQ_ACTIVE + q; 1190 marker.pc = q; 1191 marker.wire_count = 1; 1192 1193 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1194 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1195 maxscan = vm_page_queues[PQ_ACTIVE + q].lcnt; 1196 1197 /* 1198 * Queue locked at top of loop to avoid stack marker issues. 1199 */ 1200 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL && 1201 maxscan-- > 0 && (avail_shortage - delta > 0 || 1202 inactive_shortage > 0)) 1203 { 1204 KKASSERT(m->queue - m->pc == PQ_ACTIVE); 1205 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, 1206 &marker, pageq); 1207 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_ACTIVE + q].pl, m, 1208 &marker, pageq); 1209 1210 /* 1211 * Skip marker pages (atomic against other markers to avoid 1212 * infinite hop-over scans). 1213 */ 1214 if (m->flags & PG_MARKER) 1215 continue; 1216 1217 /* 1218 * Try to busy the page. Don't mess with pages which are 1219 * already busy or reorder them in the queue. 1220 */ 1221 if (vm_page_busy_try(m, TRUE)) 1222 continue; 1223 1224 /* 1225 * Remaining operations run with the page busy and neither 1226 * the page or the queue will be spin-locked. 1227 */ 1228 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1229 KKASSERT(m->queue - m->pc == PQ_ACTIVE); 1230 lwkt_yield(); 1231 1232 /* 1233 * Don't deactivate pages that are held, even if we can 1234 * busy them. (XXX why not?) 1235 */ 1236 if (m->hold_count != 0) { 1237 vm_page_and_queue_spin_lock(m); 1238 if (m->queue - m->pc == PQ_ACTIVE) { 1239 TAILQ_REMOVE( 1240 &vm_page_queues[PQ_ACTIVE + q].pl, 1241 m, pageq); 1242 TAILQ_INSERT_TAIL( 1243 &vm_page_queues[PQ_ACTIVE + q].pl, 1244 m, pageq); 1245 } 1246 vm_page_and_queue_spin_unlock(m); 1247 vm_page_wakeup(m); 1248 goto next; 1249 } 1250 1251 /* 1252 * The count for pagedaemon pages is done after checking the 1253 * page for eligibility... 1254 */ 1255 mycpu->gd_cnt.v_pdpages++; 1256 1257 /* 1258 * Check to see "how much" the page has been used and clear 1259 * the tracking access bits. If the object has no references 1260 * don't bother paying the expense. 1261 */ 1262 actcount = 0; 1263 if (m->object && m->object->ref_count != 0) { 1264 if (m->flags & PG_REFERENCED) 1265 ++actcount; 1266 actcount += pmap_ts_referenced(m); 1267 if (actcount) { 1268 m->act_count += ACT_ADVANCE + actcount; 1269 if (m->act_count > ACT_MAX) 1270 m->act_count = ACT_MAX; 1271 } 1272 } 1273 vm_page_flag_clear(m, PG_REFERENCED); 1274 1275 /* 1276 * actcount is only valid if the object ref_count is non-zero. 1277 * If the page does not have an object, actcount will be zero. 1278 */ 1279 if (actcount && m->object->ref_count != 0) { 1280 vm_page_and_queue_spin_lock(m); 1281 if (m->queue - m->pc == PQ_ACTIVE) { 1282 TAILQ_REMOVE( 1283 &vm_page_queues[PQ_ACTIVE + q].pl, 1284 m, pageq); 1285 TAILQ_INSERT_TAIL( 1286 &vm_page_queues[PQ_ACTIVE + q].pl, 1287 m, pageq); 1288 } 1289 vm_page_and_queue_spin_unlock(m); 1290 vm_page_wakeup(m); 1291 } else { 1292 switch(m->object->type) { 1293 case OBJT_DEFAULT: 1294 case OBJT_SWAP: 1295 m->act_count -= min(m->act_count, 1296 vm_anonmem_decline); 1297 break; 1298 default: 1299 m->act_count -= min(m->act_count, 1300 vm_filemem_decline); 1301 break; 1302 } 1303 if (vm_pageout_algorithm || 1304 (m->object == NULL) || 1305 (m->object && (m->object->ref_count == 0)) || 1306 m->act_count < pass + 1 1307 ) { 1308 /* 1309 * Deactivate the page. If we had a 1310 * shortage from our inactive scan try to 1311 * free (cache) the page instead. 1312 * 1313 * Don't just blindly cache the page if 1314 * we do not have a shortage from the 1315 * inactive scan, that could lead to 1316 * gigabytes being moved. 1317 */ 1318 --inactive_shortage; 1319 if (avail_shortage - delta > 0 || 1320 (m->object && (m->object->ref_count == 0))) 1321 { 1322 if (avail_shortage - delta > 0) 1323 ++*recycle_countp; 1324 vm_page_protect(m, VM_PROT_NONE); 1325 if (m->dirty == 0 && 1326 (m->flags & PG_NEED_COMMIT) == 0 && 1327 avail_shortage - delta > 0) { 1328 vm_page_cache(m); 1329 } else { 1330 vm_page_deactivate(m); 1331 vm_page_wakeup(m); 1332 } 1333 } else { 1334 vm_page_deactivate(m); 1335 vm_page_wakeup(m); 1336 } 1337 ++delta; 1338 } else { 1339 vm_page_and_queue_spin_lock(m); 1340 if (m->queue - m->pc == PQ_ACTIVE) { 1341 TAILQ_REMOVE( 1342 &vm_page_queues[PQ_ACTIVE + q].pl, 1343 m, pageq); 1344 TAILQ_INSERT_TAIL( 1345 &vm_page_queues[PQ_ACTIVE + q].pl, 1346 m, pageq); 1347 } 1348 vm_page_and_queue_spin_unlock(m); 1349 vm_page_wakeup(m); 1350 } 1351 } 1352 next: 1353 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1354 } 1355 1356 /* 1357 * Clean out our local marker. 1358 * 1359 * Page queue still spin-locked. 1360 */ 1361 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1362 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1363 1364 return (delta); 1365 } 1366 1367 /* 1368 * The number of actually free pages can drop down to v_free_reserved, 1369 * we try to build the free count back above v_free_min. Note that 1370 * vm_paging_needed() also returns TRUE if v_free_count is not at 1371 * least v_free_min so that is the minimum we must build the free 1372 * count to. 1373 * 1374 * We use a slightly higher target to improve hysteresis, 1375 * ((v_free_target + v_free_min) / 2). Since v_free_target 1376 * is usually the same as v_cache_min this maintains about 1377 * half the pages in the free queue as are in the cache queue, 1378 * providing pretty good pipelining for pageout operation. 1379 * 1380 * The system operator can manipulate vm.v_cache_min and 1381 * vm.v_free_target to tune the pageout demon. Be sure 1382 * to keep vm.v_free_min < vm.v_free_target. 1383 * 1384 * Note that the original paging target is to get at least 1385 * (free_min + cache_min) into (free + cache). The slightly 1386 * higher target will shift additional pages from cache to free 1387 * without effecting the original paging target in order to 1388 * maintain better hysteresis and not have the free count always 1389 * be dead-on v_free_min. 1390 * 1391 * NOTE: we are still in a critical section. 1392 * 1393 * Pages moved from PQ_CACHE to totally free are not counted in the 1394 * pages_freed counter. 1395 */ 1396 static void 1397 vm_pageout_scan_cache(int avail_shortage, int vnodes_skipped, int recycle_count) 1398 { 1399 struct vm_pageout_scan_info info; 1400 vm_page_t m; 1401 1402 while (vmstats.v_free_count < 1403 (vmstats.v_free_min + vmstats.v_free_target) / 2) { 1404 /* 1405 * This steals some code from vm/vm_page.c 1406 */ 1407 static int cache_rover = 0; 1408 1409 m = vm_page_list_find(PQ_CACHE, cache_rover & PQ_L2_MASK, FALSE); 1410 if (m == NULL) 1411 break; 1412 /* page is returned removed from its queue and spinlocked */ 1413 if (vm_page_busy_try(m, TRUE)) { 1414 vm_page_deactivate_locked(m); 1415 vm_page_spin_unlock(m); 1416 continue; 1417 } 1418 vm_page_spin_unlock(m); 1419 pagedaemon_wakeup(); 1420 lwkt_yield(); 1421 1422 /* 1423 * Remaining operations run with the page busy and neither 1424 * the page or the queue will be spin-locked. 1425 */ 1426 if ((m->flags & (PG_UNMANAGED | PG_NEED_COMMIT)) || 1427 m->hold_count || 1428 m->wire_count) { 1429 vm_page_deactivate(m); 1430 vm_page_wakeup(m); 1431 continue; 1432 } 1433 KKASSERT((m->flags & PG_MAPPED) == 0); 1434 KKASSERT(m->dirty == 0); 1435 cache_rover += PQ_PRIME2; 1436 vm_pageout_page_free(m); 1437 mycpu->gd_cnt.v_dfree++; 1438 } 1439 1440 #if !defined(NO_SWAPPING) 1441 /* 1442 * Idle process swapout -- run once per second. 1443 */ 1444 if (vm_swap_idle_enabled) { 1445 static time_t lsec; 1446 if (time_uptime != lsec) { 1447 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1448 vm_req_vmdaemon(); 1449 lsec = time_uptime; 1450 } 1451 } 1452 #endif 1453 1454 /* 1455 * If we didn't get enough free pages, and we have skipped a vnode 1456 * in a writeable object, wakeup the sync daemon. And kick swapout 1457 * if we did not get enough free pages. 1458 */ 1459 if (vm_paging_target() > 0) { 1460 if (vnodes_skipped && vm_page_count_min(0)) 1461 speedup_syncer(NULL); 1462 #if !defined(NO_SWAPPING) 1463 if (vm_swap_enabled && vm_page_count_target()) { 1464 vm_req_vmdaemon(); 1465 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1466 } 1467 #endif 1468 } 1469 1470 /* 1471 * Handle catastrophic conditions. Under good conditions we should 1472 * be at the target, well beyond our minimum. If we could not even 1473 * reach our minimum the system is under heavy stress. 1474 * 1475 * Determine whether we have run out of memory. This occurs when 1476 * swap_pager_full is TRUE and the only pages left in the page 1477 * queues are dirty. We will still likely have page shortages. 1478 * 1479 * - swap_pager_full is set if insufficient swap was 1480 * available to satisfy a requested pageout. 1481 * 1482 * - the inactive queue is bloated (4 x size of active queue), 1483 * meaning it is unable to get rid of dirty pages and. 1484 * 1485 * - vm_page_count_min() without counting pages recycled from the 1486 * active queue (recycle_count) means we could not recover 1487 * enough pages to meet bare minimum needs. This test only 1488 * works if the inactive queue is bloated. 1489 * 1490 * - due to a positive avail_shortage we shifted the remaining 1491 * dirty pages from the active queue to the inactive queue 1492 * trying to find clean ones to free. 1493 */ 1494 if (swap_pager_full && vm_page_count_min(recycle_count)) 1495 kprintf("Warning: system low on memory+swap!\n"); 1496 if (swap_pager_full && vm_page_count_min(recycle_count) && 1497 vmstats.v_inactive_count > vmstats.v_active_count * 4 && 1498 avail_shortage > 0) { 1499 /* 1500 * Kill something. 1501 */ 1502 info.bigproc = NULL; 1503 info.bigsize = 0; 1504 allproc_scan(vm_pageout_scan_callback, &info); 1505 if (info.bigproc != NULL) { 1506 killproc(info.bigproc, "out of swap space"); 1507 info.bigproc->p_nice = PRIO_MIN; 1508 info.bigproc->p_usched->resetpriority( 1509 FIRST_LWP_IN_PROC(info.bigproc)); 1510 wakeup(&vmstats.v_free_count); 1511 PRELE(info.bigproc); 1512 } 1513 } 1514 } 1515 1516 static int 1517 vm_pageout_scan_callback(struct proc *p, void *data) 1518 { 1519 struct vm_pageout_scan_info *info = data; 1520 vm_offset_t size; 1521 1522 /* 1523 * Never kill system processes or init. If we have configured swap 1524 * then try to avoid killing low-numbered pids. 1525 */ 1526 if ((p->p_flags & P_SYSTEM) || (p->p_pid == 1) || 1527 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1528 return (0); 1529 } 1530 1531 lwkt_gettoken(&p->p_token); 1532 1533 /* 1534 * if the process is in a non-running type state, 1535 * don't touch it. 1536 */ 1537 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) { 1538 lwkt_reltoken(&p->p_token); 1539 return (0); 1540 } 1541 1542 /* 1543 * Get the approximate process size. Note that anonymous pages 1544 * with backing swap will be counted twice, but there should not 1545 * be too many such pages due to the stress the VM system is 1546 * under at this point. 1547 */ 1548 size = vmspace_anonymous_count(p->p_vmspace) + 1549 vmspace_swap_count(p->p_vmspace); 1550 1551 /* 1552 * If the this process is bigger than the biggest one 1553 * remember it. 1554 */ 1555 if (info->bigsize < size) { 1556 if (info->bigproc) 1557 PRELE(info->bigproc); 1558 PHOLD(p); 1559 info->bigproc = p; 1560 info->bigsize = size; 1561 } 1562 lwkt_reltoken(&p->p_token); 1563 lwkt_yield(); 1564 1565 return(0); 1566 } 1567 1568 /* 1569 * This routine tries to maintain the pseudo LRU active queue, 1570 * so that during long periods of time where there is no paging, 1571 * that some statistic accumulation still occurs. This code 1572 * helps the situation where paging just starts to occur. 1573 */ 1574 static void 1575 vm_pageout_page_stats(int q) 1576 { 1577 static int fullintervalcount = 0; 1578 struct vm_page marker; 1579 vm_page_t m; 1580 int pcount, tpcount; /* Number of pages to check */ 1581 int page_shortage; 1582 1583 page_shortage = (vmstats.v_inactive_target + vmstats.v_cache_max + 1584 vmstats.v_free_min) - 1585 (vmstats.v_free_count + vmstats.v_inactive_count + 1586 vmstats.v_cache_count); 1587 1588 if (page_shortage <= 0) 1589 return; 1590 1591 pcount = vm_page_queues[PQ_ACTIVE + q].lcnt; 1592 fullintervalcount += vm_pageout_stats_interval; 1593 if (fullintervalcount < vm_pageout_full_stats_interval) { 1594 tpcount = (vm_pageout_stats_max * pcount) / 1595 vmstats.v_page_count + 1; 1596 if (pcount > tpcount) 1597 pcount = tpcount; 1598 } else { 1599 fullintervalcount = 0; 1600 } 1601 1602 bzero(&marker, sizeof(marker)); 1603 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 1604 marker.queue = PQ_ACTIVE + q; 1605 marker.pc = q; 1606 marker.wire_count = 1; 1607 1608 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1609 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1610 1611 /* 1612 * Queue locked at top of loop to avoid stack marker issues. 1613 */ 1614 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL && 1615 pcount-- > 0) 1616 { 1617 int actcount; 1618 1619 KKASSERT(m->queue - m->pc == PQ_ACTIVE); 1620 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1621 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_ACTIVE + q].pl, m, 1622 &marker, pageq); 1623 1624 /* 1625 * Skip marker pages (atomic against other markers to avoid 1626 * infinite hop-over scans). 1627 */ 1628 if (m->flags & PG_MARKER) 1629 continue; 1630 1631 /* 1632 * Ignore pages we can't busy 1633 */ 1634 if (vm_page_busy_try(m, TRUE)) 1635 continue; 1636 1637 /* 1638 * Remaining operations run with the page busy and neither 1639 * the page or the queue will be spin-locked. 1640 */ 1641 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1642 KKASSERT(m->queue - m->pc == PQ_ACTIVE); 1643 1644 /* 1645 * We now have a safely busied page, the page and queue 1646 * spinlocks have been released. 1647 * 1648 * Ignore held pages 1649 */ 1650 if (m->hold_count) { 1651 vm_page_wakeup(m); 1652 goto next; 1653 } 1654 1655 /* 1656 * Calculate activity 1657 */ 1658 actcount = 0; 1659 if (m->flags & PG_REFERENCED) { 1660 vm_page_flag_clear(m, PG_REFERENCED); 1661 actcount += 1; 1662 } 1663 actcount += pmap_ts_referenced(m); 1664 1665 /* 1666 * Update act_count and move page to end of queue. 1667 */ 1668 if (actcount) { 1669 m->act_count += ACT_ADVANCE + actcount; 1670 if (m->act_count > ACT_MAX) 1671 m->act_count = ACT_MAX; 1672 vm_page_and_queue_spin_lock(m); 1673 if (m->queue - m->pc == PQ_ACTIVE) { 1674 TAILQ_REMOVE( 1675 &vm_page_queues[PQ_ACTIVE + q].pl, 1676 m, pageq); 1677 TAILQ_INSERT_TAIL( 1678 &vm_page_queues[PQ_ACTIVE + q].pl, 1679 m, pageq); 1680 } 1681 vm_page_and_queue_spin_unlock(m); 1682 vm_page_wakeup(m); 1683 goto next; 1684 } 1685 1686 if (m->act_count == 0) { 1687 /* 1688 * We turn off page access, so that we have 1689 * more accurate RSS stats. We don't do this 1690 * in the normal page deactivation when the 1691 * system is loaded VM wise, because the 1692 * cost of the large number of page protect 1693 * operations would be higher than the value 1694 * of doing the operation. 1695 * 1696 * We use the marker to save our place so 1697 * we can release the spin lock. both (m) 1698 * and (next) will be invalid. 1699 */ 1700 vm_page_protect(m, VM_PROT_NONE); 1701 vm_page_deactivate(m); 1702 } else { 1703 m->act_count -= min(m->act_count, ACT_DECLINE); 1704 vm_page_and_queue_spin_lock(m); 1705 if (m->queue - m->pc == PQ_ACTIVE) { 1706 TAILQ_REMOVE( 1707 &vm_page_queues[PQ_ACTIVE + q].pl, 1708 m, pageq); 1709 TAILQ_INSERT_TAIL( 1710 &vm_page_queues[PQ_ACTIVE + q].pl, 1711 m, pageq); 1712 } 1713 vm_page_and_queue_spin_unlock(m); 1714 } 1715 vm_page_wakeup(m); 1716 next: 1717 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1718 } 1719 1720 /* 1721 * Remove our local marker 1722 * 1723 * Page queue still spin-locked. 1724 */ 1725 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1726 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1727 } 1728 1729 static int 1730 vm_pageout_free_page_calc(vm_size_t count) 1731 { 1732 if (count < vmstats.v_page_count) 1733 return 0; 1734 /* 1735 * free_reserved needs to include enough for the largest swap pager 1736 * structures plus enough for any pv_entry structs when paging. 1737 * 1738 * v_free_min normal allocations 1739 * v_free_reserved system allocations 1740 * v_pageout_free_min allocations by pageout daemon 1741 * v_interrupt_free_min low level allocations (e.g swap structures) 1742 */ 1743 if (vmstats.v_page_count > 1024) 1744 vmstats.v_free_min = 64 + (vmstats.v_page_count - 1024) / 200; 1745 else 1746 vmstats.v_free_min = 64; 1747 vmstats.v_free_reserved = vmstats.v_free_min * 4 / 8 + 7; 1748 vmstats.v_free_severe = vmstats.v_free_min * 4 / 8 + 0; 1749 vmstats.v_pageout_free_min = vmstats.v_free_min * 2 / 8 + 7; 1750 vmstats.v_interrupt_free_min = vmstats.v_free_min * 1 / 8 + 7; 1751 1752 return 1; 1753 } 1754 1755 1756 /* 1757 * vm_pageout is the high level pageout daemon. 1758 * 1759 * No requirements. 1760 */ 1761 static void 1762 vm_pageout_thread(void) 1763 { 1764 int pass; 1765 int q; 1766 int q1iterator = 0; 1767 int q2iterator = 0; 1768 1769 /* 1770 * Initialize some paging parameters. 1771 */ 1772 curthread->td_flags |= TDF_SYSTHREAD; 1773 1774 vm_pageout_free_page_calc(vmstats.v_page_count); 1775 1776 /* 1777 * v_free_target and v_cache_min control pageout hysteresis. Note 1778 * that these are more a measure of the VM cache queue hysteresis 1779 * then the VM free queue. Specifically, v_free_target is the 1780 * high water mark (free+cache pages). 1781 * 1782 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1783 * low water mark, while v_free_min is the stop. v_cache_min must 1784 * be big enough to handle memory needs while the pageout daemon 1785 * is signalled and run to free more pages. 1786 */ 1787 if (vmstats.v_free_count > 6144) 1788 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved; 1789 else 1790 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved; 1791 1792 /* 1793 * NOTE: With the new buffer cache b_act_count we want the default 1794 * inactive target to be a percentage of available memory. 1795 * 1796 * The inactive target essentially determines the minimum 1797 * number of 'temporary' pages capable of caching one-time-use 1798 * files when the VM system is otherwise full of pages 1799 * belonging to multi-time-use files or active program data. 1800 * 1801 * NOTE: The inactive target is aggressively persued only if the 1802 * inactive queue becomes too small. If the inactive queue 1803 * is large enough to satisfy page movement to free+cache 1804 * then it is repopulated more slowly from the active queue. 1805 * This allows a general inactive_target default to be set. 1806 * 1807 * There is an issue here for processes which sit mostly idle 1808 * 'overnight', such as sshd, tcsh, and X. Any movement from 1809 * the active queue will eventually cause such pages to 1810 * recycle eventually causing a lot of paging in the morning. 1811 * To reduce the incidence of this pages cycled out of the 1812 * buffer cache are moved directly to the inactive queue if 1813 * they were only used once or twice. 1814 * 1815 * The vfs.vm_cycle_point sysctl can be used to adjust this. 1816 * Increasing the value (up to 64) increases the number of 1817 * buffer recyclements which go directly to the inactive queue. 1818 */ 1819 if (vmstats.v_free_count > 2048) { 1820 vmstats.v_cache_min = vmstats.v_free_target; 1821 vmstats.v_cache_max = 2 * vmstats.v_cache_min; 1822 } else { 1823 vmstats.v_cache_min = 0; 1824 vmstats.v_cache_max = 0; 1825 } 1826 vmstats.v_inactive_target = vmstats.v_free_count / 4; 1827 1828 /* XXX does not really belong here */ 1829 if (vm_page_max_wired == 0) 1830 vm_page_max_wired = vmstats.v_free_count / 3; 1831 1832 if (vm_pageout_stats_max == 0) 1833 vm_pageout_stats_max = vmstats.v_free_target; 1834 1835 /* 1836 * Set interval in seconds for stats scan. 1837 */ 1838 if (vm_pageout_stats_interval == 0) 1839 vm_pageout_stats_interval = 5; 1840 if (vm_pageout_full_stats_interval == 0) 1841 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1842 1843 1844 /* 1845 * Set maximum free per pass 1846 */ 1847 if (vm_pageout_stats_free_max == 0) 1848 vm_pageout_stats_free_max = 5; 1849 1850 swap_pager_swap_init(); 1851 pass = 0; 1852 1853 /* 1854 * The pageout daemon is never done, so loop forever. 1855 */ 1856 while (TRUE) { 1857 int error; 1858 int avail_shortage; 1859 int inactive_shortage; 1860 int vnodes_skipped = 0; 1861 int recycle_count = 0; 1862 int tmp; 1863 1864 /* 1865 * Wait for an action request. If we timeout check to 1866 * see if paging is needed (in case the normal wakeup 1867 * code raced us). 1868 */ 1869 if (vm_pages_needed == 0) { 1870 error = tsleep(&vm_pages_needed, 1871 0, "psleep", 1872 vm_pageout_stats_interval * hz); 1873 if (error && 1874 vm_paging_needed() == 0 && 1875 vm_pages_needed == 0) { 1876 for (q = 0; q < PQ_L2_SIZE; ++q) 1877 vm_pageout_page_stats(q); 1878 continue; 1879 } 1880 vm_pages_needed = 1; 1881 } 1882 1883 mycpu->gd_cnt.v_pdwakeups++; 1884 1885 /* 1886 * Do whatever cleanup that the pmap code can. 1887 */ 1888 pmap_collect(); 1889 1890 /* 1891 * Scan for pageout. Try to avoid thrashing the system 1892 * with activity. 1893 * 1894 * Calculate our target for the number of free+cache pages we 1895 * want to get to. This is higher then the number that causes 1896 * allocations to stall (severe) in order to provide hysteresis, 1897 * and if we don't make it all the way but get to the minimum 1898 * we're happy. Goose it a bit if there are multipler 1899 * requests for memory. 1900 */ 1901 avail_shortage = vm_paging_target() + vm_pageout_deficit; 1902 vm_pageout_deficit = 0; 1903 1904 if (avail_shortage > 0) { 1905 for (q = 0; q < PQ_L2_SIZE; ++q) { 1906 avail_shortage -= 1907 vm_pageout_scan_inactive( 1908 pass, 1909 (q + q1iterator) & PQ_L2_MASK, 1910 PQAVERAGE(avail_shortage), 1911 &vnodes_skipped); 1912 if (avail_shortage <= 0) 1913 break; 1914 } 1915 q1iterator = q + 1; 1916 } 1917 1918 /* 1919 * Figure out how many active pages we must deactivate. If 1920 * we were able to reach our target with just the inactive 1921 * scan above we limit the number of active pages we 1922 * deactivate to reduce unnecessary work. 1923 */ 1924 inactive_shortage = vmstats.v_inactive_target - 1925 vmstats.v_inactive_count; 1926 1927 /* 1928 * If we were unable to free sufficient inactive pages to 1929 * satisfy the free/cache queue requirements then simply 1930 * reaching the inactive target may not be good enough. 1931 * Try to deactivate pages in excess of the target based 1932 * on the shortfall. 1933 * 1934 * However to prevent thrashing the VM system do not 1935 * deactivate more than an additional 1/10 the inactive 1936 * target's worth of active pages. 1937 */ 1938 if (avail_shortage > 0) { 1939 tmp = avail_shortage * 2; 1940 if (tmp > vmstats.v_inactive_target / 10) 1941 tmp = vmstats.v_inactive_target / 10; 1942 inactive_shortage += tmp; 1943 } 1944 1945 /* 1946 * Only trigger on inactive shortage. Triggering on 1947 * avail_shortage can starve the active queue with 1948 * unnecessary active->inactive transitions and destroy 1949 * performance. 1950 */ 1951 if (/*avail_shortage > 0 ||*/ inactive_shortage > 0) { 1952 int delta; 1953 1954 for (q = 0; q < PQ_L2_SIZE; ++q) { 1955 delta = vm_pageout_scan_active( 1956 pass, 1957 (q + q2iterator) & PQ_L2_MASK, 1958 PQAVERAGE(avail_shortage), 1959 PQAVERAGE(inactive_shortage), 1960 &recycle_count); 1961 inactive_shortage -= delta; 1962 avail_shortage -= delta; 1963 if (inactive_shortage <= 0 && 1964 avail_shortage <= 0) { 1965 break; 1966 } 1967 } 1968 q2iterator = q + 1; 1969 } 1970 1971 /* 1972 * Finally free enough cache pages to meet our free page 1973 * requirement and take more drastic measures if we are 1974 * still in trouble. 1975 */ 1976 vm_pageout_scan_cache(avail_shortage, vnodes_skipped, 1977 recycle_count); 1978 1979 /* 1980 * Wait for more work. 1981 */ 1982 if (avail_shortage > 0) { 1983 ++pass; 1984 if (swap_pager_full) { 1985 /* 1986 * Running out of memory, catastrophic back-off 1987 * to one-second intervals. 1988 */ 1989 tsleep(&vm_pages_needed, 0, "pdelay", hz); 1990 } else if (pass < 10 && vm_pages_needed > 1) { 1991 /* 1992 * Normal operation, additional processes 1993 * have already kicked us. Retry immediately. 1994 */ 1995 } else if (pass < 10) { 1996 /* 1997 * Normal operation, fewer processes. Delay 1998 * a bit but allow wakeups. 1999 */ 2000 vm_pages_needed = 0; 2001 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10); 2002 vm_pages_needed = 1; 2003 } else { 2004 /* 2005 * We've taken too many passes, forced delay. 2006 */ 2007 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10); 2008 } 2009 } else if (vm_pages_needed) { 2010 /* 2011 * Interlocked wakeup of waiters (non-optional). 2012 * 2013 * Similar to vm_page_free_wakeup() in vm_page.c, 2014 * wake 2015 */ 2016 pass = 0; 2017 if (!vm_page_count_min(vm_page_free_hysteresis) || 2018 !vm_page_count_target()) { 2019 vm_pages_needed = 0; 2020 wakeup(&vmstats.v_free_count); 2021 } 2022 } else { 2023 pass = 0; 2024 } 2025 } 2026 } 2027 2028 static struct kproc_desc page_kp = { 2029 "pagedaemon", 2030 vm_pageout_thread, 2031 &pagethread 2032 }; 2033 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 2034 2035 2036 /* 2037 * Called after allocating a page out of the cache or free queue 2038 * to possibly wake the pagedaemon up to replentish our supply. 2039 * 2040 * We try to generate some hysteresis by waking the pagedaemon up 2041 * when our free+cache pages go below the free_min+cache_min level. 2042 * The pagedaemon tries to get the count back up to at least the 2043 * minimum, and through to the target level if possible. 2044 * 2045 * If the pagedaemon is already active bump vm_pages_needed as a hint 2046 * that there are even more requests pending. 2047 * 2048 * SMP races ok? 2049 * No requirements. 2050 */ 2051 void 2052 pagedaemon_wakeup(void) 2053 { 2054 if (vm_paging_needed() && curthread != pagethread) { 2055 if (vm_pages_needed == 0) { 2056 vm_pages_needed = 1; /* SMP race ok */ 2057 wakeup(&vm_pages_needed); 2058 } else if (vm_page_count_min(0)) { 2059 ++vm_pages_needed; /* SMP race ok */ 2060 } 2061 } 2062 } 2063 2064 #if !defined(NO_SWAPPING) 2065 2066 /* 2067 * SMP races ok? 2068 * No requirements. 2069 */ 2070 static void 2071 vm_req_vmdaemon(void) 2072 { 2073 static int lastrun = 0; 2074 2075 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 2076 wakeup(&vm_daemon_needed); 2077 lastrun = ticks; 2078 } 2079 } 2080 2081 static int vm_daemon_callback(struct proc *p, void *data __unused); 2082 2083 /* 2084 * No requirements. 2085 */ 2086 static void 2087 vm_daemon(void) 2088 { 2089 /* 2090 * XXX vm_daemon_needed specific token? 2091 */ 2092 while (TRUE) { 2093 tsleep(&vm_daemon_needed, 0, "psleep", 0); 2094 if (vm_pageout_req_swapout) { 2095 swapout_procs(vm_pageout_req_swapout); 2096 vm_pageout_req_swapout = 0; 2097 } 2098 /* 2099 * scan the processes for exceeding their rlimits or if 2100 * process is swapped out -- deactivate pages 2101 */ 2102 allproc_scan(vm_daemon_callback, NULL); 2103 } 2104 } 2105 2106 static int 2107 vm_daemon_callback(struct proc *p, void *data __unused) 2108 { 2109 struct vmspace *vm; 2110 vm_pindex_t limit, size; 2111 2112 /* 2113 * if this is a system process or if we have already 2114 * looked at this process, skip it. 2115 */ 2116 lwkt_gettoken(&p->p_token); 2117 2118 if (p->p_flags & (P_SYSTEM | P_WEXIT)) { 2119 lwkt_reltoken(&p->p_token); 2120 return (0); 2121 } 2122 2123 /* 2124 * if the process is in a non-running type state, 2125 * don't touch it. 2126 */ 2127 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) { 2128 lwkt_reltoken(&p->p_token); 2129 return (0); 2130 } 2131 2132 /* 2133 * get a limit 2134 */ 2135 limit = OFF_TO_IDX(qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 2136 p->p_rlimit[RLIMIT_RSS].rlim_max)); 2137 2138 /* 2139 * let processes that are swapped out really be 2140 * swapped out. Set the limit to nothing to get as 2141 * many pages out to swap as possible. 2142 */ 2143 if (p->p_flags & P_SWAPPEDOUT) 2144 limit = 0; 2145 2146 vm = p->p_vmspace; 2147 vmspace_hold(vm); 2148 size = vmspace_resident_count(vm); 2149 if (limit >= 0 && size >= limit) { 2150 vm_pageout_map_deactivate_pages(&vm->vm_map, limit); 2151 } 2152 vmspace_drop(vm); 2153 2154 lwkt_reltoken(&p->p_token); 2155 2156 return (0); 2157 } 2158 2159 #endif 2160