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 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 777 778 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL && 779 maxscan-- > 0 && avail_shortage - delta > 0) 780 { 781 vm_page_and_queue_spin_lock(m); 782 if (m != TAILQ_NEXT(&marker, pageq)) { 783 vm_page_and_queue_spin_unlock(m); 784 ++maxscan; 785 continue; 786 } 787 KKASSERT(m->queue - m->pc == PQ_INACTIVE); 788 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl, 789 &marker, pageq); 790 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE + q].pl, m, 791 &marker, pageq); 792 mycpu->gd_cnt.v_pdpages++; 793 794 /* 795 * Skip marker pages 796 */ 797 if (m->flags & PG_MARKER) { 798 vm_page_and_queue_spin_unlock(m); 799 continue; 800 } 801 802 /* 803 * Try to busy the page. Don't mess with pages which are 804 * already busy or reorder them in the queue. 805 */ 806 if (vm_page_busy_try(m, TRUE)) { 807 vm_page_and_queue_spin_unlock(m); 808 continue; 809 } 810 vm_page_and_queue_spin_unlock(m); 811 KKASSERT(m->queue - m->pc == PQ_INACTIVE); 812 813 lwkt_yield(); 814 815 /* 816 * The page has been successfully busied and is now no 817 * longer spinlocked. The queue is no longer spinlocked 818 * either. 819 */ 820 821 /* 822 * It is possible for a page to be busied ad-hoc (e.g. the 823 * pmap_collect() code) and wired and race against the 824 * allocation of a new page. vm_page_alloc() may be forced 825 * to deactivate the wired page in which case it winds up 826 * on the inactive queue and must be handled here. We 827 * correct the problem simply by unqueuing the page. 828 */ 829 if (m->wire_count) { 830 vm_page_unqueue_nowakeup(m); 831 vm_page_wakeup(m); 832 kprintf("WARNING: pagedaemon: wired page on " 833 "inactive queue %p\n", m); 834 continue; 835 } 836 837 /* 838 * A held page may be undergoing I/O, so skip it. 839 */ 840 if (m->hold_count) { 841 vm_page_and_queue_spin_lock(m); 842 if (m->queue - m->pc == PQ_INACTIVE) { 843 TAILQ_REMOVE( 844 &vm_page_queues[PQ_INACTIVE + q].pl, 845 m, pageq); 846 TAILQ_INSERT_TAIL( 847 &vm_page_queues[PQ_INACTIVE + q].pl, 848 m, pageq); 849 ++vm_swapcache_inactive_heuristic; 850 } 851 vm_page_and_queue_spin_unlock(m); 852 vm_page_wakeup(m); 853 continue; 854 } 855 856 if (m->object == NULL || m->object->ref_count == 0) { 857 /* 858 * If the object is not being used, we ignore previous 859 * references. 860 */ 861 vm_page_flag_clear(m, PG_REFERENCED); 862 pmap_clear_reference(m); 863 /* fall through to end */ 864 } else if (((m->flags & PG_REFERENCED) == 0) && 865 (actcount = pmap_ts_referenced(m))) { 866 /* 867 * Otherwise, if the page has been referenced while 868 * in the inactive queue, we bump the "activation 869 * count" upwards, making it less likely that the 870 * page will be added back to the inactive queue 871 * prematurely again. Here we check the page tables 872 * (or emulated bits, if any), given the upper level 873 * VM system not knowing anything about existing 874 * references. 875 */ 876 vm_page_activate(m); 877 m->act_count += (actcount + ACT_ADVANCE); 878 vm_page_wakeup(m); 879 continue; 880 } 881 882 /* 883 * (m) is still busied. 884 * 885 * If the upper level VM system knows about any page 886 * references, we activate the page. We also set the 887 * "activation count" higher than normal so that we will less 888 * likely place pages back onto the inactive queue again. 889 */ 890 if ((m->flags & PG_REFERENCED) != 0) { 891 vm_page_flag_clear(m, PG_REFERENCED); 892 actcount = pmap_ts_referenced(m); 893 vm_page_activate(m); 894 m->act_count += (actcount + ACT_ADVANCE + 1); 895 vm_page_wakeup(m); 896 continue; 897 } 898 899 /* 900 * If the upper level VM system doesn't know anything about 901 * the page being dirty, we have to check for it again. As 902 * far as the VM code knows, any partially dirty pages are 903 * fully dirty. 904 * 905 * Pages marked PG_WRITEABLE may be mapped into the user 906 * address space of a process running on another cpu. A 907 * user process (without holding the MP lock) running on 908 * another cpu may be able to touch the page while we are 909 * trying to remove it. vm_page_cache() will handle this 910 * case for us. 911 */ 912 if (m->dirty == 0) { 913 vm_page_test_dirty(m); 914 } else { 915 vm_page_dirty(m); 916 } 917 918 if (m->valid == 0 && (m->flags & PG_NEED_COMMIT) == 0) { 919 /* 920 * Invalid pages can be easily freed 921 */ 922 vm_pageout_page_free(m); 923 mycpu->gd_cnt.v_dfree++; 924 ++delta; 925 } else if (m->dirty == 0 && (m->flags & PG_NEED_COMMIT) == 0) { 926 /* 927 * Clean pages can be placed onto the cache queue. 928 * This effectively frees them. 929 */ 930 vm_page_cache(m); 931 ++delta; 932 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 933 /* 934 * Dirty pages need to be paged out, but flushing 935 * a page is extremely expensive verses freeing 936 * a clean page. Rather then artificially limiting 937 * the number of pages we can flush, we instead give 938 * dirty pages extra priority on the inactive queue 939 * by forcing them to be cycled through the queue 940 * twice before being flushed, after which the 941 * (now clean) page will cycle through once more 942 * before being freed. This significantly extends 943 * the thrash point for a heavily loaded machine. 944 */ 945 vm_page_flag_set(m, PG_WINATCFLS); 946 vm_page_and_queue_spin_lock(m); 947 if (m->queue - m->pc == PQ_INACTIVE) { 948 TAILQ_REMOVE( 949 &vm_page_queues[PQ_INACTIVE + q].pl, 950 m, pageq); 951 TAILQ_INSERT_TAIL( 952 &vm_page_queues[PQ_INACTIVE + q].pl, 953 m, pageq); 954 ++vm_swapcache_inactive_heuristic; 955 } 956 vm_page_and_queue_spin_unlock(m); 957 vm_page_wakeup(m); 958 } else if (maxlaunder > 0) { 959 /* 960 * We always want to try to flush some dirty pages if 961 * we encounter them, to keep the system stable. 962 * Normally this number is small, but under extreme 963 * pressure where there are insufficient clean pages 964 * on the inactive queue, we may have to go all out. 965 */ 966 int swap_pageouts_ok; 967 struct vnode *vp = NULL; 968 969 swap_pageouts_ok = 0; 970 object = m->object; 971 if (object && 972 (object->type != OBJT_SWAP) && 973 (object->type != OBJT_DEFAULT)) { 974 swap_pageouts_ok = 1; 975 } else { 976 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 977 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 978 vm_page_count_min(0)); 979 980 } 981 982 /* 983 * We don't bother paging objects that are "dead". 984 * Those objects are in a "rundown" state. 985 */ 986 if (!swap_pageouts_ok || 987 (object == NULL) || 988 (object->flags & OBJ_DEAD)) { 989 vm_page_and_queue_spin_lock(m); 990 if (m->queue - m->pc == PQ_INACTIVE) { 991 TAILQ_REMOVE( 992 &vm_page_queues[PQ_INACTIVE + q].pl, 993 m, pageq); 994 TAILQ_INSERT_TAIL( 995 &vm_page_queues[PQ_INACTIVE + q].pl, 996 m, pageq); 997 ++vm_swapcache_inactive_heuristic; 998 } 999 vm_page_and_queue_spin_unlock(m); 1000 vm_page_wakeup(m); 1001 continue; 1002 } 1003 1004 /* 1005 * (m) is still busied. 1006 * 1007 * The object is already known NOT to be dead. It 1008 * is possible for the vget() to block the whole 1009 * pageout daemon, but the new low-memory handling 1010 * code should prevent it. 1011 * 1012 * The previous code skipped locked vnodes and, worse, 1013 * reordered pages in the queue. This results in 1014 * completely non-deterministic operation because, 1015 * quite often, a vm_fault has initiated an I/O and 1016 * is holding a locked vnode at just the point where 1017 * the pageout daemon is woken up. 1018 * 1019 * We can't wait forever for the vnode lock, we might 1020 * deadlock due to a vn_read() getting stuck in 1021 * vm_wait while holding this vnode. We skip the 1022 * vnode if we can't get it in a reasonable amount 1023 * of time. 1024 * 1025 * vpfailed is used to (try to) avoid the case where 1026 * a large number of pages are associated with a 1027 * locked vnode, which could cause the pageout daemon 1028 * to stall for an excessive amount of time. 1029 */ 1030 if (object->type == OBJT_VNODE) { 1031 int flags; 1032 1033 vp = object->handle; 1034 flags = LK_EXCLUSIVE; 1035 if (vp == vpfailed) 1036 flags |= LK_NOWAIT; 1037 else 1038 flags |= LK_TIMELOCK; 1039 vm_page_hold(m); 1040 vm_page_wakeup(m); 1041 1042 /* 1043 * We have unbusied (m) temporarily so we can 1044 * acquire the vp lock without deadlocking. 1045 * (m) is held to prevent destruction. 1046 */ 1047 if (vget(vp, flags) != 0) { 1048 vpfailed = vp; 1049 ++pageout_lock_miss; 1050 if (object->flags & OBJ_MIGHTBEDIRTY) 1051 ++*vnodes_skippedp; 1052 vm_page_unhold(m); 1053 continue; 1054 } 1055 1056 /* 1057 * The page might have been moved to another 1058 * queue during potential blocking in vget() 1059 * above. The page might have been freed and 1060 * reused for another vnode. The object might 1061 * have been reused for another vnode. 1062 */ 1063 if (m->queue - m->pc != PQ_INACTIVE || 1064 m->object != object || 1065 object->handle != vp) { 1066 if (object->flags & OBJ_MIGHTBEDIRTY) 1067 ++*vnodes_skippedp; 1068 vput(vp); 1069 vm_page_unhold(m); 1070 continue; 1071 } 1072 1073 /* 1074 * The page may have been busied during the 1075 * blocking in vput(); We don't move the 1076 * page back onto the end of the queue so that 1077 * statistics are more correct if we don't. 1078 */ 1079 if (vm_page_busy_try(m, TRUE)) { 1080 vput(vp); 1081 vm_page_unhold(m); 1082 continue; 1083 } 1084 vm_page_unhold(m); 1085 1086 /* 1087 * (m) is busied again 1088 * 1089 * We own the busy bit and remove our hold 1090 * bit. If the page is still held it 1091 * might be undergoing I/O, so skip it. 1092 */ 1093 if (m->hold_count) { 1094 vm_page_and_queue_spin_lock(m); 1095 if (m->queue - m->pc == PQ_INACTIVE) { 1096 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl, m, pageq); 1097 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE + q].pl, m, pageq); 1098 ++vm_swapcache_inactive_heuristic; 1099 } 1100 vm_page_and_queue_spin_unlock(m); 1101 if (object->flags & OBJ_MIGHTBEDIRTY) 1102 ++*vnodes_skippedp; 1103 vm_page_wakeup(m); 1104 vput(vp); 1105 continue; 1106 } 1107 /* (m) is left busied as we fall through */ 1108 } 1109 1110 /* 1111 * page is busy and not held here. 1112 * 1113 * If a page is dirty, then it is either being washed 1114 * (but not yet cleaned) or it is still in the 1115 * laundry. If it is still in the laundry, then we 1116 * start the cleaning operation. 1117 * 1118 * decrement inactive_shortage on success to account 1119 * for the (future) cleaned page. Otherwise we 1120 * could wind up laundering or cleaning too many 1121 * pages. 1122 */ 1123 count = vm_pageout_clean(m); 1124 delta += count; 1125 maxlaunder -= count; 1126 1127 /* 1128 * Clean ate busy, page no longer accessible 1129 */ 1130 if (vp != NULL) 1131 vput(vp); 1132 } else { 1133 vm_page_wakeup(m); 1134 } 1135 1136 /* 1137 * Systems with a ton of memory can wind up with huge 1138 * deactivation counts. Because the inactive scan is 1139 * doing a lot of flushing, the combination can result 1140 * in excessive paging even in situations where other 1141 * unrelated threads free up sufficient VM. 1142 * 1143 * To deal with this we abort the nominal active->inactive 1144 * scan before we hit the inactive target when free+cache 1145 * levels have already reached their target. 1146 * 1147 * Note that nominally the inactive scan is not freeing or 1148 * caching pages, it is deactivating active pages, so it 1149 * will not by itself cause the abort condition. 1150 */ 1151 if (vm_paging_target() < 0) 1152 break; 1153 } 1154 vm_page_queues_spin_lock(PQ_INACTIVE + q); 1155 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl, &marker, pageq); 1156 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 1157 1158 return (delta); 1159 } 1160 1161 static int 1162 vm_pageout_scan_active(int pass, int q, 1163 int avail_shortage, int inactive_shortage, 1164 int *recycle_countp) 1165 { 1166 struct vm_page marker; 1167 vm_page_t m; 1168 int actcount; 1169 int delta = 0; 1170 int maxscan; 1171 1172 /* 1173 * We want to move pages from the active queue to the inactive 1174 * queue to get the inactive queue to the inactive target. If 1175 * we still have a page shortage from above we try to directly free 1176 * clean pages instead of moving them. 1177 * 1178 * If we do still have a shortage we keep track of the number of 1179 * pages we free or cache (recycle_count) as a measure of thrashing 1180 * between the active and inactive queues. 1181 * 1182 * If we were able to completely satisfy the free+cache targets 1183 * from the inactive pool we limit the number of pages we move 1184 * from the active pool to the inactive pool to 2x the pages we 1185 * had removed from the inactive pool (with a minimum of 1/5 the 1186 * inactive target). If we were not able to completely satisfy 1187 * the free+cache targets we go for the whole target aggressively. 1188 * 1189 * NOTE: Both variables can end up negative. 1190 * NOTE: We are still in a critical section. 1191 */ 1192 1193 bzero(&marker, sizeof(marker)); 1194 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 1195 marker.queue = PQ_ACTIVE + q; 1196 marker.pc = q; 1197 marker.wire_count = 1; 1198 1199 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1200 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1201 maxscan = vm_page_queues[PQ_ACTIVE + q].lcnt; 1202 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1203 1204 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL && 1205 maxscan-- > 0 && (avail_shortage - delta > 0 || 1206 inactive_shortage > 0)) 1207 { 1208 vm_page_and_queue_spin_lock(m); 1209 if (m != TAILQ_NEXT(&marker, pageq)) { 1210 vm_page_and_queue_spin_unlock(m); 1211 ++maxscan; 1212 continue; 1213 } 1214 KKASSERT(m->queue - m->pc == PQ_ACTIVE); 1215 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, 1216 &marker, pageq); 1217 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_ACTIVE + q].pl, m, 1218 &marker, pageq); 1219 1220 /* 1221 * Skip marker pages 1222 */ 1223 if (m->flags & PG_MARKER) { 1224 vm_page_and_queue_spin_unlock(m); 1225 continue; 1226 } 1227 1228 /* 1229 * Try to busy the page. Don't mess with pages which are 1230 * already busy or reorder them in the queue. 1231 */ 1232 if (vm_page_busy_try(m, TRUE)) { 1233 vm_page_and_queue_spin_unlock(m); 1234 continue; 1235 } 1236 1237 /* 1238 * Don't deactivate pages that are held, even if we can 1239 * busy them. (XXX why not?) 1240 */ 1241 if (m->hold_count != 0) { 1242 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, 1243 m, pageq); 1244 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE + q].pl, 1245 m, pageq); 1246 vm_page_and_queue_spin_unlock(m); 1247 vm_page_wakeup(m); 1248 continue; 1249 } 1250 vm_page_and_queue_spin_unlock(m); 1251 lwkt_yield(); 1252 1253 /* 1254 * The page has been successfully busied and the page and 1255 * queue are no longer locked. 1256 */ 1257 1258 /* 1259 * The count for pagedaemon pages is done after checking the 1260 * page for eligibility... 1261 */ 1262 mycpu->gd_cnt.v_pdpages++; 1263 1264 /* 1265 * Check to see "how much" the page has been used and clear 1266 * the tracking access bits. If the object has no references 1267 * don't bother paying the expense. 1268 */ 1269 actcount = 0; 1270 if (m->object && m->object->ref_count != 0) { 1271 if (m->flags & PG_REFERENCED) 1272 ++actcount; 1273 actcount += pmap_ts_referenced(m); 1274 if (actcount) { 1275 m->act_count += ACT_ADVANCE + actcount; 1276 if (m->act_count > ACT_MAX) 1277 m->act_count = ACT_MAX; 1278 } 1279 } 1280 vm_page_flag_clear(m, PG_REFERENCED); 1281 1282 /* 1283 * actcount is only valid if the object ref_count is non-zero. 1284 * If the page does not have an object, actcount will be zero. 1285 */ 1286 if (actcount && m->object->ref_count != 0) { 1287 vm_page_and_queue_spin_lock(m); 1288 if (m->queue - m->pc == PQ_ACTIVE) { 1289 TAILQ_REMOVE( 1290 &vm_page_queues[PQ_ACTIVE + q].pl, 1291 m, pageq); 1292 TAILQ_INSERT_TAIL( 1293 &vm_page_queues[PQ_ACTIVE + q].pl, 1294 m, pageq); 1295 } 1296 vm_page_and_queue_spin_unlock(m); 1297 vm_page_wakeup(m); 1298 } else { 1299 switch(m->object->type) { 1300 case OBJT_DEFAULT: 1301 case OBJT_SWAP: 1302 m->act_count -= min(m->act_count, 1303 vm_anonmem_decline); 1304 break; 1305 default: 1306 m->act_count -= min(m->act_count, 1307 vm_filemem_decline); 1308 break; 1309 } 1310 if (vm_pageout_algorithm || 1311 (m->object == NULL) || 1312 (m->object && (m->object->ref_count == 0)) || 1313 m->act_count < pass + 1 1314 ) { 1315 /* 1316 * Deactivate the page. If we had a 1317 * shortage from our inactive scan try to 1318 * free (cache) the page instead. 1319 * 1320 * Don't just blindly cache the page if 1321 * we do not have a shortage from the 1322 * inactive scan, that could lead to 1323 * gigabytes being moved. 1324 */ 1325 --inactive_shortage; 1326 if (avail_shortage - delta > 0 || 1327 (m->object && (m->object->ref_count == 0))) 1328 { 1329 if (avail_shortage - delta > 0) 1330 ++*recycle_countp; 1331 vm_page_protect(m, VM_PROT_NONE); 1332 if (m->dirty == 0 && 1333 (m->flags & PG_NEED_COMMIT) == 0 && 1334 avail_shortage - delta > 0) { 1335 vm_page_cache(m); 1336 } else { 1337 vm_page_deactivate(m); 1338 vm_page_wakeup(m); 1339 } 1340 } else { 1341 vm_page_deactivate(m); 1342 vm_page_wakeup(m); 1343 } 1344 ++delta; 1345 } else { 1346 vm_page_and_queue_spin_lock(m); 1347 if (m->queue - m->pc == PQ_ACTIVE) { 1348 TAILQ_REMOVE( 1349 &vm_page_queues[PQ_ACTIVE + q].pl, 1350 m, pageq); 1351 TAILQ_INSERT_TAIL( 1352 &vm_page_queues[PQ_ACTIVE + q].pl, 1353 m, pageq); 1354 } 1355 vm_page_and_queue_spin_unlock(m); 1356 vm_page_wakeup(m); 1357 } 1358 } 1359 } 1360 1361 /* 1362 * Clean out our local marker. 1363 */ 1364 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1365 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1366 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1367 1368 return (delta); 1369 } 1370 1371 /* 1372 * The number of actually free pages can drop down to v_free_reserved, 1373 * we try to build the free count back above v_free_min. Note that 1374 * vm_paging_needed() also returns TRUE if v_free_count is not at 1375 * least v_free_min so that is the minimum we must build the free 1376 * count to. 1377 * 1378 * We use a slightly higher target to improve hysteresis, 1379 * ((v_free_target + v_free_min) / 2). Since v_free_target 1380 * is usually the same as v_cache_min this maintains about 1381 * half the pages in the free queue as are in the cache queue, 1382 * providing pretty good pipelining for pageout operation. 1383 * 1384 * The system operator can manipulate vm.v_cache_min and 1385 * vm.v_free_target to tune the pageout demon. Be sure 1386 * to keep vm.v_free_min < vm.v_free_target. 1387 * 1388 * Note that the original paging target is to get at least 1389 * (free_min + cache_min) into (free + cache). The slightly 1390 * higher target will shift additional pages from cache to free 1391 * without effecting the original paging target in order to 1392 * maintain better hysteresis and not have the free count always 1393 * be dead-on v_free_min. 1394 * 1395 * NOTE: we are still in a critical section. 1396 * 1397 * Pages moved from PQ_CACHE to totally free are not counted in the 1398 * pages_freed counter. 1399 */ 1400 static void 1401 vm_pageout_scan_cache(int avail_shortage, int vnodes_skipped, int recycle_count) 1402 { 1403 struct vm_pageout_scan_info info; 1404 vm_page_t m; 1405 1406 while (vmstats.v_free_count < 1407 (vmstats.v_free_min + vmstats.v_free_target) / 2) { 1408 /* 1409 * This steals some code from vm/vm_page.c 1410 */ 1411 static int cache_rover = 0; 1412 1413 m = vm_page_list_find(PQ_CACHE, cache_rover & PQ_L2_MASK, FALSE); 1414 if (m == NULL) 1415 break; 1416 /* page is returned removed from its queue and spinlocked */ 1417 if (vm_page_busy_try(m, TRUE)) { 1418 vm_page_deactivate_locked(m); 1419 vm_page_spin_unlock(m); 1420 continue; 1421 } 1422 vm_page_spin_unlock(m); 1423 pagedaemon_wakeup(); 1424 lwkt_yield(); 1425 1426 /* 1427 * Page has been successfully busied and it and its queue 1428 * is no longer spinlocked. 1429 */ 1430 if ((m->flags & (PG_UNMANAGED | PG_NEED_COMMIT)) || 1431 m->hold_count || 1432 m->wire_count) { 1433 vm_page_deactivate(m); 1434 vm_page_wakeup(m); 1435 continue; 1436 } 1437 KKASSERT((m->flags & PG_MAPPED) == 0); 1438 KKASSERT(m->dirty == 0); 1439 cache_rover += PQ_PRIME2; 1440 vm_pageout_page_free(m); 1441 mycpu->gd_cnt.v_dfree++; 1442 } 1443 1444 #if !defined(NO_SWAPPING) 1445 /* 1446 * Idle process swapout -- run once per second. 1447 */ 1448 if (vm_swap_idle_enabled) { 1449 static time_t lsec; 1450 if (time_uptime != lsec) { 1451 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1452 vm_req_vmdaemon(); 1453 lsec = time_uptime; 1454 } 1455 } 1456 #endif 1457 1458 /* 1459 * If we didn't get enough free pages, and we have skipped a vnode 1460 * in a writeable object, wakeup the sync daemon. And kick swapout 1461 * if we did not get enough free pages. 1462 */ 1463 if (vm_paging_target() > 0) { 1464 if (vnodes_skipped && vm_page_count_min(0)) 1465 speedup_syncer(NULL); 1466 #if !defined(NO_SWAPPING) 1467 if (vm_swap_enabled && vm_page_count_target()) { 1468 vm_req_vmdaemon(); 1469 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1470 } 1471 #endif 1472 } 1473 1474 /* 1475 * Handle catastrophic conditions. Under good conditions we should 1476 * be at the target, well beyond our minimum. If we could not even 1477 * reach our minimum the system is under heavy stress. 1478 * 1479 * Determine whether we have run out of memory. This occurs when 1480 * swap_pager_full is TRUE and the only pages left in the page 1481 * queues are dirty. We will still likely have page shortages. 1482 * 1483 * - swap_pager_full is set if insufficient swap was 1484 * available to satisfy a requested pageout. 1485 * 1486 * - the inactive queue is bloated (4 x size of active queue), 1487 * meaning it is unable to get rid of dirty pages and. 1488 * 1489 * - vm_page_count_min() without counting pages recycled from the 1490 * active queue (recycle_count) means we could not recover 1491 * enough pages to meet bare minimum needs. This test only 1492 * works if the inactive queue is bloated. 1493 * 1494 * - due to a positive avail_shortage we shifted the remaining 1495 * dirty pages from the active queue to the inactive queue 1496 * trying to find clean ones to free. 1497 */ 1498 if (swap_pager_full && vm_page_count_min(recycle_count)) 1499 kprintf("Warning: system low on memory+swap!\n"); 1500 if (swap_pager_full && vm_page_count_min(recycle_count) && 1501 vmstats.v_inactive_count > vmstats.v_active_count * 4 && 1502 avail_shortage > 0) { 1503 /* 1504 * Kill something. 1505 */ 1506 info.bigproc = NULL; 1507 info.bigsize = 0; 1508 allproc_scan(vm_pageout_scan_callback, &info); 1509 if (info.bigproc != NULL) { 1510 killproc(info.bigproc, "out of swap space"); 1511 info.bigproc->p_nice = PRIO_MIN; 1512 info.bigproc->p_usched->resetpriority( 1513 FIRST_LWP_IN_PROC(info.bigproc)); 1514 wakeup(&vmstats.v_free_count); 1515 PRELE(info.bigproc); 1516 } 1517 } 1518 } 1519 1520 static int 1521 vm_pageout_scan_callback(struct proc *p, void *data) 1522 { 1523 struct vm_pageout_scan_info *info = data; 1524 vm_offset_t size; 1525 1526 /* 1527 * Never kill system processes or init. If we have configured swap 1528 * then try to avoid killing low-numbered pids. 1529 */ 1530 if ((p->p_flags & P_SYSTEM) || (p->p_pid == 1) || 1531 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1532 return (0); 1533 } 1534 1535 lwkt_gettoken(&p->p_token); 1536 1537 /* 1538 * if the process is in a non-running type state, 1539 * don't touch it. 1540 */ 1541 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) { 1542 lwkt_reltoken(&p->p_token); 1543 return (0); 1544 } 1545 1546 /* 1547 * Get the approximate process size. Note that anonymous pages 1548 * with backing swap will be counted twice, but there should not 1549 * be too many such pages due to the stress the VM system is 1550 * under at this point. 1551 */ 1552 size = vmspace_anonymous_count(p->p_vmspace) + 1553 vmspace_swap_count(p->p_vmspace); 1554 1555 /* 1556 * If the this process is bigger than the biggest one 1557 * remember it. 1558 */ 1559 if (info->bigsize < size) { 1560 if (info->bigproc) 1561 PRELE(info->bigproc); 1562 PHOLD(p); 1563 info->bigproc = p; 1564 info->bigsize = size; 1565 } 1566 lwkt_reltoken(&p->p_token); 1567 lwkt_yield(); 1568 1569 return(0); 1570 } 1571 1572 /* 1573 * This routine tries to maintain the pseudo LRU active queue, 1574 * so that during long periods of time where there is no paging, 1575 * that some statistic accumulation still occurs. This code 1576 * helps the situation where paging just starts to occur. 1577 */ 1578 static void 1579 vm_pageout_page_stats(int q) 1580 { 1581 static int fullintervalcount = 0; 1582 struct vm_page marker; 1583 vm_page_t m; 1584 int pcount, tpcount; /* Number of pages to check */ 1585 int page_shortage; 1586 1587 page_shortage = (vmstats.v_inactive_target + vmstats.v_cache_max + 1588 vmstats.v_free_min) - 1589 (vmstats.v_free_count + vmstats.v_inactive_count + 1590 vmstats.v_cache_count); 1591 1592 if (page_shortage <= 0) 1593 return; 1594 1595 pcount = vm_page_queues[PQ_ACTIVE + q].lcnt; 1596 fullintervalcount += vm_pageout_stats_interval; 1597 if (fullintervalcount < vm_pageout_full_stats_interval) { 1598 tpcount = (vm_pageout_stats_max * pcount) / 1599 vmstats.v_page_count + 1; 1600 if (pcount > tpcount) 1601 pcount = tpcount; 1602 } else { 1603 fullintervalcount = 0; 1604 } 1605 1606 bzero(&marker, sizeof(marker)); 1607 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 1608 marker.queue = PQ_ACTIVE + q; 1609 marker.pc = q; 1610 marker.wire_count = 1; 1611 1612 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1613 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1614 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1615 1616 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL && 1617 pcount-- > 0) 1618 { 1619 int actcount; 1620 1621 vm_page_and_queue_spin_lock(m); 1622 if (m != TAILQ_NEXT(&marker, pageq)) { 1623 vm_page_and_queue_spin_unlock(m); 1624 ++pcount; 1625 continue; 1626 } 1627 KKASSERT(m->queue - m->pc == PQ_ACTIVE); 1628 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1629 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_ACTIVE + q].pl, m, 1630 &marker, pageq); 1631 1632 /* 1633 * Ignore markers 1634 */ 1635 if (m->flags & PG_MARKER) { 1636 vm_page_and_queue_spin_unlock(m); 1637 continue; 1638 } 1639 1640 /* 1641 * Ignore pages we can't busy 1642 */ 1643 if (vm_page_busy_try(m, TRUE)) { 1644 vm_page_and_queue_spin_unlock(m); 1645 continue; 1646 } 1647 vm_page_and_queue_spin_unlock(m); 1648 KKASSERT(m->queue - m->pc == PQ_ACTIVE); 1649 1650 /* 1651 * We now have a safely busied page, the page and queue 1652 * spinlocks have been released. 1653 * 1654 * Ignore held pages 1655 */ 1656 if (m->hold_count) { 1657 vm_page_wakeup(m); 1658 continue; 1659 } 1660 1661 /* 1662 * Calculate activity 1663 */ 1664 actcount = 0; 1665 if (m->flags & PG_REFERENCED) { 1666 vm_page_flag_clear(m, PG_REFERENCED); 1667 actcount += 1; 1668 } 1669 actcount += pmap_ts_referenced(m); 1670 1671 /* 1672 * Update act_count and move page to end of queue. 1673 */ 1674 if (actcount) { 1675 m->act_count += ACT_ADVANCE + actcount; 1676 if (m->act_count > ACT_MAX) 1677 m->act_count = ACT_MAX; 1678 vm_page_and_queue_spin_lock(m); 1679 if (m->queue - m->pc == PQ_ACTIVE) { 1680 TAILQ_REMOVE( 1681 &vm_page_queues[PQ_ACTIVE + q].pl, 1682 m, pageq); 1683 TAILQ_INSERT_TAIL( 1684 &vm_page_queues[PQ_ACTIVE + q].pl, 1685 m, pageq); 1686 } 1687 vm_page_and_queue_spin_unlock(m); 1688 vm_page_wakeup(m); 1689 continue; 1690 } 1691 1692 if (m->act_count == 0) { 1693 /* 1694 * We turn off page access, so that we have 1695 * more accurate RSS stats. We don't do this 1696 * in the normal page deactivation when the 1697 * system is loaded VM wise, because the 1698 * cost of the large number of page protect 1699 * operations would be higher than the value 1700 * of doing the operation. 1701 * 1702 * We use the marker to save our place so 1703 * we can release the spin lock. both (m) 1704 * and (next) will be invalid. 1705 */ 1706 vm_page_protect(m, VM_PROT_NONE); 1707 vm_page_deactivate(m); 1708 } else { 1709 m->act_count -= min(m->act_count, ACT_DECLINE); 1710 vm_page_and_queue_spin_lock(m); 1711 if (m->queue - m->pc == PQ_ACTIVE) { 1712 TAILQ_REMOVE( 1713 &vm_page_queues[PQ_ACTIVE + q].pl, 1714 m, pageq); 1715 TAILQ_INSERT_TAIL( 1716 &vm_page_queues[PQ_ACTIVE + q].pl, 1717 m, pageq); 1718 } 1719 vm_page_and_queue_spin_unlock(m); 1720 } 1721 vm_page_wakeup(m); 1722 } 1723 1724 /* 1725 * Remove our local marker 1726 */ 1727 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1728 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1729 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1730 } 1731 1732 static int 1733 vm_pageout_free_page_calc(vm_size_t count) 1734 { 1735 if (count < vmstats.v_page_count) 1736 return 0; 1737 /* 1738 * free_reserved needs to include enough for the largest swap pager 1739 * structures plus enough for any pv_entry structs when paging. 1740 * 1741 * v_free_min normal allocations 1742 * v_free_reserved system allocations 1743 * v_pageout_free_min allocations by pageout daemon 1744 * v_interrupt_free_min low level allocations (e.g swap structures) 1745 */ 1746 if (vmstats.v_page_count > 1024) 1747 vmstats.v_free_min = 64 + (vmstats.v_page_count - 1024) / 200; 1748 else 1749 vmstats.v_free_min = 64; 1750 vmstats.v_free_reserved = vmstats.v_free_min * 4 / 8 + 7; 1751 vmstats.v_free_severe = vmstats.v_free_min * 4 / 8 + 0; 1752 vmstats.v_pageout_free_min = vmstats.v_free_min * 2 / 8 + 7; 1753 vmstats.v_interrupt_free_min = vmstats.v_free_min * 1 / 8 + 7; 1754 1755 return 1; 1756 } 1757 1758 1759 /* 1760 * vm_pageout is the high level pageout daemon. 1761 * 1762 * No requirements. 1763 */ 1764 static void 1765 vm_pageout_thread(void) 1766 { 1767 int pass; 1768 int q; 1769 int q1iterator = 0; 1770 int q2iterator = 0; 1771 1772 /* 1773 * Initialize some paging parameters. 1774 */ 1775 curthread->td_flags |= TDF_SYSTHREAD; 1776 1777 vm_pageout_free_page_calc(vmstats.v_page_count); 1778 1779 /* 1780 * v_free_target and v_cache_min control pageout hysteresis. Note 1781 * that these are more a measure of the VM cache queue hysteresis 1782 * then the VM free queue. Specifically, v_free_target is the 1783 * high water mark (free+cache pages). 1784 * 1785 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1786 * low water mark, while v_free_min is the stop. v_cache_min must 1787 * be big enough to handle memory needs while the pageout daemon 1788 * is signalled and run to free more pages. 1789 */ 1790 if (vmstats.v_free_count > 6144) 1791 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved; 1792 else 1793 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved; 1794 1795 /* 1796 * NOTE: With the new buffer cache b_act_count we want the default 1797 * inactive target to be a percentage of available memory. 1798 * 1799 * The inactive target essentially determines the minimum 1800 * number of 'temporary' pages capable of caching one-time-use 1801 * files when the VM system is otherwise full of pages 1802 * belonging to multi-time-use files or active program data. 1803 * 1804 * NOTE: The inactive target is aggressively persued only if the 1805 * inactive queue becomes too small. If the inactive queue 1806 * is large enough to satisfy page movement to free+cache 1807 * then it is repopulated more slowly from the active queue. 1808 * This allows a general inactive_target default to be set. 1809 * 1810 * There is an issue here for processes which sit mostly idle 1811 * 'overnight', such as sshd, tcsh, and X. Any movement from 1812 * the active queue will eventually cause such pages to 1813 * recycle eventually causing a lot of paging in the morning. 1814 * To reduce the incidence of this pages cycled out of the 1815 * buffer cache are moved directly to the inactive queue if 1816 * they were only used once or twice. 1817 * 1818 * The vfs.vm_cycle_point sysctl can be used to adjust this. 1819 * Increasing the value (up to 64) increases the number of 1820 * buffer recyclements which go directly to the inactive queue. 1821 */ 1822 if (vmstats.v_free_count > 2048) { 1823 vmstats.v_cache_min = vmstats.v_free_target; 1824 vmstats.v_cache_max = 2 * vmstats.v_cache_min; 1825 } else { 1826 vmstats.v_cache_min = 0; 1827 vmstats.v_cache_max = 0; 1828 } 1829 vmstats.v_inactive_target = vmstats.v_free_count / 4; 1830 1831 /* XXX does not really belong here */ 1832 if (vm_page_max_wired == 0) 1833 vm_page_max_wired = vmstats.v_free_count / 3; 1834 1835 if (vm_pageout_stats_max == 0) 1836 vm_pageout_stats_max = vmstats.v_free_target; 1837 1838 /* 1839 * Set interval in seconds for stats scan. 1840 */ 1841 if (vm_pageout_stats_interval == 0) 1842 vm_pageout_stats_interval = 5; 1843 if (vm_pageout_full_stats_interval == 0) 1844 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1845 1846 1847 /* 1848 * Set maximum free per pass 1849 */ 1850 if (vm_pageout_stats_free_max == 0) 1851 vm_pageout_stats_free_max = 5; 1852 1853 swap_pager_swap_init(); 1854 pass = 0; 1855 1856 /* 1857 * The pageout daemon is never done, so loop forever. 1858 */ 1859 while (TRUE) { 1860 int error; 1861 int avail_shortage; 1862 int inactive_shortage; 1863 int vnodes_skipped = 0; 1864 int recycle_count = 0; 1865 int tmp; 1866 1867 /* 1868 * Wait for an action request. If we timeout check to 1869 * see if paging is needed (in case the normal wakeup 1870 * code raced us). 1871 */ 1872 if (vm_pages_needed == 0) { 1873 error = tsleep(&vm_pages_needed, 1874 0, "psleep", 1875 vm_pageout_stats_interval * hz); 1876 if (error && 1877 vm_paging_needed() == 0 && 1878 vm_pages_needed == 0) { 1879 for (q = 0; q < PQ_L2_SIZE; ++q) 1880 vm_pageout_page_stats(q); 1881 continue; 1882 } 1883 vm_pages_needed = 1; 1884 } 1885 1886 mycpu->gd_cnt.v_pdwakeups++; 1887 1888 /* 1889 * Do whatever cleanup that the pmap code can. 1890 */ 1891 pmap_collect(); 1892 1893 /* 1894 * Scan for pageout. Try to avoid thrashing the system 1895 * with activity. 1896 * 1897 * Calculate our target for the number of free+cache pages we 1898 * want to get to. This is higher then the number that causes 1899 * allocations to stall (severe) in order to provide hysteresis, 1900 * and if we don't make it all the way but get to the minimum 1901 * we're happy. Goose it a bit if there are multipler 1902 * requests for memory. 1903 */ 1904 avail_shortage = vm_paging_target() + vm_pageout_deficit; 1905 vm_pageout_deficit = 0; 1906 1907 if (avail_shortage > 0) { 1908 for (q = 0; q < PQ_L2_SIZE; ++q) { 1909 avail_shortage -= 1910 vm_pageout_scan_inactive( 1911 pass, 1912 (q + q1iterator) & PQ_L2_MASK, 1913 PQAVERAGE(avail_shortage), 1914 &vnodes_skipped); 1915 if (avail_shortage <= 0) 1916 break; 1917 } 1918 q1iterator = q + 1; 1919 } 1920 1921 /* 1922 * Figure out how many active pages we must deactivate. If 1923 * we were able to reach our target with just the inactive 1924 * scan above we limit the number of active pages we 1925 * deactivate to reduce unnecessary work. 1926 */ 1927 inactive_shortage = vmstats.v_inactive_target - 1928 vmstats.v_inactive_count; 1929 1930 /* 1931 * If we were unable to free sufficient inactive pages to 1932 * satisfy the free/cache queue requirements then simply 1933 * reaching the inactive target may not be good enough. 1934 * Try to deactivate pages in excess of the target based 1935 * on the shortfall. 1936 * 1937 * However to prevent thrashing the VM system do not 1938 * deactivate more than an additional 1/10 the inactive 1939 * target's worth of active pages. 1940 */ 1941 if (avail_shortage > 0) { 1942 tmp = avail_shortage * 2; 1943 if (tmp > vmstats.v_inactive_target / 10) 1944 tmp = vmstats.v_inactive_target / 10; 1945 inactive_shortage += tmp; 1946 } 1947 1948 /* 1949 * Only trigger on inactive shortage. Triggering on 1950 * avail_shortage can starve the active queue with 1951 * unnecessary active->inactive transitions and destroy 1952 * performance. 1953 */ 1954 if (/*avail_shortage > 0 ||*/ inactive_shortage > 0) { 1955 int delta; 1956 1957 for (q = 0; q < PQ_L2_SIZE; ++q) { 1958 delta = vm_pageout_scan_active( 1959 pass, 1960 (q + q2iterator) & PQ_L2_MASK, 1961 PQAVERAGE(avail_shortage), 1962 PQAVERAGE(inactive_shortage), 1963 &recycle_count); 1964 inactive_shortage -= delta; 1965 avail_shortage -= delta; 1966 if (inactive_shortage <= 0 && 1967 avail_shortage <= 0) { 1968 break; 1969 } 1970 } 1971 q2iterator = q + 1; 1972 } 1973 1974 /* 1975 * Finally free enough cache pages to meet our free page 1976 * requirement and take more drastic measures if we are 1977 * still in trouble. 1978 */ 1979 vm_pageout_scan_cache(avail_shortage, vnodes_skipped, 1980 recycle_count); 1981 1982 /* 1983 * Wait for more work. 1984 */ 1985 if (avail_shortage > 0) { 1986 ++pass; 1987 if (swap_pager_full) { 1988 /* 1989 * Running out of memory, catastrophic back-off 1990 * to one-second intervals. 1991 */ 1992 tsleep(&vm_pages_needed, 0, "pdelay", hz); 1993 } else if (pass < 10 && vm_pages_needed > 1) { 1994 /* 1995 * Normal operation, additional processes 1996 * have already kicked us. Retry immediately. 1997 */ 1998 } else if (pass < 10) { 1999 /* 2000 * Normal operation, fewer processes. Delay 2001 * a bit but allow wakeups. 2002 */ 2003 vm_pages_needed = 0; 2004 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10); 2005 vm_pages_needed = 1; 2006 } else { 2007 /* 2008 * We've taken too many passes, forced delay. 2009 */ 2010 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10); 2011 } 2012 } else if (vm_pages_needed) { 2013 /* 2014 * Interlocked wakeup of waiters (non-optional). 2015 * 2016 * Similar to vm_page_free_wakeup() in vm_page.c, 2017 * wake 2018 */ 2019 pass = 0; 2020 if (!vm_page_count_min(vm_page_free_hysteresis) || 2021 !vm_page_count_target()) { 2022 vm_pages_needed = 0; 2023 wakeup(&vmstats.v_free_count); 2024 } 2025 } else { 2026 pass = 0; 2027 } 2028 } 2029 } 2030 2031 static struct kproc_desc page_kp = { 2032 "pagedaemon", 2033 vm_pageout_thread, 2034 &pagethread 2035 }; 2036 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 2037 2038 2039 /* 2040 * Called after allocating a page out of the cache or free queue 2041 * to possibly wake the pagedaemon up to replentish our supply. 2042 * 2043 * We try to generate some hysteresis by waking the pagedaemon up 2044 * when our free+cache pages go below the free_min+cache_min level. 2045 * The pagedaemon tries to get the count back up to at least the 2046 * minimum, and through to the target level if possible. 2047 * 2048 * If the pagedaemon is already active bump vm_pages_needed as a hint 2049 * that there are even more requests pending. 2050 * 2051 * SMP races ok? 2052 * No requirements. 2053 */ 2054 void 2055 pagedaemon_wakeup(void) 2056 { 2057 if (vm_paging_needed() && curthread != pagethread) { 2058 if (vm_pages_needed == 0) { 2059 vm_pages_needed = 1; /* SMP race ok */ 2060 wakeup(&vm_pages_needed); 2061 } else if (vm_page_count_min(0)) { 2062 ++vm_pages_needed; /* SMP race ok */ 2063 } 2064 } 2065 } 2066 2067 #if !defined(NO_SWAPPING) 2068 2069 /* 2070 * SMP races ok? 2071 * No requirements. 2072 */ 2073 static void 2074 vm_req_vmdaemon(void) 2075 { 2076 static int lastrun = 0; 2077 2078 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 2079 wakeup(&vm_daemon_needed); 2080 lastrun = ticks; 2081 } 2082 } 2083 2084 static int vm_daemon_callback(struct proc *p, void *data __unused); 2085 2086 /* 2087 * No requirements. 2088 */ 2089 static void 2090 vm_daemon(void) 2091 { 2092 /* 2093 * XXX vm_daemon_needed specific token? 2094 */ 2095 while (TRUE) { 2096 tsleep(&vm_daemon_needed, 0, "psleep", 0); 2097 if (vm_pageout_req_swapout) { 2098 swapout_procs(vm_pageout_req_swapout); 2099 vm_pageout_req_swapout = 0; 2100 } 2101 /* 2102 * scan the processes for exceeding their rlimits or if 2103 * process is swapped out -- deactivate pages 2104 */ 2105 allproc_scan(vm_daemon_callback, NULL); 2106 } 2107 } 2108 2109 static int 2110 vm_daemon_callback(struct proc *p, void *data __unused) 2111 { 2112 struct vmspace *vm; 2113 vm_pindex_t limit, size; 2114 2115 /* 2116 * if this is a system process or if we have already 2117 * looked at this process, skip it. 2118 */ 2119 lwkt_gettoken(&p->p_token); 2120 2121 if (p->p_flags & (P_SYSTEM | P_WEXIT)) { 2122 lwkt_reltoken(&p->p_token); 2123 return (0); 2124 } 2125 2126 /* 2127 * if the process is in a non-running type state, 2128 * don't touch it. 2129 */ 2130 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) { 2131 lwkt_reltoken(&p->p_token); 2132 return (0); 2133 } 2134 2135 /* 2136 * get a limit 2137 */ 2138 limit = OFF_TO_IDX(qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 2139 p->p_rlimit[RLIMIT_RSS].rlim_max)); 2140 2141 /* 2142 * let processes that are swapped out really be 2143 * swapped out. Set the limit to nothing to get as 2144 * many pages out to swap as possible. 2145 */ 2146 if (p->p_flags & P_SWAPPEDOUT) 2147 limit = 0; 2148 2149 vm = p->p_vmspace; 2150 vmspace_hold(vm); 2151 size = vmspace_resident_count(vm); 2152 if (limit >= 0 && size >= limit) { 2153 vm_pageout_map_deactivate_pages(&vm->vm_map, limit); 2154 } 2155 vmspace_drop(vm); 2156 2157 lwkt_reltoken(&p->p_token); 2158 2159 return (0); 2160 } 2161 2162 #endif 2163