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 /* 204 * Calculate approximately how many pages on each queue to try to 205 * clean. An exact calculation creates an edge condition when the 206 * queues are unbalanced so add significant slop. The queue scans 207 * will stop early when targets are reached and will start where they 208 * left off on the next pass. 209 */ 210 static __inline int 211 PQAVERAGE(int n) 212 { 213 int avg; 214 215 if (n >= 0) { 216 avg = ((n + (PQ_L2_SIZE - 1)) / PQ_L2_SIZE + 1); 217 avg += avg / 2 + 1; 218 } else { 219 avg = ((n - (PQ_L2_SIZE - 1)) / PQ_L2_SIZE - 1); 220 avg += avg / 2 - 1; 221 } 222 return avg; 223 } 224 225 /* 226 * vm_pageout_clean: 227 * 228 * Clean the page and remove it from the laundry. The page must not be 229 * busy on-call. 230 * 231 * We set the busy bit to cause potential page faults on this page to 232 * block. Note the careful timing, however, the busy bit isn't set till 233 * late and we cannot do anything that will mess with the page. 234 */ 235 static int 236 vm_pageout_clean(vm_page_t m) 237 { 238 vm_object_t object; 239 vm_page_t mc[BLIST_MAX_ALLOC]; 240 int error; 241 int ib, is, page_base; 242 vm_pindex_t pindex = m->pindex; 243 244 object = m->object; 245 246 /* 247 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 248 * with the new swapper, but we could have serious problems paging 249 * out other object types if there is insufficient memory. 250 * 251 * Unfortunately, checking free memory here is far too late, so the 252 * check has been moved up a procedural level. 253 */ 254 255 /* 256 * Don't mess with the page if it's busy, held, or special 257 * 258 * XXX do we really need to check hold_count here? hold_count 259 * isn't supposed to mess with vm_page ops except prevent the 260 * page from being reused. 261 */ 262 if (m->hold_count != 0 || (m->flags & PG_UNMANAGED)) { 263 vm_page_wakeup(m); 264 return 0; 265 } 266 267 /* 268 * Place page in cluster. Align cluster for optimal swap space 269 * allocation (whether it is swap or not). This is typically ~16-32 270 * pages, which also tends to align the cluster to multiples of the 271 * filesystem block size if backed by a filesystem. 272 */ 273 page_base = pindex % BLIST_MAX_ALLOC; 274 mc[page_base] = m; 275 ib = page_base - 1; 276 is = page_base + 1; 277 278 /* 279 * Scan object for clusterable pages. 280 * 281 * We can cluster ONLY if: ->> the page is NOT 282 * clean, wired, busy, held, or mapped into a 283 * buffer, and one of the following: 284 * 1) The page is inactive, or a seldom used 285 * active page. 286 * -or- 287 * 2) we force the issue. 288 * 289 * During heavy mmap/modification loads the pageout 290 * daemon can really fragment the underlying file 291 * due to flushing pages out of order and not trying 292 * align the clusters (which leave sporatic out-of-order 293 * holes). To solve this problem we do the reverse scan 294 * first and attempt to align our cluster, then do a 295 * forward scan if room remains. 296 */ 297 298 vm_object_hold(object); 299 while (ib >= 0) { 300 vm_page_t p; 301 302 p = vm_page_lookup_busy_try(object, pindex - page_base + ib, 303 TRUE, &error); 304 if (error || p == NULL) 305 break; 306 if ((p->queue - p->pc) == PQ_CACHE || 307 (p->flags & PG_UNMANAGED)) { 308 vm_page_wakeup(p); 309 break; 310 } 311 vm_page_test_dirty(p); 312 if (((p->dirty & p->valid) == 0 && 313 (p->flags & PG_NEED_COMMIT) == 0) || 314 p->queue - p->pc != PQ_INACTIVE || 315 p->wire_count != 0 || /* may be held by buf cache */ 316 p->hold_count != 0) { /* may be undergoing I/O */ 317 vm_page_wakeup(p); 318 break; 319 } 320 mc[ib] = p; 321 --ib; 322 } 323 ++ib; /* fixup */ 324 325 while (is < BLIST_MAX_ALLOC && 326 pindex - page_base + is < object->size) { 327 vm_page_t p; 328 329 p = vm_page_lookup_busy_try(object, pindex - page_base + is, 330 TRUE, &error); 331 if (error || p == NULL) 332 break; 333 if (((p->queue - p->pc) == PQ_CACHE) || 334 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 335 vm_page_wakeup(p); 336 break; 337 } 338 vm_page_test_dirty(p); 339 if (((p->dirty & p->valid) == 0 && 340 (p->flags & PG_NEED_COMMIT) == 0) || 341 p->queue - p->pc != PQ_INACTIVE || 342 p->wire_count != 0 || /* may be held by buf cache */ 343 p->hold_count != 0) { /* may be undergoing I/O */ 344 vm_page_wakeup(p); 345 break; 346 } 347 mc[is] = p; 348 ++is; 349 } 350 351 vm_object_drop(object); 352 353 /* 354 * we allow reads during pageouts... 355 */ 356 return vm_pageout_flush(&mc[ib], is - ib, 0); 357 } 358 359 /* 360 * vm_pageout_flush() - launder the given pages 361 * 362 * The given pages are laundered. Note that we setup for the start of 363 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 364 * reference count all in here rather then in the parent. If we want 365 * the parent to do more sophisticated things we may have to change 366 * the ordering. 367 * 368 * The pages in the array must be busied by the caller and will be 369 * unbusied by this function. 370 */ 371 int 372 vm_pageout_flush(vm_page_t *mc, int count, int flags) 373 { 374 vm_object_t object; 375 int pageout_status[count]; 376 int numpagedout = 0; 377 int i; 378 379 /* 380 * Initiate I/O. Bump the vm_page_t->busy counter. 381 */ 382 for (i = 0; i < count; i++) { 383 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, 384 ("vm_pageout_flush page %p index %d/%d: partially " 385 "invalid page", mc[i], i, count)); 386 vm_page_io_start(mc[i]); 387 } 388 389 /* 390 * We must make the pages read-only. This will also force the 391 * modified bit in the related pmaps to be cleared. The pager 392 * cannot clear the bit for us since the I/O completion code 393 * typically runs from an interrupt. The act of making the page 394 * read-only handles the case for us. 395 * 396 * Then we can unbusy the pages, we still hold a reference by virtue 397 * of our soft-busy. 398 */ 399 for (i = 0; i < count; i++) { 400 vm_page_protect(mc[i], VM_PROT_READ); 401 vm_page_wakeup(mc[i]); 402 } 403 404 object = mc[0]->object; 405 vm_object_pip_add(object, count); 406 407 vm_pager_put_pages(object, mc, count, 408 (flags | ((object == &kernel_object) ? VM_PAGER_PUT_SYNC : 0)), 409 pageout_status); 410 411 for (i = 0; i < count; i++) { 412 vm_page_t mt = mc[i]; 413 414 switch (pageout_status[i]) { 415 case VM_PAGER_OK: 416 numpagedout++; 417 break; 418 case VM_PAGER_PEND: 419 numpagedout++; 420 break; 421 case VM_PAGER_BAD: 422 /* 423 * Page outside of range of object. Right now we 424 * essentially lose the changes by pretending it 425 * worked. 426 */ 427 vm_page_busy_wait(mt, FALSE, "pgbad"); 428 pmap_clear_modify(mt); 429 vm_page_undirty(mt); 430 vm_page_wakeup(mt); 431 break; 432 case VM_PAGER_ERROR: 433 case VM_PAGER_FAIL: 434 /* 435 * A page typically cannot be paged out when we 436 * have run out of swap. We leave the page 437 * marked inactive and will try to page it out 438 * again later. 439 * 440 * Starvation of the active page list is used to 441 * determine when the system is massively memory 442 * starved. 443 */ 444 break; 445 case VM_PAGER_AGAIN: 446 break; 447 } 448 449 /* 450 * If the operation is still going, leave the page busy to 451 * block all other accesses. Also, leave the paging in 452 * progress indicator set so that we don't attempt an object 453 * collapse. 454 * 455 * For any pages which have completed synchronously, 456 * deactivate the page if we are under a severe deficit. 457 * Do not try to enter them into the cache, though, they 458 * might still be read-heavy. 459 */ 460 if (pageout_status[i] != VM_PAGER_PEND) { 461 vm_page_busy_wait(mt, FALSE, "pgouw"); 462 if (vm_page_count_severe()) 463 vm_page_deactivate(mt); 464 #if 0 465 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt)) 466 vm_page_protect(mt, VM_PROT_READ); 467 #endif 468 vm_page_io_finish(mt); 469 vm_page_wakeup(mt); 470 vm_object_pip_wakeup(object); 471 } 472 } 473 return numpagedout; 474 } 475 476 #if !defined(NO_SWAPPING) 477 /* 478 * deactivate enough pages to satisfy the inactive target 479 * requirements or if vm_page_proc_limit is set, then 480 * deactivate all of the pages in the object and its 481 * backing_objects. 482 * 483 * The map must be locked. 484 * The caller must hold the vm_object. 485 */ 486 static int vm_pageout_object_deactivate_pages_callback(vm_page_t, void *); 487 488 static void 489 vm_pageout_object_deactivate_pages(vm_map_t map, vm_object_t object, 490 vm_pindex_t desired, int map_remove_only) 491 { 492 struct rb_vm_page_scan_info info; 493 vm_object_t lobject; 494 vm_object_t tobject; 495 int remove_mode; 496 497 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 498 lobject = object; 499 500 while (lobject) { 501 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 502 break; 503 if (lobject->type == OBJT_DEVICE || 504 lobject->type == OBJT_MGTDEVICE || 505 lobject->type == OBJT_PHYS) 506 break; 507 if (lobject->paging_in_progress) 508 break; 509 510 remove_mode = map_remove_only; 511 if (lobject->shadow_count > 1) 512 remove_mode = 1; 513 514 /* 515 * scan the objects entire memory queue. We hold the 516 * object's token so the scan should not race anything. 517 */ 518 info.limit = remove_mode; 519 info.map = map; 520 info.desired = desired; 521 vm_page_rb_tree_RB_SCAN(&lobject->rb_memq, NULL, 522 vm_pageout_object_deactivate_pages_callback, 523 &info 524 ); 525 while ((tobject = lobject->backing_object) != NULL) { 526 KKASSERT(tobject != object); 527 vm_object_hold(tobject); 528 if (tobject == lobject->backing_object) 529 break; 530 vm_object_drop(tobject); 531 } 532 if (lobject != object) { 533 if (tobject) 534 vm_object_lock_swap(); 535 vm_object_drop(lobject); 536 /* leaves tobject locked & at top */ 537 } 538 lobject = tobject; 539 } 540 if (lobject != object) 541 vm_object_drop(lobject); /* NULL ok */ 542 } 543 544 /* 545 * The caller must hold the vm_object. 546 */ 547 static int 548 vm_pageout_object_deactivate_pages_callback(vm_page_t p, void *data) 549 { 550 struct rb_vm_page_scan_info *info = data; 551 int actcount; 552 553 if (pmap_resident_count(vm_map_pmap(info->map)) <= info->desired) { 554 return(-1); 555 } 556 mycpu->gd_cnt.v_pdpages++; 557 558 if (vm_page_busy_try(p, TRUE)) 559 return(0); 560 if (p->wire_count || p->hold_count || (p->flags & PG_UNMANAGED)) { 561 vm_page_wakeup(p); 562 return(0); 563 } 564 if (!pmap_page_exists_quick(vm_map_pmap(info->map), p)) { 565 vm_page_wakeup(p); 566 return(0); 567 } 568 569 actcount = pmap_ts_referenced(p); 570 if (actcount) { 571 vm_page_flag_set(p, PG_REFERENCED); 572 } else if (p->flags & PG_REFERENCED) { 573 actcount = 1; 574 } 575 576 vm_page_and_queue_spin_lock(p); 577 if (p->queue - p->pc != PQ_ACTIVE && (p->flags & PG_REFERENCED)) { 578 vm_page_and_queue_spin_unlock(p); 579 vm_page_activate(p); 580 p->act_count += actcount; 581 vm_page_flag_clear(p, PG_REFERENCED); 582 } else if (p->queue - p->pc == PQ_ACTIVE) { 583 if ((p->flags & PG_REFERENCED) == 0) { 584 p->act_count -= min(p->act_count, ACT_DECLINE); 585 if (!info->limit && 586 (vm_pageout_algorithm || (p->act_count == 0))) { 587 vm_page_and_queue_spin_unlock(p); 588 vm_page_protect(p, VM_PROT_NONE); 589 vm_page_deactivate(p); 590 } else { 591 TAILQ_REMOVE(&vm_page_queues[p->queue].pl, 592 p, pageq); 593 TAILQ_INSERT_TAIL(&vm_page_queues[p->queue].pl, 594 p, pageq); 595 vm_page_and_queue_spin_unlock(p); 596 } 597 } else { 598 vm_page_and_queue_spin_unlock(p); 599 vm_page_activate(p); 600 vm_page_flag_clear(p, PG_REFERENCED); 601 602 vm_page_and_queue_spin_lock(p); 603 if (p->queue - p->pc == PQ_ACTIVE) { 604 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 605 p->act_count += ACT_ADVANCE; 606 TAILQ_REMOVE(&vm_page_queues[p->queue].pl, 607 p, pageq); 608 TAILQ_INSERT_TAIL(&vm_page_queues[p->queue].pl, 609 p, pageq); 610 } 611 vm_page_and_queue_spin_unlock(p); 612 } 613 } else if (p->queue - p->pc == PQ_INACTIVE) { 614 vm_page_and_queue_spin_unlock(p); 615 vm_page_protect(p, VM_PROT_NONE); 616 } else { 617 vm_page_and_queue_spin_unlock(p); 618 } 619 vm_page_wakeup(p); 620 return(0); 621 } 622 623 /* 624 * Deactivate some number of pages in a map, try to do it fairly, but 625 * that is really hard to do. 626 */ 627 static void 628 vm_pageout_map_deactivate_pages(vm_map_t map, vm_pindex_t desired) 629 { 630 vm_map_entry_t tmpe; 631 vm_object_t obj, bigobj; 632 int nothingwired; 633 634 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT)) { 635 return; 636 } 637 638 bigobj = NULL; 639 nothingwired = TRUE; 640 641 /* 642 * first, search out the biggest object, and try to free pages from 643 * that. 644 */ 645 tmpe = map->header.next; 646 while (tmpe != &map->header) { 647 switch(tmpe->maptype) { 648 case VM_MAPTYPE_NORMAL: 649 case VM_MAPTYPE_VPAGETABLE: 650 obj = tmpe->object.vm_object; 651 if ((obj != NULL) && (obj->shadow_count <= 1) && 652 ((bigobj == NULL) || 653 (bigobj->resident_page_count < obj->resident_page_count))) { 654 bigobj = obj; 655 } 656 break; 657 default: 658 break; 659 } 660 if (tmpe->wired_count > 0) 661 nothingwired = FALSE; 662 tmpe = tmpe->next; 663 } 664 665 if (bigobj) { 666 vm_object_hold(bigobj); 667 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 668 vm_object_drop(bigobj); 669 } 670 671 /* 672 * Next, hunt around for other pages to deactivate. We actually 673 * do this search sort of wrong -- .text first is not the best idea. 674 */ 675 tmpe = map->header.next; 676 while (tmpe != &map->header) { 677 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 678 break; 679 switch(tmpe->maptype) { 680 case VM_MAPTYPE_NORMAL: 681 case VM_MAPTYPE_VPAGETABLE: 682 obj = tmpe->object.vm_object; 683 if (obj) { 684 vm_object_hold(obj); 685 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 686 vm_object_drop(obj); 687 } 688 break; 689 default: 690 break; 691 } 692 tmpe = tmpe->next; 693 } 694 695 /* 696 * Remove all mappings if a process is swapped out, this will free page 697 * table pages. 698 */ 699 if (desired == 0 && nothingwired) 700 pmap_remove(vm_map_pmap(map), 701 VM_MIN_USER_ADDRESS, VM_MAX_USER_ADDRESS); 702 vm_map_unlock(map); 703 } 704 #endif 705 706 /* 707 * Called when the pageout scan wants to free a page. We no longer 708 * try to cycle the vm_object here with a reference & dealloc, which can 709 * cause a non-trivial object collapse in a critical path. 710 * 711 * It is unclear why we cycled the ref_count in the past, perhaps to try 712 * to optimize shadow chain collapses but I don't quite see why it would 713 * be necessary. An OBJ_DEAD object should terminate any and all vm_pages 714 * synchronously and not have to be kicked-start. 715 */ 716 static void 717 vm_pageout_page_free(vm_page_t m) 718 { 719 vm_page_protect(m, VM_PROT_NONE); 720 vm_page_free(m); 721 } 722 723 /* 724 * vm_pageout_scan does the dirty work for the pageout daemon. 725 */ 726 struct vm_pageout_scan_info { 727 struct proc *bigproc; 728 vm_offset_t bigsize; 729 }; 730 731 static int vm_pageout_scan_callback(struct proc *p, void *data); 732 733 static int 734 vm_pageout_scan_inactive(int pass, int q, int avail_shortage, 735 int *vnodes_skippedp) 736 { 737 vm_page_t m; 738 struct vm_page marker; 739 struct vnode *vpfailed; /* warning, allowed to be stale */ 740 int maxscan; 741 int count; 742 int delta = 0; 743 vm_object_t object; 744 int actcount; 745 int maxlaunder; 746 747 /* 748 * Start scanning the inactive queue for pages we can move to the 749 * cache or free. The scan will stop when the target is reached or 750 * we have scanned the entire inactive queue. Note that m->act_count 751 * is not used to form decisions for the inactive queue, only for the 752 * active queue. 753 * 754 * maxlaunder limits the number of dirty pages we flush per scan. 755 * For most systems a smaller value (16 or 32) is more robust under 756 * extreme memory and disk pressure because any unnecessary writes 757 * to disk can result in extreme performance degredation. However, 758 * systems with excessive dirty pages (especially when MAP_NOSYNC is 759 * used) will die horribly with limited laundering. If the pageout 760 * daemon cannot clean enough pages in the first pass, we let it go 761 * all out in succeeding passes. 762 */ 763 if ((maxlaunder = vm_max_launder) <= 1) 764 maxlaunder = 1; 765 if (pass) 766 maxlaunder = 10000; 767 768 /* 769 * Initialize our marker 770 */ 771 bzero(&marker, sizeof(marker)); 772 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 773 marker.queue = PQ_INACTIVE + q; 774 marker.pc = q; 775 marker.wire_count = 1; 776 777 /* 778 * Inactive queue scan. 779 * 780 * NOTE: The vm_page must be spinlocked before the queue to avoid 781 * deadlocks, so it is easiest to simply iterate the loop 782 * with the queue unlocked at the top. 783 */ 784 vpfailed = NULL; 785 786 vm_page_queues_spin_lock(PQ_INACTIVE + q); 787 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE + q].pl, &marker, pageq); 788 maxscan = vm_page_queues[PQ_INACTIVE + q].lcnt; 789 790 /* 791 * Queue locked at top of loop to avoid stack marker issues. 792 */ 793 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL && 794 maxscan-- > 0 && avail_shortage - delta > 0) 795 { 796 KKASSERT(m->queue - m->pc == PQ_INACTIVE); 797 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl, 798 &marker, pageq); 799 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE + q].pl, m, 800 &marker, pageq); 801 mycpu->gd_cnt.v_pdpages++; 802 803 /* 804 * Skip marker pages (atomic against other markers to avoid 805 * infinite hop-over scans). 806 */ 807 if (m->flags & PG_MARKER) 808 continue; 809 810 /* 811 * Try to busy the page. Don't mess with pages which are 812 * already busy or reorder them in the queue. 813 */ 814 if (vm_page_busy_try(m, TRUE)) 815 continue; 816 817 /* 818 * Remaining operations run with the page busy and neither 819 * the page or the queue will be spin-locked. 820 */ 821 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 822 KKASSERT(m->queue - m->pc == PQ_INACTIVE); 823 lwkt_yield(); 824 825 /* 826 * It is possible for a page to be busied ad-hoc (e.g. the 827 * pmap_collect() code) and wired and race against the 828 * allocation of a new page. vm_page_alloc() may be forced 829 * to deactivate the wired page in which case it winds up 830 * on the inactive queue and must be handled here. We 831 * correct the problem simply by unqueuing the page. 832 */ 833 if (m->wire_count) { 834 vm_page_unqueue_nowakeup(m); 835 vm_page_wakeup(m); 836 kprintf("WARNING: pagedaemon: wired page on " 837 "inactive queue %p\n", m); 838 goto next; 839 } 840 841 /* 842 * A held page may be undergoing I/O, so skip it. 843 */ 844 if (m->hold_count) { 845 vm_page_and_queue_spin_lock(m); 846 if (m->queue - m->pc == PQ_INACTIVE) { 847 TAILQ_REMOVE( 848 &vm_page_queues[PQ_INACTIVE + q].pl, 849 m, pageq); 850 TAILQ_INSERT_TAIL( 851 &vm_page_queues[PQ_INACTIVE + q].pl, 852 m, pageq); 853 ++vm_swapcache_inactive_heuristic; 854 } 855 vm_page_and_queue_spin_unlock(m); 856 vm_page_wakeup(m); 857 goto next; 858 } 859 860 if (m->object == NULL || m->object->ref_count == 0) { 861 /* 862 * If the object is not being used, we ignore previous 863 * references. 864 */ 865 vm_page_flag_clear(m, PG_REFERENCED); 866 pmap_clear_reference(m); 867 /* fall through to end */ 868 } else if (((m->flags & PG_REFERENCED) == 0) && 869 (actcount = pmap_ts_referenced(m))) { 870 /* 871 * Otherwise, if the page has been referenced while 872 * in the inactive queue, we bump the "activation 873 * count" upwards, making it less likely that the 874 * page will be added back to the inactive queue 875 * prematurely again. Here we check the page tables 876 * (or emulated bits, if any), given the upper level 877 * VM system not knowing anything about existing 878 * references. 879 */ 880 vm_page_activate(m); 881 m->act_count += (actcount + ACT_ADVANCE); 882 vm_page_wakeup(m); 883 goto next; 884 } 885 886 /* 887 * (m) is still busied. 888 * 889 * If the upper level VM system knows about any page 890 * references, we activate the page. We also set the 891 * "activation count" higher than normal so that we will less 892 * likely place pages back onto the inactive queue again. 893 */ 894 if ((m->flags & PG_REFERENCED) != 0) { 895 vm_page_flag_clear(m, PG_REFERENCED); 896 actcount = pmap_ts_referenced(m); 897 vm_page_activate(m); 898 m->act_count += (actcount + ACT_ADVANCE + 1); 899 vm_page_wakeup(m); 900 goto next; 901 } 902 903 /* 904 * If the upper level VM system doesn't know anything about 905 * the page being dirty, we have to check for it again. As 906 * far as the VM code knows, any partially dirty pages are 907 * fully dirty. 908 * 909 * Pages marked PG_WRITEABLE may be mapped into the user 910 * address space of a process running on another cpu. A 911 * user process (without holding the MP lock) running on 912 * another cpu may be able to touch the page while we are 913 * trying to remove it. vm_page_cache() will handle this 914 * case for us. 915 */ 916 if (m->dirty == 0) { 917 vm_page_test_dirty(m); 918 } else { 919 vm_page_dirty(m); 920 } 921 922 if (m->valid == 0 && (m->flags & PG_NEED_COMMIT) == 0) { 923 /* 924 * Invalid pages can be easily freed 925 */ 926 vm_pageout_page_free(m); 927 mycpu->gd_cnt.v_dfree++; 928 ++delta; 929 } else if (m->dirty == 0 && (m->flags & PG_NEED_COMMIT) == 0) { 930 /* 931 * Clean pages can be placed onto the cache queue. 932 * This effectively frees them. 933 */ 934 vm_page_cache(m); 935 ++delta; 936 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 937 /* 938 * Dirty pages need to be paged out, but flushing 939 * a page is extremely expensive verses freeing 940 * a clean page. Rather then artificially limiting 941 * the number of pages we can flush, we instead give 942 * dirty pages extra priority on the inactive queue 943 * by forcing them to be cycled through the queue 944 * twice before being flushed, after which the 945 * (now clean) page will cycle through once more 946 * before being freed. This significantly extends 947 * the thrash point for a heavily loaded machine. 948 */ 949 vm_page_flag_set(m, PG_WINATCFLS); 950 vm_page_and_queue_spin_lock(m); 951 if (m->queue - m->pc == PQ_INACTIVE) { 952 TAILQ_REMOVE( 953 &vm_page_queues[PQ_INACTIVE + q].pl, 954 m, pageq); 955 TAILQ_INSERT_TAIL( 956 &vm_page_queues[PQ_INACTIVE + q].pl, 957 m, pageq); 958 ++vm_swapcache_inactive_heuristic; 959 } 960 vm_page_and_queue_spin_unlock(m); 961 vm_page_wakeup(m); 962 } else if (maxlaunder > 0) { 963 /* 964 * We always want to try to flush some dirty pages if 965 * we encounter them, to keep the system stable. 966 * Normally this number is small, but under extreme 967 * pressure where there are insufficient clean pages 968 * on the inactive queue, we may have to go all out. 969 */ 970 int swap_pageouts_ok; 971 struct vnode *vp = NULL; 972 973 swap_pageouts_ok = 0; 974 object = m->object; 975 if (object && 976 (object->type != OBJT_SWAP) && 977 (object->type != OBJT_DEFAULT)) { 978 swap_pageouts_ok = 1; 979 } else { 980 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 981 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 982 vm_page_count_min(0)); 983 984 } 985 986 /* 987 * We don't bother paging objects that are "dead". 988 * Those objects are in a "rundown" state. 989 */ 990 if (!swap_pageouts_ok || 991 (object == NULL) || 992 (object->flags & OBJ_DEAD)) { 993 vm_page_and_queue_spin_lock(m); 994 if (m->queue - m->pc == PQ_INACTIVE) { 995 TAILQ_REMOVE( 996 &vm_page_queues[PQ_INACTIVE + q].pl, 997 m, pageq); 998 TAILQ_INSERT_TAIL( 999 &vm_page_queues[PQ_INACTIVE + q].pl, 1000 m, pageq); 1001 ++vm_swapcache_inactive_heuristic; 1002 } 1003 vm_page_and_queue_spin_unlock(m); 1004 vm_page_wakeup(m); 1005 goto next; 1006 } 1007 1008 /* 1009 * (m) is still busied. 1010 * 1011 * The object is already known NOT to be dead. It 1012 * is possible for the vget() to block the whole 1013 * pageout daemon, but the new low-memory handling 1014 * code should prevent it. 1015 * 1016 * The previous code skipped locked vnodes and, worse, 1017 * reordered pages in the queue. This results in 1018 * completely non-deterministic operation because, 1019 * quite often, a vm_fault has initiated an I/O and 1020 * is holding a locked vnode at just the point where 1021 * the pageout daemon is woken up. 1022 * 1023 * We can't wait forever for the vnode lock, we might 1024 * deadlock due to a vn_read() getting stuck in 1025 * vm_wait while holding this vnode. We skip the 1026 * vnode if we can't get it in a reasonable amount 1027 * of time. 1028 * 1029 * vpfailed is used to (try to) avoid the case where 1030 * a large number of pages are associated with a 1031 * locked vnode, which could cause the pageout daemon 1032 * to stall for an excessive amount of time. 1033 */ 1034 if (object->type == OBJT_VNODE) { 1035 int flags; 1036 1037 vp = object->handle; 1038 flags = LK_EXCLUSIVE; 1039 if (vp == vpfailed) 1040 flags |= LK_NOWAIT; 1041 else 1042 flags |= LK_TIMELOCK; 1043 vm_page_hold(m); 1044 vm_page_wakeup(m); 1045 1046 /* 1047 * We have unbusied (m) temporarily so we can 1048 * acquire the vp lock without deadlocking. 1049 * (m) is held to prevent destruction. 1050 */ 1051 if (vget(vp, flags) != 0) { 1052 vpfailed = vp; 1053 ++pageout_lock_miss; 1054 if (object->flags & OBJ_MIGHTBEDIRTY) 1055 ++*vnodes_skippedp; 1056 vm_page_unhold(m); 1057 goto next; 1058 } 1059 1060 /* 1061 * The page might have been moved to another 1062 * queue during potential blocking in vget() 1063 * above. The page might have been freed and 1064 * reused for another vnode. The object might 1065 * have been reused for another vnode. 1066 */ 1067 if (m->queue - m->pc != PQ_INACTIVE || 1068 m->object != object || 1069 object->handle != vp) { 1070 if (object->flags & OBJ_MIGHTBEDIRTY) 1071 ++*vnodes_skippedp; 1072 vput(vp); 1073 vm_page_unhold(m); 1074 goto next; 1075 } 1076 1077 /* 1078 * The page may have been busied during the 1079 * blocking in vput(); We don't move the 1080 * page back onto the end of the queue so that 1081 * statistics are more correct if we don't. 1082 */ 1083 if (vm_page_busy_try(m, TRUE)) { 1084 vput(vp); 1085 vm_page_unhold(m); 1086 goto next; 1087 } 1088 vm_page_unhold(m); 1089 1090 /* 1091 * (m) is busied again 1092 * 1093 * We own the busy bit and remove our hold 1094 * bit. If the page is still held it 1095 * might be undergoing I/O, so skip it. 1096 */ 1097 if (m->hold_count) { 1098 vm_page_and_queue_spin_lock(m); 1099 if (m->queue - m->pc == PQ_INACTIVE) { 1100 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl, m, pageq); 1101 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE + q].pl, m, pageq); 1102 ++vm_swapcache_inactive_heuristic; 1103 } 1104 vm_page_and_queue_spin_unlock(m); 1105 if (object->flags & OBJ_MIGHTBEDIRTY) 1106 ++*vnodes_skippedp; 1107 vm_page_wakeup(m); 1108 vput(vp); 1109 goto next; 1110 } 1111 /* (m) is left busied as we fall through */ 1112 } 1113 1114 /* 1115 * page is busy and not held here. 1116 * 1117 * If a page is dirty, then it is either being washed 1118 * (but not yet cleaned) or it is still in the 1119 * laundry. If it is still in the laundry, then we 1120 * start the cleaning operation. 1121 * 1122 * decrement inactive_shortage on success to account 1123 * for the (future) cleaned page. Otherwise we 1124 * could wind up laundering or cleaning too many 1125 * pages. 1126 */ 1127 count = vm_pageout_clean(m); 1128 delta += count; 1129 maxlaunder -= count; 1130 1131 /* 1132 * Clean ate busy, page no longer accessible 1133 */ 1134 if (vp != NULL) 1135 vput(vp); 1136 } else { 1137 vm_page_wakeup(m); 1138 } 1139 1140 next: 1141 /* 1142 * Systems with a ton of memory can wind up with huge 1143 * deactivation counts. Because the inactive scan is 1144 * doing a lot of flushing, the combination can result 1145 * in excessive paging even in situations where other 1146 * unrelated threads free up sufficient VM. 1147 * 1148 * To deal with this we abort the nominal active->inactive 1149 * scan before we hit the inactive target when free+cache 1150 * levels have reached a reasonable target. 1151 * 1152 * When deciding to stop early we need to add some slop to 1153 * the test and we need to return full completion to the caller 1154 * to prevent the caller from thinking there is something 1155 * wrong and issuing a low-memory+swap warning or pkill. 1156 */ 1157 vm_page_queues_spin_lock(PQ_INACTIVE + q); 1158 if (vm_paging_target() < -vm_max_launder) { 1159 /* 1160 * Stopping early, return full completion to caller. 1161 */ 1162 if (delta < avail_shortage) 1163 delta = avail_shortage; 1164 break; 1165 } 1166 } 1167 1168 /* page queue still spin-locked */ 1169 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl, &marker, pageq); 1170 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 1171 1172 return (delta); 1173 } 1174 1175 static int 1176 vm_pageout_scan_active(int pass, int q, 1177 int avail_shortage, int inactive_shortage, 1178 int *recycle_countp) 1179 { 1180 struct vm_page marker; 1181 vm_page_t m; 1182 int actcount; 1183 int delta = 0; 1184 int maxscan; 1185 1186 /* 1187 * We want to move pages from the active queue to the inactive 1188 * queue to get the inactive queue to the inactive target. If 1189 * we still have a page shortage from above we try to directly free 1190 * clean pages instead of moving them. 1191 * 1192 * If we do still have a shortage we keep track of the number of 1193 * pages we free or cache (recycle_count) as a measure of thrashing 1194 * between the active and inactive queues. 1195 * 1196 * If we were able to completely satisfy the free+cache targets 1197 * from the inactive pool we limit the number of pages we move 1198 * from the active pool to the inactive pool to 2x the pages we 1199 * had removed from the inactive pool (with a minimum of 1/5 the 1200 * inactive target). If we were not able to completely satisfy 1201 * the free+cache targets we go for the whole target aggressively. 1202 * 1203 * NOTE: Both variables can end up negative. 1204 * NOTE: We are still in a critical section. 1205 */ 1206 1207 bzero(&marker, sizeof(marker)); 1208 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 1209 marker.queue = PQ_ACTIVE + q; 1210 marker.pc = q; 1211 marker.wire_count = 1; 1212 1213 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1214 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1215 maxscan = vm_page_queues[PQ_ACTIVE + q].lcnt; 1216 1217 /* 1218 * Queue locked at top of loop to avoid stack marker issues. 1219 */ 1220 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL && 1221 maxscan-- > 0 && (avail_shortage - delta > 0 || 1222 inactive_shortage > 0)) 1223 { 1224 KKASSERT(m->queue - m->pc == PQ_ACTIVE); 1225 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, 1226 &marker, pageq); 1227 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_ACTIVE + q].pl, m, 1228 &marker, pageq); 1229 1230 /* 1231 * Skip marker pages (atomic against other markers to avoid 1232 * infinite hop-over scans). 1233 */ 1234 if (m->flags & PG_MARKER) 1235 continue; 1236 1237 /* 1238 * Try to busy the page. Don't mess with pages which are 1239 * already busy or reorder them in the queue. 1240 */ 1241 if (vm_page_busy_try(m, TRUE)) 1242 continue; 1243 1244 /* 1245 * Remaining operations run with the page busy and neither 1246 * the page or the queue will be spin-locked. 1247 */ 1248 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1249 KKASSERT(m->queue - m->pc == PQ_ACTIVE); 1250 lwkt_yield(); 1251 1252 /* 1253 * Don't deactivate pages that are held, even if we can 1254 * busy them. (XXX why not?) 1255 */ 1256 if (m->hold_count != 0) { 1257 vm_page_and_queue_spin_lock(m); 1258 if (m->queue - m->pc == PQ_ACTIVE) { 1259 TAILQ_REMOVE( 1260 &vm_page_queues[PQ_ACTIVE + q].pl, 1261 m, pageq); 1262 TAILQ_INSERT_TAIL( 1263 &vm_page_queues[PQ_ACTIVE + q].pl, 1264 m, pageq); 1265 } 1266 vm_page_and_queue_spin_unlock(m); 1267 vm_page_wakeup(m); 1268 goto next; 1269 } 1270 1271 /* 1272 * The count for pagedaemon pages is done after checking the 1273 * page for eligibility... 1274 */ 1275 mycpu->gd_cnt.v_pdpages++; 1276 1277 /* 1278 * Check to see "how much" the page has been used and clear 1279 * the tracking access bits. If the object has no references 1280 * don't bother paying the expense. 1281 */ 1282 actcount = 0; 1283 if (m->object && m->object->ref_count != 0) { 1284 if (m->flags & PG_REFERENCED) 1285 ++actcount; 1286 actcount += pmap_ts_referenced(m); 1287 if (actcount) { 1288 m->act_count += ACT_ADVANCE + actcount; 1289 if (m->act_count > ACT_MAX) 1290 m->act_count = ACT_MAX; 1291 } 1292 } 1293 vm_page_flag_clear(m, PG_REFERENCED); 1294 1295 /* 1296 * actcount is only valid if the object ref_count is non-zero. 1297 * If the page does not have an object, actcount will be zero. 1298 */ 1299 if (actcount && m->object->ref_count != 0) { 1300 vm_page_and_queue_spin_lock(m); 1301 if (m->queue - m->pc == PQ_ACTIVE) { 1302 TAILQ_REMOVE( 1303 &vm_page_queues[PQ_ACTIVE + q].pl, 1304 m, pageq); 1305 TAILQ_INSERT_TAIL( 1306 &vm_page_queues[PQ_ACTIVE + q].pl, 1307 m, pageq); 1308 } 1309 vm_page_and_queue_spin_unlock(m); 1310 vm_page_wakeup(m); 1311 } else { 1312 switch(m->object->type) { 1313 case OBJT_DEFAULT: 1314 case OBJT_SWAP: 1315 m->act_count -= min(m->act_count, 1316 vm_anonmem_decline); 1317 break; 1318 default: 1319 m->act_count -= min(m->act_count, 1320 vm_filemem_decline); 1321 break; 1322 } 1323 if (vm_pageout_algorithm || 1324 (m->object == NULL) || 1325 (m->object && (m->object->ref_count == 0)) || 1326 m->act_count < pass + 1 1327 ) { 1328 /* 1329 * Deactivate the page. If we had a 1330 * shortage from our inactive scan try to 1331 * free (cache) the page instead. 1332 * 1333 * Don't just blindly cache the page if 1334 * we do not have a shortage from the 1335 * inactive scan, that could lead to 1336 * gigabytes being moved. 1337 */ 1338 --inactive_shortage; 1339 if (avail_shortage - delta > 0 || 1340 (m->object && (m->object->ref_count == 0))) 1341 { 1342 if (avail_shortage - delta > 0) 1343 ++*recycle_countp; 1344 vm_page_protect(m, VM_PROT_NONE); 1345 if (m->dirty == 0 && 1346 (m->flags & PG_NEED_COMMIT) == 0 && 1347 avail_shortage - delta > 0) { 1348 vm_page_cache(m); 1349 } else { 1350 vm_page_deactivate(m); 1351 vm_page_wakeup(m); 1352 } 1353 } else { 1354 vm_page_deactivate(m); 1355 vm_page_wakeup(m); 1356 } 1357 ++delta; 1358 } else { 1359 vm_page_and_queue_spin_lock(m); 1360 if (m->queue - m->pc == PQ_ACTIVE) { 1361 TAILQ_REMOVE( 1362 &vm_page_queues[PQ_ACTIVE + q].pl, 1363 m, pageq); 1364 TAILQ_INSERT_TAIL( 1365 &vm_page_queues[PQ_ACTIVE + q].pl, 1366 m, pageq); 1367 } 1368 vm_page_and_queue_spin_unlock(m); 1369 vm_page_wakeup(m); 1370 } 1371 } 1372 next: 1373 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1374 } 1375 1376 /* 1377 * Clean out our local marker. 1378 * 1379 * Page queue still spin-locked. 1380 */ 1381 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1382 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1383 1384 return (delta); 1385 } 1386 1387 /* 1388 * The number of actually free pages can drop down to v_free_reserved, 1389 * we try to build the free count back above v_free_min. Note that 1390 * vm_paging_needed() also returns TRUE if v_free_count is not at 1391 * least v_free_min so that is the minimum we must build the free 1392 * count to. 1393 * 1394 * We use a slightly higher target to improve hysteresis, 1395 * ((v_free_target + v_free_min) / 2). Since v_free_target 1396 * is usually the same as v_cache_min this maintains about 1397 * half the pages in the free queue as are in the cache queue, 1398 * providing pretty good pipelining for pageout operation. 1399 * 1400 * The system operator can manipulate vm.v_cache_min and 1401 * vm.v_free_target to tune the pageout demon. Be sure 1402 * to keep vm.v_free_min < vm.v_free_target. 1403 * 1404 * Note that the original paging target is to get at least 1405 * (free_min + cache_min) into (free + cache). The slightly 1406 * higher target will shift additional pages from cache to free 1407 * without effecting the original paging target in order to 1408 * maintain better hysteresis and not have the free count always 1409 * be dead-on v_free_min. 1410 * 1411 * NOTE: we are still in a critical section. 1412 * 1413 * Pages moved from PQ_CACHE to totally free are not counted in the 1414 * pages_freed counter. 1415 */ 1416 static void 1417 vm_pageout_scan_cache(int avail_shortage, int pass, 1418 int vnodes_skipped, int recycle_count) 1419 { 1420 static int lastkillticks; 1421 struct vm_pageout_scan_info info; 1422 vm_page_t m; 1423 1424 while (vmstats.v_free_count < 1425 (vmstats.v_free_min + vmstats.v_free_target) / 2) { 1426 /* 1427 * This steals some code from vm/vm_page.c 1428 */ 1429 static int cache_rover = 0; 1430 1431 m = vm_page_list_find(PQ_CACHE, 1432 cache_rover & PQ_L2_MASK, FALSE); 1433 if (m == NULL) 1434 break; 1435 /* page is returned removed from its queue and spinlocked */ 1436 if (vm_page_busy_try(m, TRUE)) { 1437 vm_page_deactivate_locked(m); 1438 vm_page_spin_unlock(m); 1439 continue; 1440 } 1441 vm_page_spin_unlock(m); 1442 pagedaemon_wakeup(); 1443 lwkt_yield(); 1444 1445 /* 1446 * Remaining operations run with the page busy and neither 1447 * the page or the queue will be spin-locked. 1448 */ 1449 if ((m->flags & (PG_UNMANAGED | PG_NEED_COMMIT)) || 1450 m->hold_count || 1451 m->wire_count) { 1452 vm_page_deactivate(m); 1453 vm_page_wakeup(m); 1454 continue; 1455 } 1456 KKASSERT((m->flags & PG_MAPPED) == 0); 1457 KKASSERT(m->dirty == 0); 1458 cache_rover += PQ_PRIME2; 1459 vm_pageout_page_free(m); 1460 mycpu->gd_cnt.v_dfree++; 1461 } 1462 1463 #if !defined(NO_SWAPPING) 1464 /* 1465 * Idle process swapout -- run once per second. 1466 */ 1467 if (vm_swap_idle_enabled) { 1468 static time_t lsec; 1469 if (time_uptime != lsec) { 1470 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1471 vm_req_vmdaemon(); 1472 lsec = time_uptime; 1473 } 1474 } 1475 #endif 1476 1477 /* 1478 * If we didn't get enough free pages, and we have skipped a vnode 1479 * in a writeable object, wakeup the sync daemon. And kick swapout 1480 * if we did not get enough free pages. 1481 */ 1482 if (vm_paging_target() > 0) { 1483 if (vnodes_skipped && vm_page_count_min(0)) 1484 speedup_syncer(NULL); 1485 #if !defined(NO_SWAPPING) 1486 if (vm_swap_enabled && vm_page_count_target()) { 1487 vm_req_vmdaemon(); 1488 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1489 } 1490 #endif 1491 } 1492 1493 /* 1494 * Handle catastrophic conditions. Under good conditions we should 1495 * be at the target, well beyond our minimum. If we could not even 1496 * reach our minimum the system is under heavy stress. But just being 1497 * under heavy stress does not trigger process killing. 1498 * 1499 * We consider ourselves to have run out of memory if the swap pager 1500 * is full and avail_shortage is still positive. The secondary check 1501 * ensures that we do not kill processes if the instantanious 1502 * availability is good, even if the pageout demon pass says it 1503 * couldn't get to the target. 1504 */ 1505 if (swap_pager_almost_full && 1506 pass > 0 && 1507 (vm_page_count_min(recycle_count) || avail_shortage > 0)) { 1508 kprintf("Warning: system low on memory+swap " 1509 "shortage %d for %d ticks!\n", 1510 avail_shortage, ticks - swap_fail_ticks); 1511 } 1512 if (swap_pager_full && 1513 pass > 1 && 1514 avail_shortage > 0 && 1515 vm_paging_target() > 0 && 1516 (unsigned int)(ticks - lastkillticks) >= hz) { 1517 /* 1518 * Kill something, maximum rate once per second to give 1519 * the process time to free up sufficient memory. 1520 */ 1521 lastkillticks = ticks; 1522 info.bigproc = NULL; 1523 info.bigsize = 0; 1524 allproc_scan(vm_pageout_scan_callback, &info); 1525 if (info.bigproc != NULL) { 1526 info.bigproc->p_nice = PRIO_MIN; 1527 info.bigproc->p_usched->resetpriority( 1528 FIRST_LWP_IN_PROC(info.bigproc)); 1529 killproc(info.bigproc, "out of swap space"); 1530 wakeup(&vmstats.v_free_count); 1531 PRELE(info.bigproc); 1532 } 1533 } 1534 } 1535 1536 static int 1537 vm_pageout_scan_callback(struct proc *p, void *data) 1538 { 1539 struct vm_pageout_scan_info *info = data; 1540 vm_offset_t size; 1541 1542 /* 1543 * Never kill system processes or init. If we have configured swap 1544 * then try to avoid killing low-numbered pids. 1545 */ 1546 if ((p->p_flags & P_SYSTEM) || (p->p_pid == 1) || 1547 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1548 return (0); 1549 } 1550 1551 lwkt_gettoken(&p->p_token); 1552 1553 /* 1554 * if the process is in a non-running type state, 1555 * don't touch it. 1556 */ 1557 if (p->p_stat != SACTIVE && p->p_stat != SSTOP && p->p_stat != SCORE) { 1558 lwkt_reltoken(&p->p_token); 1559 return (0); 1560 } 1561 1562 /* 1563 * Get the approximate process size. Note that anonymous pages 1564 * with backing swap will be counted twice, but there should not 1565 * be too many such pages due to the stress the VM system is 1566 * under at this point. 1567 */ 1568 size = vmspace_anonymous_count(p->p_vmspace) + 1569 vmspace_swap_count(p->p_vmspace); 1570 1571 /* 1572 * If the this process is bigger than the biggest one 1573 * remember it. 1574 */ 1575 if (info->bigsize < size) { 1576 if (info->bigproc) 1577 PRELE(info->bigproc); 1578 PHOLD(p); 1579 info->bigproc = p; 1580 info->bigsize = size; 1581 } 1582 lwkt_reltoken(&p->p_token); 1583 lwkt_yield(); 1584 1585 return(0); 1586 } 1587 1588 /* 1589 * This routine tries to maintain the pseudo LRU active queue, 1590 * so that during long periods of time where there is no paging, 1591 * that some statistic accumulation still occurs. This code 1592 * helps the situation where paging just starts to occur. 1593 */ 1594 static void 1595 vm_pageout_page_stats(int q) 1596 { 1597 static int fullintervalcount = 0; 1598 struct vm_page marker; 1599 vm_page_t m; 1600 int pcount, tpcount; /* Number of pages to check */ 1601 int page_shortage; 1602 1603 page_shortage = (vmstats.v_inactive_target + vmstats.v_cache_max + 1604 vmstats.v_free_min) - 1605 (vmstats.v_free_count + vmstats.v_inactive_count + 1606 vmstats.v_cache_count); 1607 1608 if (page_shortage <= 0) 1609 return; 1610 1611 pcount = vm_page_queues[PQ_ACTIVE + q].lcnt; 1612 fullintervalcount += vm_pageout_stats_interval; 1613 if (fullintervalcount < vm_pageout_full_stats_interval) { 1614 tpcount = (vm_pageout_stats_max * pcount) / 1615 vmstats.v_page_count + 1; 1616 if (pcount > tpcount) 1617 pcount = tpcount; 1618 } else { 1619 fullintervalcount = 0; 1620 } 1621 1622 bzero(&marker, sizeof(marker)); 1623 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 1624 marker.queue = PQ_ACTIVE + q; 1625 marker.pc = q; 1626 marker.wire_count = 1; 1627 1628 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1629 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1630 1631 /* 1632 * Queue locked at top of loop to avoid stack marker issues. 1633 */ 1634 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL && 1635 pcount-- > 0) 1636 { 1637 int actcount; 1638 1639 KKASSERT(m->queue - m->pc == PQ_ACTIVE); 1640 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1641 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_ACTIVE + q].pl, m, 1642 &marker, pageq); 1643 1644 /* 1645 * Skip marker pages (atomic against other markers to avoid 1646 * infinite hop-over scans). 1647 */ 1648 if (m->flags & PG_MARKER) 1649 continue; 1650 1651 /* 1652 * Ignore pages we can't busy 1653 */ 1654 if (vm_page_busy_try(m, TRUE)) 1655 continue; 1656 1657 /* 1658 * Remaining operations run with the page busy and neither 1659 * the page or the queue will be spin-locked. 1660 */ 1661 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1662 KKASSERT(m->queue - m->pc == PQ_ACTIVE); 1663 1664 /* 1665 * We now have a safely busied page, the page and queue 1666 * spinlocks have been released. 1667 * 1668 * Ignore held pages 1669 */ 1670 if (m->hold_count) { 1671 vm_page_wakeup(m); 1672 goto next; 1673 } 1674 1675 /* 1676 * Calculate activity 1677 */ 1678 actcount = 0; 1679 if (m->flags & PG_REFERENCED) { 1680 vm_page_flag_clear(m, PG_REFERENCED); 1681 actcount += 1; 1682 } 1683 actcount += pmap_ts_referenced(m); 1684 1685 /* 1686 * Update act_count and move page to end of queue. 1687 */ 1688 if (actcount) { 1689 m->act_count += ACT_ADVANCE + actcount; 1690 if (m->act_count > ACT_MAX) 1691 m->act_count = ACT_MAX; 1692 vm_page_and_queue_spin_lock(m); 1693 if (m->queue - m->pc == PQ_ACTIVE) { 1694 TAILQ_REMOVE( 1695 &vm_page_queues[PQ_ACTIVE + q].pl, 1696 m, pageq); 1697 TAILQ_INSERT_TAIL( 1698 &vm_page_queues[PQ_ACTIVE + q].pl, 1699 m, pageq); 1700 } 1701 vm_page_and_queue_spin_unlock(m); 1702 vm_page_wakeup(m); 1703 goto next; 1704 } 1705 1706 if (m->act_count == 0) { 1707 /* 1708 * We turn off page access, so that we have 1709 * more accurate RSS stats. We don't do this 1710 * in the normal page deactivation when the 1711 * system is loaded VM wise, because the 1712 * cost of the large number of page protect 1713 * operations would be higher than the value 1714 * of doing the operation. 1715 * 1716 * We use the marker to save our place so 1717 * we can release the spin lock. both (m) 1718 * and (next) will be invalid. 1719 */ 1720 vm_page_protect(m, VM_PROT_NONE); 1721 vm_page_deactivate(m); 1722 } else { 1723 m->act_count -= min(m->act_count, ACT_DECLINE); 1724 vm_page_and_queue_spin_lock(m); 1725 if (m->queue - m->pc == PQ_ACTIVE) { 1726 TAILQ_REMOVE( 1727 &vm_page_queues[PQ_ACTIVE + q].pl, 1728 m, pageq); 1729 TAILQ_INSERT_TAIL( 1730 &vm_page_queues[PQ_ACTIVE + q].pl, 1731 m, pageq); 1732 } 1733 vm_page_and_queue_spin_unlock(m); 1734 } 1735 vm_page_wakeup(m); 1736 next: 1737 vm_page_queues_spin_lock(PQ_ACTIVE + q); 1738 } 1739 1740 /* 1741 * Remove our local marker 1742 * 1743 * Page queue still spin-locked. 1744 */ 1745 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq); 1746 vm_page_queues_spin_unlock(PQ_ACTIVE + q); 1747 } 1748 1749 static int 1750 vm_pageout_free_page_calc(vm_size_t count) 1751 { 1752 if (count < vmstats.v_page_count) 1753 return 0; 1754 /* 1755 * free_reserved needs to include enough for the largest swap pager 1756 * structures plus enough for any pv_entry structs when paging. 1757 * 1758 * v_free_min normal allocations 1759 * v_free_reserved system allocations 1760 * v_pageout_free_min allocations by pageout daemon 1761 * v_interrupt_free_min low level allocations (e.g swap structures) 1762 */ 1763 if (vmstats.v_page_count > 1024) 1764 vmstats.v_free_min = 64 + (vmstats.v_page_count - 1024) / 200; 1765 else 1766 vmstats.v_free_min = 64; 1767 vmstats.v_free_reserved = vmstats.v_free_min * 4 / 8 + 7; 1768 vmstats.v_free_severe = vmstats.v_free_min * 4 / 8 + 0; 1769 vmstats.v_pageout_free_min = vmstats.v_free_min * 2 / 8 + 7; 1770 vmstats.v_interrupt_free_min = vmstats.v_free_min * 1 / 8 + 7; 1771 1772 return 1; 1773 } 1774 1775 1776 /* 1777 * vm_pageout is the high level pageout daemon. 1778 * 1779 * No requirements. 1780 */ 1781 static void 1782 vm_pageout_thread(void) 1783 { 1784 int pass; 1785 int q; 1786 int q1iterator = 0; 1787 int q2iterator = 0; 1788 1789 /* 1790 * Initialize some paging parameters. 1791 */ 1792 curthread->td_flags |= TDF_SYSTHREAD; 1793 1794 vm_pageout_free_page_calc(vmstats.v_page_count); 1795 1796 /* 1797 * v_free_target and v_cache_min control pageout hysteresis. Note 1798 * that these are more a measure of the VM cache queue hysteresis 1799 * then the VM free queue. Specifically, v_free_target is the 1800 * high water mark (free+cache pages). 1801 * 1802 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1803 * low water mark, while v_free_min is the stop. v_cache_min must 1804 * be big enough to handle memory needs while the pageout daemon 1805 * is signalled and run to free more pages. 1806 */ 1807 if (vmstats.v_free_count > 6144) 1808 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved; 1809 else 1810 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved; 1811 1812 /* 1813 * NOTE: With the new buffer cache b_act_count we want the default 1814 * inactive target to be a percentage of available memory. 1815 * 1816 * The inactive target essentially determines the minimum 1817 * number of 'temporary' pages capable of caching one-time-use 1818 * files when the VM system is otherwise full of pages 1819 * belonging to multi-time-use files or active program data. 1820 * 1821 * NOTE: The inactive target is aggressively persued only if the 1822 * inactive queue becomes too small. If the inactive queue 1823 * is large enough to satisfy page movement to free+cache 1824 * then it is repopulated more slowly from the active queue. 1825 * This allows a general inactive_target default to be set. 1826 * 1827 * There is an issue here for processes which sit mostly idle 1828 * 'overnight', such as sshd, tcsh, and X. Any movement from 1829 * the active queue will eventually cause such pages to 1830 * recycle eventually causing a lot of paging in the morning. 1831 * To reduce the incidence of this pages cycled out of the 1832 * buffer cache are moved directly to the inactive queue if 1833 * they were only used once or twice. 1834 * 1835 * The vfs.vm_cycle_point sysctl can be used to adjust this. 1836 * Increasing the value (up to 64) increases the number of 1837 * buffer recyclements which go directly to the inactive queue. 1838 */ 1839 if (vmstats.v_free_count > 2048) { 1840 vmstats.v_cache_min = vmstats.v_free_target; 1841 vmstats.v_cache_max = 2 * vmstats.v_cache_min; 1842 } else { 1843 vmstats.v_cache_min = 0; 1844 vmstats.v_cache_max = 0; 1845 } 1846 vmstats.v_inactive_target = vmstats.v_free_count / 4; 1847 1848 /* XXX does not really belong here */ 1849 if (vm_page_max_wired == 0) 1850 vm_page_max_wired = vmstats.v_free_count / 3; 1851 1852 if (vm_pageout_stats_max == 0) 1853 vm_pageout_stats_max = vmstats.v_free_target; 1854 1855 /* 1856 * Set interval in seconds for stats scan. 1857 */ 1858 if (vm_pageout_stats_interval == 0) 1859 vm_pageout_stats_interval = 5; 1860 if (vm_pageout_full_stats_interval == 0) 1861 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1862 1863 1864 /* 1865 * Set maximum free per pass 1866 */ 1867 if (vm_pageout_stats_free_max == 0) 1868 vm_pageout_stats_free_max = 5; 1869 1870 swap_pager_swap_init(); 1871 pass = 0; 1872 1873 /* 1874 * The pageout daemon is never done, so loop forever. 1875 */ 1876 while (TRUE) { 1877 int error; 1878 int avail_shortage; 1879 int inactive_shortage; 1880 int vnodes_skipped = 0; 1881 int recycle_count = 0; 1882 int tmp; 1883 1884 /* 1885 * Wait for an action request. If we timeout check to 1886 * see if paging is needed (in case the normal wakeup 1887 * code raced us). 1888 */ 1889 if (vm_pages_needed == 0) { 1890 error = tsleep(&vm_pages_needed, 1891 0, "psleep", 1892 vm_pageout_stats_interval * hz); 1893 if (error && 1894 vm_paging_needed() == 0 && 1895 vm_pages_needed == 0) { 1896 for (q = 0; q < PQ_L2_SIZE; ++q) 1897 vm_pageout_page_stats(q); 1898 continue; 1899 } 1900 vm_pages_needed = 1; 1901 } 1902 1903 mycpu->gd_cnt.v_pdwakeups++; 1904 1905 /* 1906 * Do whatever cleanup that the pmap code can. 1907 */ 1908 pmap_collect(); 1909 1910 /* 1911 * Scan for pageout. Try to avoid thrashing the system 1912 * with activity. 1913 * 1914 * Calculate our target for the number of free+cache pages we 1915 * want to get to. This is higher then the number that causes 1916 * allocations to stall (severe) in order to provide hysteresis, 1917 * and if we don't make it all the way but get to the minimum 1918 * we're happy. Goose it a bit if there are multiple requests 1919 * for memory. 1920 * 1921 * Don't reduce avail_shortage inside the loop or the 1922 * PQAVERAGE() calculation will break. 1923 */ 1924 avail_shortage = vm_paging_target() + vm_pageout_deficit; 1925 vm_pageout_deficit = 0; 1926 1927 if (avail_shortage > 0) { 1928 int delta = 0; 1929 1930 for (q = 0; q < PQ_L2_SIZE; ++q) { 1931 delta += vm_pageout_scan_inactive( 1932 pass, 1933 (q + q1iterator) & PQ_L2_MASK, 1934 PQAVERAGE(avail_shortage), 1935 &vnodes_skipped); 1936 if (avail_shortage - delta <= 0) 1937 break; 1938 } 1939 avail_shortage -= delta; 1940 q1iterator = q + 1; 1941 } 1942 1943 /* 1944 * Figure out how many active pages we must deactivate. If 1945 * we were able to reach our target with just the inactive 1946 * scan above we limit the number of active pages we 1947 * deactivate to reduce unnecessary work. 1948 */ 1949 inactive_shortage = vmstats.v_inactive_target - 1950 vmstats.v_inactive_count; 1951 1952 /* 1953 * If we were unable to free sufficient inactive pages to 1954 * satisfy the free/cache queue requirements then simply 1955 * reaching the inactive target may not be good enough. 1956 * Try to deactivate pages in excess of the target based 1957 * on the shortfall. 1958 * 1959 * However to prevent thrashing the VM system do not 1960 * deactivate more than an additional 1/10 the inactive 1961 * target's worth of active pages. 1962 */ 1963 if (avail_shortage > 0) { 1964 tmp = avail_shortage * 2; 1965 if (tmp > vmstats.v_inactive_target / 10) 1966 tmp = vmstats.v_inactive_target / 10; 1967 inactive_shortage += tmp; 1968 } 1969 1970 /* 1971 * Only trigger on inactive shortage. Triggering on 1972 * avail_shortage can starve the active queue with 1973 * unnecessary active->inactive transitions and destroy 1974 * performance. 1975 */ 1976 if (/*avail_shortage > 0 ||*/ inactive_shortage > 0) { 1977 int delta = 0; 1978 1979 for (q = 0; q < PQ_L2_SIZE; ++q) { 1980 delta += vm_pageout_scan_active( 1981 pass, 1982 (q + q2iterator) & PQ_L2_MASK, 1983 PQAVERAGE(avail_shortage), 1984 PQAVERAGE(inactive_shortage), 1985 &recycle_count); 1986 if (inactive_shortage - delta <= 0 && 1987 avail_shortage - delta <= 0) { 1988 break; 1989 } 1990 } 1991 inactive_shortage -= delta; 1992 avail_shortage -= delta; 1993 q2iterator = q + 1; 1994 } 1995 1996 /* 1997 * Finally free enough cache pages to meet our free page 1998 * requirement and take more drastic measures if we are 1999 * still in trouble. 2000 */ 2001 vm_pageout_scan_cache(avail_shortage, pass, 2002 vnodes_skipped, recycle_count); 2003 2004 /* 2005 * Wait for more work. 2006 */ 2007 if (avail_shortage > 0) { 2008 ++pass; 2009 if (pass < 10 && vm_pages_needed > 1) { 2010 /* 2011 * Normal operation, additional processes 2012 * have already kicked us. Retry immediately 2013 * unless swap space is completely full in 2014 * which case delay a bit. 2015 */ 2016 if (swap_pager_full) { 2017 tsleep(&vm_pages_needed, 0, "pdelay", 2018 hz / 5); 2019 } /* else immediate retry */ 2020 } else if (pass < 10) { 2021 /* 2022 * Normal operation, fewer processes. Delay 2023 * a bit but allow wakeups. 2024 */ 2025 vm_pages_needed = 0; 2026 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10); 2027 vm_pages_needed = 1; 2028 } else if (swap_pager_full == 0) { 2029 /* 2030 * We've taken too many passes, forced delay. 2031 */ 2032 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10); 2033 } else { 2034 /* 2035 * Running out of memory, catastrophic 2036 * back-off to one-second intervals. 2037 */ 2038 tsleep(&vm_pages_needed, 0, "pdelay", hz); 2039 } 2040 } else if (vm_pages_needed) { 2041 /* 2042 * Interlocked wakeup of waiters (non-optional). 2043 * 2044 * Similar to vm_page_free_wakeup() in vm_page.c, 2045 * wake 2046 */ 2047 pass = 0; 2048 if (!vm_page_count_min(vm_page_free_hysteresis) || 2049 !vm_page_count_target()) { 2050 vm_pages_needed = 0; 2051 wakeup(&vmstats.v_free_count); 2052 } 2053 } else { 2054 pass = 0; 2055 } 2056 } 2057 } 2058 2059 static struct kproc_desc page_kp = { 2060 "pagedaemon", 2061 vm_pageout_thread, 2062 &pagethread 2063 }; 2064 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp); 2065 2066 2067 /* 2068 * Called after allocating a page out of the cache or free queue 2069 * to possibly wake the pagedaemon up to replentish our supply. 2070 * 2071 * We try to generate some hysteresis by waking the pagedaemon up 2072 * when our free+cache pages go below the free_min+cache_min level. 2073 * The pagedaemon tries to get the count back up to at least the 2074 * minimum, and through to the target level if possible. 2075 * 2076 * If the pagedaemon is already active bump vm_pages_needed as a hint 2077 * that there are even more requests pending. 2078 * 2079 * SMP races ok? 2080 * No requirements. 2081 */ 2082 void 2083 pagedaemon_wakeup(void) 2084 { 2085 if (vm_paging_needed() && curthread != pagethread) { 2086 if (vm_pages_needed == 0) { 2087 vm_pages_needed = 1; /* SMP race ok */ 2088 wakeup(&vm_pages_needed); 2089 } else if (vm_page_count_min(0)) { 2090 ++vm_pages_needed; /* SMP race ok */ 2091 } 2092 } 2093 } 2094 2095 #if !defined(NO_SWAPPING) 2096 2097 /* 2098 * SMP races ok? 2099 * No requirements. 2100 */ 2101 static void 2102 vm_req_vmdaemon(void) 2103 { 2104 static int lastrun = 0; 2105 2106 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 2107 wakeup(&vm_daemon_needed); 2108 lastrun = ticks; 2109 } 2110 } 2111 2112 static int vm_daemon_callback(struct proc *p, void *data __unused); 2113 2114 /* 2115 * No requirements. 2116 */ 2117 static void 2118 vm_daemon(void) 2119 { 2120 /* 2121 * XXX vm_daemon_needed specific token? 2122 */ 2123 while (TRUE) { 2124 tsleep(&vm_daemon_needed, 0, "psleep", 0); 2125 if (vm_pageout_req_swapout) { 2126 swapout_procs(vm_pageout_req_swapout); 2127 vm_pageout_req_swapout = 0; 2128 } 2129 /* 2130 * scan the processes for exceeding their rlimits or if 2131 * process is swapped out -- deactivate pages 2132 */ 2133 allproc_scan(vm_daemon_callback, NULL); 2134 } 2135 } 2136 2137 static int 2138 vm_daemon_callback(struct proc *p, void *data __unused) 2139 { 2140 struct vmspace *vm; 2141 vm_pindex_t limit, size; 2142 2143 /* 2144 * if this is a system process or if we have already 2145 * looked at this process, skip it. 2146 */ 2147 lwkt_gettoken(&p->p_token); 2148 2149 if (p->p_flags & (P_SYSTEM | P_WEXIT)) { 2150 lwkt_reltoken(&p->p_token); 2151 return (0); 2152 } 2153 2154 /* 2155 * if the process is in a non-running type state, 2156 * don't touch it. 2157 */ 2158 if (p->p_stat != SACTIVE && p->p_stat != SSTOP && p->p_stat != SCORE) { 2159 lwkt_reltoken(&p->p_token); 2160 return (0); 2161 } 2162 2163 /* 2164 * get a limit 2165 */ 2166 limit = OFF_TO_IDX(qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 2167 p->p_rlimit[RLIMIT_RSS].rlim_max)); 2168 2169 /* 2170 * let processes that are swapped out really be 2171 * swapped out. Set the limit to nothing to get as 2172 * many pages out to swap as possible. 2173 */ 2174 if (p->p_flags & P_SWAPPEDOUT) 2175 limit = 0; 2176 2177 vm = p->p_vmspace; 2178 vmspace_hold(vm); 2179 size = vmspace_resident_count(vm); 2180 if (limit >= 0 && size >= limit) { 2181 vm_pageout_map_deactivate_pages(&vm->vm_map, limit); 2182 } 2183 vmspace_drop(vm); 2184 2185 lwkt_reltoken(&p->p_token); 2186 2187 return (0); 2188 } 2189 2190 #endif 2191