1 /* 2 * Copyright (c) 1991 Regents of the University of California. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * The Mach Operating System project at Carnegie-Mellon University. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * from: @(#)vm_page.c 7.4 (Berkeley) 5/7/91 37 * $FreeBSD: src/sys/vm/vm_page.c,v 1.147.2.18 2002/03/10 05:03:19 alc Exp $ 38 * $DragonFly: src/sys/vm/vm_page.c,v 1.19 2004/04/01 17:41:19 dillon Exp $ 39 */ 40 41 /* 42 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 43 * All rights reserved. 44 * 45 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 46 * 47 * Permission to use, copy, modify and distribute this software and 48 * its documentation is hereby granted, provided that both the copyright 49 * notice and this permission notice appear in all copies of the 50 * software, derivative works or modified versions, and any portions 51 * thereof, and that both notices appear in supporting documentation. 52 * 53 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 54 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 55 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 56 * 57 * Carnegie Mellon requests users of this software to return to 58 * 59 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 60 * School of Computer Science 61 * Carnegie Mellon University 62 * Pittsburgh PA 15213-3890 63 * 64 * any improvements or extensions that they make and grant Carnegie the 65 * rights to redistribute these changes. 66 */ 67 68 /* 69 * Resident memory management module. 70 */ 71 72 #include <sys/param.h> 73 #include <sys/systm.h> 74 #include <sys/malloc.h> 75 #include <sys/proc.h> 76 #include <sys/vmmeter.h> 77 #include <sys/vnode.h> 78 79 #include <vm/vm.h> 80 #include <vm/vm_param.h> 81 #include <sys/lock.h> 82 #include <vm/vm_kern.h> 83 #include <vm/pmap.h> 84 #include <vm/vm_map.h> 85 #include <vm/vm_object.h> 86 #include <vm/vm_page.h> 87 #include <vm/vm_pageout.h> 88 #include <vm/vm_pager.h> 89 #include <vm/vm_extern.h> 90 #include <vm/vm_page2.h> 91 92 static void vm_page_queue_init (void); 93 static vm_page_t vm_page_select_cache (vm_object_t, vm_pindex_t); 94 95 /* 96 * Associated with page of user-allocatable memory is a 97 * page structure. 98 */ 99 100 static struct vm_page **vm_page_buckets; /* Array of buckets */ 101 static int vm_page_bucket_count; /* How big is array? */ 102 static int vm_page_hash_mask; /* Mask for hash function */ 103 static volatile int vm_page_bucket_generation; 104 105 struct vpgqueues vm_page_queues[PQ_COUNT]; 106 107 static void 108 vm_page_queue_init(void) { 109 int i; 110 111 for(i=0;i<PQ_L2_SIZE;i++) { 112 vm_page_queues[PQ_FREE+i].cnt = &vmstats.v_free_count; 113 } 114 vm_page_queues[PQ_INACTIVE].cnt = &vmstats.v_inactive_count; 115 116 vm_page_queues[PQ_ACTIVE].cnt = &vmstats.v_active_count; 117 vm_page_queues[PQ_HOLD].cnt = &vmstats.v_active_count; 118 for(i=0;i<PQ_L2_SIZE;i++) { 119 vm_page_queues[PQ_CACHE+i].cnt = &vmstats.v_cache_count; 120 } 121 for(i=0;i<PQ_COUNT;i++) { 122 TAILQ_INIT(&vm_page_queues[i].pl); 123 } 124 } 125 126 vm_page_t vm_page_array = 0; 127 int vm_page_array_size = 0; 128 long first_page = 0; 129 int vm_page_zero_count = 0; 130 131 static __inline int vm_page_hash (vm_object_t object, vm_pindex_t pindex); 132 static void vm_page_free_wakeup (void); 133 134 /* 135 * vm_set_page_size: 136 * 137 * Sets the page size, perhaps based upon the memory 138 * size. Must be called before any use of page-size 139 * dependent functions. 140 */ 141 void 142 vm_set_page_size(void) 143 { 144 if (vmstats.v_page_size == 0) 145 vmstats.v_page_size = PAGE_SIZE; 146 if (((vmstats.v_page_size - 1) & vmstats.v_page_size) != 0) 147 panic("vm_set_page_size: page size not a power of two"); 148 } 149 150 /* 151 * vm_add_new_page: 152 * 153 * Add a new page to the freelist for use by the system. New pages 154 * are added to both the head and tail of the associated free page 155 * queue in a bottom-up fashion, so both zero'd and non-zero'd page 156 * requests pull 'recent' adds (higher physical addresses) first. 157 * 158 * Must be called at splhigh(). 159 */ 160 vm_page_t 161 vm_add_new_page(vm_paddr_t pa) 162 { 163 vm_page_t m; 164 struct vpgqueues *vpq; 165 166 ++vmstats.v_page_count; 167 ++vmstats.v_free_count; 168 m = PHYS_TO_VM_PAGE(pa); 169 m->phys_addr = pa; 170 m->flags = 0; 171 m->pc = (pa >> PAGE_SHIFT) & PQ_L2_MASK; 172 m->queue = m->pc + PQ_FREE; 173 vpq = &vm_page_queues[m->queue]; 174 if (vpq->flipflop) 175 TAILQ_INSERT_TAIL(&vpq->pl, m, pageq); 176 else 177 TAILQ_INSERT_HEAD(&vpq->pl, m, pageq); 178 vpq->flipflop = 1 - vpq->flipflop; 179 vm_page_queues[m->queue].lcnt++; 180 return (m); 181 } 182 183 /* 184 * vm_page_startup: 185 * 186 * Initializes the resident memory module. 187 * 188 * Allocates memory for the page cells, and 189 * for the object/offset-to-page hash table headers. 190 * Each page cell is initialized and placed on the free list. 191 */ 192 193 vm_offset_t 194 vm_page_startup(vm_offset_t starta, vm_offset_t enda, vm_offset_t vaddr) 195 { 196 vm_offset_t mapped; 197 struct vm_page **bucket; 198 vm_size_t npages; 199 vm_paddr_t page_range; 200 vm_paddr_t new_end; 201 int i; 202 vm_paddr_t pa; 203 int nblocks; 204 vm_paddr_t last_pa; 205 206 /* the biggest memory array is the second group of pages */ 207 vm_paddr_t end; 208 vm_paddr_t biggestone, biggestsize; 209 210 vm_paddr_t total; 211 212 total = 0; 213 biggestsize = 0; 214 biggestone = 0; 215 nblocks = 0; 216 vaddr = round_page(vaddr); 217 218 for (i = 0; phys_avail[i + 1]; i += 2) { 219 phys_avail[i] = round_page(phys_avail[i]); 220 phys_avail[i + 1] = trunc_page(phys_avail[i + 1]); 221 } 222 223 for (i = 0; phys_avail[i + 1]; i += 2) { 224 vm_paddr_t size = phys_avail[i + 1] - phys_avail[i]; 225 226 if (size > biggestsize) { 227 biggestone = i; 228 biggestsize = size; 229 } 230 ++nblocks; 231 total += size; 232 } 233 234 end = phys_avail[biggestone+1]; 235 236 /* 237 * Initialize the queue headers for the free queue, the active queue 238 * and the inactive queue. 239 */ 240 241 vm_page_queue_init(); 242 243 /* 244 * Allocate (and initialize) the hash table buckets. 245 * 246 * The number of buckets MUST BE a power of 2, and the actual value is 247 * the next power of 2 greater than the number of physical pages in 248 * the system. 249 * 250 * We make the hash table approximately 2x the number of pages to 251 * reduce the chain length. This is about the same size using the 252 * singly-linked list as the 1x hash table we were using before 253 * using TAILQ but the chain length will be smaller. 254 * 255 * Note: This computation can be tweaked if desired. 256 */ 257 vm_page_buckets = (struct vm_page **)vaddr; 258 bucket = vm_page_buckets; 259 if (vm_page_bucket_count == 0) { 260 vm_page_bucket_count = 1; 261 while (vm_page_bucket_count < atop(total)) 262 vm_page_bucket_count <<= 1; 263 } 264 vm_page_bucket_count <<= 1; 265 vm_page_hash_mask = vm_page_bucket_count - 1; 266 267 /* 268 * Validate these addresses. 269 */ 270 new_end = end - vm_page_bucket_count * sizeof(struct vm_page *); 271 new_end = trunc_page(new_end); 272 mapped = round_page(vaddr); 273 vaddr = pmap_map(mapped, new_end, end, 274 VM_PROT_READ | VM_PROT_WRITE); 275 vaddr = round_page(vaddr); 276 bzero((caddr_t) mapped, vaddr - mapped); 277 278 for (i = 0; i < vm_page_bucket_count; i++) { 279 *bucket = NULL; 280 bucket++; 281 } 282 283 /* 284 * Compute the number of pages of memory that will be available for 285 * use (taking into account the overhead of a page structure per 286 * page). 287 */ 288 289 first_page = phys_avail[0] / PAGE_SIZE; 290 291 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE - first_page; 292 npages = (total - (page_range * sizeof(struct vm_page)) - 293 (end - new_end)) / PAGE_SIZE; 294 295 end = new_end; 296 /* 297 * Initialize the mem entry structures now, and put them in the free 298 * queue. 299 */ 300 vm_page_array = (vm_page_t) vaddr; 301 mapped = vaddr; 302 303 /* 304 * Validate these addresses. 305 */ 306 307 new_end = trunc_page(end - page_range * sizeof(struct vm_page)); 308 mapped = pmap_map(mapped, new_end, end, 309 VM_PROT_READ | VM_PROT_WRITE); 310 311 /* 312 * Clear all of the page structures 313 */ 314 bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page)); 315 vm_page_array_size = page_range; 316 317 /* 318 * Construct the free queue(s) in ascending order (by physical 319 * address) so that the first 16MB of physical memory is allocated 320 * last rather than first. On large-memory machines, this avoids 321 * the exhaustion of low physical memory before isa_dmainit has run. 322 */ 323 vmstats.v_page_count = 0; 324 vmstats.v_free_count = 0; 325 for (i = 0; phys_avail[i + 1] && npages > 0; i += 2) { 326 pa = phys_avail[i]; 327 if (i == biggestone) 328 last_pa = new_end; 329 else 330 last_pa = phys_avail[i + 1]; 331 while (pa < last_pa && npages-- > 0) { 332 vm_add_new_page(pa); 333 pa += PAGE_SIZE; 334 } 335 } 336 return (mapped); 337 } 338 339 /* 340 * vm_page_hash: 341 * 342 * Distributes the object/offset key pair among hash buckets. 343 * 344 * NOTE: This macro depends on vm_page_bucket_count being a power of 2. 345 * This routine may not block. 346 * 347 * We try to randomize the hash based on the object to spread the pages 348 * out in the hash table without it costing us too much. 349 */ 350 static __inline int 351 vm_page_hash(vm_object_t object, vm_pindex_t pindex) 352 { 353 int i = ((uintptr_t)object + pindex) ^ object->hash_rand; 354 355 return(i & vm_page_hash_mask); 356 } 357 358 void 359 vm_page_unhold(vm_page_t mem) 360 { 361 --mem->hold_count; 362 KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); 363 if (mem->hold_count == 0 && mem->queue == PQ_HOLD) 364 vm_page_free_toq(mem); 365 } 366 367 /* 368 * vm_page_insert: [ internal use only ] 369 * 370 * Inserts the given mem entry into the object and object list. 371 * 372 * The pagetables are not updated but will presumably fault the page 373 * in if necessary, or if a kernel page the caller will at some point 374 * enter the page into the kernel's pmap. We are not allowed to block 375 * here so we *can't* do this anyway. 376 * 377 * The object and page must be locked, and must be splhigh. 378 * This routine may not block. 379 */ 380 381 void 382 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) 383 { 384 struct vm_page **bucket; 385 386 if (m->object != NULL) 387 panic("vm_page_insert: already inserted"); 388 389 /* 390 * Record the object/offset pair in this page 391 */ 392 393 m->object = object; 394 m->pindex = pindex; 395 396 /* 397 * Insert it into the object_object/offset hash table 398 */ 399 400 bucket = &vm_page_buckets[vm_page_hash(object, pindex)]; 401 m->hnext = *bucket; 402 *bucket = m; 403 vm_page_bucket_generation++; 404 405 /* 406 * Now link into the object's list of backed pages. 407 */ 408 409 TAILQ_INSERT_TAIL(&object->memq, m, listq); 410 object->generation++; 411 412 /* 413 * show that the object has one more resident page. 414 */ 415 416 object->resident_page_count++; 417 418 /* 419 * Since we are inserting a new and possibly dirty page, 420 * update the object's OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY flags. 421 */ 422 if (m->flags & PG_WRITEABLE) 423 vm_object_set_writeable_dirty(object); 424 } 425 426 /* 427 * vm_page_remove: 428 * NOTE: used by device pager as well -wfj 429 * 430 * Removes the given mem entry from the object/offset-page 431 * table and the object page list, but do not invalidate/terminate 432 * the backing store. 433 * 434 * The object and page must be locked, and at splhigh. 435 * The underlying pmap entry (if any) is NOT removed here. 436 * This routine may not block. 437 */ 438 439 void 440 vm_page_remove(vm_page_t m) 441 { 442 vm_object_t object; 443 444 if (m->object == NULL) 445 return; 446 447 if ((m->flags & PG_BUSY) == 0) { 448 panic("vm_page_remove: page not busy"); 449 } 450 451 /* 452 * Basically destroy the page. 453 */ 454 455 vm_page_wakeup(m); 456 457 object = m->object; 458 459 /* 460 * Remove from the object_object/offset hash table. The object 461 * must be on the hash queue, we will panic if it isn't 462 * 463 * Note: we must NULL-out m->hnext to prevent loops in detached 464 * buffers with vm_page_lookup(). 465 */ 466 467 { 468 struct vm_page **bucket; 469 470 bucket = &vm_page_buckets[vm_page_hash(m->object, m->pindex)]; 471 while (*bucket != m) { 472 if (*bucket == NULL) 473 panic("vm_page_remove(): page not found in hash"); 474 bucket = &(*bucket)->hnext; 475 } 476 *bucket = m->hnext; 477 m->hnext = NULL; 478 vm_page_bucket_generation++; 479 } 480 481 /* 482 * Now remove from the object's list of backed pages. 483 */ 484 485 TAILQ_REMOVE(&object->memq, m, listq); 486 487 /* 488 * And show that the object has one fewer resident page. 489 */ 490 491 object->resident_page_count--; 492 object->generation++; 493 494 m->object = NULL; 495 } 496 497 /* 498 * vm_page_lookup: 499 * 500 * Returns the page associated with the object/offset 501 * pair specified; if none is found, NULL is returned. 502 * 503 * NOTE: the code below does not lock. It will operate properly if 504 * an interrupt makes a change, but the generation algorithm will not 505 * operate properly in an SMP environment where both cpu's are able to run 506 * kernel code simultaneously. 507 * 508 * The object must be locked. No side effects. 509 * This routine may not block. 510 * This is a critical path routine 511 */ 512 513 vm_page_t 514 vm_page_lookup(vm_object_t object, vm_pindex_t pindex) 515 { 516 vm_page_t m; 517 struct vm_page **bucket; 518 int generation; 519 520 /* 521 * Search the hash table for this object/offset pair 522 */ 523 524 retry: 525 generation = vm_page_bucket_generation; 526 bucket = &vm_page_buckets[vm_page_hash(object, pindex)]; 527 for (m = *bucket; m != NULL; m = m->hnext) { 528 if ((m->object == object) && (m->pindex == pindex)) { 529 if (vm_page_bucket_generation != generation) 530 goto retry; 531 return (m); 532 } 533 } 534 if (vm_page_bucket_generation != generation) 535 goto retry; 536 return (NULL); 537 } 538 539 /* 540 * vm_page_rename: 541 * 542 * Move the given memory entry from its 543 * current object to the specified target object/offset. 544 * 545 * The object must be locked. 546 * This routine may not block. 547 * 548 * Note: this routine will raise itself to splvm(), the caller need not. 549 * 550 * Note: swap associated with the page must be invalidated by the move. We 551 * have to do this for several reasons: (1) we aren't freeing the 552 * page, (2) we are dirtying the page, (3) the VM system is probably 553 * moving the page from object A to B, and will then later move 554 * the backing store from A to B and we can't have a conflict. 555 * 556 * Note: we *always* dirty the page. It is necessary both for the 557 * fact that we moved it, and because we may be invalidating 558 * swap. If the page is on the cache, we have to deactivate it 559 * or vm_page_dirty() will panic. Dirty pages are not allowed 560 * on the cache. 561 */ 562 563 void 564 vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) 565 { 566 int s; 567 568 s = splvm(); 569 vm_page_remove(m); 570 vm_page_insert(m, new_object, new_pindex); 571 if (m->queue - m->pc == PQ_CACHE) 572 vm_page_deactivate(m); 573 vm_page_dirty(m); 574 splx(s); 575 } 576 577 /* 578 * vm_page_unqueue_nowakeup: 579 * 580 * vm_page_unqueue() without any wakeup 581 * 582 * This routine must be called at splhigh(). 583 * This routine may not block. 584 */ 585 586 void 587 vm_page_unqueue_nowakeup(vm_page_t m) 588 { 589 int queue = m->queue; 590 struct vpgqueues *pq; 591 if (queue != PQ_NONE) { 592 pq = &vm_page_queues[queue]; 593 m->queue = PQ_NONE; 594 TAILQ_REMOVE(&pq->pl, m, pageq); 595 (*pq->cnt)--; 596 pq->lcnt--; 597 } 598 } 599 600 /* 601 * vm_page_unqueue: 602 * 603 * Remove a page from its queue. 604 * 605 * This routine must be called at splhigh(). 606 * This routine may not block. 607 */ 608 609 void 610 vm_page_unqueue(vm_page_t m) 611 { 612 int queue = m->queue; 613 struct vpgqueues *pq; 614 if (queue != PQ_NONE) { 615 m->queue = PQ_NONE; 616 pq = &vm_page_queues[queue]; 617 TAILQ_REMOVE(&pq->pl, m, pageq); 618 (*pq->cnt)--; 619 pq->lcnt--; 620 if ((queue - m->pc) == PQ_CACHE) { 621 if (vm_paging_needed()) 622 pagedaemon_wakeup(); 623 } 624 } 625 } 626 627 #if PQ_L2_SIZE > 1 628 629 /* 630 * vm_page_list_find: 631 * 632 * Find a page on the specified queue with color optimization. 633 * 634 * The page coloring optimization attempts to locate a page 635 * that does not overload other nearby pages in the object in 636 * the cpu's L1 or L2 caches. We need this optimization because 637 * cpu caches tend to be physical caches, while object spaces tend 638 * to be virtual. 639 * 640 * This routine must be called at splvm(). 641 * This routine may not block. 642 * 643 * This routine may only be called from the vm_page_list_find() macro 644 * in vm_page.h 645 */ 646 vm_page_t 647 _vm_page_list_find(int basequeue, int index) 648 { 649 int i; 650 vm_page_t m = NULL; 651 struct vpgqueues *pq; 652 653 pq = &vm_page_queues[basequeue]; 654 655 /* 656 * Note that for the first loop, index+i and index-i wind up at the 657 * same place. Even though this is not totally optimal, we've already 658 * blown it by missing the cache case so we do not care. 659 */ 660 661 for(i = PQ_L2_SIZE / 2; i > 0; --i) { 662 if ((m = TAILQ_FIRST(&pq[(index + i) & PQ_L2_MASK].pl)) != NULL) 663 break; 664 665 if ((m = TAILQ_FIRST(&pq[(index - i) & PQ_L2_MASK].pl)) != NULL) 666 break; 667 } 668 return(m); 669 } 670 671 #endif 672 673 /* 674 * vm_page_select_cache: 675 * 676 * Find a page on the cache queue with color optimization. As pages 677 * might be found, but not applicable, they are deactivated. This 678 * keeps us from using potentially busy cached pages. 679 * 680 * This routine must be called at splvm(). 681 * This routine may not block. 682 */ 683 vm_page_t 684 vm_page_select_cache(vm_object_t object, vm_pindex_t pindex) 685 { 686 vm_page_t m; 687 688 while (TRUE) { 689 m = vm_page_list_find( 690 PQ_CACHE, 691 (pindex + object->pg_color) & PQ_L2_MASK, 692 FALSE 693 ); 694 if (m && ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 695 m->hold_count || m->wire_count)) { 696 vm_page_deactivate(m); 697 continue; 698 } 699 return m; 700 } 701 } 702 703 /* 704 * vm_page_select_free: 705 * 706 * Find a free or zero page, with specified preference. We attempt to 707 * inline the nominal case and fall back to _vm_page_select_free() 708 * otherwise. 709 * 710 * This routine must be called at splvm(). 711 * This routine may not block. 712 */ 713 714 static __inline vm_page_t 715 vm_page_select_free(vm_object_t object, vm_pindex_t pindex, boolean_t prefer_zero) 716 { 717 vm_page_t m; 718 719 m = vm_page_list_find( 720 PQ_FREE, 721 (pindex + object->pg_color) & PQ_L2_MASK, 722 prefer_zero 723 ); 724 return(m); 725 } 726 727 /* 728 * vm_page_alloc: 729 * 730 * Allocate and return a memory cell associated 731 * with this VM object/offset pair. 732 * 733 * page_req classes: 734 * VM_ALLOC_NORMAL allow use of cache pages, nominal free drain 735 * VM_ALLOC_SYSTEM greater free drain 736 * VM_ALLOC_INTERRUPT allow free list to be completely drained 737 * VM_ALLOC_ZERO advisory request for pre-zero'd page 738 * 739 * Object must be locked. 740 * This routine may not block. 741 * 742 * Additional special handling is required when called from an 743 * interrupt (VM_ALLOC_INTERRUPT). We are not allowed to mess with 744 * the page cache in this case. 745 */ 746 747 vm_page_t 748 vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int page_req) 749 { 750 vm_page_t m = NULL; 751 int s; 752 753 KASSERT(!vm_page_lookup(object, pindex), 754 ("vm_page_alloc: page already allocated")); 755 KKASSERT(page_req & 756 (VM_ALLOC_NORMAL|VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 757 758 /* 759 * The pager is allowed to eat deeper into the free page list. 760 */ 761 if (curthread == pagethread) 762 page_req |= VM_ALLOC_SYSTEM; 763 764 s = splvm(); 765 loop: 766 if (vmstats.v_free_count > vmstats.v_free_reserved || 767 ((page_req & VM_ALLOC_INTERRUPT) && vmstats.v_free_count > 0) || 768 ((page_req & VM_ALLOC_SYSTEM) && vmstats.v_cache_count == 0 && 769 vmstats.v_free_count > vmstats.v_interrupt_free_min) 770 ) { 771 /* 772 * The free queue has sufficient free pages to take one out. 773 */ 774 if (page_req & VM_ALLOC_ZERO) 775 m = vm_page_select_free(object, pindex, TRUE); 776 else 777 m = vm_page_select_free(object, pindex, FALSE); 778 } else if (page_req & VM_ALLOC_NORMAL) { 779 /* 780 * Allocatable from the cache (non-interrupt only). On 781 * success, we must free the page and try again, thus 782 * ensuring that vmstats.v_*_free_min counters are replenished. 783 */ 784 #ifdef INVARIANTS 785 if (curthread->td_preempted) { 786 printf("vm_page_alloc(): warning, attempt to allocate" 787 " cache page from preempting interrupt\n"); 788 m = NULL; 789 } else { 790 m = vm_page_select_cache(object, pindex); 791 } 792 #else 793 m = vm_page_select_cache(object, pindex); 794 #endif 795 /* 796 * On succuess move the page into the free queue and loop. 797 */ 798 if (m != NULL) { 799 KASSERT(m->dirty == 0, 800 ("Found dirty cache page %p", m)); 801 vm_page_busy(m); 802 vm_page_protect(m, VM_PROT_NONE); 803 vm_page_free(m); 804 goto loop; 805 } 806 807 /* 808 * On failure return NULL 809 */ 810 splx(s); 811 #if defined(DIAGNOSTIC) 812 if (vmstats.v_cache_count > 0) 813 printf("vm_page_alloc(NORMAL): missing pages on cache queue: %d\n", vmstats.v_cache_count); 814 #endif 815 vm_pageout_deficit++; 816 pagedaemon_wakeup(); 817 return (NULL); 818 } else { 819 /* 820 * No pages available, wakeup the pageout daemon and give up. 821 */ 822 splx(s); 823 vm_pageout_deficit++; 824 pagedaemon_wakeup(); 825 return (NULL); 826 } 827 828 /* 829 * Good page found. 830 */ 831 KASSERT(m != NULL, ("vm_page_alloc(): missing page on free queue\n")); 832 833 /* 834 * Remove from free queue 835 */ 836 vm_page_unqueue_nowakeup(m); 837 838 /* 839 * Initialize structure. Only the PG_ZERO flag is inherited. 840 */ 841 if (m->flags & PG_ZERO) { 842 vm_page_zero_count--; 843 m->flags = PG_ZERO | PG_BUSY; 844 } else { 845 m->flags = PG_BUSY; 846 } 847 m->wire_count = 0; 848 m->hold_count = 0; 849 m->act_count = 0; 850 m->busy = 0; 851 m->valid = 0; 852 KASSERT(m->dirty == 0, 853 ("vm_page_alloc: free/cache page %p was dirty", m)); 854 855 /* 856 * vm_page_insert() is safe prior to the splx(). Note also that 857 * inserting a page here does not insert it into the pmap (which 858 * could cause us to block allocating memory). We cannot block 859 * anywhere. 860 */ 861 vm_page_insert(m, object, pindex); 862 863 /* 864 * Don't wakeup too often - wakeup the pageout daemon when 865 * we would be nearly out of memory. 866 */ 867 if (vm_paging_needed()) 868 pagedaemon_wakeup(); 869 870 splx(s); 871 return (m); 872 } 873 874 /* 875 * vm_wait: (also see VM_WAIT macro) 876 * 877 * Block until free pages are available for allocation 878 * - Called in various places before memory allocations. 879 */ 880 881 void 882 vm_wait(void) 883 { 884 int s; 885 886 s = splvm(); 887 if (curthread == pagethread) { 888 vm_pageout_pages_needed = 1; 889 tsleep(&vm_pageout_pages_needed, 0, "VMWait", 0); 890 } else { 891 if (!vm_pages_needed) { 892 vm_pages_needed = 1; 893 wakeup(&vm_pages_needed); 894 } 895 tsleep(&vmstats.v_free_count, 0, "vmwait", 0); 896 } 897 splx(s); 898 } 899 900 /* 901 * vm_waitpfault: (also see VM_WAITPFAULT macro) 902 * 903 * Block until free pages are available for allocation 904 * - Called only in vm_fault so that processes page faulting 905 * can be easily tracked. 906 * - Sleeps at a lower priority than vm_wait() so that vm_wait()ing 907 * processes will be able to grab memory first. Do not change 908 * this balance without careful testing first. 909 */ 910 911 void 912 vm_waitpfault(void) 913 { 914 int s; 915 916 s = splvm(); 917 if (!vm_pages_needed) { 918 vm_pages_needed = 1; 919 wakeup(&vm_pages_needed); 920 } 921 tsleep(&vmstats.v_free_count, 0, "pfault", 0); 922 splx(s); 923 } 924 925 /* 926 * vm_page_activate: 927 * 928 * Put the specified page on the active list (if appropriate). 929 * Ensure that act_count is at least ACT_INIT but do not otherwise 930 * mess with it. 931 * 932 * The page queues must be locked. 933 * This routine may not block. 934 */ 935 void 936 vm_page_activate(vm_page_t m) 937 { 938 int s; 939 940 s = splvm(); 941 if (m->queue != PQ_ACTIVE) { 942 if ((m->queue - m->pc) == PQ_CACHE) 943 mycpu->gd_cnt.v_reactivated++; 944 945 vm_page_unqueue(m); 946 947 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 948 m->queue = PQ_ACTIVE; 949 vm_page_queues[PQ_ACTIVE].lcnt++; 950 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 951 if (m->act_count < ACT_INIT) 952 m->act_count = ACT_INIT; 953 vmstats.v_active_count++; 954 } 955 } else { 956 if (m->act_count < ACT_INIT) 957 m->act_count = ACT_INIT; 958 } 959 960 splx(s); 961 } 962 963 /* 964 * vm_page_free_wakeup: 965 * 966 * Helper routine for vm_page_free_toq() and vm_page_cache(). This 967 * routine is called when a page has been added to the cache or free 968 * queues. 969 * 970 * This routine may not block. 971 * This routine must be called at splvm() 972 */ 973 static __inline void 974 vm_page_free_wakeup(void) 975 { 976 /* 977 * if pageout daemon needs pages, then tell it that there are 978 * some free. 979 */ 980 if (vm_pageout_pages_needed && 981 vmstats.v_cache_count + vmstats.v_free_count >= vmstats.v_pageout_free_min) { 982 wakeup(&vm_pageout_pages_needed); 983 vm_pageout_pages_needed = 0; 984 } 985 /* 986 * wakeup processes that are waiting on memory if we hit a 987 * high water mark. And wakeup scheduler process if we have 988 * lots of memory. this process will swapin processes. 989 */ 990 if (vm_pages_needed && !vm_page_count_min()) { 991 vm_pages_needed = 0; 992 wakeup(&vmstats.v_free_count); 993 } 994 } 995 996 /* 997 * vm_page_free_toq: 998 * 999 * Returns the given page to the PQ_FREE list, 1000 * disassociating it with any VM object. 1001 * 1002 * Object and page must be locked prior to entry. 1003 * This routine may not block. 1004 */ 1005 1006 void 1007 vm_page_free_toq(vm_page_t m) 1008 { 1009 int s; 1010 struct vpgqueues *pq; 1011 #if 0 1012 vm_object_t object = m->object; 1013 #endif 1014 1015 s = splvm(); 1016 1017 mycpu->gd_cnt.v_tfree++; 1018 1019 if (m->busy || ((m->queue - m->pc) == PQ_FREE)) { 1020 printf( 1021 "vm_page_free: pindex(%lu), busy(%d), PG_BUSY(%d), hold(%d)\n", 1022 (u_long)m->pindex, m->busy, (m->flags & PG_BUSY) ? 1 : 0, 1023 m->hold_count); 1024 if ((m->queue - m->pc) == PQ_FREE) 1025 panic("vm_page_free: freeing free page"); 1026 else 1027 panic("vm_page_free: freeing busy page"); 1028 } 1029 1030 /* 1031 * unqueue, then remove page. Note that we cannot destroy 1032 * the page here because we do not want to call the pager's 1033 * callback routine until after we've put the page on the 1034 * appropriate free queue. 1035 */ 1036 1037 vm_page_unqueue_nowakeup(m); 1038 vm_page_remove(m); 1039 1040 /* 1041 * If fictitious remove object association and 1042 * return, otherwise delay object association removal. 1043 */ 1044 1045 if ((m->flags & PG_FICTITIOUS) != 0) { 1046 splx(s); 1047 return; 1048 } 1049 1050 m->valid = 0; 1051 vm_page_undirty(m); 1052 1053 if (m->wire_count != 0) { 1054 if (m->wire_count > 1) { 1055 panic("vm_page_free: invalid wire count (%d), pindex: 0x%lx", 1056 m->wire_count, (long)m->pindex); 1057 } 1058 panic("vm_page_free: freeing wired page\n"); 1059 } 1060 1061 /* 1062 * We used to free the underlying vnode if the object was empty, 1063 * but we no longer do that because it can block. Instead, the 1064 * sync code is made responsible for the cleanup. 1065 */ 1066 #if 0 1067 if (object && 1068 (object->type == OBJT_VNODE) && 1069 ((object->flags & OBJ_DEAD) == 0) && 1070 object->handle != NULL 1071 ) { 1072 struct vnode *vp = (struct vnode *)object->handle; 1073 1074 if (vp && VSHOULDFREE(vp)) 1075 vfree(vp); 1076 } 1077 #endif 1078 1079 /* 1080 * Clear the UNMANAGED flag when freeing an unmanaged page. 1081 */ 1082 1083 if (m->flags & PG_UNMANAGED) { 1084 m->flags &= ~PG_UNMANAGED; 1085 } else { 1086 #ifdef __alpha__ 1087 pmap_page_is_free(m); 1088 #endif 1089 } 1090 1091 if (m->hold_count != 0) { 1092 m->flags &= ~PG_ZERO; 1093 m->queue = PQ_HOLD; 1094 } else 1095 m->queue = PQ_FREE + m->pc; 1096 pq = &vm_page_queues[m->queue]; 1097 pq->lcnt++; 1098 ++(*pq->cnt); 1099 1100 /* 1101 * Put zero'd pages on the end ( where we look for zero'd pages 1102 * first ) and non-zerod pages at the head. 1103 */ 1104 1105 if (m->flags & PG_ZERO) { 1106 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 1107 ++vm_page_zero_count; 1108 } else { 1109 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1110 } 1111 1112 vm_page_free_wakeup(); 1113 1114 splx(s); 1115 } 1116 1117 /* 1118 * vm_page_unmanage: 1119 * 1120 * Prevent PV management from being done on the page. The page is 1121 * removed from the paging queues as if it were wired, and as a 1122 * consequence of no longer being managed the pageout daemon will not 1123 * touch it (since there is no way to locate the pte mappings for the 1124 * page). madvise() calls that mess with the pmap will also no longer 1125 * operate on the page. 1126 * 1127 * Beyond that the page is still reasonably 'normal'. Freeing the page 1128 * will clear the flag. 1129 * 1130 * This routine is used by OBJT_PHYS objects - objects using unswappable 1131 * physical memory as backing store rather then swap-backed memory and 1132 * will eventually be extended to support 4MB unmanaged physical 1133 * mappings. 1134 */ 1135 1136 void 1137 vm_page_unmanage(vm_page_t m) 1138 { 1139 int s; 1140 1141 s = splvm(); 1142 if ((m->flags & PG_UNMANAGED) == 0) { 1143 if (m->wire_count == 0) 1144 vm_page_unqueue(m); 1145 } 1146 vm_page_flag_set(m, PG_UNMANAGED); 1147 splx(s); 1148 } 1149 1150 /* 1151 * vm_page_wire: 1152 * 1153 * Mark this page as wired down by yet 1154 * another map, removing it from paging queues 1155 * as necessary. 1156 * 1157 * The page queues must be locked. 1158 * This routine may not block. 1159 */ 1160 void 1161 vm_page_wire(vm_page_t m) 1162 { 1163 int s; 1164 1165 /* 1166 * Only bump the wire statistics if the page is not already wired, 1167 * and only unqueue the page if it is on some queue (if it is unmanaged 1168 * it is already off the queues). 1169 */ 1170 s = splvm(); 1171 if (m->wire_count == 0) { 1172 if ((m->flags & PG_UNMANAGED) == 0) 1173 vm_page_unqueue(m); 1174 vmstats.v_wire_count++; 1175 } 1176 m->wire_count++; 1177 KASSERT(m->wire_count != 0, 1178 ("vm_page_wire: wire_count overflow m=%p", m)); 1179 1180 splx(s); 1181 vm_page_flag_set(m, PG_MAPPED); 1182 } 1183 1184 /* 1185 * vm_page_unwire: 1186 * 1187 * Release one wiring of this page, potentially 1188 * enabling it to be paged again. 1189 * 1190 * Many pages placed on the inactive queue should actually go 1191 * into the cache, but it is difficult to figure out which. What 1192 * we do instead, if the inactive target is well met, is to put 1193 * clean pages at the head of the inactive queue instead of the tail. 1194 * This will cause them to be moved to the cache more quickly and 1195 * if not actively re-referenced, freed more quickly. If we just 1196 * stick these pages at the end of the inactive queue, heavy filesystem 1197 * meta-data accesses can cause an unnecessary paging load on memory bound 1198 * processes. This optimization causes one-time-use metadata to be 1199 * reused more quickly. 1200 * 1201 * BUT, if we are in a low-memory situation we have no choice but to 1202 * put clean pages on the cache queue. 1203 * 1204 * A number of routines use vm_page_unwire() to guarantee that the page 1205 * will go into either the inactive or active queues, and will NEVER 1206 * be placed in the cache - for example, just after dirtying a page. 1207 * dirty pages in the cache are not allowed. 1208 * 1209 * The page queues must be locked. 1210 * This routine may not block. 1211 */ 1212 void 1213 vm_page_unwire(vm_page_t m, int activate) 1214 { 1215 int s; 1216 1217 s = splvm(); 1218 1219 if (m->wire_count > 0) { 1220 m->wire_count--; 1221 if (m->wire_count == 0) { 1222 vmstats.v_wire_count--; 1223 if (m->flags & PG_UNMANAGED) { 1224 ; 1225 } else if (activate) { 1226 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1227 m->queue = PQ_ACTIVE; 1228 vm_page_queues[PQ_ACTIVE].lcnt++; 1229 vmstats.v_active_count++; 1230 } else { 1231 vm_page_flag_clear(m, PG_WINATCFLS); 1232 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1233 m->queue = PQ_INACTIVE; 1234 vm_page_queues[PQ_INACTIVE].lcnt++; 1235 vmstats.v_inactive_count++; 1236 } 1237 } 1238 } else { 1239 panic("vm_page_unwire: invalid wire count: %d\n", m->wire_count); 1240 } 1241 splx(s); 1242 } 1243 1244 1245 /* 1246 * Move the specified page to the inactive queue. If the page has 1247 * any associated swap, the swap is deallocated. 1248 * 1249 * Normally athead is 0 resulting in LRU operation. athead is set 1250 * to 1 if we want this page to be 'as if it were placed in the cache', 1251 * except without unmapping it from the process address space. 1252 * 1253 * This routine may not block. 1254 */ 1255 static __inline void 1256 _vm_page_deactivate(vm_page_t m, int athead) 1257 { 1258 int s; 1259 1260 /* 1261 * Ignore if already inactive. 1262 */ 1263 if (m->queue == PQ_INACTIVE) 1264 return; 1265 1266 s = splvm(); 1267 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1268 if ((m->queue - m->pc) == PQ_CACHE) 1269 mycpu->gd_cnt.v_reactivated++; 1270 vm_page_flag_clear(m, PG_WINATCFLS); 1271 vm_page_unqueue(m); 1272 if (athead) 1273 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1274 else 1275 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1276 m->queue = PQ_INACTIVE; 1277 vm_page_queues[PQ_INACTIVE].lcnt++; 1278 vmstats.v_inactive_count++; 1279 } 1280 splx(s); 1281 } 1282 1283 void 1284 vm_page_deactivate(vm_page_t m) 1285 { 1286 _vm_page_deactivate(m, 0); 1287 } 1288 1289 /* 1290 * vm_page_try_to_cache: 1291 * 1292 * Returns 0 on failure, 1 on success 1293 */ 1294 int 1295 vm_page_try_to_cache(vm_page_t m) 1296 { 1297 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1298 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1299 return(0); 1300 } 1301 vm_page_test_dirty(m); 1302 if (m->dirty) 1303 return(0); 1304 vm_page_cache(m); 1305 return(1); 1306 } 1307 1308 /* 1309 * vm_page_try_to_free() 1310 * 1311 * Attempt to free the page. If we cannot free it, we do nothing. 1312 * 1 is returned on success, 0 on failure. 1313 */ 1314 1315 int 1316 vm_page_try_to_free(vm_page_t m) 1317 { 1318 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1319 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1320 return(0); 1321 } 1322 vm_page_test_dirty(m); 1323 if (m->dirty) 1324 return(0); 1325 vm_page_busy(m); 1326 vm_page_protect(m, VM_PROT_NONE); 1327 vm_page_free(m); 1328 return(1); 1329 } 1330 1331 1332 /* 1333 * vm_page_cache 1334 * 1335 * Put the specified page onto the page cache queue (if appropriate). 1336 * 1337 * This routine may not block. 1338 */ 1339 void 1340 vm_page_cache(vm_page_t m) 1341 { 1342 int s; 1343 1344 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 1345 m->wire_count || m->hold_count) { 1346 printf("vm_page_cache: attempting to cache busy/held page\n"); 1347 return; 1348 } 1349 if ((m->queue - m->pc) == PQ_CACHE) 1350 return; 1351 1352 /* 1353 * Remove all pmaps and indicate that the page is not 1354 * writeable or mapped. 1355 */ 1356 1357 vm_page_protect(m, VM_PROT_NONE); 1358 if (m->dirty != 0) { 1359 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1360 (long)m->pindex); 1361 } 1362 s = splvm(); 1363 vm_page_unqueue_nowakeup(m); 1364 m->queue = PQ_CACHE + m->pc; 1365 vm_page_queues[m->queue].lcnt++; 1366 TAILQ_INSERT_TAIL(&vm_page_queues[m->queue].pl, m, pageq); 1367 vmstats.v_cache_count++; 1368 vm_page_free_wakeup(); 1369 splx(s); 1370 } 1371 1372 /* 1373 * vm_page_dontneed 1374 * 1375 * Cache, deactivate, or do nothing as appropriate. This routine 1376 * is typically used by madvise() MADV_DONTNEED. 1377 * 1378 * Generally speaking we want to move the page into the cache so 1379 * it gets reused quickly. However, this can result in a silly syndrome 1380 * due to the page recycling too quickly. Small objects will not be 1381 * fully cached. On the otherhand, if we move the page to the inactive 1382 * queue we wind up with a problem whereby very large objects 1383 * unnecessarily blow away our inactive and cache queues. 1384 * 1385 * The solution is to move the pages based on a fixed weighting. We 1386 * either leave them alone, deactivate them, or move them to the cache, 1387 * where moving them to the cache has the highest weighting. 1388 * By forcing some pages into other queues we eventually force the 1389 * system to balance the queues, potentially recovering other unrelated 1390 * space from active. The idea is to not force this to happen too 1391 * often. 1392 */ 1393 1394 void 1395 vm_page_dontneed(vm_page_t m) 1396 { 1397 static int dnweight; 1398 int dnw; 1399 int head; 1400 1401 dnw = ++dnweight; 1402 1403 /* 1404 * occassionally leave the page alone 1405 */ 1406 1407 if ((dnw & 0x01F0) == 0 || 1408 m->queue == PQ_INACTIVE || 1409 m->queue - m->pc == PQ_CACHE 1410 ) { 1411 if (m->act_count >= ACT_INIT) 1412 --m->act_count; 1413 return; 1414 } 1415 1416 if (m->dirty == 0) 1417 vm_page_test_dirty(m); 1418 1419 if (m->dirty || (dnw & 0x0070) == 0) { 1420 /* 1421 * Deactivate the page 3 times out of 32. 1422 */ 1423 head = 0; 1424 } else { 1425 /* 1426 * Cache the page 28 times out of every 32. Note that 1427 * the page is deactivated instead of cached, but placed 1428 * at the head of the queue instead of the tail. 1429 */ 1430 head = 1; 1431 } 1432 _vm_page_deactivate(m, head); 1433 } 1434 1435 /* 1436 * Grab a page, waiting until we are waken up due to the page 1437 * changing state. We keep on waiting, if the page continues 1438 * to be in the object. If the page doesn't exist, allocate it. 1439 * 1440 * If VM_ALLOC_RETRY is specified VM_ALLOC_NORMAL must also be specified. 1441 * 1442 * This routine may block. 1443 */ 1444 vm_page_t 1445 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1446 { 1447 vm_page_t m; 1448 int s, generation; 1449 1450 KKASSERT(allocflags & 1451 (VM_ALLOC_NORMAL|VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 1452 retrylookup: 1453 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1454 if (m->busy || (m->flags & PG_BUSY)) { 1455 generation = object->generation; 1456 1457 s = splvm(); 1458 while ((object->generation == generation) && 1459 (m->busy || (m->flags & PG_BUSY))) { 1460 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 1461 tsleep(m, 0, "pgrbwt", 0); 1462 if ((allocflags & VM_ALLOC_RETRY) == 0) { 1463 splx(s); 1464 return NULL; 1465 } 1466 } 1467 splx(s); 1468 goto retrylookup; 1469 } else { 1470 vm_page_busy(m); 1471 return m; 1472 } 1473 } 1474 1475 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1476 if (m == NULL) { 1477 VM_WAIT; 1478 if ((allocflags & VM_ALLOC_RETRY) == 0) 1479 return NULL; 1480 goto retrylookup; 1481 } 1482 1483 return m; 1484 } 1485 1486 /* 1487 * Mapping function for valid bits or for dirty bits in 1488 * a page. May not block. 1489 * 1490 * Inputs are required to range within a page. 1491 */ 1492 1493 __inline int 1494 vm_page_bits(int base, int size) 1495 { 1496 int first_bit; 1497 int last_bit; 1498 1499 KASSERT( 1500 base + size <= PAGE_SIZE, 1501 ("vm_page_bits: illegal base/size %d/%d", base, size) 1502 ); 1503 1504 if (size == 0) /* handle degenerate case */ 1505 return(0); 1506 1507 first_bit = base >> DEV_BSHIFT; 1508 last_bit = (base + size - 1) >> DEV_BSHIFT; 1509 1510 return ((2 << last_bit) - (1 << first_bit)); 1511 } 1512 1513 /* 1514 * vm_page_set_validclean: 1515 * 1516 * Sets portions of a page valid and clean. The arguments are expected 1517 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1518 * of any partial chunks touched by the range. The invalid portion of 1519 * such chunks will be zero'd. 1520 * 1521 * This routine may not block. 1522 * 1523 * (base + size) must be less then or equal to PAGE_SIZE. 1524 */ 1525 void 1526 vm_page_set_validclean(vm_page_t m, int base, int size) 1527 { 1528 int pagebits; 1529 int frag; 1530 int endoff; 1531 1532 if (size == 0) /* handle degenerate case */ 1533 return; 1534 1535 /* 1536 * If the base is not DEV_BSIZE aligned and the valid 1537 * bit is clear, we have to zero out a portion of the 1538 * first block. 1539 */ 1540 1541 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1542 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0 1543 ) { 1544 pmap_zero_page_area( 1545 VM_PAGE_TO_PHYS(m), 1546 frag, 1547 base - frag 1548 ); 1549 } 1550 1551 /* 1552 * If the ending offset is not DEV_BSIZE aligned and the 1553 * valid bit is clear, we have to zero out a portion of 1554 * the last block. 1555 */ 1556 1557 endoff = base + size; 1558 1559 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1560 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0 1561 ) { 1562 pmap_zero_page_area( 1563 VM_PAGE_TO_PHYS(m), 1564 endoff, 1565 DEV_BSIZE - (endoff & (DEV_BSIZE - 1)) 1566 ); 1567 } 1568 1569 /* 1570 * Set valid, clear dirty bits. If validating the entire 1571 * page we can safely clear the pmap modify bit. We also 1572 * use this opportunity to clear the PG_NOSYNC flag. If a process 1573 * takes a write fault on a MAP_NOSYNC memory area the flag will 1574 * be set again. 1575 * 1576 * We set valid bits inclusive of any overlap, but we can only 1577 * clear dirty bits for DEV_BSIZE chunks that are fully within 1578 * the range. 1579 */ 1580 1581 pagebits = vm_page_bits(base, size); 1582 m->valid |= pagebits; 1583 #if 0 /* NOT YET */ 1584 if ((frag = base & (DEV_BSIZE - 1)) != 0) { 1585 frag = DEV_BSIZE - frag; 1586 base += frag; 1587 size -= frag; 1588 if (size < 0) 1589 size = 0; 1590 } 1591 pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1)); 1592 #endif 1593 m->dirty &= ~pagebits; 1594 if (base == 0 && size == PAGE_SIZE) { 1595 pmap_clear_modify(m); 1596 vm_page_flag_clear(m, PG_NOSYNC); 1597 } 1598 } 1599 1600 #if 0 1601 1602 void 1603 vm_page_set_dirty(vm_page_t m, int base, int size) 1604 { 1605 m->dirty |= vm_page_bits(base, size); 1606 } 1607 1608 #endif 1609 1610 void 1611 vm_page_clear_dirty(vm_page_t m, int base, int size) 1612 { 1613 m->dirty &= ~vm_page_bits(base, size); 1614 } 1615 1616 /* 1617 * vm_page_set_invalid: 1618 * 1619 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1620 * valid and dirty bits for the effected areas are cleared. 1621 * 1622 * May not block. 1623 */ 1624 void 1625 vm_page_set_invalid(vm_page_t m, int base, int size) 1626 { 1627 int bits; 1628 1629 bits = vm_page_bits(base, size); 1630 m->valid &= ~bits; 1631 m->dirty &= ~bits; 1632 m->object->generation++; 1633 } 1634 1635 /* 1636 * vm_page_zero_invalid() 1637 * 1638 * The kernel assumes that the invalid portions of a page contain 1639 * garbage, but such pages can be mapped into memory by user code. 1640 * When this occurs, we must zero out the non-valid portions of the 1641 * page so user code sees what it expects. 1642 * 1643 * Pages are most often semi-valid when the end of a file is mapped 1644 * into memory and the file's size is not page aligned. 1645 */ 1646 1647 void 1648 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1649 { 1650 int b; 1651 int i; 1652 1653 /* 1654 * Scan the valid bits looking for invalid sections that 1655 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1656 * valid bit may be set ) have already been zerod by 1657 * vm_page_set_validclean(). 1658 */ 1659 1660 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1661 if (i == (PAGE_SIZE / DEV_BSIZE) || 1662 (m->valid & (1 << i)) 1663 ) { 1664 if (i > b) { 1665 pmap_zero_page_area( 1666 VM_PAGE_TO_PHYS(m), 1667 b << DEV_BSHIFT, 1668 (i - b) << DEV_BSHIFT 1669 ); 1670 } 1671 b = i + 1; 1672 } 1673 } 1674 1675 /* 1676 * setvalid is TRUE when we can safely set the zero'd areas 1677 * as being valid. We can do this if there are no cache consistency 1678 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1679 */ 1680 1681 if (setvalid) 1682 m->valid = VM_PAGE_BITS_ALL; 1683 } 1684 1685 /* 1686 * vm_page_is_valid: 1687 * 1688 * Is (partial) page valid? Note that the case where size == 0 1689 * will return FALSE in the degenerate case where the page is 1690 * entirely invalid, and TRUE otherwise. 1691 * 1692 * May not block. 1693 */ 1694 1695 int 1696 vm_page_is_valid(vm_page_t m, int base, int size) 1697 { 1698 int bits = vm_page_bits(base, size); 1699 1700 if (m->valid && ((m->valid & bits) == bits)) 1701 return 1; 1702 else 1703 return 0; 1704 } 1705 1706 /* 1707 * update dirty bits from pmap/mmu. May not block. 1708 */ 1709 1710 void 1711 vm_page_test_dirty(vm_page_t m) 1712 { 1713 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1714 vm_page_dirty(m); 1715 } 1716 } 1717 1718 #include "opt_ddb.h" 1719 #ifdef DDB 1720 #include <sys/kernel.h> 1721 1722 #include <ddb/ddb.h> 1723 1724 DB_SHOW_COMMAND(page, vm_page_print_page_info) 1725 { 1726 db_printf("vmstats.v_free_count: %d\n", vmstats.v_free_count); 1727 db_printf("vmstats.v_cache_count: %d\n", vmstats.v_cache_count); 1728 db_printf("vmstats.v_inactive_count: %d\n", vmstats.v_inactive_count); 1729 db_printf("vmstats.v_active_count: %d\n", vmstats.v_active_count); 1730 db_printf("vmstats.v_wire_count: %d\n", vmstats.v_wire_count); 1731 db_printf("vmstats.v_free_reserved: %d\n", vmstats.v_free_reserved); 1732 db_printf("vmstats.v_free_min: %d\n", vmstats.v_free_min); 1733 db_printf("vmstats.v_free_target: %d\n", vmstats.v_free_target); 1734 db_printf("vmstats.v_cache_min: %d\n", vmstats.v_cache_min); 1735 db_printf("vmstats.v_inactive_target: %d\n", vmstats.v_inactive_target); 1736 } 1737 1738 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1739 { 1740 int i; 1741 db_printf("PQ_FREE:"); 1742 for(i=0;i<PQ_L2_SIZE;i++) { 1743 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1744 } 1745 db_printf("\n"); 1746 1747 db_printf("PQ_CACHE:"); 1748 for(i=0;i<PQ_L2_SIZE;i++) { 1749 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 1750 } 1751 db_printf("\n"); 1752 1753 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 1754 vm_page_queues[PQ_ACTIVE].lcnt, 1755 vm_page_queues[PQ_INACTIVE].lcnt); 1756 } 1757 #endif /* DDB */ 1758