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 1.16 2004/01/20 05:04:08 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 vm_object_t object = m->object; 1012 1013 s = splvm(); 1014 1015 mycpu->gd_cnt.v_tfree++; 1016 1017 if (m->busy || ((m->queue - m->pc) == PQ_FREE)) { 1018 printf( 1019 "vm_page_free: pindex(%lu), busy(%d), PG_BUSY(%d), hold(%d)\n", 1020 (u_long)m->pindex, m->busy, (m->flags & PG_BUSY) ? 1 : 0, 1021 m->hold_count); 1022 if ((m->queue - m->pc) == PQ_FREE) 1023 panic("vm_page_free: freeing free page"); 1024 else 1025 panic("vm_page_free: freeing busy page"); 1026 } 1027 1028 /* 1029 * unqueue, then remove page. Note that we cannot destroy 1030 * the page here because we do not want to call the pager's 1031 * callback routine until after we've put the page on the 1032 * appropriate free queue. 1033 */ 1034 1035 vm_page_unqueue_nowakeup(m); 1036 vm_page_remove(m); 1037 1038 /* 1039 * If fictitious remove object association and 1040 * return, otherwise delay object association removal. 1041 */ 1042 1043 if ((m->flags & PG_FICTITIOUS) != 0) { 1044 splx(s); 1045 return; 1046 } 1047 1048 m->valid = 0; 1049 vm_page_undirty(m); 1050 1051 if (m->wire_count != 0) { 1052 if (m->wire_count > 1) { 1053 panic("vm_page_free: invalid wire count (%d), pindex: 0x%lx", 1054 m->wire_count, (long)m->pindex); 1055 } 1056 panic("vm_page_free: freeing wired page\n"); 1057 } 1058 1059 /* 1060 * If we've exhausted the object's resident pages we want to free 1061 * it up. 1062 */ 1063 1064 if (object && 1065 (object->type == OBJT_VNODE) && 1066 ((object->flags & OBJ_DEAD) == 0) 1067 ) { 1068 struct vnode *vp = (struct vnode *)object->handle; 1069 1070 if (vp && VSHOULDFREE(vp)) 1071 vfree(vp); 1072 } 1073 1074 /* 1075 * Clear the UNMANAGED flag when freeing an unmanaged page. 1076 */ 1077 1078 if (m->flags & PG_UNMANAGED) { 1079 m->flags &= ~PG_UNMANAGED; 1080 } else { 1081 #ifdef __alpha__ 1082 pmap_page_is_free(m); 1083 #endif 1084 } 1085 1086 if (m->hold_count != 0) { 1087 m->flags &= ~PG_ZERO; 1088 m->queue = PQ_HOLD; 1089 } else 1090 m->queue = PQ_FREE + m->pc; 1091 pq = &vm_page_queues[m->queue]; 1092 pq->lcnt++; 1093 ++(*pq->cnt); 1094 1095 /* 1096 * Put zero'd pages on the end ( where we look for zero'd pages 1097 * first ) and non-zerod pages at the head. 1098 */ 1099 1100 if (m->flags & PG_ZERO) { 1101 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 1102 ++vm_page_zero_count; 1103 } else { 1104 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1105 } 1106 1107 vm_page_free_wakeup(); 1108 1109 splx(s); 1110 } 1111 1112 /* 1113 * vm_page_unmanage: 1114 * 1115 * Prevent PV management from being done on the page. The page is 1116 * removed from the paging queues as if it were wired, and as a 1117 * consequence of no longer being managed the pageout daemon will not 1118 * touch it (since there is no way to locate the pte mappings for the 1119 * page). madvise() calls that mess with the pmap will also no longer 1120 * operate on the page. 1121 * 1122 * Beyond that the page is still reasonably 'normal'. Freeing the page 1123 * will clear the flag. 1124 * 1125 * This routine is used by OBJT_PHYS objects - objects using unswappable 1126 * physical memory as backing store rather then swap-backed memory and 1127 * will eventually be extended to support 4MB unmanaged physical 1128 * mappings. 1129 */ 1130 1131 void 1132 vm_page_unmanage(vm_page_t m) 1133 { 1134 int s; 1135 1136 s = splvm(); 1137 if ((m->flags & PG_UNMANAGED) == 0) { 1138 if (m->wire_count == 0) 1139 vm_page_unqueue(m); 1140 } 1141 vm_page_flag_set(m, PG_UNMANAGED); 1142 splx(s); 1143 } 1144 1145 /* 1146 * vm_page_wire: 1147 * 1148 * Mark this page as wired down by yet 1149 * another map, removing it from paging queues 1150 * as necessary. 1151 * 1152 * The page queues must be locked. 1153 * This routine may not block. 1154 */ 1155 void 1156 vm_page_wire(vm_page_t m) 1157 { 1158 int s; 1159 1160 /* 1161 * Only bump the wire statistics if the page is not already wired, 1162 * and only unqueue the page if it is on some queue (if it is unmanaged 1163 * it is already off the queues). 1164 */ 1165 s = splvm(); 1166 if (m->wire_count == 0) { 1167 if ((m->flags & PG_UNMANAGED) == 0) 1168 vm_page_unqueue(m); 1169 vmstats.v_wire_count++; 1170 } 1171 m->wire_count++; 1172 KASSERT(m->wire_count != 0, 1173 ("vm_page_wire: wire_count overflow m=%p", m)); 1174 1175 splx(s); 1176 vm_page_flag_set(m, PG_MAPPED); 1177 } 1178 1179 /* 1180 * vm_page_unwire: 1181 * 1182 * Release one wiring of this page, potentially 1183 * enabling it to be paged again. 1184 * 1185 * Many pages placed on the inactive queue should actually go 1186 * into the cache, but it is difficult to figure out which. What 1187 * we do instead, if the inactive target is well met, is to put 1188 * clean pages at the head of the inactive queue instead of the tail. 1189 * This will cause them to be moved to the cache more quickly and 1190 * if not actively re-referenced, freed more quickly. If we just 1191 * stick these pages at the end of the inactive queue, heavy filesystem 1192 * meta-data accesses can cause an unnecessary paging load on memory bound 1193 * processes. This optimization causes one-time-use metadata to be 1194 * reused more quickly. 1195 * 1196 * BUT, if we are in a low-memory situation we have no choice but to 1197 * put clean pages on the cache queue. 1198 * 1199 * A number of routines use vm_page_unwire() to guarantee that the page 1200 * will go into either the inactive or active queues, and will NEVER 1201 * be placed in the cache - for example, just after dirtying a page. 1202 * dirty pages in the cache are not allowed. 1203 * 1204 * The page queues must be locked. 1205 * This routine may not block. 1206 */ 1207 void 1208 vm_page_unwire(vm_page_t m, int activate) 1209 { 1210 int s; 1211 1212 s = splvm(); 1213 1214 if (m->wire_count > 0) { 1215 m->wire_count--; 1216 if (m->wire_count == 0) { 1217 vmstats.v_wire_count--; 1218 if (m->flags & PG_UNMANAGED) { 1219 ; 1220 } else if (activate) { 1221 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1222 m->queue = PQ_ACTIVE; 1223 vm_page_queues[PQ_ACTIVE].lcnt++; 1224 vmstats.v_active_count++; 1225 } else { 1226 vm_page_flag_clear(m, PG_WINATCFLS); 1227 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1228 m->queue = PQ_INACTIVE; 1229 vm_page_queues[PQ_INACTIVE].lcnt++; 1230 vmstats.v_inactive_count++; 1231 } 1232 } 1233 } else { 1234 panic("vm_page_unwire: invalid wire count: %d\n", m->wire_count); 1235 } 1236 splx(s); 1237 } 1238 1239 1240 /* 1241 * Move the specified page to the inactive queue. If the page has 1242 * any associated swap, the swap is deallocated. 1243 * 1244 * Normally athead is 0 resulting in LRU operation. athead is set 1245 * to 1 if we want this page to be 'as if it were placed in the cache', 1246 * except without unmapping it from the process address space. 1247 * 1248 * This routine may not block. 1249 */ 1250 static __inline void 1251 _vm_page_deactivate(vm_page_t m, int athead) 1252 { 1253 int s; 1254 1255 /* 1256 * Ignore if already inactive. 1257 */ 1258 if (m->queue == PQ_INACTIVE) 1259 return; 1260 1261 s = splvm(); 1262 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1263 if ((m->queue - m->pc) == PQ_CACHE) 1264 mycpu->gd_cnt.v_reactivated++; 1265 vm_page_flag_clear(m, PG_WINATCFLS); 1266 vm_page_unqueue(m); 1267 if (athead) 1268 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1269 else 1270 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1271 m->queue = PQ_INACTIVE; 1272 vm_page_queues[PQ_INACTIVE].lcnt++; 1273 vmstats.v_inactive_count++; 1274 } 1275 splx(s); 1276 } 1277 1278 void 1279 vm_page_deactivate(vm_page_t m) 1280 { 1281 _vm_page_deactivate(m, 0); 1282 } 1283 1284 /* 1285 * vm_page_try_to_cache: 1286 * 1287 * Returns 0 on failure, 1 on success 1288 */ 1289 int 1290 vm_page_try_to_cache(vm_page_t m) 1291 { 1292 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1293 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1294 return(0); 1295 } 1296 vm_page_test_dirty(m); 1297 if (m->dirty) 1298 return(0); 1299 vm_page_cache(m); 1300 return(1); 1301 } 1302 1303 /* 1304 * vm_page_try_to_free() 1305 * 1306 * Attempt to free the page. If we cannot free it, we do nothing. 1307 * 1 is returned on success, 0 on failure. 1308 */ 1309 1310 int 1311 vm_page_try_to_free(vm_page_t m) 1312 { 1313 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1314 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1315 return(0); 1316 } 1317 vm_page_test_dirty(m); 1318 if (m->dirty) 1319 return(0); 1320 vm_page_busy(m); 1321 vm_page_protect(m, VM_PROT_NONE); 1322 vm_page_free(m); 1323 return(1); 1324 } 1325 1326 1327 /* 1328 * vm_page_cache 1329 * 1330 * Put the specified page onto the page cache queue (if appropriate). 1331 * 1332 * This routine may not block. 1333 */ 1334 void 1335 vm_page_cache(vm_page_t m) 1336 { 1337 int s; 1338 1339 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || m->wire_count) { 1340 printf("vm_page_cache: attempting to cache busy page\n"); 1341 return; 1342 } 1343 if ((m->queue - m->pc) == PQ_CACHE) 1344 return; 1345 1346 /* 1347 * Remove all pmaps and indicate that the page is not 1348 * writeable or mapped. 1349 */ 1350 1351 vm_page_protect(m, VM_PROT_NONE); 1352 if (m->dirty != 0) { 1353 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1354 (long)m->pindex); 1355 } 1356 s = splvm(); 1357 vm_page_unqueue_nowakeup(m); 1358 m->queue = PQ_CACHE + m->pc; 1359 vm_page_queues[m->queue].lcnt++; 1360 TAILQ_INSERT_TAIL(&vm_page_queues[m->queue].pl, m, pageq); 1361 vmstats.v_cache_count++; 1362 vm_page_free_wakeup(); 1363 splx(s); 1364 } 1365 1366 /* 1367 * vm_page_dontneed 1368 * 1369 * Cache, deactivate, or do nothing as appropriate. This routine 1370 * is typically used by madvise() MADV_DONTNEED. 1371 * 1372 * Generally speaking we want to move the page into the cache so 1373 * it gets reused quickly. However, this can result in a silly syndrome 1374 * due to the page recycling too quickly. Small objects will not be 1375 * fully cached. On the otherhand, if we move the page to the inactive 1376 * queue we wind up with a problem whereby very large objects 1377 * unnecessarily blow away our inactive and cache queues. 1378 * 1379 * The solution is to move the pages based on a fixed weighting. We 1380 * either leave them alone, deactivate them, or move them to the cache, 1381 * where moving them to the cache has the highest weighting. 1382 * By forcing some pages into other queues we eventually force the 1383 * system to balance the queues, potentially recovering other unrelated 1384 * space from active. The idea is to not force this to happen too 1385 * often. 1386 */ 1387 1388 void 1389 vm_page_dontneed(vm_page_t m) 1390 { 1391 static int dnweight; 1392 int dnw; 1393 int head; 1394 1395 dnw = ++dnweight; 1396 1397 /* 1398 * occassionally leave the page alone 1399 */ 1400 1401 if ((dnw & 0x01F0) == 0 || 1402 m->queue == PQ_INACTIVE || 1403 m->queue - m->pc == PQ_CACHE 1404 ) { 1405 if (m->act_count >= ACT_INIT) 1406 --m->act_count; 1407 return; 1408 } 1409 1410 if (m->dirty == 0) 1411 vm_page_test_dirty(m); 1412 1413 if (m->dirty || (dnw & 0x0070) == 0) { 1414 /* 1415 * Deactivate the page 3 times out of 32. 1416 */ 1417 head = 0; 1418 } else { 1419 /* 1420 * Cache the page 28 times out of every 32. Note that 1421 * the page is deactivated instead of cached, but placed 1422 * at the head of the queue instead of the tail. 1423 */ 1424 head = 1; 1425 } 1426 _vm_page_deactivate(m, head); 1427 } 1428 1429 /* 1430 * Grab a page, waiting until we are waken up due to the page 1431 * changing state. We keep on waiting, if the page continues 1432 * to be in the object. If the page doesn't exist, allocate it. 1433 * 1434 * If VM_ALLOC_RETRY is specified VM_ALLOC_NORMAL must also be specified. 1435 * 1436 * This routine may block. 1437 */ 1438 vm_page_t 1439 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1440 { 1441 vm_page_t m; 1442 int s, generation; 1443 1444 KKASSERT(allocflags & 1445 (VM_ALLOC_NORMAL|VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 1446 retrylookup: 1447 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1448 if (m->busy || (m->flags & PG_BUSY)) { 1449 generation = object->generation; 1450 1451 s = splvm(); 1452 while ((object->generation == generation) && 1453 (m->busy || (m->flags & PG_BUSY))) { 1454 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 1455 tsleep(m, 0, "pgrbwt", 0); 1456 if ((allocflags & VM_ALLOC_RETRY) == 0) { 1457 splx(s); 1458 return NULL; 1459 } 1460 } 1461 splx(s); 1462 goto retrylookup; 1463 } else { 1464 vm_page_busy(m); 1465 return m; 1466 } 1467 } 1468 1469 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1470 if (m == NULL) { 1471 VM_WAIT; 1472 if ((allocflags & VM_ALLOC_RETRY) == 0) 1473 return NULL; 1474 goto retrylookup; 1475 } 1476 1477 return m; 1478 } 1479 1480 /* 1481 * Mapping function for valid bits or for dirty bits in 1482 * a page. May not block. 1483 * 1484 * Inputs are required to range within a page. 1485 */ 1486 1487 __inline int 1488 vm_page_bits(int base, int size) 1489 { 1490 int first_bit; 1491 int last_bit; 1492 1493 KASSERT( 1494 base + size <= PAGE_SIZE, 1495 ("vm_page_bits: illegal base/size %d/%d", base, size) 1496 ); 1497 1498 if (size == 0) /* handle degenerate case */ 1499 return(0); 1500 1501 first_bit = base >> DEV_BSHIFT; 1502 last_bit = (base + size - 1) >> DEV_BSHIFT; 1503 1504 return ((2 << last_bit) - (1 << first_bit)); 1505 } 1506 1507 /* 1508 * vm_page_set_validclean: 1509 * 1510 * Sets portions of a page valid and clean. The arguments are expected 1511 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1512 * of any partial chunks touched by the range. The invalid portion of 1513 * such chunks will be zero'd. 1514 * 1515 * This routine may not block. 1516 * 1517 * (base + size) must be less then or equal to PAGE_SIZE. 1518 */ 1519 void 1520 vm_page_set_validclean(vm_page_t m, int base, int size) 1521 { 1522 int pagebits; 1523 int frag; 1524 int endoff; 1525 1526 if (size == 0) /* handle degenerate case */ 1527 return; 1528 1529 /* 1530 * If the base is not DEV_BSIZE aligned and the valid 1531 * bit is clear, we have to zero out a portion of the 1532 * first block. 1533 */ 1534 1535 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1536 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0 1537 ) { 1538 pmap_zero_page_area( 1539 VM_PAGE_TO_PHYS(m), 1540 frag, 1541 base - frag 1542 ); 1543 } 1544 1545 /* 1546 * If the ending offset is not DEV_BSIZE aligned and the 1547 * valid bit is clear, we have to zero out a portion of 1548 * the last block. 1549 */ 1550 1551 endoff = base + size; 1552 1553 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1554 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0 1555 ) { 1556 pmap_zero_page_area( 1557 VM_PAGE_TO_PHYS(m), 1558 endoff, 1559 DEV_BSIZE - (endoff & (DEV_BSIZE - 1)) 1560 ); 1561 } 1562 1563 /* 1564 * Set valid, clear dirty bits. If validating the entire 1565 * page we can safely clear the pmap modify bit. We also 1566 * use this opportunity to clear the PG_NOSYNC flag. If a process 1567 * takes a write fault on a MAP_NOSYNC memory area the flag will 1568 * be set again. 1569 * 1570 * We set valid bits inclusive of any overlap, but we can only 1571 * clear dirty bits for DEV_BSIZE chunks that are fully within 1572 * the range. 1573 */ 1574 1575 pagebits = vm_page_bits(base, size); 1576 m->valid |= pagebits; 1577 #if 0 /* NOT YET */ 1578 if ((frag = base & (DEV_BSIZE - 1)) != 0) { 1579 frag = DEV_BSIZE - frag; 1580 base += frag; 1581 size -= frag; 1582 if (size < 0) 1583 size = 0; 1584 } 1585 pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1)); 1586 #endif 1587 m->dirty &= ~pagebits; 1588 if (base == 0 && size == PAGE_SIZE) { 1589 pmap_clear_modify(m); 1590 vm_page_flag_clear(m, PG_NOSYNC); 1591 } 1592 } 1593 1594 #if 0 1595 1596 void 1597 vm_page_set_dirty(vm_page_t m, int base, int size) 1598 { 1599 m->dirty |= vm_page_bits(base, size); 1600 } 1601 1602 #endif 1603 1604 void 1605 vm_page_clear_dirty(vm_page_t m, int base, int size) 1606 { 1607 m->dirty &= ~vm_page_bits(base, size); 1608 } 1609 1610 /* 1611 * vm_page_set_invalid: 1612 * 1613 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1614 * valid and dirty bits for the effected areas are cleared. 1615 * 1616 * May not block. 1617 */ 1618 void 1619 vm_page_set_invalid(vm_page_t m, int base, int size) 1620 { 1621 int bits; 1622 1623 bits = vm_page_bits(base, size); 1624 m->valid &= ~bits; 1625 m->dirty &= ~bits; 1626 m->object->generation++; 1627 } 1628 1629 /* 1630 * vm_page_zero_invalid() 1631 * 1632 * The kernel assumes that the invalid portions of a page contain 1633 * garbage, but such pages can be mapped into memory by user code. 1634 * When this occurs, we must zero out the non-valid portions of the 1635 * page so user code sees what it expects. 1636 * 1637 * Pages are most often semi-valid when the end of a file is mapped 1638 * into memory and the file's size is not page aligned. 1639 */ 1640 1641 void 1642 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1643 { 1644 int b; 1645 int i; 1646 1647 /* 1648 * Scan the valid bits looking for invalid sections that 1649 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1650 * valid bit may be set ) have already been zerod by 1651 * vm_page_set_validclean(). 1652 */ 1653 1654 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1655 if (i == (PAGE_SIZE / DEV_BSIZE) || 1656 (m->valid & (1 << i)) 1657 ) { 1658 if (i > b) { 1659 pmap_zero_page_area( 1660 VM_PAGE_TO_PHYS(m), 1661 b << DEV_BSHIFT, 1662 (i - b) << DEV_BSHIFT 1663 ); 1664 } 1665 b = i + 1; 1666 } 1667 } 1668 1669 /* 1670 * setvalid is TRUE when we can safely set the zero'd areas 1671 * as being valid. We can do this if there are no cache consistency 1672 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1673 */ 1674 1675 if (setvalid) 1676 m->valid = VM_PAGE_BITS_ALL; 1677 } 1678 1679 /* 1680 * vm_page_is_valid: 1681 * 1682 * Is (partial) page valid? Note that the case where size == 0 1683 * will return FALSE in the degenerate case where the page is 1684 * entirely invalid, and TRUE otherwise. 1685 * 1686 * May not block. 1687 */ 1688 1689 int 1690 vm_page_is_valid(vm_page_t m, int base, int size) 1691 { 1692 int bits = vm_page_bits(base, size); 1693 1694 if (m->valid && ((m->valid & bits) == bits)) 1695 return 1; 1696 else 1697 return 0; 1698 } 1699 1700 /* 1701 * update dirty bits from pmap/mmu. May not block. 1702 */ 1703 1704 void 1705 vm_page_test_dirty(vm_page_t m) 1706 { 1707 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1708 vm_page_dirty(m); 1709 } 1710 } 1711 1712 #include "opt_ddb.h" 1713 #ifdef DDB 1714 #include <sys/kernel.h> 1715 1716 #include <ddb/ddb.h> 1717 1718 DB_SHOW_COMMAND(page, vm_page_print_page_info) 1719 { 1720 db_printf("vmstats.v_free_count: %d\n", vmstats.v_free_count); 1721 db_printf("vmstats.v_cache_count: %d\n", vmstats.v_cache_count); 1722 db_printf("vmstats.v_inactive_count: %d\n", vmstats.v_inactive_count); 1723 db_printf("vmstats.v_active_count: %d\n", vmstats.v_active_count); 1724 db_printf("vmstats.v_wire_count: %d\n", vmstats.v_wire_count); 1725 db_printf("vmstats.v_free_reserved: %d\n", vmstats.v_free_reserved); 1726 db_printf("vmstats.v_free_min: %d\n", vmstats.v_free_min); 1727 db_printf("vmstats.v_free_target: %d\n", vmstats.v_free_target); 1728 db_printf("vmstats.v_cache_min: %d\n", vmstats.v_cache_min); 1729 db_printf("vmstats.v_inactive_target: %d\n", vmstats.v_inactive_target); 1730 } 1731 1732 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1733 { 1734 int i; 1735 db_printf("PQ_FREE:"); 1736 for(i=0;i<PQ_L2_SIZE;i++) { 1737 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1738 } 1739 db_printf("\n"); 1740 1741 db_printf("PQ_CACHE:"); 1742 for(i=0;i<PQ_L2_SIZE;i++) { 1743 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 1744 } 1745 db_printf("\n"); 1746 1747 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 1748 vm_page_queues[PQ_ACTIVE].lcnt, 1749 vm_page_queues[PQ_INACTIVE].lcnt); 1750 } 1751 #endif /* DDB */ 1752