| 1 | /* |
| 2 | * Copyright (c) 1990 University of Utah. |
| 3 | * Copyright (c) 1991 The Regents of the University of California. |
| 4 | * All rights reserved. |
| 5 | * |
| 6 | * This code is derived from software contributed to Berkeley by |
| 7 | * the Systems Programming Group of the University of Utah Computer |
| 8 | * Science Department. |
| 9 | * |
| 10 | * Redistribution and use in source and binary forms, with or without |
| 11 | * modification, are permitted provided that the following conditions |
| 12 | * are met: |
| 13 | * 1. Redistributions of source code must retain the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer. |
| 15 | * 2. Redistributions in binary form must reproduce the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer in the |
| 17 | * documentation and/or other materials provided with the distribution. |
| 18 | * 3. All advertising materials mentioning features or use of this software |
| 19 | * must display the following acknowledgement: |
| 20 | * This product includes software developed by the University of |
| 21 | * California, Berkeley and its contributors. |
| 22 | * 4. Neither the name of the University nor the names of its contributors |
| 23 | * may be used to endorse or promote products derived from this software |
| 24 | * without specific prior written permission. |
| 25 | * |
| 26 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 27 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 28 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 29 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 30 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 31 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 32 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 33 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 34 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 35 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 36 | * SUCH DAMAGE. |
| 37 | * |
| 38 | * @(#)swap_pager.h 7.1 (Berkeley) 12/5/90 |
| 39 | */ |
| 40 | |
| 41 | #ifndef _SWAP_PAGER_ |
| 42 | #define _SWAP_PAGER_ 1 |
| 43 | |
| 44 | /* |
| 45 | * In the swap pager, the backing store for an object is organized as an |
| 46 | * array of some number of "swap blocks". A swap block consists of a bitmask |
| 47 | * and some number of contiguous DEV_BSIZE disk blocks. The minimum size |
| 48 | * of a swap block is: |
| 49 | * |
| 50 | * max(PAGE_SIZE, dmmin*DEV_BSIZE) [ 32k currently ] |
| 51 | * |
| 52 | * bytes (since the pager interface is page oriented), the maximum size is: |
| 53 | * |
| 54 | * min(#bits(swb_mask)*PAGE_SIZE, dmmax*DEV_BSIZE) [ 128k currently ] |
| 55 | * |
| 56 | * where dmmin and dmmax are left over from the old VM interface. The bitmask |
| 57 | * (swb_mask) is used by swap_pager_haspage() to determine if a particular |
| 58 | * page has actually been written; i.e. the pager copy of the page is valid. |
| 59 | * All swap blocks in the backing store of an object will be the same size. |
| 60 | * |
| 61 | * The reason for variable sized swap blocks is to reduce fragmentation of |
| 62 | * swap resources. Whenever possible we allocate smaller swap blocks to |
| 63 | * smaller objects. The swap block size is determined from a table of |
| 64 | * object-size vs. swap-block-size computed at boot time. |
| 65 | */ |
| 66 | typedef int sw_bm_t; /* pager bitmask */ |
| 67 | |
| 68 | struct swblock { |
| 69 | sw_bm_t swb_mask; /* bitmask of valid pages in this block */ |
| 70 | daddr_t swb_block; /* starting disk block for this block */ |
| 71 | }; |
| 72 | typedef struct swblock *sw_blk_t; |
| 73 | |
| 74 | /* |
| 75 | * Swap pager private data. |
| 76 | */ |
| 77 | struct swpager { |
| 78 | vm_size_t sw_osize; /* size of object we are backing (bytes) */ |
| 79 | int sw_bsize; /* size of swap blocks (DEV_BSIZE units) */ |
| 80 | int sw_nblocks;/* number of blocks in list (sw_blk_t units) */ |
| 81 | sw_blk_t sw_blocks; /* pointer to list of swap blocks */ |
| 82 | short sw_flags; /* flags */ |
| 83 | short sw_poip; /* pageouts in progress */ |
| 84 | }; |
| 85 | typedef struct swpager *sw_pager_t; |
| 86 | |
| 87 | #define SW_WANTED 0x01 |
| 88 | #define SW_NAMED 0x02 |
| 89 | |
| 90 | #ifdef KERNEL |
| 91 | |
| 92 | void swap_pager_init(); |
| 93 | vm_pager_t swap_pager_alloc(); |
| 94 | void swap_pager_dealloc(); |
| 95 | boolean_t swap_pager_getpage(), swap_pager_putpage(); |
| 96 | boolean_t swap_pager_haspage(); |
| 97 | |
| 98 | struct pagerops swappagerops = { |
| 99 | swap_pager_init, |
| 100 | swap_pager_alloc, |
| 101 | swap_pager_dealloc, |
| 102 | swap_pager_getpage, |
| 103 | swap_pager_putpage, |
| 104 | swap_pager_haspage |
| 105 | }; |
| 106 | |
| 107 | int swap_pager_iodone(); |
| 108 | boolean_t swap_pager_clean(); |
| 109 | |
| 110 | #endif |
| 111 | |
| 112 | #endif /* _SWAP_PAGER_ */ |