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Diffstat (limited to 'sys/vm/swap_pager.h')
| -rw-r--r-- | sys/vm/swap_pager.h | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/sys/vm/swap_pager.h b/sys/vm/swap_pager.h new file mode 100644 index 00000000000..07b25ecbe8b --- /dev/null +++ b/sys/vm/swap_pager.h @@ -0,0 +1,92 @@ +/* $NetBSD: swap_pager.h,v 1.6 1994/06/29 06:47:49 cgd Exp $ */ + +/* + * Copyright (c) 1990 University of Utah. + * Copyright (c) 1991, 1993 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * the Systems Programming Group of the University of Utah Computer + * Science Department. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * @(#)swap_pager.h 8.1 (Berkeley) 6/11/93 + */ + +#ifndef _SWAP_PAGER_ +#define _SWAP_PAGER_ 1 + +/* + * In the swap pager, the backing store for an object is organized as an + * array of some number of "swap blocks". A swap block consists of a bitmask + * and some number of contiguous DEV_BSIZE disk blocks. The minimum size + * of a swap block is: + * + * max(PAGE_SIZE, dmmin*DEV_BSIZE) [ 32k currently ] + * + * bytes (since the pager interface is page oriented), the maximum size is: + * + * min(#bits(swb_mask)*PAGE_SIZE, dmmax*DEV_BSIZE) [ 128k currently ] + * + * where dmmin and dmmax are left over from the old VM interface. The bitmask + * (swb_mask) is used by swap_pager_haspage() to determine if a particular + * page has actually been written; i.e. the pager copy of the page is valid. + * All swap blocks in the backing store of an object will be the same size. + * + * The reason for variable sized swap blocks is to reduce fragmentation of + * swap resources. Whenever possible we allocate smaller swap blocks to + * smaller objects. The swap block size is determined from a table of + * object-size vs. swap-block-size computed at boot time. + */ +typedef int sw_bm_t; /* pager bitmask */ + +struct swblock { + sw_bm_t swb_mask; /* bitmask of valid pages in this block */ + daddr_t swb_block; /* starting disk block for this block */ +}; +typedef struct swblock *sw_blk_t; + +/* + * Swap pager private data. + */ +struct swpager { + vm_size_t sw_osize; /* size of object we are backing (bytes) */ + int sw_bsize; /* size of swap blocks (DEV_BSIZE units) */ + int sw_nblocks;/* number of blocks in list (sw_blk_t units) */ + sw_blk_t sw_blocks; /* pointer to list of swap blocks */ + short sw_flags; /* flags */ + short sw_poip; /* pageouts in progress */ +}; +typedef struct swpager *sw_pager_t; + +#define SW_WANTED 0x01 +#define SW_NAMED 0x02 + +#endif /* _SWAP_PAGER_ */ |