92 lines
3.9 KiB
C
92 lines
3.9 KiB
C
/*
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* Copyright (c) 1990 University of Utah.
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* the Systems Programming Group of the University of Utah Computer
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* Science Department.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)swap_pager.h 8.1 (Berkeley) 6/11/93
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* $Id: swap_pager.h,v 1.4 1993/12/20 12:40:01 cgd Exp $
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*/
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#ifndef _SWAP_PAGER_
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#define _SWAP_PAGER_ 1
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/*
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* In the swap pager, the backing store for an object is organized as an
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* array of some number of "swap blocks". A swap block consists of a bitmask
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* and some number of contiguous DEV_BSIZE disk blocks. The minimum size
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* of a swap block is:
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*
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* max(PAGE_SIZE, dmmin*DEV_BSIZE) [ 32k currently ]
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*
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* bytes (since the pager interface is page oriented), the maximum size is:
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*
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* min(#bits(swb_mask)*PAGE_SIZE, dmmax*DEV_BSIZE) [ 128k currently ]
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*
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* where dmmin and dmmax are left over from the old VM interface. The bitmask
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* (swb_mask) is used by swap_pager_haspage() to determine if a particular
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* page has actually been written; i.e. the pager copy of the page is valid.
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* All swap blocks in the backing store of an object will be the same size.
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*
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* The reason for variable sized swap blocks is to reduce fragmentation of
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* swap resources. Whenever possible we allocate smaller swap blocks to
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* smaller objects. The swap block size is determined from a table of
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* object-size vs. swap-block-size computed at boot time.
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*/
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typedef int sw_bm_t; /* pager bitmask */
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struct swblock {
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sw_bm_t swb_mask; /* bitmask of valid pages in this block */
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daddr_t swb_block; /* starting disk block for this block */
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};
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typedef struct swblock *sw_blk_t;
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/*
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* Swap pager private data.
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*/
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struct swpager {
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vm_size_t sw_osize; /* size of object we are backing (bytes) */
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int sw_bsize; /* size of swap blocks (DEV_BSIZE units) */
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int sw_nblocks;/* number of blocks in list (sw_blk_t units) */
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sw_blk_t sw_blocks; /* pointer to list of swap blocks */
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short sw_flags; /* flags */
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short sw_poip; /* pageouts in progress */
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};
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typedef struct swpager *sw_pager_t;
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#define SW_WANTED 0x01
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#define SW_NAMED 0x02
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#endif /* _SWAP_PAGER_ */
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