swap_pager.h revision 1541
1135446Strhodes/* 2262706Serwin * Copyright (c) 1990 University of Utah. 3135446Strhodes * Copyright (c) 1991, 1993 4135446Strhodes * The Regents of the University of California. All rights reserved. 5174187Sdougb * 6135446Strhodes * This code is derived from software contributed to Berkeley by 7135446Strhodes * the Systems Programming Group of the University of Utah Computer 8135446Strhodes * Science Department. 9135446Strhodes * 10135446Strhodes * Redistribution and use in source and binary forms, with or without 11135446Strhodes * modification, are permitted provided that the following conditions 12135446Strhodes * are met: 13135446Strhodes * 1. Redistributions of source code must retain the above copyright 14135446Strhodes * notice, this list of conditions and the following disclaimer. 15135446Strhodes * 2. Redistributions in binary form must reproduce the above copyright 16135446Strhodes * notice, this list of conditions and the following disclaimer in the 17135446Strhodes * documentation and/or other materials provided with the distribution. 18254897Serwin * 3. All advertising materials mentioning features or use of this software 19135446Strhodes * must display the following acknowledgement: 20186462Sdougb * This product includes software developed by the University of 21135446Strhodes * California, Berkeley and its contributors. 22170222Sdougb * 4. Neither the name of the University nor the names of its contributors 23135446Strhodes * may be used to endorse or promote products derived from this software 24135446Strhodes * without specific prior written permission. 25135446Strhodes * 26135446Strhodes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27135446Strhodes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28135446Strhodes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29135446Strhodes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30135446Strhodes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31135446Strhodes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32135446Strhodes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33135446Strhodes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34135446Strhodes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35135446Strhodes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36193149Sdougb * SUCH DAMAGE. 37193149Sdougb * 38135446Strhodes * @(#)swap_pager.h 8.1 (Berkeley) 6/11/93 39135446Strhodes */ 40135446Strhodes 41135446Strhodes#ifndef _SWAP_PAGER_ 42135446Strhodes#define _SWAP_PAGER_ 1 43135446Strhodes 44135446Strhodes/* 45135446Strhodes * In the swap pager, the backing store for an object is organized as an 46135446Strhodes * array of some number of "swap blocks". A swap block consists of a bitmask 47135446Strhodes * and some number of contiguous DEV_BSIZE disk blocks. The minimum size 48170222Sdougb * of a swap block is: 49135446Strhodes * 50135446Strhodes * max(PAGE_SIZE, dmmin*DEV_BSIZE) [ 32k currently ] 51193149Sdougb * 52135446Strhodes * bytes (since the pager interface is page oriented), the maximum size is: 53193149Sdougb * 54193149Sdougb * min(#bits(swb_mask)*PAGE_SIZE, dmmax*DEV_BSIZE) [ 128k currently ] 55193149Sdougb * 56193149Sdougb * where dmmin and dmmax are left over from the old VM interface. The bitmask 57193149Sdougb * (swb_mask) is used by swap_pager_haspage() to determine if a particular 58135446Strhodes * page has actually been written; i.e. the pager copy of the page is valid. 59193149Sdougb * All swap blocks in the backing store of an object will be the same size. 60170222Sdougb * 61193149Sdougb * The reason for variable sized swap blocks is to reduce fragmentation of 62193149Sdougb * swap resources. Whenever possible we allocate smaller swap blocks to 63193149Sdougb * smaller objects. The swap block size is determined from a table of 64193149Sdougb * object-size vs. swap-block-size computed at boot time. 65193149Sdougb */ 66193149Sdougbtypedef int sw_bm_t; /* pager bitmask */ 67135446Strhodes 68186462Sdougbstruct swblock { 69135446Strhodes sw_bm_t swb_mask; /* bitmask of valid pages in this block */ 70135446Strhodes daddr_t swb_block; /* starting disk block for this block */ 71135446Strhodes}; 72135446Strhodestypedef struct swblock *sw_blk_t; 73135446Strhodes 74193149Sdougb/* 75193149Sdougb * Swap pager private data. 76193149Sdougb */ 77135446Strhodesstruct swpager { 78170222Sdougb vm_size_t sw_osize; /* size of object we are backing (bytes) */ 79193149Sdougb int sw_bsize; /* size of swap blocks (DEV_BSIZE units) */ 80193149Sdougb int sw_nblocks;/* number of blocks in list (sw_blk_t units) */ 81193149Sdougb sw_blk_t sw_blocks; /* pointer to list of swap blocks */ 82135446Strhodes short sw_flags; /* flags */ 83193149Sdougb short sw_poip; /* pageouts in progress */ 84193149Sdougb}; 85193149Sdougbtypedef struct swpager *sw_pager_t; 86135446Strhodes 87193149Sdougb#define SW_WANTED 0x01 88193149Sdougb#define SW_NAMED 0x02 89135446Strhodes 90193149Sdougb#endif /* _SWAP_PAGER_ */ 91135446Strhodes