sys/vm/swap_pager.h

   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  *      from: @(#)swap_pager.h  7.1 (Berkeley) 12/5/90
  39  * $FreeBSD: src/sys/vm/swap_pager.h,v 1.28.2.1 2000/10/13 07:13:23 dillon Exp $
  40  * $DragonFly: src/sys/vm/swap_pager.h,v 1.3 2003/08/20 08:03:01 rob Exp $
  41  */
  42
  43 /*
  44  * Modifications to the block allocation data structure by John S. Dyson
  45  * 18 Dec 93.
  46  */
  47
  48 #ifndef _SWAP_PAGER_
  49 #define _SWAP_PAGER_    1
  50
  51 /*
  52  * SWB_NPAGES must be a power of 2.  It may be set to 1, 2, 4, 8, or 16
  53  * pages per allocation.  We recommend you stick with the default of 8.
  54  * The 16-page limit is due to the radix code (kern/subr_blist.c).
  55  */
  56 #if !defined(SWB_NPAGES)
  57 #define SWB_NPAGES 8
  58 #endif
  59
  60 /*
  61  * Piecemeal swap metadata structure.  Swap is stored in a radix tree.
  62  *
  63  * If SWB_NPAGES is 8 and sizeof(char *) == sizeof(daddr_t), our radix
  64  * is basically 8.  Assuming PAGE_SIZE == 4096, one tree level represents
  65  * 32K worth of data, two levels represent 256K, three levels represent
  66  * 2 MBytes.   This is acceptable.
  67  *
  68  * Overall memory utilization is about the same as the old swap structure.
  69  */
  70
  71 #define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t))
  72
  73 #define SWAP_META_PAGES         (SWB_NPAGES * 2)
  74 #define SWAP_META_MASK          (SWAP_META_PAGES - 1)
  75
  76 struct swblock {
  77         struct swblock  *swb_hnext;
  78         vm_object_t     swb_object;
  79         vm_pindex_t     swb_index;
  80         int             swb_count;
  81         daddr_t         swb_pages[SWAP_META_PAGES];
  82 };
  83
  84 #ifdef _KERNEL
  85 extern struct pagerlst swap_pager_un_object_list;
  86 extern int swap_pager_full;
  87 extern struct blist *swapblist;
  88
  89 void swap_pager_putpages (vm_object_t, vm_page_t *, int, boolean_t, int *);
  90 boolean_t swap_pager_haspage (vm_object_t object, vm_pindex_t pindex, int *before, int *after);
  91
  92 int swap_pager_swp_alloc (vm_object_t, int);
  93 void swap_pager_copy (vm_object_t, vm_object_t, vm_pindex_t, int);
  94 void swap_pager_freespace (vm_object_t, vm_pindex_t, vm_size_t);
  95 void swap_pager_dmzspace (vm_object_t, vm_pindex_t, vm_size_t);
  96 void swap_pager_swap_init (void);
  97 int swap_pager_reserve (vm_object_t, vm_pindex_t, vm_size_t);
  98
  99 /*
 100  * newswap functions
 101  */
 102
 103 void swap_pager_page_removed (vm_page_t, vm_object_t);
 104
 105 /* choose underlying swap device and queue up I/O */
 106 struct buf;
 107 void swstrategy (struct buf *bp);       /* probably needs to move elsewhere */
 108
 109 #endif
 110
 111 #endif                          /* _SWAP_PAGER_ */