FreeBSD/Linux Kernel Cross Reference
sys/vm/swap_pager.h

     /*
      * Copyright (c) 1990 University of Utah.
      * Copyright (c) 1991 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.
     *
     *      from: @(#)swap_pager.h  7.1 (Berkeley) 12/5/90
     * $FreeBSD: releng/5.0/sys/vm/swap_pager.h 102966 2002-09-05 14:04:34Z bde $
     */
    
    /*
     * Modifications to the block allocation data structure by John S. Dyson
     * 18 Dec 93.
     */
    
    #ifndef _SWAP_PAGER_
    #define _SWAP_PAGER_    1
    
    /*
     * SWB_NPAGES must be a power of 2.  It may be set to 1, 2, 4, 8, or 16
     * pages per allocation.  We recommend you stick with the default of 8.
     * The 16-page limit is due to the radix code (kern/subr_blist.c).
     */
    #if !defined(SWB_NPAGES)
    #define SWB_NPAGES 8
    #endif
    
    /*
     * Piecemeal swap metadata structure.  Swap is stored in a radix tree.
     *
     * If SWB_NPAGES is 8 and sizeof(char *) == sizeof(daddr_t), our radix
     * is basically 8.  Assuming PAGE_SIZE == 4096, one tree level represents
     * 32K worth of data, two levels represent 256K, three levels represent
     * 2 MBytes.   This is acceptable.
     *
     * Overall memory utilization is about the same as the old swap structure.
     */
    #define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t))
    #define SWAP_META_PAGES         (SWB_NPAGES * 2)
    #define SWAP_META_MASK          (SWAP_META_PAGES - 1)
    
    struct swblock {
            struct swblock  *swb_hnext;
            vm_object_t     swb_object;
            vm_pindex_t     swb_index;
            int             swb_count;
            daddr_t         swb_pages[SWAP_META_PAGES];
    };
    
    #ifdef _KERNEL
    extern struct pagerlst swap_pager_un_object_list;
    extern int swap_pager_full;
    extern struct blist *swapblist;
    extern struct uma_zone *swap_zone;
    
    void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *);
    boolean_t swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after);
    
    int swap_pager_swp_alloc(vm_object_t, int);
    void swap_pager_copy(vm_object_t, vm_object_t, vm_pindex_t, int);
    void swap_pager_freespace(vm_object_t, vm_pindex_t, vm_size_t);
    void swap_pager_dmzspace(vm_object_t, vm_pindex_t, vm_size_t);
    void swap_pager_swap_init(void);
    int swap_pager_reserve(vm_object_t, vm_pindex_t, vm_size_t);
    
    /*
     * newswap functions
     */
   
   void swap_pager_page_removed(vm_page_t, vm_object_t);
   
   /* choose underlying swap device and queue up I/O */
   struct buf;
   void swstrategy(struct buf *bp);        /* probably needs to move elsewhere */
   
   #endif                          /* _KERNEL */
   #endif                          /* _SWAP_PAGER_ */

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