freebsd-dev/sys/vm/swap_pager.h

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/*
* Copyright (c) 1990 University of Utah.
* Copyright (c) 1991 The Regents of the University of California.
* All rights reserved.
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*
* 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
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* $FreeBSD$
*/
/*
* Modifications to the block allocation data structure by John S. Dyson
* 18 Dec 93.
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*/
#ifndef _VM_SWAP_PAGER_H_
#define _VM_SWAP_PAGER_H_ 1
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/*
* Swap device table
*/
struct swdevt {
udev_t sw_dev; /* For quasibogus swapdev reporting */
int sw_flags;
int sw_nblks;
int sw_used;
struct vnode *sw_vp;
dev_t sw_device;
};
#define SW_FREED 0x01
#define SW_SEQUENTIAL 0x02
#define SW_CLOSING 0x04
#define sw_freed sw_flags /* XXX compat */
#ifdef _KERNEL
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/*
* 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).
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*/
#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)
These changes embody the support of the fully coherent merged VM buffer cache, much higher filesystem I/O performance, and much better paging performance. It represents the culmination of over 6 months of R&D. The majority of the merged VM/cache work is by John Dyson. The following highlights the most significant changes. Additionally, there are (mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to support the new VM/buffer scheme. vfs_bio.c: Significant rewrite of most of vfs_bio to support the merged VM buffer cache scheme. The scheme is almost fully compatible with the old filesystem interface. Significant improvement in the number of opportunities for write clustering. vfs_cluster.c, vfs_subr.c Upgrade and performance enhancements in vfs layer code to support merged VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff. vm_object.c: Yet more improvements in the collapse code. Elimination of some windows that can cause list corruption. vm_pageout.c: Fixed it, it really works better now. Somehow in 2.0, some "enhancements" broke the code. This code has been reworked from the ground-up. vm_fault.c, vm_page.c, pmap.c, vm_object.c Support for small-block filesystems with merged VM/buffer cache scheme. pmap.c vm_map.c Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of kernel PTs. vm_glue.c Much simpler and more effective swapping code. No more gratuitous swapping. proc.h Fixed the problem that the p_lock flag was not being cleared on a fork. swap_pager.c, vnode_pager.c Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the code doesn't need it anymore. machdep.c Changes to better support the parameter values for the merged VM/buffer cache scheme. machdep.c, kern_exec.c, vm_glue.c Implemented a seperate submap for temporary exec string space and another one to contain process upages. This eliminates all map fragmentation problems that previously existed. ffs_inode.c, ufs_inode.c, ufs_readwrite.c Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on busy buffers. Submitted by: John Dyson and David Greenman
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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];
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};
extern struct pagerlst swap_pager_un_object_list;
extern int swap_pager_full;
extern struct blist *swapblist;
extern struct uma_zone *swap_zone;
extern int nswap_lowat, nswap_hiwat;
extern int dmmax, dmmax_mask;
extern struct vnode *swapdev_vp;
extern struct swdevt *swdevt;
extern int nswdev;
/*
* vm_swap_size is in page-sized chunks now. It was DEV_BSIZE'd chunks
* in the old system.
*/
extern int vm_swap_size; /* number of free swap blocks, in pages */
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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);
void swap_pager_swapoff(int devidx, int *sw_used);
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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
*/
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void swap_pager_page_removed(vm_page_t, vm_object_t);
/* choose underlying swap device and queue up I/O */
struct buf;
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void swstrategy(struct buf *bp); /* probably needs to move elsewhere */
#endif /* _KERNEL */
#endif /* _VM_SWAP_PAGER_H_ */