7a0052d268
Swap space can be freed from an interrupt and so swap reservation and
freeing must occur at splvm.
Add swap_pager_reserve() code to support a new swap pre-reservation
capability for the VN device.
Generally cleanup the swap code by simplifying the swp_pager_meta_build()
static function and consolidating the SWAPBLK_NONE test from a bit test
to an absolute compare. The bit test was left over from a rejected
swap allocation scheme that was not ultimately committed. A few other
minor cleanups were also made.
Reorganize the swap strategy code, again for VN support, to not
reallocate swap when writing as this messes up pre-reservation and
can fragment I/O unnecessarily as VN-baesd disk is messed around with.
Reviewed by: Alan Cox <alc@cs.rice.edu>, David Greenman <dg@root.com>
110 lines
4.1 KiB
C
110 lines
4.1 KiB
C
/*
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* Copyright (c) 1990 University of Utah.
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* Copyright (c) 1991 The Regents of the University of California.
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* 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 7.1 (Berkeley) 12/5/90
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* $FreeBSD$
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*/
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/*
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* Modifications to the block allocation data structure by John S. Dyson
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* 18 Dec 93.
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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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* SWB_NPAGES can be set to any value from 1 to 16 pages per allocation,
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* however, due to the allocation spilling into non-swap pager backed memory,
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* suggest keeping SWB_NPAGES small (1-4). If high performance is mandatory
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* perhaps up to 8 pages might be in order????
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* Above problem has been fixed, now we support 16 pages per block. Unused
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* space is recovered by the swap pager now...
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*/
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#if !defined(SWB_NPAGES)
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#define SWB_NPAGES 8
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#endif
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/*
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* Piecemeal swap metadata structure. Swap is stored in a radix tree.
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*
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* If SWB_NPAGES is 8 and sizeof(char *) == sizeof(daddr_t), our radix
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* is basically 8. Assuming PAGE_SIZE == 4096, one tree level represents
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* 32K worth of data, two levels represent 256K, three levels represent
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* 2 MBytes. This is acceptable.
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*
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* Overall memory utilization is about the same as the old swap structure.
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*/
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#define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t))
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#define SWAP_META_PAGES (SWB_NPAGES * 2)
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#define SWAP_META_MASK (SWAP_META_PAGES - 1)
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struct swblock {
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struct swblock *swb_hnext;
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vm_object_t swb_object;
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vm_pindex_t swb_index;
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int swb_count;
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daddr_t swb_pages[SWAP_META_PAGES];
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};
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#ifdef KERNEL
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extern struct pagerlst swap_pager_un_object_list;
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extern int swap_pager_full;
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extern struct blist *swapblist;
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void swap_pager_putpages __P((vm_object_t, vm_page_t *, int, boolean_t, int *));
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boolean_t swap_pager_haspage __P((vm_object_t object, vm_pindex_t pindex, int *before, int *after));
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int swap_pager_swp_alloc __P((vm_object_t, int));
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void swap_pager_copy __P((vm_object_t, vm_object_t, vm_pindex_t, int));
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void swap_pager_freespace __P((vm_object_t, vm_pindex_t, vm_size_t));
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void swap_pager_dmzspace __P((vm_object_t, vm_pindex_t, vm_size_t));
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void swap_pager_swap_init __P((void));
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int swap_pager_reserve __P((vm_object_t, vm_pindex_t, vm_size_t));
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/*
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* newswap functions
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*/
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void swap_pager_page_removed __P((vm_page_t, vm_object_t));
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#endif
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#endif /* _SWAP_PAGER_ */
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