77d6fd97ef
As noted in the removed comment, it is possible and not prohibitively costly to look up the swap blocks for the given page index. Implement a swap_pager_find_least() function to do that, and use it to iterate simultaneously over both backing object page queue and swap allocations when looking for shadowed pages. Testing shows that number of new succesful scans, enabled by this addition, is small but non-zero. When worked out, the change both further reduces the depth of the shadow object chain, and frees unused but allocated swap and memory. Suggested and reviewed by: alc Tested by: pho (previous version) Sponsored by: The FreeBSD Foundation MFC after: 2 weeks
92 lines
3.2 KiB
C
92 lines
3.2 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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* 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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#ifndef _VM_SWAP_PAGER_H_
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#define _VM_SWAP_PAGER_H_ 1
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typedef int32_t swblk_t; /*
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* swap offset. This is the type used to
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* address the "virtual swap device" and
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* therefore the maximum swap space is
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* 2^32 pages.
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*/
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struct buf;
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struct swdevt;
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typedef void sw_strategy_t(struct buf *, struct swdevt *);
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typedef void sw_close_t(struct thread *, struct swdevt *);
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/*
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* Swap device table
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*/
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struct swdevt {
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int sw_flags;
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int sw_nblks;
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int sw_used;
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dev_t sw_dev;
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struct vnode *sw_vp;
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void *sw_id;
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swblk_t sw_first;
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swblk_t sw_end;
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struct blist *sw_blist;
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TAILQ_ENTRY(swdevt) sw_list;
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sw_strategy_t *sw_strategy;
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sw_close_t *sw_close;
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};
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#define SW_UNMAPPED 0x01
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#define SW_CLOSING 0x04
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#ifdef _KERNEL
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extern int swap_pager_full;
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extern int swap_pager_avail;
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struct xswdev;
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int swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len);
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void swap_pager_copy(vm_object_t, vm_object_t, vm_pindex_t, int);
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vm_pindex_t swap_pager_find_least(vm_object_t object, vm_pindex_t pindex);
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void swap_pager_freespace(vm_object_t, vm_pindex_t, vm_size_t);
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void swap_pager_swap_init(void);
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int swap_pager_isswapped(vm_object_t, struct swdevt *);
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int swap_pager_reserve(vm_object_t, vm_pindex_t, vm_size_t);
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void swap_pager_status(int *total, int *used);
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void swapoff_all(void);
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#endif /* _KERNEL */
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#endif /* _VM_SWAP_PAGER_H_ */
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