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striping to a per device round-robin algorithm. Because of the policy of not attempting to retain previous swap allocation on page-out, this means that a newly added swap device almost instantly takes its 1/N share of the I/O load but it takes somewhat longer for it to assume it's 1/N share of the pages if there is plenty of space on the other devices. Change the 8G total swapspace limitation to 8G per device instead by using a per device blist rather than one global blist. This reduces the memory footprint by 75% (typically a couple hundred kilobytes) for the common case with one swapdevice but NSWAPDEV=4. Remove the compile time constant limit of number of swap devices, there is no limit now. Instead of a fixed size array, store the per swapdev structure in a TAILQ. Total swap space is still addressed by a 32 bit page number and therefore the upper limit is now 2^42 bytes = 16TB (for i386). We still do not allocate the first page of each device in order to give some amount of protection to any bsdlabel at the start of the device. A new device is appended after the existing devices in the swap space, no attempt is made to fill in holes left behind by swapoff (this can trivially be changed should it ever become a problem). The sysctl vm.nswapdev now reflects the number of currently configured swap devices. Rename vm_swap_size to swap_pager_avail for consistency with other exported names. Change argument type for vm_proc_swapin_all() and swap_pager_isswapped() to be a struct swdevt pointer rather than an index. Not changed: we are still using blists to manage the free space, but since the swapspace is no longer fragmented by the striping different resource managers might fare better.
114 lines
3.9 KiB
C
114 lines
3.9 KiB
C
/*
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. 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 Mach Operating System project at Carnegie-Mellon University.
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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: @(#)vm_pageout.h 8.2 (Berkeley) 1/12/94
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*
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*
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* Copyright (c) 1987, 1990 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Author: Avadis Tevanian, Jr.
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*
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* $FreeBSD$
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*/
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#ifndef _VM_VM_PAGEOUT_H_
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#define _VM_VM_PAGEOUT_H_
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/*
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* Header file for pageout daemon.
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*/
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/*
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* Exported data structures.
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*/
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extern int vm_page_max_wired;
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extern int vm_pages_needed; /* should be some "event" structure */
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extern int vm_pageout_pages_needed;
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extern int vm_pageout_deficit;
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extern int vm_pageout_page_count;
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/*
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* Swap out requests
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*/
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#define VM_SWAP_NORMAL 1
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#define VM_SWAP_IDLE 2
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/*
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* Exported routines.
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*/
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/*
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* Signal pageout-daemon and wait for it.
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*/
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extern void pagedaemon_wakeup(void);
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#define VM_WAIT vm_wait()
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#define VM_WAITPFAULT vm_waitpfault()
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extern void vm_wait(void);
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extern void vm_waitpfault(void);
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/* XXX This is probably misplaced. */
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#ifndef NO_SWAPPING
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struct swdevt;
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void vm_proc_swapin_all(struct swdevt *);
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#endif /* !NO_SWAPPING */
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#ifdef _KERNEL
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int vm_pageout_flush(vm_page_t *, int, int, int is_object_locked);
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#endif
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#endif /* _VM_VM_PAGEOUT_H_ */
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