7f3a40933b
In order to determine what to page out, the vm_daemon checks reference bits on all pages belonging to all processes. Unfortunately, the algorithm used reacted badly with shared pages; each shared page would be checked once per process sharing it; this caused an O(N^2) growth of tlb invalidations. The algorithm has been changed so that each page will be checked only 16 times. Prior to this change, a fork/sleepbomb of 1300 processes could cause the vm_daemon to take over 60 seconds to complete, effectively freezing the system for that time period. With this change in place, the vm_daemon completes in less than a second. Any system with hundreds of processes sharing pages should benefit from this change. Note that the vm_daemon is only run when the system is under extreme memory pressure. It is likely that many people with loaded systems saw no symptoms of this problem until they reached the point where swapping began. Special thanks go to dillon, peter, and Chuck Cranor, who helped me get up to speed with vm internals. PR: 33542, 20393 Reviewed by: dillon MFC after: 1 week
154 lines
6.3 KiB
C
154 lines
6.3 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: @(#)pmap.h 8.1 (Berkeley) 6/11/93
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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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/*
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* Machine address mapping definitions -- machine-independent
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* section. [For machine-dependent section, see "machine/pmap.h".]
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*/
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#ifndef _PMAP_VM_
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#define _PMAP_VM_
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/*
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* Each machine dependent implementation is expected to
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* keep certain statistics. They may do this anyway they
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* so choose, but are expected to return the statistics
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* in the following structure.
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*/
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struct pmap_statistics {
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long resident_count; /* # of pages mapped (total) */
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long wired_count; /* # of pages wired */
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};
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typedef struct pmap_statistics *pmap_statistics_t;
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#include <machine/pmap.h>
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#ifdef _KERNEL
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struct proc;
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struct thread;
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#ifdef __alpha__
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void pmap_page_is_free __P((vm_page_t m));
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#endif
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void pmap_change_wiring __P((pmap_t, vm_offset_t, boolean_t));
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void pmap_clear_modify __P((vm_page_t m));
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void pmap_clear_reference __P((vm_page_t m));
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void pmap_collect __P((void));
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void pmap_copy __P((pmap_t, pmap_t, vm_offset_t, vm_size_t,
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vm_offset_t));
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void pmap_copy_page __P((vm_offset_t, vm_offset_t));
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void pmap_destroy __P((pmap_t));
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void pmap_enter __P((pmap_t, vm_offset_t, vm_page_t, vm_prot_t,
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boolean_t));
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vm_offset_t pmap_extract __P((pmap_t pmap, vm_offset_t va));
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void pmap_growkernel __P((vm_offset_t));
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void pmap_init __P((vm_offset_t, vm_offset_t));
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boolean_t pmap_is_modified __P((vm_page_t m));
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boolean_t pmap_ts_referenced __P((vm_page_t m));
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void pmap_kenter __P((vm_offset_t va, vm_offset_t pa));
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void pmap_kremove __P((vm_offset_t));
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vm_offset_t pmap_map __P((vm_offset_t *, vm_offset_t, vm_offset_t, int));
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void pmap_object_init_pt __P((pmap_t pmap, vm_offset_t addr,
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vm_object_t object, vm_pindex_t pindex, vm_offset_t size,
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int pagelimit));
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boolean_t pmap_page_exists_quick __P((pmap_t pmap, vm_page_t m));
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void pmap_page_protect __P((vm_page_t m, vm_prot_t prot));
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void pmap_pageable __P((pmap_t, vm_offset_t, vm_offset_t,
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boolean_t));
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vm_offset_t pmap_phys_address __P((int));
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void pmap_pinit __P((pmap_t));
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void pmap_pinit0 __P((pmap_t));
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void pmap_pinit2 __P((pmap_t));
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void pmap_protect __P((pmap_t, vm_offset_t, vm_offset_t,
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vm_prot_t));
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void pmap_qenter __P((vm_offset_t, vm_page_t *, int));
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void pmap_qremove __P((vm_offset_t, int));
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void pmap_reference __P((pmap_t));
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void pmap_release __P((pmap_t));
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void pmap_remove __P((pmap_t, vm_offset_t, vm_offset_t));
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void pmap_remove_pages __P((pmap_t, vm_offset_t, vm_offset_t));
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void pmap_zero_page __P((vm_offset_t));
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void pmap_zero_page_area __P((vm_offset_t, int off, int size));
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void pmap_prefault __P((pmap_t, vm_offset_t, vm_map_entry_t));
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int pmap_mincore __P((pmap_t pmap, vm_offset_t addr));
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void pmap_new_proc __P((struct proc *p));
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void pmap_dispose_proc __P((struct proc *p));
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void pmap_swapout_proc __P((struct proc *p));
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void pmap_swapin_proc __P((struct proc *p));
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void pmap_new_thread __P((struct thread *td));
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void pmap_dispose_thread __P((struct thread *td));
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void pmap_swapout_thread __P((struct thread *td));
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void pmap_swapin_thread __P((struct thread *td));
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void pmap_activate __P((struct thread *td));
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vm_offset_t pmap_addr_hint __P((vm_object_t obj, vm_offset_t addr, vm_size_t size));
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void *pmap_kenter_temporary __P((vm_offset_t pa, int i));
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void pmap_init2 __P((void));
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#endif /* _KERNEL */
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#endif /* _PMAP_VM_ */
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