dbbaf04f1e
Idle page zeroing has been disabled by default on all architectures since r170816 and has some bugs that make it seemingly unusable. Specifically, the idle-priority pagezero thread exacerbates contention for the free page lock, and yields the CPU without releasing it in non-preemptive kernels. The pagezero thread also does not behave correctly when superpage reservations are enabled: its target is a function of v_free_count, which includes reserved-but-free pages, but it is only able to zero pages belonging to the physical memory allocator. Reviewed by: alc, imp, kib Differential Revision: https://reviews.freebsd.org/D7714
129 lines
3.6 KiB
Groff
129 lines
3.6 KiB
Groff
.\"
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.\" Copyright (c) 2003 Bruce M Simpson <bms@spc.org>
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.\" All rights reserved.
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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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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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.\" $FreeBSD$
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.\"
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.Dd August 30, 2016
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.Dt PMAP 9
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.Os
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.Sh NAME
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.Nm pmap
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.Nd machine-dependent portion of virtual memory subsystem
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.Sh SYNOPSIS
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.In sys/param.h
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.In vm/vm.h
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.In vm/pmap.h
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.Sh DESCRIPTION
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The
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.Nm
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module is the machine-dependent portion of the
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.Fx
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VM (Virtual Memory) sub-system.
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Each function documented herein must have its own
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architecture-dependent implementation.
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.Pp
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The
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.Nm
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module
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is responsible for managing hardware-dependent objects such as page tables,
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address maps, TLBs, etc.
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.Pp
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Machine-dependent code must provide the header file
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.In machine/pmap.h .
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This file contains the definition of the
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.Vt pmap
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structure:
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.Bd -literal -offset indent
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struct pmap {
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/* Contents defined by pmap implementation. */
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};
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typedef struct pmap *pmap_t;
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.Ed
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.Pp
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This header file may also define other data structures used by the
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.Nm
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implementation.
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.Pp
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The header file
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.In vm/pmap.h
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defines a structure for tracking
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.Nm
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statistics (see below).
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This structure is defined as:
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.Bd -literal -offset indent
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struct pmap_statistics {
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long resident_count; /* number of mapped pages */
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long wired_count; /* number of wired pages */
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};
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.Ed
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.Pp
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The implementation's
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.Vt "struct pmap"
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must contain an instance of this structure having the name
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.Va pm_stats ,
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and it must be updated by the implementation after each relevant
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.Nm
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operation.
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.Sh SEE ALSO
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.Xr pmap_activate 9 ,
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.Xr pmap_clear_modify 9 ,
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.Xr pmap_copy 9 ,
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.Xr pmap_copy_page 9 ,
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.Xr pmap_enter 9 ,
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.Xr pmap_extract 9 ,
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.Xr pmap_extract_and_hold 9 ,
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.Xr pmap_growkernel 9 ,
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.Xr pmap_init 9 ,
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.Xr pmap_init2 9 ,
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.Xr pmap_is_modified 9 ,
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.Xr pmap_is_prefaultable 9 ,
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.Xr pmap_map 9 ,
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.Xr pmap_mincore 9 ,
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.Xr pmap_object_init_pt 9 ,
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.Xr pmap_page_exists_quick 9 ,
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.Xr pmap_page_init 9 ,
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.Xr pmap_pinit 9 ,
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.Xr pmap_pinit0 9 ,
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.Xr pmap_pinit2 9 ,
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.Xr pmap_protect 9 ,
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.Xr pmap_qenter 9 ,
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.Xr pmap_qremove 9 ,
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.Xr pmap_quick_enter_page 9 ,
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.Xr pmap_quick_remove_page 9 ,
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.Xr pmap_release 9 ,
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.Xr pmap_remove 9 ,
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.Xr pmap_remove_all 9 ,
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.Xr pmap_remove_pages 9 ,
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.Xr pmap_resident_count 9 ,
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.Xr pmap_ts_referenced 9 ,
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.Xr pmap_unwire 9 ,
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.Xr pmap_wired_count 9 ,
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.Xr pmap_zero_area 9 ,
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.Xr pmap_zero_page 9 ,
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.Xr vm_map 9
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.Sh AUTHORS
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This manual page was written by
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.An Bruce M Simpson Aq Mt bms@spc.org .
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