168 lines
4.6 KiB
Groff
168 lines
4.6 KiB
Groff
.\"
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.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. 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(s), this list of conditions and the following disclaimer as
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.\" the first lines of this file unmodified other than the possible
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.\" addition of one or more copyright notices.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice(s), 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 COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
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.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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.\" 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 SUCH
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.\" DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 1, 2001
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.Dt VM_PAGE_BITS 9
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.Os
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.Sh NAME
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.Nm vm_page_bits ,
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.Nm vm_page_set_validclean ,
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.Nm vm_page_clear_dirty ,
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.Nm vm_page_set_invalid ,
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.Nm vm_page_zero_invalid ,
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.Nm vm_page_is_valid ,
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.Nm vm_page_test_dirty ,
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.Nm vm_page_dirty ,
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.Nm vm_page_undirty
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.Nd "manage page clean and dirty bits"
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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/vm_page.h
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.Ft int
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.Fn vm_page_bits "int base" "int size"
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.Ft void
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.Fn vm_page_set_validclean "vm_page_t m" "int base" "int size"
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.Ft void
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.Fn vm_page_clear_dirty "vm_page_t m" "int base" "int size"
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.Ft void
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.Fn vm_page_set_invalid "vm_page_t m" "int base" "int size"
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.Ft void
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.Fn vm_page_zero_invalid "vm_page_t m" "boolean_t setvalid"
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.Ft int
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.Fn vm_page_is_valid "vm_page_t m" "int base" "int size"
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.Ft void
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.Fn vm_page_test_dirty "vm_page_t m"
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.Ft void
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.Fn vm_page_dirty "vm_page_t m"
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.Ft void
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.Fn vm_page_undirty "vm_page_t m"
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.Sh DESCRIPTION
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.Fn vm_page_bits
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calculates the bits representing the
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.Dv DEV_BSIZE
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range of bytes between
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.Fa base
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and
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.Fa size .
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The byte range is expected to be within a single page, and if
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.Fa size
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is zero, no bits will be set.
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.Pp
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.Fn vm_page_set_validclean
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flags the byte range between
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.Fa base
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and
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.Fa size
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as valid and clean.
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The range is expected to be
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.Dv DEV_BSIZE
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aligned and no larger than
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.Dv PAGE_SIZE .
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If it is not properly aligned, any unaligned chucks of the
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.Dv DEV_BSIZE
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blocks at the beginning and end of the range will be zeroed.
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.Pp
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If
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.Fa base
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is zero and
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.Fa size
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is one page, the modified bit in the page map is cleared; as well,
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the
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.Dv PG_NOSYNC
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flag is cleared.
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.Pp
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.Fn vm_page_clear_dirty
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clears the dirty bits within a page in the range between
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.Fa base
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and
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.Fa size .
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The bits representing the range are calculated by calling
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.Fn vm_page_bits .
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.Pp
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.Fn vm_page_set_invalid
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clears the bits in both the valid and dirty flags representing
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the
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.Dv DEV_BSIZE
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blocks between
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.Fa base
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and
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.Fa size
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in the page.
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The bits are calculated by calling
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.Fn vm_page_bits .
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As well as clearing the bits within the page, the generation
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number within the object holding the page is incremented.
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.Pp
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.Fn vm_page_zero_invalid
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zeroes all of the blocks within the page that are currently
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flagged as invalid.
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If
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.Fa setvalid
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is
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.Dv TRUE ,
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all of the valid bits within the page are set.
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.Pp
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In some cases, such as NFS, the valid bits cannot be set
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in order to maintain cache consistency.
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.Pp
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.Fn vm_page_is_valid
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checks to determine if the all of the
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.Dv DEV_BSIZE
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blocks between
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.Fa base
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and
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.Fa size
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of the page are valid.
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If
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.Fa size
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is zero and the page is entirely invalid
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.Fn vm_page_is_valid
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will return
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.Dv TRUE ,
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in all other cases a size of zero will return
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.Dv FALSE .
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.Pp
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.Fn vm_page_test_dirty
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checks if a page has been modified via any of its physical maps,
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and if so, flags the entire page as dirty.
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.Fn vm_page_dirty
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is called to modify the dirty bits.
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.Pp
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.Fn vm_page_dirty
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flags the entire page as dirty.
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It is expected that the page is not currently on the cache queue.
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.Pp
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.Fn vm_page_undirty
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clears all of the dirty bits in a page.
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.Sh NOTES
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None of these functions are allowed to block.
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.Sh AUTHORS
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This man page was written by
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.An Chad David Aq davidc@acns.ab.ca .
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