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VM_PAGE_BITS (9) | Kernel routines | Unix Manual Pages | :man

NAME

vm_page_bits, vm_page_set_validclean, vm_page_clear_dirty, vm_page_set_invalid, vm_page_zero_invalid, vm_page_is_valid, vm_page_test_dirty, vm_page_dirty, vm_page_undirty - "manage page clean and dirty bits"

CONTENTS

Synopsis
Description
Notes
Authors

SYNOPSIS


.In sys/param.h
.In vm/vm.h
.In vm/vm_page.h int vm_page_bits "int base" "int size" void vm_page_set_validclean "vm_page_t m" "int base" "int size" void vm_page_clear_dirty "vm_page_t m" "int base" "int size" void vm_page_set_invalid "vm_page_t m" "int base" "int size" void vm_page_zero_invalid "vm_page_t m" "boolean_t setvalid" int vm_page_is_valid "vm_page_t m" "int base" "int size" void vm_page_test_dirty "vm_page_t m" void vm_page_dirty "vm_page_t m" void vm_page_undirty "vm_page_t m"

DESCRIPTION

vm_page_bits calculates the bits representing the DEV_BSIZE range of bytes between base and size. The byte range is expected to be within a single page, and if size is zero, no bits will be set.

vm_page_set_validclean flags the byte range between base and size as valid and clean. The range is expected to be DEV_BSIZE aligned and no larger than PAGE_SIZE. If it is not properly aligned, any unaligned chucks of the DEV_BSIZE blocks at the beginning and end of the range will be zeroed.

If base is zero and size is one page, the modified bit in the page map is cleared; as well, the PG_NOSYNC flag is cleared.

vm_page_clear_dirty clears the dirty bits within a page in the range between base and size. The bits representing the range are calculated by calling vm_page_bits.

vm_page_set_invalid clears the bits in both the valid and dirty flags representing the DEV_BSIZE blocks between base and size in the page. The bits are calculated by calling vm_page_bits. As well as clearing the bits within the page, the generation number within the object holding the page is incremented.

vm_page_zero_invalid zeroes all of the blocks within the page that are currently flagged as invalid. If setvalid is TRUE, all of the valid bits within the page are set.

In some cases, such as NFS, the valid bits cannot be set in order to maintain cache consistency.

vm_page_is_valid checks to determine if the all of the DEV_BSIZE blocks between base and size of the page are valid. If size is zero and the page is entirely invalid vm_page_is_valid will return TRUE, in all other cases a size of zero will return FALSE.

vm_page_test_dirty checks if a page has been modified via any of its physical maps, and if so, flags the entire page as dirty. vm_page_dirty is called to modify the dirty bits.

vm_page_dirty flags the entire page as dirty. It is expected that the page is not currently on the cache queue.

vm_page_undirty clears all of the dirty bits in a page.

NOTES

None of these functions are allowed to block.

AUTHORS

This manual page was written by
.An Chad David Aq
davidc@acns.ab.ca .

December 1, 2001 VM_PAGE_BITS (9)
shtml">manServer 1.07 from vm_page_bits.9 using doc macros.


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