table of contents
VM_PAGE_BITS(9) | Kernel Developer's Manual | VM_PAGE_BITS(9) |
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 bitsSYNOPSIS¶
#include <sys/param.h>#include <vm/vm.h>
#include <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 theDEV_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
VPO_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 Chad David ⟨davidc@acns.ab.ca⟩.December 1, 2001 | Debian |