vm_page_is_valid (9)

Leading comments

Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.

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(The comments found at the beginning of the groff file "man9/vm_page_is_valid.9freebsd".)

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

SYNOPSIS

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

DESCRIPTION

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

Fn vm_page_set_validclean flags the byte range between Fa base and Fa 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 chunks of the DEV_BSIZE blocks at the beginning and end of the range will be zeroed.

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

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

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

Fn vm_page_zero_invalid zeroes all of the blocks within the page that are currently flagged as invalid. If Fa 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.

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

Fn 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. Fn vm_page_dirty is called to modify the dirty bits.

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

Fn 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 .