vm_page_io_finish(9) [osx man page]

VM_PAGE_IO_START(9)					   BSD Kernel Developer's Manual				       VM_PAGE_IO_START(9)

NAME

     vm_page_io_start, vm_page_io_finish -- ready or unready a page for I/O

SYNOPSIS

     #include <sys/param.h>
     #include <vm/vm.h>
     #include <vm/vm_page.h>

     void
     vm_page_io_start(vm_page_t m);

     void
     vm_page_io_finish(vm_page_t m);

DESCRIPTION

     The vm_page_io_start() function prepares the page for I/O by incrementing its busy flag by one.

     The vm_page_io_finish() function lowers the busy count on the page by one, if the resulting busy count is zero, a wakeup(9) will be issued if
     the page has been marked VPO_WANTED.  A page is typically marked VPO_WANTED by a thread to register its interest in the page to either com-
     plete I/O or becoming available for general use.

AUTHORS

     This manual page was written by Chad David <davidc@acns.ab.ca> and Alfred Perlstein <alfred@FreeBSD.org>.

BSD
								   July 17, 2001							       BSD

VM_PAGE_FREE(9) 					   BSD Kernel Developer's Manual					   VM_PAGE_FREE(9)

NAME

     vm_page_free, vm_page_free_toq, vm_page_free_zero, vm_page_try_to_free -- free a page

SYNOPSIS

     #include <sys/param.h>
     #include <vm/vm.h>
     #include <vm/vm_page.h>

     void
     vm_page_free(vm_page_t m);

     void
     vm_page_free_toq(vm_page_t m);

     void
     vm_page_free_zero(vm_page_t m);

     int
     vm_page_try_to_free(vm_page_t m);

DESCRIPTION

     The vm_page_free_toq() function moves a page into the free queue, and disassociates it from its object.  If the page is held, wired, already
     free, or its busy count is not zero, the system will panic.  If the PG_ZERO flag is set on the page, it is placed at the end of the free
     queue; otherwise, it is placed at the front.

     If the page's object is of type OBJT_VNODE and it is the last page associated with the object, the underlying vnode may be freed.

     The vm_page_free() and vm_page_free_zero() functions both call vm_page_free_toq() to actually free the page, but vm_page_free_zero() sets the
     PG_ZERO flag and vm_page_free() clears the PG_ZERO flag prior to the call to vm_page_free_toq().

     The vm_page_try_to_free() function verifies that the page is not held, wired, busy or dirty, and if so, marks the page as busy, drops any
     protection that may be set on the page, and frees it.

RETURN VALUES

     vm_page_try_to_free() returns 1 if it is able to free the page; otherwise, 0 is returned.

SEE ALSO

     vm_page_busy(9), vm_page_hold(9), vm_page_wire(9)

AUTHORS

     This manual page was written by Chad David <davidc@acns.ab.ca>.

BSD
								   July 24, 2001							       BSD