NAME

       vm_page_hold, vm_page_unhold — update a page's hold count

SYNOPSIS

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

       void
       vm_page_hold(vm_page_t m);

       void
       vm_page_unhold(vm_page_t m);

DESCRIPTION

       The  vm_page_hold()  function  increases  the  hold  count on a page.  This prevents the page daemon from
       freeing the page.

       vm_page_hold() should only be used for very temporary wiring  of  a  page,  as  that  page  will  not  be
       considered for paging or reallocation for as long as its hold count is greater than zero.  Also note that
       while  wired  pages  are  removed  from  whatever  queue  they are on, vm_page_hold() does not affect the
       location of the page.  If it is on a queue prior to the call, it will still be there afterward.

       If the page needs to be held for a long period of time, vm_page_wire(9) should be used.

       vm_page_unhold() function reduces the hold count on a page.  If the hold count is  zero  it  is  possible
       that the page will be freed by the page daemon.

SEE ALSO

       vm_page_unwire(9), vm_page_wire(9)

AUTHORS

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

Debian                                            July 13, 2001                                  VM_PAGE_HOLD(9)