freebsd man page for vm_page_hold

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

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>.

BSD
								   July 13, 2001							       BSD