NAME
vm_page_alloc —
allocate a page for a
vm_object
SYNOPSIS
#include
<sys/param.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
vm_page_t
vm_page_alloc(vm_object_t
object, vm_pindex_t
pindex, int
page_req);
DESCRIPTION
Thevm_page_alloc()
function allocates a page at pindex within
object. It is assumed that a page has not already been
allocated at pindex. The page returned is inserted into
the object, but is not inserted into the pmap. The vm_object must be locked on
entry.
vm_page_alloc()
will not block.
Its arguments are:
- object
- The VM object to allocate the page for.
- pindex
- The index into the object at which the page should be inserted.
- page_req
- A flag indicating how the page should be allocated.
VM_ALLOC_NORMAL- The page should be allocated with no special treatment.
VM_ALLOC_QUICK- The page should only be allocated from the free queue.
VM_ALLOC_SYSTEM- The page can be allocated if the cache queue is empty and the free
page count is above the interrupt reserved water mark. If
VM_ALLOC_INTERRUPTis set, the page can be allocated as long as the free page count is greater than zero. This flag should be used only when the system really needs the page. VM_ALLOC_INTERRUPTvm_page_alloc() is being called during an interrupt and therefore the cache cannot be accessed. The page will only be returned successfully if the free count is greater than zero.VM_ALLOC_ZERO- Indicate a preference for a pre-zeroed page. There is no guarantee that the page thus returned will be zeroed, but it will be marked as such.
RETURN VALUES
The vm_page_t that was allocated is returned
if successful; otherwise, NULL is returned. The
returned page will be marked busy.
AUTHORS
This manual page was written by Chad David <davidc@acns.ab.ca>.