table of contents
|VM_PAGE_ALLOC(9)||Kernel Developer's Manual||VM_PAGE_ALLOC(9)|
NAME¶vm_page_alloc — allocate a page for a vm_object
#include <vm/vm_page.h> vm_page_t
vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req);
DESCRIPTION¶The vm_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, unless
VM_ALLOC_NOOBJis specified in the req. The page may exist in the vm object cache, in which case it will be reactivated instead, moving from the cache into the object page list. vm_page_alloc() will not sleep. Its arguments are:
- The VM object to allocate the page for. The
object must be locked if
VM_ALLOC_NOOBJis not specified.
- The index into the object at which the page should be inserted.
- The bitwise-inclusive OR of a class and any optional flags
indicating how the page should be allocated.
Exactly one of the following classes must be specified:
- The page should be allocated with no special treatment.
- The page can be allocated if the cache is empty and the free page count is above the interrupt reserved water mark. This flag should be used only when the system really needs the page.
- vm_page_alloc() is being called during an interrupt. A page will be returned successfully if the free page count is greater than zero.
- Indicate a preference for a pre-zeroed page. There is
no guarantee that the returned page will be zeroed, but it will have
PG_ZEROflag set if it is zeroed.
- Do not associate the allocated page with a vm object. The object argument is ignored.
- The returned page will not have the
- The returned page will be wired.
- Allocate the page only if it is cached. Otherwise,
- Only allocate the page if it is not cached in the object. If the page at the specified pindex is cached, NULL is returned instead.
RETURN VALUES¶The vm_page_t that was allocated is returned if successful; otherwise,
NOTES¶The pager process is always upgraded to
AUTHORS¶This manual page was written by Chad David ⟨email@example.com⟩.
|July 3, 2010||Debian|