vm_page_grab(9) [debian man page]

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

NAME

     vm_page_grab -- returns a page from an object

SYNOPSIS

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

     vm_page_t
     vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags);

DESCRIPTION

     The vm_page_grab() function returns the page at pindex from the given object.  If the page exists and is busy, vm_page_grab() will sleep
     while waiting for it.  If the page does not exist, it is allocated.

     If VM_ALLOC_RETRY is not set in allocflags and the function sleeps, either getting the page from the object or while allocating it, NULL is
     returned.

RETURN VALUES

     If successful, vm_page_grab() returns the page; otherwise, NULL is returned.

SEE ALSO

     vm_page_alloc(9)

AUTHORS

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

BSD
								  August 7, 2001							       BSD

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

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 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_NOOBJ is 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:

     object  The VM object to allocate the page for.  The object must be locked if VM_ALLOC_NOOBJ is not specified.

     pindex  The index into the object at which the page should be inserted.

     req     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:

	     VM_ALLOC_NORMAL	 The page should be allocated with no special treatment.

	     VM_ALLOC_SYSTEM	 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_ALLOC_INTERRUPT  vm_page_alloc() is being called during an interrupt.  A page will be returned successfully if the free page count
				 is greater than zero.

	     The optional flags are:

	     VM_ALLOC_ZERO	   Indicate a preference for a pre-zeroed page.  There is no guarantee that the returned page will be zeroed, but
				   it will have the PG_ZERO flag set if it is zeroed.

	     VM_ALLOC_NOOBJ	   Do not associate the allocated page with a vm object.  The object argument is ignored.

	     VM_ALLOC_NOBUSY	   The returned page will not have the VPO_BUSY flag set.

	     VM_ALLOC_WIRED	   The returned page will be wired.

	     VM_ALLOC_IFCACHED	   Allocate the page only if it is cached.  Otherwise, return NULL.

	     VM_ALLOC_IFNOTCACHED  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, NULL is returned.

NOTES

     The pager process is always upgraded to VM_ALLOC_SYSTEM unless VM_ALLOC_INTERRUPT is set.

AUTHORS

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

BSD
								   July 3, 2010 							       BSD