def pin_memory_(self):
        """Pin the storage into page-locked memory.

        Does nothing if the storage is already pinned.
        """
        if not self.pinned_by_dgl and not F.is_pinned(self.data):
            self._data_nd = pin_memory_inplace(self.data)
            self.pinned_by_dgl = True
Pin the storage into page-locked memory.

        Does nothing if the storage is already pinned.
        
python/dgl/frame.py