Virtual Compound Pages

“‘Allocations of larger pages are not reliable in Linux. If
larger pages have to be allocated then one faces various choices of
allowing graceful fallback or using vmalloc with a performance
penalty due to the use of a page table,’ began Christoph Lameter,
describing the third version of his virtual compound page support
patchset. He continued, ‘a virtual compound allocation means that
there will be first of all an attempt to satisfy the request with
physically contiguous memory. If that is not possible then a
virtually contiguous memory will be created…'”