benefits of allocating huge pages at boot

[ moving the question from StackOverflow where it seems less appropriate ] The kernel boots with default_hugepagesz=1G option, which defines size of the default page size. So when an application want large memory, the kernel will allocate it with 1G pages. If the kernel boots with hugepages=N, i.e. allocate N huge pages at boot. So in this case, the kernel will automatically take a page from this pool, thus saving time on allocating memory? When this pool runs out of available pages, how will the kernel allocate huge memory?