Active Memory Defragmentation : Need?

Why is Active Memory Defragmentation needed? (Reference : Paper by Daniel Phillips , titled "Patch:My research agenda for 2.7").

Is there any case or example of the Linux memory
allocator (buddy allocator) failing due to memory fragmentation? If yes,what sorts of programs or
applications cause this failure?
Could anyone kindly supply me with statistical
data & arguments to justify the need for Active Memory Defragmentation?

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