Writing or using an existing custom allocator is common enough. Networking developer Jesper Dangaard Brouer must have looked into that approach and found it wanting for what the article describes as “The networking code could then grab a pile of memory, and quickly hand out pages as needed.”

What does the improvement described in the “Batch page allocation” section add that a custom allocator would be unable to? Or is it a widely-used pattern that many custom allocators can take advantage of? In that case, why put it in the kernel?

Etc.