From the Linux documentation provided, I ported over the SLOB allocator (GPL to MIT). It's just a K&R memory allocator, but with multiple levels. Depending on the size requested, it puts it in the appropriate "level". From there, first and next fit algorithms is used to service the request.
I never heard of bget, but I'll look into it.
It all really depends on your usage and how big your requests are going to be. SLOB isn't good for large requests (say, you want to allocate 32KiB, for example).
In terms of performance, typically the allocations would be done when you're loading assets/preparing the scene. You wouldn't allocate memory during actual game play.