I have wanted to write for some time about UMA changes I recently made. UMA is the "universal memory allocator" which serves as FreeBSD's kernel memory allocator. I initially wrote this 7 years ago or so and many other people have since contributed. I named it 'universal' because at that time FreeBSD had 3 separate kernel memory allocators and this unified them. The two new features relate to network performance work I've been doing lately and allow the use of more efficient layout of network buffers.