kernel memory allocator: UMA or malloc?

[Rick Macklem]

Hi,

I've been working on a patch provided by wollman@, where
he uses UMA instead of malloc() to allocate an iovec array
for use by the NFS server's read.

So, my question is:
When is it preferable to use UMA(9) vs malloc(9) if the
allocation is going to be a fixed size?

Thanks in advance for any info, rick