I thought SMP meant "symetric multi-processing," a technology where two or more processors share equal access to memory, device I/O, and interrupts. Ideally one would expect a 100 percent improvement in processing performance for each additional processor, but in reality only 80-90 percent is achieved.
However, I have discovered that to some people, SMP means "shared-memory multi-processing." This technology allows multiple processors to run user programs, but one processor reserves interrupt and I/O handling for itself. This is traditionally called "asymetric multi-processing," and I have tentatively concluded that only "marketing types" would use this terminology to confuse potential customers.