Smithfield is the same as Nocona, as far as the issues dealt with by compiler flags are concerned. So, gcc -march=nocona is suitable, along with any other gcc flags you would normally use, including -ftree-vectorize. icc -xW or -xP would be chosen, according to the desired choice between Opteron compatibility and SSE3 optimization. For applications I have dealt with, the same optimizations work for dual single core Nocona and for single socket dual core Smithfield.
