> I think the reason why you didn't see parallelism come out earlier in > the PC market was because they needed to create new mechanisms for I/O. > AMD did this with Hypertransport, and I've seen 32-core (8-socket) > systems with this. Now Intel has their own I/O rethink out there.
i think what you're saying is equivalent to saying (in terms i understand) that memory bandwidth was so bad that a second processor couldn't do much work. but i haven't found this to be the case. even the highly constrained pentium 4 gets some milage out of hyperthreading for the tests i've run. the intel 5000-series still use a fsb. and they seem to scale well from 1 to 4 cores. are there benchmarks that show otherwise similar hypertransport systems trouncing intel in multithreaded performance? i don't recall seeing anything more than a moderate (15-20%) advantage. - erik
