Extreme Multithreading on a Chip

kid writes "There's an interesting interview with Dr. Marc Tremblay at Ace's Hardware. Dr. Tremblay is a distinguished engineer at Sun and the co-architect of the UltraSPARC processor. He is currently working on a processor that is claimed to deliver 30 times the performance of current CPUs utilizing an agressive multi-core/multi-threaded architecture. He talks about upcoming highly multithreaded CPUs from Sun as well as a wide range of problems facing today's CPU designers, from branch mispredictions to DRAM latency/bandwidth and power dissipation, and the ways in which he is working on solving them."

Comments

Re:Hard to program?

[Circuit Breaker]

When you say "fast", do you mean "responsive"?

There's no speed magic to multithreading on a single thread single CPU system - actually, preemptive multitasking can only reduce raw CPU power.

For desktop systems, responsiveness is far more important than raw speed - but Sun is in the server business, in which desktop-style responsiveness is less important.

Furthermore, do not confuse CPU threads with O/S threads; CPU threads may just as well run distinct processes which have no relation to each other - in fact there are architectures that use this as an advantage and do away with a memory cache.

Multiple threads make software hard to develop (and to debug and test). Multiple processes, essentially threads without a shared address space, much less so. Assuming, of course, that the address space is NOT shared....

Tera Multithreaded computer

[fitten]

It's been done for a while. Check out

http://www.supercomp.org/sc98/TechPapers/sc98_Fu ll Abstracts/Brunett1063/Index.htm

to see about the Tera Multithreaded computer. 128 hardware threads per single cpu. It was interesting and was actually built (I saw a few).