Comment Re:wrong wrong wrong (Score 4, Informative) 180
Amazing. Everything you said about HT is completely wrong. Where ever did you get this information?
Intel's hyperthreading consists of two logical processors sharing the same compute resources. Each logical processor has its own register set but shares decoders, adders, shifters, cache, etc. as it goes about executing its assigned thread. The sharing process is vastly more complex and efficient than you seem to think -- there's no alternating of cycles. Once instructions are decoded into uops, they flow through the pipeline in a dynamic fashion that sometimes leads to one thread using most of the resources while the other one waits. In fact, this is a big advantage of the design -- when one thread stalls from a cache miss, the other one uses all the resources until the first thread's memory access completes. A much better plan than your scheme of using only even/odd cycles.
Managing this process is not simple, and steps must be taken to avoid both deadlocks and livelocks as the two threads compete for resources. But the process is dynamic -- the design allows one thread to run unimpeded when it makes sense to do so, while still preventing one thread from being starved at the other's expense. But this "every other cycle" notion of yours is pure nonsense. The core can retire up to four uops per cycle, and at times these all come from the same thread.