How does one assess the potential performance of a new dual core processor, say a 2.6 ghz pair, on a single-thread job (optimally compiled single thread, been that way a long time) that has previously run well on a 3.8 ghz single core cpu? If the task actually-demands- that the 2nd core be shut off to run properly, will the remaining 2.6 ghz core execute that same job faster than a 3.8 ghz single core would?
This is a devil of a question; I can never seem to get a straight answer. Thanks for any insight you can supply!
Your single thread job would run in only one of the cores. So it would run at 2.6 GHz.
However, the different processor will likely have a different internal structure, cache size may be different, and memory performance may be different. It is difficult to say how one core at 2.6GHz stacks up against the one core on the 3.8GHz.
Another difference though is if your application requires an additional application to run or significant OS services to run e.g. real-time graphics presentation. In which case your computation thread won't get interfered with by the other "overhead" programs.