Quote Originally Posted by dess View Post
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No, you can't give it the whole resources on CMT.
Why not ? What stops the shared decoder to feed instructions from the same thread to both integer clusters ? It would be the magical "reverse hyperthreading" everyone talks about.

Do you mean disabling the second thread on one core? Yes, with SMT the first thread will earn much.
Core 2 isn't SMT enabled. You have 2 cores, 2 threads with a shared cache. If you disable one core, the other will have access to the whole cache and offer better single threaded performance. This is what we see with the 4m/4c aproach on BD. Inside the module you have 1 thread which isn't fighting for shared resources => perf. is better. Overall throughoutput is lower, it's basically an exercise.
2M/4c < 4m/4c < 4m/8c altough highest per thread performance is with the 4m/4c.