Processors or cores?

Question

Processors

In one form or another, the question has been raised in various places, but usually it becomes a broad discussion about smart or beautiful. I'll try to formulate the question clearly.
Which computer configuration will give more performance: with one processor with 2N cores or with two processors with N cores, provided that the other parameters are the same? Why? If the result is different for different applications, then for which ones and why? .. The
question was born from the announcement of the new Mac Pro. It will be single-processor, but it will have 12 cores (taking into account HT or not, I don’t know). Many Mac users are disappointed by this. Would it be better for CPU-intensive applications, or worse than if it had two processors with 6 cores each?

Answer 1

Data exchange between cores is faster than between processors. 2 different processors with tasks (one for each) that do not intersect in any way will work faster than 2 cores with the same conditions. Because the cores have a shared cache, while the processors have an exclusive cache. If the scheduler distributes tasks well, then, in theory, many processors with fewer cores will be more efficient.
All this is my personal opinion, because I did not do any real tests.

Answer 2

Yes, there is not much difference, and two and four processors are set in order to double or quadruple the number of cores, and not in order to put two processors of two cores instead of four core processors and increase performance.

Answer 3

The question is posed incorrectly and not at all about that.
If we have exactly two identical cores, and the difference is whether they sit on the same crystal or on two different ones, it comes down to problems of heat dissipation and cooling.
However, if you leave the total cache the same, but make it shared between the cores, then this alone will win. (actually, this is how Intel did it).
But the essence of the matter is different. I dare to suggest that Mac drivers are disappointed that instead of increasing the power of one core, their number has increased. Meanwhile, not all tasks are well parallelized and not all are able, at the moment, to use all 12 cores.

Answer 4

if there are 2 processors, it will probably be easier to cool them, each of them will heat up less than one with 2N cores

Answer 5

It seems to me that we should look not at the number of cores, but at the bus width and caching. Logically, 2 processors will be better in this regard.