How to Design a Self-Balancing Multicore CPU for Fine-Grain Parallel Applications

Traveler · 2007-10-13T17:26:47+00:00

From the Blog:The Real Purpose of the CPUThe most important question a CPU designer must ask himself or herselfis, what is the purpose of the CPU? Most people in the business willimmediately answer that the purpose of the CPU is to execute sequencesof coded instructions. Sorry, this is the wrong answer. Thisdefinition is precisely what got us in the mess that we are in. Inorder to figure out the answer to this crucial question, we must firstgrok the true nature of computing. And the sooner we learn that acomputer is really a collection of concurrently behaving andcommunicating entities, the sooner it will dawn on us that the CPU isa necessary evil.Necessary EvilWhy necessary evil? Because, ideally, each and every elementary entityin a computer should be its own self-processor, not unlike a neuron ina biological nervous system that sits around most of the time waitingfor a signal to do something. In other words, ideally speaking,additions should add by themselves and multiplications shouldmultilply by themselves. Unfortunately, we have not yet progressed tothe point where we can build super-parallel systems like the brainwith its tens of billions of tiny, interconnected, self-executingprocessors. That will come one day, but not today.CPU as SimulatorFortunately, what we lack in numbers, we make up in speed. We can havea single fast CPU do the work of thousands or even millions ofelementary processors (cells). Ideally, adding more CPUs or cores intothe mix should improve performance linearly. At least, that is thegoal. So this, then, is the true purpose of the CPU, to simulate thebehavior of a large number of behaving and inter-communicating cells.So, essentially, the CPU is a cell simulator, or cell processor if youwish. If the reader disagrees with my argument so far, there is nopoint in reading any further because what I am going to say belowdepends on what I said above.

Oct 13, 2007 20 Replies

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Alex Colvin 19 years ago

isn't that what's inside the current crop of out-of-order processors? It looks like dataflow within a sliding window. In which case, everyone IS using it.

Is anyone using somthing like the Tera full/empty bits ?

mac the naïf

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