yoy.be "Why-o-Why"

Could you do a mill architecture with RISC-V?

2020-09-29 22:26  millrisc  actueel coding computers dagboek  [permalink]

I wondered today if it would be feasable to build a processing unit according to the mill architecture with the RISC-V instruction set. But as always, I also wonder if I'm out of my league and know far too little of these things to come even close to forming an accurate answer, or even if I'm anywhere close to a good idea. If I understood correctly, the mill architecture does what modern CPU's already do: use a bank of virtual registers with multiple heavily pipelined streams of translated instructions. CPU's that do hyperthreading have two streams of instructions, but that's about it. I'm really rooting for the first article I read about a real system that has more than two, but with just a little imagination, and if you know the 'price per transistor' keeps going down, you can image a huge bank of virtual registers, with a bank of ALU's close, that processes a 'large' number of instruction streams. Ideally even a totally variant number of instruction streams. This may be a caching nightmare, but instead of wasting a lot of in-system logic to do branch prediction and other bookkeepingof what an instruction stream is doing, what if you could just load another instruction stream, just up until you get all of the piplined stages fully occupied...

Alas, I'm so much out of that business that I guess I need to conclude I'm a wild dreamer. I may stumble on a good idea now and then, but know too little to be sure. So I'll note it down here. I hope I haven't bored you, and with just a little luck, you are able to judge about this idea. If so let me know...

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