If the CPU redesigned today, with no legacy incentives what can change?

Question

Something I often hear is that the modern CPU has bunch of sort of &ldquo;poly fills&rdquo; to merge the programming paradigms of past with new tech. Microcode perhaps mostly. Like that C programming, which mostly forms basis for other absractions no longer captures how a cpu works, and the cpu tries to optimize C type abstractions for modern post 80/90s innovations.What would a new paradigm for CPU and GPUs look like? Is there some aspect of the legacy system that is not ideal but clearly economically impossible to change. Does the poly fill type design of cpu microcode have drawbacks?One analogy is planes. Plane design has remained pretty unchanged since 1960s because of regulations, very different design = pay to retrain pilots. Of course planes have still drastically improved across board, but but they are still controrting themselves to adhere to the paradigm of the pilots for economic reasons. Without this, a new plane design might be quite different. (This is part of the Boeing crisis- the software was designed to &ldquo;polyfill&rdquo; the change in flight beahvior caused by the contorting themselves to get a better engine on similiar plane frame)

bjourne · Accepted Answer

I think next gen cpus should be tuned for actual workloads rather than the synthetic benchmarks they are often designed to beat. Essentially latency and not throughput. Right now I'm entering text into a text field on a web page and I don't care about sustained throughput but it would annoy me greatly if, say, switching tabs would cause noticeable lag and/or make the noisy cpu fans spin up.How do you optimize architectures for event-based "do nothing 99.9% of the time, do A LOT 0.1% of the time" workloads? I don't know. My hunch is that you should prioritize memory latency and pay more attention to worst case rather than best case performance.

Leftium · Answer

1. [Ternary computers]: Base-3 is the most efficient of all integer bases; numbers are stored most economically with trits.
2. Something like a [Lisp machine] that is optimized for functional-style programming with immutable data.
[Ternary computers]: https://www.wikiwand.com/en/Ternary_computer
[Lisp machine]: https://www.wikiwand.com/en/Lisp_machine

Am4TIfIsER0ppos · Answer

Without being too radical you might merge some things. Hardware detection like on x86. Feature identification like on x86 (cpuid). Fixed size instructions seem to be "more popular". Variable length vector operations/loops seem intriguing (decent presentation about it at fosdem this year).What's probably going to happen is more integration and more drm.

eimrine · Answer

I refuse to understand your C programming point, but answering your question, a computer might be a Lisp machine and/or having von-Neumann architecture instead of Harvard one. CPU might be more multithread and GPU might be better suited for such things as calling eval().

warrenm · Answer

Planes have remained pretty much unchanged because aerodynamics works the same for everyoneUnless you mean cockpit design :)