Comment by BirAdam | Hacker News Reader

Comment by BirAdam | Hacker News Reader

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$17 64 bit RISC-V https://linuxgizmos.com/17-sbc-runs-linux-on-allwinner-d1-ri...

$29 64 bit RISC-V in the same form factor as an RPi CM3 https://www.clockworkpi.com/product-page/copy-of-clockworkpi...

If you never look for it, you will believe it doesn’t exist.

I was very skeptical of ARM back in the day thinking that it was great for crappy little iTrinkets and Androids but not for “real computing”. I was clearly wrong. I was very skeptical of RISC-V until I recently heard Jim Keller explain why RISC-V has a bright future. He was rather convincing. This is especially true given his track record of straight-up magical results. Looking at different RISC-V machines, I think that the greatest advantage is that it is simple and can therefore be optimized more easily than complex designs, and due to being open, it has very low cost which will encourage more eyes trying more and different optimizations.

EDIT: Link to Jim Keller interview https://www.anandtech.com/show/16762/an-anandtech-interview-...

I agree mostly with Keller's take but I think he left of one key factor, the quality of the software tool chain.

The x86 tool chains are amazing. They're practically black magic in the kinds of optimizations they can do. Honestly, I think they're a lot of what is keeping Intel competitive in performance. ARM tool chains are also very good. I think they're a lot of the reason behind why ARM can beat RISCV in code space and performance on equivalent class hardware because honestly, like Keller says, they're not all that different for common case software. But frankly x86 and ARM toolchains should dominate RISCV when we just consider the amount of person-hours that have been devoted to these tools.

So for me the real question is, where are the resources that make RISCV toolchains competitive going to come from (and keep in mind x86 and ARM have open source toolchains too)? And, will these optimizations be made available to the public?

If we see significant investment in the toolchains from the likes of Google, Apple and nVidia, or even Intel. ARM needs to be really worried.

I don't know that such a heavy investment in the toolchains for RISC-V are actually needed.

If you look at generated code, it seems fairly straightforward. There aren't a lot of tricks or anything.

It's not so much "tricks" that one needs to look out for.

The compiler has just tons of internal heuristics on when and when not to apply various code transformations. Those heuristics, first off may not even be applicable for your platform of choice, and even if they are, their magic numbers aren't necessarily tuned well to the platform and application at hand.

Here is a well written and concise case study, albeit somewhat old (2010), that illustrates what I am talking about. The results of variations measurements will have changed since then but the overall high level situation hasn't. If you read the paper, in your mind, just replace every instance of x86 with ARM and every instance of ARM with RISCV and you'll get the idea.

https://ctuning.org/dissemination/grow10-03.pdf

I think the serious investment will be from Intel, Apple (with LLVM), and possibly Microsoft (into the GCC/Linux ecosystem).

> I recently heard Jim Keller explain why RISC-V has a bright future

Would like to hear it too. Can you share a link?

Updated my response to include a link to the transcription. The audio/video is here: https://www.youtube.com/watch?v=AFVDZeg4RVY

It’s actually important (if you’re not an engineer) to listen to the whole thing, because he drops knowledge all over the place.

Watching that was my best use of time in the past month.

I watched at 1.5x speed.

ARM has proven their place for real computing on Newton OS and Acorn Archimedes, no need to prove it again on crappy little iTrinkets and Androids.

Where is a RISC-V doing “real computing” on a Acorn Archimedes like personal computer?

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