alt Hacker NewsI'm working on making SIMD better in Dart. Dart supports RISC-V as a target architecture for compilation, but I'm not really excited about figuring out how to map the wasm-SIMD-style primitives to RISC-V's RVV and so I don't really plan to look into it at all.
This is mostly because their approach to SIMD is so different, but also because I can't test it at all. Are there any RISC-V "machines"? that one can use to do something useful or fun with that someone here could recommend?
I guess it would be fun seeing all my SIMD-fiable use-cases become orders of magnitude faster on RISC-V, too, but I sadly never hear anything about machines that use RISC-V.
Replies
You can buy a RISC-V mainboard for the Framework Laptop, and it's relatively cheap (£170)
https://frame.work/gb/en/products/deep-computing-risc-v-main...
There are several RISC-V machines. In the microcontroller world it's becoming more and more usual, but those won't have RVV. SpacemiT K3 based machines are probably your best bet when it comes to RISC-V processors with SIMD support. There are several manufacturers: Milk-V with the Jupiter II, Sipeed, Banana Pi, ...
> Dart supports RISC-V as a target architecture for compilation, but I'm not really excited about figuring out how to map the wasm-SIMD-style primitives to RISC-V's RVV and so I don't really plan to look into it at all.
On the one hand, this will be quite straight forward, but on the other hand quite disappointing.
Afaik Dart has a 128-bit only SIMD abstraction (so not performance portable by default). Since the base "V" extension mandates a mininum vector length of 128-bit, you can trivially make codegen work for all vector length, by simply setting vl to 128/elementwidth.
But as with x86, if your native hardware vector length is larger than 128-bit, you leave performance on the table.
> This is mostly because their approach to SIMD is so different, but also because I can't test it at all. Are there any RISC-V "machines"?
I'd recommend using qemu for initial testing.
Hardware wise, the cheapest option is the orange pi rv2, which has 8 SpacemiT X60 cores, which are in-order and support 256-bit RVV. The Zhihe A210 is also interesting, but way to expensive for what it is.
If you have a higher budget, I'd recommend the SpacemiT K3, which is the fist RISC-V SBC with RVA23 support. It is has 8 SpacemiT X100 4-wide out-of-order cores, with 256-bit RVV.