> But hopefully they'll have something RVA23-compliant out soon (SpacemiT K3?).

A handful of developers already have access to SpacemiT K3 hardware, which is indeed RVA23 compliant and already runs Ubuntu 26.04.

geekbench: https://browser.geekbench.com/v6/cpu/16145076

rvv-bench: https://camel-cdr.github.io/rvv-bench-results/spacemit_x100/... (which as instruction throughput measurements and more)

▲

ahoka 2 hours ago | parent [-]

This is around the performance of a Core 2 Duo, if I understand correctly?

▲

camel-cdr an hour ago | parent | next [-]

The single core performance is roughly in the middle between Pi4 Cortex-A72 and Pi5 Cortex-A76.

It's slightly faster than a 3GHz Core 2 Dua in scalar single threaded performance, but it has 8 cores instead of two and more SIMD performance. There are also 8 additional SpacemiT-A100 cores with 1024-bit wide vectors, which are more like an additional accelerator.

The geekbench score is a bit lower than it should be, because at least three benchmarks are still missing SIMD acceleration on RISC-V (File Compression, Asset Compression, Ray Tracer), and the HTML5 browser test is also missing optimizations.

I'd estimate it should be able to get to the 500 range with comparable optimization to other architectures.

The Milk-V Titan mention in the original post is actually slightly faster in scalar performance, but has no RISC-V Vector support at all, which causes it's geekbench score to be way lower.

▲

oxxoxoxooo 34 minutes ago | parent [-]

Do you happen to know how does one access/use those A100 cores?

	▲	camel-cdr 23 minutes ago \| parent [-]
		No. The problem is that you can't migrate threads between cores with different vector length. The current ubuntu 26.04 image, that is installed, lists 16 cores in htop, but you can only run applications on the first 8 (e.g. taskset -c 10 fails). If you query whats running on the A100 cores you see things like a "kworker" processes. I suspect that it should be possible to write a custom kernel module that runs on the A100s with the current kernel, but I'm not sure. I expect it will definitely be possible to boot a OS only one the 8 A100 cores. Well have to see if they manage to figure out how to add support for explicitly pinning user mode processes to the cores. The ideal configuration would be to have everything run only on the X100s, but with an opt-in mechanism to run a program only on an A100 core.

▲

6SixTy 27 minutes ago | parent | prev [-]

Something is odd here, the Core 2 Duo only has up to SSE 4.1, while the RVA23 instruction set is analogous to x64-v3. I find it hard to believe that the SpacemiT K3 matched a Core 2 duo single core score while leveraging those new instructions.

To wit the Geekbench 6.5.0 RISC-V preview has 3 files, 'geekbench6', 'geekbench_riscv64', and 'geekbench_rv64gcv', which are presumably the executables for the benchmark in addition to their supported instruction sets. This makes the score an unreliable narrator of performance, as someone could have run the other benchmarks and the posted score would not be genuine. And that's on top of a perennial remark that even the benchmark(s) could just not be optimized for RISC-V.