Nyuzi: open-source processor designed for highly parallel and GPGPU applications | Hacker News Reader

Nyuzi: open-source processor designed for highly parallel and GPGPU applications

nyuzi.org

77 pointsmatt_d21 comments

Regardless of the Nyuzi's merits, that demo is unimpressive.

We (RenderMorphics and then Microsoft D3D) were happily spinning teapots on 50 MHz 486s, significantly faster than that.

On it's own, that's not much information to make a useful comparison (in my opinion). There's a lot more to consider (power usage on an equivalent node, display resolution incl. bit-depth, # of tris, shading model, etc).

From a performance perspective, admittedly. The software 3D renderer it is running is not highly optimized. But it's probably not an apples-to-apples comparison, since this has programmable vertex/pixel shaders that uses floating point for parameter interpolation and color values. I assume 486 class 3D renderers were probably taking some shortcuts (no shaders, fixed point math, etc.)

What I think it does demonstrate is that the hardware design can run a non-trivial programs reliably on FPGA. Maybe that's not impressive either, but I thought it was kinda cool. :) While this doesn't mean anyone needs to go shorting NVidia stock, it does allow anyone who is interested in CPU/GPU architecture to experiment with and modify a full featured design (pipelined, vector floating point, L1 & L2 caches, hardware multithreading).

I analyzed the basic performance and scalability of the 3D renderer here:

http://latchup.blogspot.com/2015/02/improved-3d-engine-profi...

And dove a bit deeper into performance using a custom Quake level renderer:

http://latchup.blogspot.com/2015/06/not-so-fast.html

It may still not be an apples-to-apples comparison, but since it was running on the 486, it was by definition, doing programmable vertex transformation and shading.

> it was by definition, doing programmable vertex transformation and shading

Yes, all software renderers are—by definition—programmable, but those terms usually imply some kind of shading language like GLSL that is accepted at runtime, compiled and then executed by the graphics engine (hardware or software).

It seems unlikely that Mr. Teapot went through the effort to write his own JIT for a 486-class machine, but certainly it could be done…

What I meant was that the shader is a pluggable function in this implementation. If you wanted to change the shader function (say add texture or environment mapping) in this implementation, it would be a fairly minor code change that would have a relatively small incremental performance hit. If you wanted to do that for a highly optimized 90s era fixed pipeline software renderer, you'd most likely need to rewrite it from scratch, and certain operations wouldn't be feasible at all. So, this is paying a lot of the cost for flexibility up front.

Nice blog, it's a fascinating project to build something like this from the ground up.

(I actually have some phong-teapot-on-a-486 code, written when I was 16, which I keep meaning to dig up and post. It managed a few tens of thousands of triangles/sec.)

That's probably a good thing. A small, private company can base their development off the existing design and deliver IP that's 95% as fast as the best in class for 30% of the cost. Nvidia/AMD/imagination disrupted.

Thanks for the negative top comment, negative comment man. These kinda posts are really turning me off to hacker news. Yeah, you were awesome back in the day. Congrats.

I wonder how well this would run my recently discussed Cuckoo Cycle proof-of-work [1], where the bottleneck is atomically updating bit-pairs in a huge array randomly accessed by truncated outputs of siphash_2_4, by as many threads as possible.

The hyperthreading should allow for many outstanding loads/stores hopefully saturating the memory subsystem, while the ability to add instructions could be useful in reducing the instruction count of each siphash round.

[1] https://news.ycombinator.com/item?id=10957765

Have you looked at the Knights Landing architecture? It seems that the 3d stacked memory design would greatly accelerate such an application.

Yes; I tried a Xeon Phi. And I reported my experience as:

I wanted to treat the Xeon Phi like a regular Xeon with just many more cores. So I ran my benchmark mostly unchanged. I was surprised however that the single threaded performance was roughly 20x lower than a normal Xeon. Using all 240 threads I was still doing no better than with 12 cores on a normal Xeon. It seems that the Xeon Phi memory subsystem is not really optimized for multithreaded random access.

The provider of that system suggested that I ought to perform computation and memory access (including prefetching) on the SIMD units (VPUs), but I haven't gotten around to studying the use of VPUs yet...

The Knights Corner (2012-2015) Xeon Phi was based on a modified and scaled down version of the Intel P54C core... the same one used in the original 1995 Pentium. On top of that, each core only runs at 1.053 to 1.1GHz. Why would you think that single threaded performance would be any good for an in order superscalar core that is 20 years old?

IIRC, it's actually a bit worse: each core could run two threads, but they'd run alternating clock cycles, like the Cell PPUs - unless you have two threads running, each core has half that speed. A normal optimization trick of spreading across as many cores as possible backfires here.

But that was integer performance. Each core also had a beefy SIMD unit, twice as wide as the one in then current Xeons.

I was specifically asking about Knights Landing because it has an entirely different memory subsystem than Xeon Phi. You might want to take a look at that.

Nice work! Now someone just needs to port it to Chisel.[0]

Open Source GPUs seem like they are more "in range" these days thanks to projects like Vulkan and SPIR-V[1] which significantly improves the driver situation for GPGPUs.

[0] https://github.com/ucb-bar/chisel

[1] https://www.khronos.org/vulkan/

Manufacturing is still the critical barrier for open source hardware. It's not infinitely replicable at zero cost like software.

Oh for sure, but not all hardware is for consumers. I used to design (and redesign every six months or so) a specialized hardware rendering cluster from commodity parts and at this point, the entire design is memory bandwidth limited.

FPGAs might be cost effective given that the total hardware cost is currently around $2 million with commodity motherboards, CPUs, and GPUs, since I could spend the silicon more wisely (and ideally, cut power usage at the same time) by implementing the actual software algorithms I use more carefully. I'm keeping a close eye on RISC-V and related projects.

This is juicy! [RISC-V+Nyuzi] running Linux/BSD at the same performance/watt as [ARM+Mali] opens up both the smartphone/embedded market & servers.

The author has plenty of other great hardware/software projects https://github.com/jbush001

Nyuzi is a Swahili word for threads.

Reply on news.ycombinator.com