tensil VS VexRiscv

This is an example project on the higher side of complexity: https://github.com/tensil-ai/tensil.

You might be interested to checkout www.tensil.ai, an open source ML accelerator for FPGA. We don't officially support Stratix yet but you should be able to adapt it quite easily. Reach out on our Discord if you want to talk about it!

www.tensil.ai

You should check out Tensil. That's what i had the most success with. You can just follow the tutorial for pynq-z1, only diffrence is that you need to define pynq-z2 board files instead of the ones listed in the tutorial when making your vivado project. The developers are also very active and helpful on discord and github. You can find them at www.tensil.ai

Hello HN! I'm Tom, co-founder at Tensil (https://www.tensil.ai/). We design free and open source machine learning accelerators that anyone can use.

A machine learning inference accelerator is a specialized chip that can run the operations used in ML models very quickly and efficiently. It can be either an ASIC or an FPGA, with ASIC giving better performance but FPGA being more flexible.

Custom accelerators offer dramatically better performance per watt than existing GPU and CPU options. Massive companies like Google and Facebook use them to make training and inference cheaper. However, everyone else has been left out: small and mid-sized companies, students and academics, hobbyists and tinkerers currently have no chance of getting ML hardware that perfectly suits their needs. We aim to change that, starting with ML inference on embedded and edge FPGA platforms. Our dream is that our accelerators help people make new applications possible that simply weren't feasible before.

We believe that advances in AI go hand in hand with advances in computing hardware. As a couple of software and ML engineers hoping to live in a world alongside intelligent machines, we wanted to know why those hardware advances were taking so long! We taught ourselves digital design and gradually realized that the next generation of hardware will need to be finely customized to enable state of the art ML models at the edge, that is, running on your devices and not in the cloud. In the CPU world, the RISC-V RocketChip implementation has proven the value of customizable compute hardware. The problem was that no-one was building that kind of capability for ML acceleration. We started Tensil to build customizable ML accelerators and see what kind of applications people can create with them.

Tensil is a set of tools for running ML models on custom accelerator architectures. It includes an RTL generator, a model compiler, and a set of drivers. It enables you to create a custom accelerator, compile an ML model targeted at it, and then deploy and run that compiled model. To see how to do this and get it running on an FPGA platform, check out our tutorial at https://www.tensil.ai/docs/tutorials/resnet20-ultra96v2/.

We developed an accelerator generator in Chisel and then wrote a parameterizable graph compiler in Scala. (Fun fact: unlike in software, formal verification is actually a totally viable way to test digital circuits and we have made great use of this technique.) The accelerator generator takes in the desired architecture parameters and produces an instance of the accelerator which can be synthesized using standard EDA tools. The compiler implements ML models using the accelerator’s instruction set and can target any possible instance of the accelerator.

Currently, the accelerator architecture is based around a systolic array, similar to well-known ML ASICs. You can view the architecture spec in our documentation. The compiler performs a wide variety of tasks but is optimized for convolutional neural networks. There are also drivers for each supported platform, currently limited to FPGAs running bare-metal or with a host OS.

When you tell the driver to run your ML model, it sets up the input data and then streams the compiled model into the accelerator. The accelerator independently accesses host memory during execution. When the accelerator is done, the driver is notified and looks for the output in the pre-assigned area of host memory.

How are we different from other accelerator options? There are many ML ASICs out there but they are all locked into a single architecture, whereas we have customization at the core of our technology. This offers the potential for a better trade-off between performance/price/watts/accuracy. Compared with other FPGA options, Xilinx DPU is great but it’s closed source and can be difficult to work with if your model is in any way customized. By going open source, we aim to support the widest possible range of models. FINN is a very cool project but requires big changes to your model in order to work, and also typically requires large FPGAs which are unsuitable for edge deployments. We work out of the box with any model (no need to quantize), and on small edge FPGAs. For embedded systems, tflite/tfmicro are great for deploying very small ML models on extremely constrained edge devices, but they are limited in terms of the performance and accuracy that can be achieved. Our tools allow you to work with full size state of the art models at high accuracy and speed.

Currently we're focused on the edge and embedded ML inference use case. If you

With LiteX you can synthesize a VexRiscV processor. You can run Linux on it. The toolchain is pretty easy to use, as long as you use Xilinx Vivado to compile to gateware.

I don't get what's going on with licensing and device support. I'm missing something here perhaps, but we use Cyclone 10 GX onwards and Quartus Pro so I don't have enough context maybe. Have you considered swapping your Nios ii to a VexRISCV as a side note? At ~1 Dhrystone MIPS/MHz it's roughly double that of the Nios V, for very few resources. All open source too. None of the migration documentation support though, so I can't judge how hard it would be.

If you use LiteX to generate a VexRiscV system-on-a-chip, you can include an open source DDR DRAM PHY. This works on Xilinx Spartan-6, Spartan7Artix7/Kintex7/Virtex7 FPGAs, and Lattice ECP5 FPGAs. DDR/LPDDR/DDR2/DDR3 depending on the FPGA.

Something like https://github.com/SpinalHDL/VexRiscv will take far fewer

A CPU built around the Gentoo philosophy would look like https://github.com/SpinalHDL/VexRiscv ;). Don't want an MMU? Fine. Need a larger RAM interface? You got it. Barrel ALU for DSP? Sure.

Interpreted languages work by consolidating all of the optimization effort in the interpreter. This is similar to how CPUs work now, instead of extremely specific optimizations that are hard to create distributed among all code we use very general optimizations that push the limits of mathematics that is centralized in a CPU.

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Itanium had a lot of contemporary issues that made it not work. I would certainly blame Intel's business practices and reputation for a large part of it. There are likely niches for such processors. The VLIW is useful for DSP or graphics. Indeed, the only extant VLIW (that I know of) processor is the Russian Elbrus. I think the VLIW is only included to let them reuse a lot of the core logic of the CPU to drive a DSP engine, useful for radar and scientific simulation, though the sci sim would probably use commercial hardware which would be faster.

It works on GPUs because they're doing DSP, basically. We could have weirder topologies for GPUs however, like a massive string of ALUs driven off an embedded core, so you try to kachunk all your data in a single clock domain after configuring the ALU string.

4) https://github.com/SpinalHDL/VexRiscv

I really like Chisel HDL or any other new HDL languages like SpinalHDL or migen b/c it allows you to create some very complex yet modular designs. See VexRiscv or LiteX for instance. Languages like this exist b/c there is a need for it, but I wouldn't say that you should learn these new languages over verilog. All these languages output verilog/VHDL for now, but there is work being to done eliminate the need for outputting verilog; eventually, Chisel will output an open source CIRCT IR. Hope is to get EDA vendors to support this IR which I'm sure will take a while. For now, you should definitely learn Verilog or VHDL before Chisel.

I'd recommend giving vexriscv a look. It'll handily fit on your FPGA, leaving plants of room for I2C, VGA output, and whatever multiplication you end up wanting to do. It's very easy to get set up, and their example "briey" SOC even has VGA output already, but not hardware I2C (though you could easily bitbang it with the core). Adding in I2C via a "plugin" should be trivial.