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FPGAs Need a New Future

allaboutcircuits.com

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Re: FPGAs Need a New Future

#121

Post by pjc50 »

tyami94 wrote: post #28
nospice wrote: post #12

To folks who wax lyrical about FPGAs: why do they need a future? I agree with another commenter: I think there are parallels to "the bitter lesson" here. There's little reason for specialized solutions when increasingly capable general-purpose platforms are getting faster, cheaper, and more energy efficient with every passing month. Another software engineering analogy is that you almost never need to write in assemb…

I can't say I agree with you here, if anything FPGAs and general purpose microprocessors go hand in hand. It would be an absolute game changer to be able to literally download hardware acceleration for a new video codec or encryption algorithm. Currently this is all handled by fixed function silicon which rapidly becomes obsolete. AV1 support is only just now appearing in mainstream chips after almost 8 years, and so…

> It would be an absolute game changer to be able to literally download hardware acceleration for a new video codec or encryption algorithm

That relies on "FPGAs everywhere", which is much further out than "GPUs everywhere".

I'm not sure where the state of the art is on this, but given the way that codecs work - bitstream splitting into tiles, each of which is numerically heavy but can be handled separately - how is development of hybrid codecs, where the GPU does the heavy lifting using its general purpose cores rather than fixed function decoder pipeline?

Re: FPGAs Need a New Future

#122

Post by imtringued »

exmadscientist wrote: post #14
blackguardx wrote: post #10

Earlier quoted context omitted.

You can pretty much do everything in Vivado from the command line as long as you know Tcl... Also, modern Verilog (AKA Systemverilog) fixes a bunch of the issues you might have had. There isn't much advantage to VHDL these days unless perhaps you are in Europe or work in certain US defense companies.

The main advantage to VHDL is the style of thinking it enforces. If you write your Verilog or SystemVerilog like it's VHDL, everything works great. If you write your VHDL like it's Verilog, you'll get piles of synthesis errors... and many of them will be real problems. So if you learn VHDL first, you'll be on a solid footing.

I haven't learned Verilog, only VHDL and even that with the explicit _ff pattern when I need flips flops and I never felt like there is anything difficult about VHDL

Is the North American insistence on teaching Verilog what's setting up students for failure since Verilog looks a bit more like a sequential programming language at first glance?

Re: FPGAs Need a New Future

#124

Post by imtringued »

KeplerBoy wrote: post #109
rfv6723 wrote: post #105

Earlier quoted context omitted.

FPGA for AI only makes sense when machine learning had diverse model architectures. After Transformer took over AI, FPGA for AI is totally dead now. Because Transformer is all about math matrix calculation, ASIC is the solution. Modern Datacenter GPU is nearly AISC now.

Yes, if you're doing what everyone else is doing you can just use tensor cores and libraries which optimize for that. Contrarily if you're doing something that doesn't map that well to tensor cores you have a problem: every generation a larger portion of the die is devoted to low/mixed precision mma operations. Maybe FGPAs can find a niche that is underserved by current GPUs, but I doubt it. Writing a cuda/hip/kokkos…

The primary niche of FPGAs is low latency, determinism and low power consumption. Basically what if you needed an MCU, or many MCUs but the ones in the market don't have enough processing power?

The Versal AI Edge line is very power efficient compared to trying to achieve the same number of FLOPs using a Ryzen based CPU.

Re: FPGAs Need a New Future

#125

Post by imtringued »

tverbeure wrote: post #97
xgstation wrote: post #68

I imagine FPGA could just be part of general CPU that provides user space APIs to program them to accelerate certain work flow, in other words, this sounds like exactly JIT to me. People may program FPGA as they need to, e.g. AV1 encoder/decoder, accelerate some NN layers, or even a JS runtime, am I thinking something too wild for hardware capability or is it just the ecosystem isn't there yet to allow such flexible…

My rule of thumb is a 40x silicon area ratio between FPGA and ASIC, a clock speed that is around 5x lower. And a lot more power consumption. If you have an application that can be done on a CPU, with lots of sequences dependencies (such as video compression/decompression), an FPGA doesn’t stand a chance compared to adding dedicated silicon area. That’s even more so if you’d embed an FPGA on a CPU die. Intel tried it…

I have yet to see the "FPGA is less power efficient" thing to be true. People are always comparing the same circuit in an FPGA Vs an ASIC but this is a nonsensical comparison because of three reasons:

FPGAs have hard wired blocks like DSPs which do not have any power disadvantages vs "ASIC" (only advantages actually)

the likelihood that there is an ASIC that happens to implement your particular design is very low

and off the shelf ASICs like GPUs and CPUs have significant amounts of overhead for each operation. This is especially evident with CPUs. They perform a small number of operations per cycle, but they have to pay the entire fixed energy cost of caches, registers, instruction decoding, etc per cycle. This is way way worse than programmable logic if you're mostly using the DSP and the block RAM slices.

Re: FPGAs Need a New Future

#126

Post by summa_tech »

exmadscientist wrote: post #37
exmadscientist wrote: post #31

Earlier quoted context omitted.

> you’d have to drop support for multiple voltage rails and thus multiple IO standards, which is exactly what you don’t want to lose. Yes? Yes it is? 9 times out of 10, my entire board is LVCMOS33. I would love to have the option to drop all of the power rail complexity in a simplified series of parts. Sometimes you need maximum I/O speed. Sometimes you need maximum I/O flexibility. Sometimes you need processing hors…

> often, what I actually need is just a little bit of weird logic that's asynchronous As a concrete example of this: two weeks ago I wanted a 21-input OR gate. It would have been wonderful if I could spend a little bit of money, buy a programmable thing in a 24-pin package, put it down, figure out some way to get the bitstream in (this is never pleasant in medium-volume manufacturing, so it's not like we're going to…

Would a SLG46880 work for you? It has 28 GPIOs, enough LUTs to make a 21-input OR gate, runs off 2.3-5.5V (two VCCIO partitions, but you can tie them together). It costs like a buck in 5k quantities - they used to be much cheaper when you bought them directly from Silego, but now that they've been acquired the price has been _improved_.

https://www.renesas.com/en/products/slg46880

Re: FPGAs Need a New Future

#127

Post by [deleted] »

rramadass wrote: post #73
exmadscientist wrote: post #13

FPGAs need their "Arduino moment". There have been so, so, so many projects where I've wanted just a little bit of moderately-complicated glue logic. Something pretty easy to dash off in VHDL or whatever. But the damn things require so much support infrastructure: they're complicated to put down on boards, they're complicated to load bitstreams in to, they're complicated to build those bitstreams for, and they're com…

> FPGAs need their "Arduino moment". This is exactly it. Why hasn't some expert group produced a very simple open design board with a simple Arduino-like IDE for FPGAs? Make it easy to access and use, get it into the hands of makers/hobbyists and watch the apps/ecosystem explode. As an example, one could provide soft-cores for 8051/RISC-V etc. right out of the box with a menu of peripherals to mix and match. Provide…

[deleted]

Re: FPGAs Need a New Future

#128

Post by kown7 »

ImPleadThe5th wrote: post #123

I have an old FPGA sitting around at home and I'm relatively comfortable with VHDL. I've never really thought of any interesting projects to do with it. Anyone know of anything?

That was my point as well: what can't you do with a uC or RPi?

It feels the use cases are dwindling and eaten by ASICs and uC

Re: FPGAs Need a New Future

#129

Post by Traster »

I was quite surprised the direction this article took. I wasn't expecting reheated whinging about the toolchain.

FPGAs do need a new future. They need a future where someone tapes out an FPGA! Xilinx produced Ultrascale+ over a decade ago and haven't done anything interesting since. Their Versal devices went off a tangent into SoCs, NOCs, AI engines - you know what they didn't do? Build a decent FPGA.

Altera did something ambitious back in 2014 when they proposed the hyper-register design, totally failed to execute on it and have been treading water because of the Intel cluster**. They're now an independent company but literally don't have anyone who knows how to tape out a chip.

I'm less familiar with the Lattice stuff, but since their most advanced product is still 16nm finfet I suspect they aren't doing anything newer than Xilinx or Altera.

We need a company that builds an FPGA. It doesn't matter what tooling you have because the fundamental performance gap between a custom FPGA solution and a CPU or GPU based solution is entirely eaten up by the fact the newest FPGA you can buy is a decade old and inexplicably still tens of thousands of dollars.

If FPGA technology had progressed at the same rate NVidia or Apple had pushed forward CPU/GPU performance, thered be some amazing opportunities to accelerate AI (on the path to then creating ASICs). But they haven't, so all the scaling laws have worked against them and the places they have a performance benefit have shrunk massively.

Re: FPGAs Need a New Future

#130

Post by ab71e5 »

ImPleadThe5th wrote: post #123

I have an old FPGA sitting around at home and I'm relatively comfortable with VHDL. I've never really thought of any interesting projects to do with it. Anyone know of anything?

I knew someone who created a mandelbrot set viewer that would display over an VGA port, you had a game controller to move around and zoom into it. Something like that?
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