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Making AMD GPUs competitive for LLM inference (2023)

blog.mlc.ai

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Re: Making AMD GPUs competitive for LLM inference (2023)

#151

Earlier quoted context omitted.

The 4090 offers 82.58 teraflops of single-precision performance compared to the Radeon Pro VII's 13.06 teraflops.

On the other hand, for double precision a Radeon Pro VII is many times faster than a RTX 4090 (due to 1:2 vs. 1:64 FP64:FP32 ratio). Moreover, for workloads limited by the memory bandwidth, a Radeon Pro VII and a RTX 4090 will have about the same speed, regardless what kind of computations are performed. It is said that speed limitation by memory bandwidth happens frequently for ML/AI inferencing.

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Re: Making AMD GPUs competitive for LLM inference (2023)

#152
post #9

I have come across quite few startups who are trying a similar idea: break the nvidia monopoly by utilizing AMD GPUs (for inference at least): Felafax, Lamini, tensorwave (partially), SlashML. Even saw optimistic claims like CUDA moat is only 18 months deep from some of them [1]. Let's see. [1] https://www.linkedin.com/feed/update/urn:li:activity:7275885...

AMD GPUs are becoming a serious contender for LLM inference. vLLM is already showing impressive performance on AMD [1], even with consumer-grade Radeon cards (even support GGUF) [2]. This could be a game-changer for folks who want to run LLMs without shelling out for expensive NVIDIA hardware. [1] https://blog.vllm.ai/2024/10/23/vllm-serving-amd.html [2] https://embeddedllm.com/blog/vllm-now-supports-running-gguf-...

AMD decided not to release a high-end GPU this cycle so any investment into 7x00 or 6x00 is going to be wasted as Nvidia 5x00 is likely going to destroy any ROI from the older cards and AMD won't have an answer for at least two years, possibly never due to being non-existing in high-end consumer GPUs usable for compute.

Re: Making AMD GPUs competitive for LLM inference (2023)

#154
post #125
post #97

Earlier quoted context omitted.

The problem is that the specs of AMD consumer-grade GPUs do not translate to computer performance when you try and chain more than one together. I have 7 NVidia 4090s under my desk happily chugging along on week long training runs. I once managed to get a Radeon VII to run for six hours without shitting itself.

> I have 7 NVidia 4090s under my desk I have 6 Radeon Pro VII under my desk (in a single system BTW), and they run hard for weeks until I choose to reboot e.g. for Linux kernel updates. I bought them "new old stock" for $300 apiece. So that's $1800 for all six.

Are you running ml workloads or solving differential equations?

The two are rather different and one market is worth trillions, the other isn't.

Re: Making AMD GPUs competitive for LLM inference (2023)

#155

Great, I have yet to understand why does not the ML community really push or move away from CUDA? To me, it feel like a dinosaur move to build on top of CUDA which is screaming proprietary nothing about it is open source or cross platform. The reason why I say its dinosaur is, imagine, we as a dev community continued to build on top of Flash or Microsoft Silverlight... LLM and ML has been out for quiet a while, with…

For me personally, hacking together projects as a hobbiest, 2 reasons : 1. It just works. When i tried to build things on Intel Arcs, i spent way more hours bikeshedding ipex and driver issues than developing 2. LLMs seem to have more cuda code in their training data. I can leverage claude and 4o to help me build things with cuda, but trying to get them to help me do the same things on ipex just doesn't work. I'd ver…

If CUDA counts as “just works”, I dread to see the dark, unholy rituals you need to invoke to get ROCm to work. I have spent too many hours browsing the Nvidia forums for obscure error codes and driver messages to ever consider updating my CUDA install and every time I reboot my desktop for an update I dread having to do it all over again.

Re: Making AMD GPUs competitive for LLM inference (2023)

#156
post #5

Earlier quoted context omitted.

They don’t, but GPUs were designed for doing matrix multiplications even without the special hardware instructions for doing matrix multiplication tiles. Also, the forward pass for transformers is memory bound, and that is what does token generation.

Well sure, but in other GPU tasks, like Raytracing, the difference between these GPUs is far more pronounced. And AMD has passable Raytracing units (NVidias are better but the difference is bigger than these LLM results). If RAM is the main bottleneck then CPUs should be on the table.

The main bottleneck is memory bandwidth. CPUs have less memory bandwidth than GPUs.

Re: Making AMD GPUs competitive for LLM inference (2023)

#157

Earlier quoted context omitted.

Gigabytes per second? What is this, bandwidth for ants? My years old pleb tier non-HBM GPU has more than 4 times the bandwidth you would get from a PCIe Gen 7 x16 link, which doesn't even officially exist yet.

> 4 times the bandwidth you would get from a PCIe Gen 7 x16 link So you have a full terabyte per second of bandwidth? What GPU is that? (The 64GB/s number is an x4 link. If you meant you have over four times that, then it sounds like CXL would be pretty competitive.)

The 3090 Ti and 4090 both have 1.01TB/sec memory bandwidth:

https://www.techpowerup.com/gpu-specs/geforce-rtx-3090-ti.c3...

Re: Making AMD GPUs competitive for LLM inference (2023)

#158

Earlier quoted context omitted.

Already an ancient Radeon VII from 5 years ago had 1 terabyte per second of memory bandwidth. Later consumer GPUs have regressed and only RTX 4090 offers the same memory bandwidth in the current NVIDIA generation.

Radeon VII had HBM. So I can understand a call for returning to HBM, but it's an expensive choice and doesn't fit the description.

That seems unlikely given that the full HBM supply for the next year has been earmarked for enterprise GPUs. That said, it would be definitely nice if HBM became available for consumer GPUs.

Re: Making AMD GPUs competitive for LLM inference (2023)

#159

Earlier quoted context omitted.

Yes CXL will soon benefit from PCIe Gen 7 x16 with expected 64GB/s in 2025 and the non-HBM bandwidth I/O alternative is increasing rapidly by the day. For most inferences of near real-time LLM it will be feasible. For majority of SME companies and other DIY users (humans or ants) with their localized LLM should not be any issues [1],[2]. In addition new techniques for more efficient LLM are being discover to reduce t…

No. Memory bandwidth is the important factor for LLM inference. 64GB/s is 4x less than the hypothetical I granted you (Gen7x16 = 256GB/s), which is 4x less than the memory bandwidth on my 2 year old pleb GPU (1TB/s), which is 10x less than a state of the art professional GPU (10TB/s), which is what the cloud services will be using. That's 160x worse than cloud and 16x worse than what I'm using for local LLM. I am kee…

It is reportedly 242GB/sec due to overhead:

https://en.wikipedia.org/wiki/PCI_Express#PCI_Express_7.0

Re: Making AMD GPUs competitive for LLM inference (2023)

#160

Earlier quoted context omitted.

Well sure, but in other GPU tasks, like Raytracing, the difference between these GPUs is far more pronounced. And AMD has passable Raytracing units (NVidias are better but the difference is bigger than these LLM results). If RAM is the main bottleneck then CPUs should be on the table.

RAM is (often) the bottleneck for highly parallel GPUs, but not for CPUs. Though the distinction between the two categories is blurring.

Memory bandwidth is the bottleneck for both when running GEMV, which is the main operation used by token generation in inference. It has always been this way.
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