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Hacked Nvidia 4090 GPU driver to enable P2P

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Re: Hacked Nvidia 4090 GPU driver to enable P2P

#91

Can someone ELI5 what this may make possible that wasn't possible before? Does this mean I can buy a handful of 4090s and use it in lieu of an h100? Just adding the memory together?

No. The Nvidia A100 has a multi-lane NVLink interface with a total bandwidth of 600 GB/s. The "unlocked" Nvidia RTX 4090 uses PCIe P2P at 50 GB/s. It's not going to replace A100 GPUs for serious production work, but it does unlock a datacenter-exclusive feature and has some small-scale applications.

Re: Hacked Nvidia 4090 GPU driver to enable P2P

#92
post #89

I wish more hardware companies would publish more documentation and let the community figure out the rest, sort of like what happened to the original IBM VGA (look up "Mode X" and the other non-BIOS modes the hardware is actually capable of - even 800x600x16!) Sadly it seems the majority of them would rather tightly control every aspect of their products' usage since they can then milk the userbase for more $$$, but…

Then they couldn't charge different customers different amounts for the same HW. It's not a win for everyone.

The price of 4090 may increase now, in theory locking out some features might have been a favor for some of the customers.

Re: Hacked Nvidia 4090 GPU driver to enable P2P

#93

I was always fascinated by George Hotz's hacking abilities. Inspired me a lot for my personal projects.

I agree. It is fascinating. When you observe his development process (btw, it is worth noting his generosity in sharing it like he does) he gets frequently stuck on random shallow problems which a perhaps more knowledgable engineer would find less difficult. It is frequent to see him writing really bad code, or even wrong code. The whole twitter chapter is a good example. Yet, himself, alone just iterating resiliently, just as frequently creates remarkable improvements. A good example to learn from. Thank you geohot.

Re: Hacked Nvidia 4090 GPU driver to enable P2P

#94
post #80

Incredible! I'd been wondering if this was possible. Now the only thing standing in the way of my 4x4090 rig for local LLMs is finding time to build it. With tensor parallelism, this will be both massively cheaper and faster for inference than a H100 SXM. I still don't understand why they went with 6 GPUs for the tinybox. Many things will only function well with 4 or 8 GPUs. It seems like the worst of both worlds now…

A macbook is cheaper though

Re: Hacked Nvidia 4090 GPU driver to enable P2P

#96
post #80

Incredible! I'd been wondering if this was possible. Now the only thing standing in the way of my 4x4090 rig for local LLMs is finding time to build it. With tensor parallelism, this will be both massively cheaper and faster for inference than a H100 SXM. I still don't understand why they went with 6 GPUs for the tinybox. Many things will only function well with 4 or 8 GPUs. It seems like the worst of both worlds now…

6 GPUs because they want fast storage and it uses PCIe lanes.

Besides the goal was to run a 70b FP16 model (requiring roughly 140GB VRAM). 6*24GB = 144GB

Re: Hacked Nvidia 4090 GPU driver to enable P2P

#98
post #42

Earlier quoted context omitted.

Looks like we're only a few years away from a bona fide cyberpunk dystopia, in which only governments and megacorps are allowed to use AI, and hackers working on their own hardware face regular raids from the authorities.

I find it baffling that ideas like "govern compute" are even taken seriously. What the hell has happened to the ideals of freedom?! Does the government own us or something?

If AI is actually capable of fulfilling all the capabilities suggested by people who believe in the singularity, it has far more capacity for harm than nuclear weapons.

I think most people who are strongly pro-AI/pro-acceleration - or, at any rate, not anti-AI - believe that either (A) there is no control problem (B) it will be solved (C) AI won't become independent and agentic (i.e. it won't face evolutionary pressure towards survival) or (D) AI capabilities will hit a ceiling soon (more so than just not becoming agentic).

If you strongly believe, or take as a prior, one of those things, then it makes sense to push the gas as hard as possible.

If you hold the opposite opinions, then it makes perfect sense to push the brakes as hard as possible, which is why "govern compute" can make sense as an idea.

Re: Hacked Nvidia 4090 GPU driver to enable P2P

#99
post #80

Incredible! I'd been wondering if this was possible. Now the only thing standing in the way of my 4x4090 rig for local LLMs is finding time to build it. With tensor parallelism, this will be both massively cheaper and faster for inference than a H100 SXM. I still don't understand why they went with 6 GPUs for the tinybox. Many things will only function well with 4 or 8 GPUs. It seems like the worst of both worlds now…

A macbook is cheaper though

The extra $3k you'd spend on a quad-4090 rig vs the top mbp... ignoring the fact you can't put the two on even ground for versatility (very few libraries are adapted to apple silicone let alone optimized).

Very few people that would consider an H100/A100/A800 are going to be cross-shopping a macbook pro for their workloads.

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