> MegaTrain stores parameters and optimizer states in host memory (CPU memory) and treats GPUs as transient compute engines. For each layer, we stream parameters in and compute gradients out, minimizing persistent device state
This is pretty awesome. The only compute I have at home is an RTX 3080 with 10 GB of VRAM, so I struggle with training larger models (>40M, 50M params). I get OOM errors and have to optimize a lot.
I have a lot more CPU RAM in my PC, and this would likely increase the size of models I can train locally.
To make the most of these architectures I think the key is essentially moving more of the knowledge/capabilities out of the "weights" and into the complimentary parts of the system in a way that's proportionate to the capabilities of the hardware.
In the past couple months there's been a kind of explosion in small-models that are occupying a niche in this kind of AI-transcoding space. What I'm hoping we're right on the cusp of achieving is a similar explosion in what I'd call tool-adaptation, where an LLM paired with some mostly-fixed suite of tools and problem cases can trade off some generality for a specialized (potentially hyper-specialized to the company or user) role.
The thing about more transcoding-related tasks is that they in general stay in sync with what the user of the device is actively doing, which will also typically be closely aligned with the capabilities of the user's hardware and what they want to do with their computer. So most people aren't being intentional about this kind of stuff right now, partly out of habit I think, because only just now does it make sense to think of personal computer as "stranded hardware" now that they can be steered/programmed somewhat autonomously.
I'm wondering if with the right approach to MoE on local devices (which local llms are heading towards) we could basically amortize the expensive hit from loading weights in and out of VRAM through some kind of extreme batch use case that users still find useful enough to be worth the latency. LoRa is already really useful for this but obviously sometimes you need more expertise/specialization than just a few layers' difference. Experimenting with this right now. It's the same basic principle as in the paper except less of a technical optimization and more workload optimization. Also it's literally the beginning of machine culture so that's kind of cool
The claims of the article assumes far more compute and far more VRAM..while the trick enables less back and forth, they don't eliminate it.
I doubt you meant 50M. Rather 50B?
You can only give it a try, but don't get your hopes high on a large context. If their technique works I would guess 8096k context limits would still OOM. 2048 maybe.
I'm extrapolating based on my experiment without this paper's trick to leverage the system memory.
> You can only give it a try, but don't get your hopes high on a large context.
You may or may not know this, but: when training off-the-shelf LLMs (i.e. ones which have a huge vocabulary) what consumes a huge amount of memory usage is calculating the cross-entropy loss (which gets worse the more tokens you stuff in your batch), so always use a fused cross-entropy kernel.
For example, for a Gemma 2 model with 2B parameters at a batch size of 8k this consumes 24GB of VRAM by default (!); you can fuse your cross-entropy loss with @torch.compile and that can cut down this memory usage to something like a few gigabytes, but with a dedicated kernel this becomes a few megabytes.
> This is pretty awesome. The only compute I have at home is an RTX 3080 with 10 GB of VRAM, so I struggle with training larger models (>40M, 50M params). I get OOM errors and have to optimize a lot.
I'm on the same GPU, its intimidating to me if I even want to bother training anything at all. Do you mind sharing what kind of training you've done with that GPU? :)
This isn't really anything new; I've been doing something like this for quite a while, I just haven't bothered writing a paper. (: Probably anyone who would seriously tackle the problem of "how do I train a huge model on a tiny amount of VRAM?" would come up with something similar.
However, most people in the field don't, because the actual practical utility of training huge models on a single GPU is quite low. (e.g they got 341 tok/s for a 14B model on a single 3090 while with my method I was getting ~1k tok/s on a single 4090; that's still very slow)
Also, there are more tricks one can use to speed up training/lower VRAM usage which they're not using. For example, you don't need any gradient offloading (you can just accumulate the gradients directly into the optimizers' states if you modify your optimizer), you can use Muon instead of Adam (which needs only half of VRAM of Adam), you can use quantization (both for parameters and for the optimizer states; e.g. I found Muon quantized into 4-bit working relatively well), etc.
341 is two orders of magnitude faster than your 1 tok/s so it doesn’t seem like their stuff is all that obvious. I also have no baseline for training to know if 341tok/s is slow but it seems speedy for a 3090.
The GPU is no longer the brain, it's the hand. The brain is your RAM. Suddenly that 256GB DDR5 build your wife questioned is 'research infrastructure.'
There isn't really such a thing as 'too slow' as an objective fact though. It depends on how much patience and money for electricity you have. In AI image gen circles I see people complaining if a model takes more than 5s to generate an image, and other people on very limited hardware who happily wait half an hour per image. It's hard to make a judgement call about what 'too slow' means. It's quite subjective.
If it would take so long to train that the model will be obsolete before the training is finished that might be considered too long. With ML you can definitely hit a point where it is too slow for any practical purpose.
Obsolete because of what? Because with limited hardware you’re never aiming for state of the art, and for fine-tuning, you don’t steer for too long anyway.
That’s just playing semantics. Nobody is talking about, “objective facts” or need define them here. If the step time is measured in days, and your model takes years to train, then it will never get trained to completion on consumer hardware (the entire point).
So distribute copies of the model in RAM to multiple machines, have each machine update different parts of the model weights, and sync updates over the network
> MegaTrain stores parameters and optimizer states in host memory (CPU memory) and treats GPUs as transient compute engines. For each layer, we stream parameters in and compute gradients out, minimizing persistent device state
This is pretty awesome. The only compute I have at home is an RTX 3080 with 10 GB of VRAM, so I struggle with training larger models (>40M, 50M params). I get OOM errors and have to optimize a lot.
I have a lot more CPU RAM in my PC, and this would likely increase the size of models I can train locally.
To make the most of these architectures I think the key is essentially moving more of the knowledge/capabilities out of the "weights" and into the complimentary parts of the system in a way that's proportionate to the capabilities of the hardware.
In the past couple months there's been a kind of explosion in small-models that are occupying a niche in this kind of AI-transcoding space. What I'm hoping we're right on the cusp of achieving is a similar explosion in what I'd call tool-adaptation, where an LLM paired with some mostly-fixed suite of tools and problem cases can trade off some generality for a specialized (potentially hyper-specialized to the company or user) role.
The thing about more transcoding-related tasks is that they in general stay in sync with what the user of the device is actively doing, which will also typically be closely aligned with the capabilities of the user's hardware and what they want to do with their computer. So most people aren't being intentional about this kind of stuff right now, partly out of habit I think, because only just now does it make sense to think of personal computer as "stranded hardware" now that they can be steered/programmed somewhat autonomously.
I'm wondering if with the right approach to MoE on local devices (which local llms are heading towards) we could basically amortize the expensive hit from loading weights in and out of VRAM through some kind of extreme batch use case that users still find useful enough to be worth the latency. LoRa is already really useful for this but obviously sometimes you need more expertise/specialization than just a few layers' difference. Experimenting with this right now. It's the same basic principle as in the paper except less of a technical optimization and more workload optimization. Also it's literally the beginning of machine culture so that's kind of cool
[delayed]
The claims of the article assumes far more compute and far more VRAM..while the trick enables less back and forth, they don't eliminate it.
I doubt you meant 50M. Rather 50B?
You can only give it a try, but don't get your hopes high on a large context. If their technique works I would guess 8096k context limits would still OOM. 2048 maybe.
I'm extrapolating based on my experiment without this paper's trick to leverage the system memory.
> You can only give it a try, but don't get your hopes high on a large context.
You may or may not know this, but: when training off-the-shelf LLMs (i.e. ones which have a huge vocabulary) what consumes a huge amount of memory usage is calculating the cross-entropy loss (which gets worse the more tokens you stuff in your batch), so always use a fused cross-entropy kernel.
For example, for a Gemma 2 model with 2B parameters at a batch size of 8k this consumes 24GB of VRAM by default (!); you can fuse your cross-entropy loss with @torch.compile and that can cut down this memory usage to something like a few gigabytes, but with a dedicated kernel this becomes a few megabytes.
> This is pretty awesome. The only compute I have at home is an RTX 3080 with 10 GB of VRAM, so I struggle with training larger models (>40M, 50M params). I get OOM errors and have to optimize a lot.
I'm on the same GPU, its intimidating to me if I even want to bother training anything at all. Do you mind sharing what kind of training you've done with that GPU? :)
This isn't really anything new; I've been doing something like this for quite a while, I just haven't bothered writing a paper. (: Probably anyone who would seriously tackle the problem of "how do I train a huge model on a tiny amount of VRAM?" would come up with something similar.
However, most people in the field don't, because the actual practical utility of training huge models on a single GPU is quite low. (e.g they got 341 tok/s for a 14B model on a single 3090 while with my method I was getting ~1k tok/s on a single 4090; that's still very slow)
Also, there are more tricks one can use to speed up training/lower VRAM usage which they're not using. For example, you don't need any gradient offloading (you can just accumulate the gradients directly into the optimizers' states if you modify your optimizer), you can use Muon instead of Adam (which needs only half of VRAM of Adam), you can use quantization (both for parameters and for the optimizer states; e.g. I found Muon quantized into 4-bit working relatively well), etc.
341 is two orders of magnitude faster than your 1 tok/s so it doesn’t seem like their stuff is all that obvious. I also have no baseline for training to know if 341tok/s is slow but it seems speedy for a 3090.
1k tok/s = 1000 tok/s...
OP said 1k, not 1
The GPU is no longer the brain, it's the hand. The brain is your RAM. Suddenly that 256GB DDR5 build your wife questioned is 'research infrastructure.'
I was wondering how well this would work :) You can definitely push this further, the question is: how well can the gradients and updates compress?
How long would it actually take to train a 120B model on an H200? What if you have 8?
sounds very similar to https://docs.pytorch.org/docs/stable/distributed.fsdp.fully_... i wonder how much this could be replicated using only this pytorch primitive
This would likely only get used for small finetuning jobs. It’s too slow for the scale of pretraining.
It’s too slow for the scale of pretraining.
There isn't really such a thing as 'too slow' as an objective fact though. It depends on how much patience and money for electricity you have. In AI image gen circles I see people complaining if a model takes more than 5s to generate an image, and other people on very limited hardware who happily wait half an hour per image. It's hard to make a judgement call about what 'too slow' means. It's quite subjective.
If it would take so long to train that the model will be obsolete before the training is finished that might be considered too long. With ML you can definitely hit a point where it is too slow for any practical purpose.
Obsolete because of what? Because with limited hardware you’re never aiming for state of the art, and for fine-tuning, you don’t steer for too long anyway.
Because there is a new model that is better, faster, more refined, etc...
If your training time is measured in years or decades it probably won't be practical.
That’s just playing semantics. Nobody is talking about, “objective facts” or need define them here. If the step time is measured in days, and your model takes years to train, then it will never get trained to completion on consumer hardware (the entire point).
So distribute copies of the model in RAM to multiple machines, have each machine update different parts of the model weights, and sync updates over the network
Seems similar to Microsoft DeepSpeed.
The compare against “DeepSpeed ZeRO-3” apparently.