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by Mehdi2277
688 days ago
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My experience working on ml at couple faang like companies is gpus actually tend to be too fast compute wise and often models are unable to come close to theoretical nvidia flops numbers. In that very frequently bottlenecks from profiling are elsewhere. It is very easy to have your data reading code be bottleneck. I have seen some models where our networking was bottleneck and could not keep up with the compute and we had adjust model architecture in ways to reduce amount of data transferred in training steps across the cluster. Or maybe you have gpu memory bandwidth as bottleneck. Key idea in flash attention work is optimizing attention kernels to lower amount of vram usage and stick to smaller/faster sram. This is valuable work, but is also kind of work that is pretty rare engineer I have worked with would have cuda kernel experience to create custom efficient kernels. Some of the models I train use a lot of sparse tensors as features and tensorflow’s sparse gpu kernel is rather bad with many operations either falling back to cpu or sometimes I have had gpu sparse kernel that was slower than cpu equivalent kernel. Several times densifying and padding tensors with large fraction of 0’s was faster than using sparse kernel. I’m sure a few companies/models are optimized enough to fit ideal case but it’s rare. Edit: Another aspect of this is nature of model architecture that are good today is very hardware driven. Major advantage of transformers over recurrent lstm models is training efficiency on gpu. The gap in training efficiency is much more dramatic with gpu than cpu for these two architectures. Similarly other architectures with sequential components like tree structured/recursive dynamic models tend to fit badly for gpu performance wise. |
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Let me reframe the question - assume it's not only 100x GPUs, but all the performance bottlenecks you've mentioned are also solved or accelerated x100.
What kind of improvement would we observe, given the current state of the models and knowledge ?