[HN Gopher] Techniques for Training Large Neural Networks
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       Techniques for Training Large Neural Networks
        
       Author : todsacerdoti
       Score  : 80 points
       Date   : 2022-06-09 16:01 UTC (6 hours ago)
        
 (HTM) web link (openai.com)
 (TXT) w3m dump (openai.com)
        
       | Der_Einzige wrote:
       | What if you abandoned gradients/back-prop entirely? They knew
       | that for reinforcement learning this was good clear back in 2017!
       | 
       | https://openai.com/blog/evolution-strategies/
       | 
       | Put engineering effort into creating fast, GPU powered
       | (tensorflow/pytorch) algorithms for neuroevolution of the
       | _weights_ of a neural network. I 'm still not convinced that
       | properly leveraged gradient free/Feed-forward only optimizers
       | have been tried yet by researchers - namely because they never
       | actually wrote fast gradient free optimizers!
        
         | erwincoumans wrote:
         | Black box optimization such as CMA-ES or Augmented Random
         | Search (ars) are used by researchers, for example:
         | 
         | CMA-ES: https://blog.otoro.net/2017/10/29/visual-evolution-
         | strategie...
         | 
         | ARS: https://arxiv.org/abs/1803.07055
         | 
         | Those optimizers are efficient up to certain neural network
         | sizes.
        
         | pchiusano wrote:
         | You might like these posts on gradient free optimization:
         | 
         | http://pchiusano.github.io/2019-07-06/learning-without-a-gra...
         | 
         | http://pchiusano.github.io/2020-10-12/learning-without-a-gra...
         | 
         | I think you're right that the area is underexplored.
        
           | eismcc wrote:
           | Has anyone tried using another NN as the "gradient" function?
           | With the hope of making it less "blind?"
        
             | rolisz wrote:
             | DeepMind has a thing called synthetic gradients:
             | https://www.deepmind.com/blog/decoupled-neural-interfaces-
             | us....
        
       | liuliu wrote:
       | 1. I missed this paper https://www.microsoft.com/en-
       | us/research/uploads/prod/2018/0... when doing my own feature map
       | compression research: https://liuliu.me/eyes/reduce-
       | another-70-memory-usage-for-de.... Thanks for point it out!
       | 
       | 2. Otherwise, most of these are obvious optimizations. One widely
       | popular optimization (that I consider non-obvious) is ZeRO-
       | Offload, in particularly the gradient sharding scheme (although
       | once learned, the sharding itself is pretty straightforward, just
       | a bit chatty). One thing I think undervalued these years though
       | is Alex's "One weird trick": https://arxiv.org/abs/1404.5997.
       | This scheme is much convoluted but very effective when training
       | large MLP. It is not popular probably because a). the
       | implementation is non-obvious; b). large MLP fall out of fashion
       | quickly, and the computation shape for transformer looks probably
       | very different from the MLP its originally trying to solve (with
       | 4096 activations per layer).
        
       | mirker wrote:
       | Seems similar to the Huggingface tutorial:
       | https://huggingface.co/docs/transformers/parallelism.
       | 
       | What's different?
        
       | sydthrowaway wrote:
       | Amazing
        
       | superb-owl wrote:
       | I'm really excited to see folks starting to talk about
       | parallelizing machine learning. The conversation has been
       | dominated by GPU-friendly techniques - a classic example of
       | "everything looks like a nail when you have a hammer".
       | 
       | I hope we start seeing more massively parallel training
       | strategies (most likely with GPUs under the hood still)
        
         | ShamelessC wrote:
         | Strange comment. May need to edit something? I can't parse it -
         | parallel (e.g. CUDA) techniques have been popular since
         | AlexNet.
        
           | Tostino wrote:
           | I parsed that as meaning something more like BOINC to
           | distribute the work and piece together the final result.
        
         | kristjansson wrote:
         | > starting
         | 
         | This is a strange comment to see. The techniques in TFA have
         | been at the heart of a the last few years of progress in large-
         | scale language models, image generation, etc?
        
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