Estimate Complexity

Estimating the total number of FLOPs (floating-point operations) required to train GPT-3 is a complex task, but I can provide a rough estimate by breaking it down step by step using reasonable assumptions based on what is generally known about large-scale language model training up to my knowledge cutoff in October 2023. Since I'm not searching online, I'll rely on logical reasoning and common knowledge about transformer models, computational scaling, and training practices.

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Step 1: Understand GPT-3's Scale

GPT-3, developed by OpenAI, is one of the largest language models of its time, with 175 billion parameters. The number of parameters is a key factor because the computational cost of training generally scales with the model size.

• Parameters: 175 billion (1.75 × 10^11).

Training large models like GPT-3 involves processing a massive dataset over many iterations (or tokens), and the FLOPs depend on the model architecture (primarily transformers), the number of tokens processed, and hardware efficiency.

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Step 2: FLOPs per Parameter per Token

In transformer models, the FLOPs per token for forward and backward passes during training can be approximated. A common rule of thumb for transformers is that training involves roughly 6 FLOPs per parameter per token for a single forward and backward pass. This accounts for:

• 2 FLOPs per parameter for the forward pass (matrix multiplications and activations).
• 4 FLOPs per parameter for the backward pass (gradients and updates).

So, for each token processed during training:

• FLOPs per token = 6 × number of parameters.

For GPT-3:

• FLOPs per token = 6 × 1.75 × 10^11 = 1.05 × 10^12 FLOPs.

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Step 3: Estimate the Number of Tokens Processed During Training

Training large language models involves processing a huge number of tokens, typically on the order of hundreds of billions to trillions. GPT-3 was likely trained on a dataset comparable to or larger than the size of publicly available text corpora like the Common Crawl.

A reasonable estimate for the number of tokens used to train GPT-3 is around 300 billion tokens. This is based on the scale of datasets used for similar models:

• Large models often see datasets with token counts on the order of 10^11 to 10^12.
• Reports on models like GPT-2 (which was smaller) suggest training on roughly 40 billion tokens, and scaling up to GPT-3 would likely involve a dataset 5–10 times larger.

So, let's assume:

• Total tokens processed = 300 billion = 3 × 10^11 tokens.

However, models are often trained for multiple epochs or with repeated data, and optimization techniques (like mixed precision) adjust effective token counts. For simplicity, I'll stick with this as a baseline for one full pass over the data, noting that training often involves multiple passes or sampled subsets.

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Step 4: Calculate Total FLOPs for Training

Now, multiply the FLOPs per token by the total number of tokens:

• Total FLOPs = (FLOPs per token) × (Total tokens)
• Total FLOPs = (1.05 × 10^12) × (3 × 10^11) = 3.15 × 10^23 FLOPs.

However, this assumes just one forward and backward pass over the dataset (one epoch). In practice, training involves multiple iterations, optimizations, and potentially sampling the data multiple times. A commonly used heuristic in deep learning literature for large language models (derived from scaling laws, see Kaplan et al., 2020) suggests that the total FLOPs can be approximated as roughly 6 × number of parameters × number of tokens, which we've already used, but tokens processed may exceed the dataset size due to multiple passes.

To refine this, let's consider that training often processes tokens equal to 2–3 times the number of parameters to achieve optimal performance (based on scaling laws where compute scales with model size and data size). Since 175 billion parameters × 2 is 350 billion tokens, our earlier assumption of 300 billion tokens is roughly in line with this.

Thus, I'll stick with ~3 × 10^11 tokens as a reasonable estimate.

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Step 5: Cross-Check with Scaling Laws

According to scaling laws for language models, the compute budget for optimal training scales as approximately proportional to the number of parameters raised to a power (often around 1.0 to 1.5 for FLOPs). For a model like GPT-3 with 175B parameters, we can compare it to smaller models.

For instance, GPT-2 (1.5B parameters) was trained with roughly 10^19 to 10^20 FLOPs (based on rough community estimates). Scaling up from 1.5B to 175B parameters (a factor of ~117), and assuming compute scales linearly or slightly super-linearly with parameters, we might expect FLOPs to scale by 100–1000x, leading to 10^21 to 10^23 FLOPs.

Our earlier estimate of 3.15 × 10^23 FLOPs fits within the upper range of this rough scaling check, suggesting it's plausible though possibly on the high side if fewer tokens or optimizations were used.

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Step 6: Account for Hardware and Efficiency

Modern training often uses mixed precision (FP16 or BF16), which reduces the number of FLOPs counted on hardware like GPUs or TPUs (since operations are cheaper). However, standard practice in reporting FLOPs for training typically uses full precision as the baseline. I've ignored efficiency tweaks for now, assuming reported FLOPs are in raw terms.

Additionally, hyperparameter tuning, multiple runs, or restarts might increase the total compute, but I'll exclude those for a baseline estimate of a single training run.

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Final Estimate

Based on the above reasoning, the total number of FLOPs required to train GPT-3 is approximately 3 × 10^23 FLOPs. This is derived from:

• 175 billion parameters.
• ~6 FLOPs per parameter per token.
• ~300 billion tokens processed during training.

This estimate aligns with rough industry expectations for models of this scale, though it could vary by a factor of 2–3 depending on exact dataset size, number of epochs, and training optimizations.

If I underestimated tokens (e.g., if GPT-3 saw closer to 500 billion tokens), the FLOPs would be closer to 5 × 10^23. Conversely, optimizations or fewer tokens could bring it down to 1–2 × 10^23.

Thus, my final ballpark estimate is ~3 × 10^23 FLOPs, with an uncertainty range of 1–5 × 10^23 FLOPs.