Estimate Complexity

Let's estimate the total number of floating-point operations (FLOPs) required to train GPT-3 step by step, using reasonable assumptions and approximations:

Step 1: Identify GPT-3 Parameters and Training Setup

• GPT-3 has approximately (175 ext{ billion}) parameters.
• Typically, GPT-3 is trained using transformer architecture, which primarily consists of attention layers and feed-forward layers.
• Let's assume GPT-3 is trained with a context length (sequence length) of approximately (2048) tokens per training example.
• Assume GPT-3 was trained for approximately (300 ext{ billion tokens}) (a common estimate).

Step 2: Estimate FLOPs per Token

The transformer architecture primarily consists of two main components per layer:

• Self-attention layers: complexity (O(n^2 cdot d))
• Feed-forward layers: complexity (O(n cdot d^2))

Where:

• (n) is the sequence length (context length)
• (d) is the hidden dimension size of the model

GPT-3 (175B) typically has:

• Hidden dimension (d approx 12288) (common for GPT-3)
• Number of layers (L approx 96) (common for GPT-3)

Let's verify quickly:

• Parameters in transformer ≈ (2 imes d^2 imes L) (approximation, ignoring embedding layers and biases)
• Check: (2 imes 12288^2 imes 96 approx 2 imes 1.51 imes 10^8 imes 96 approx 2.9 imes 10^{10}) parameters. This is about 29 billion parameters. GPT-3 has 175 billion parameters, meaning the actual GPT-3 has more complexity (due to embedding layers, attention heads, biases, and output layers). Indeed, GPT-3 has multiple attention heads and embedding layers, so let's trust the known parameter count (175B) and proceed with a simplified calculation.

Step 3: Simplified FLOPs per Token Estimation

A common simplified rule-of-thumb for transformer models is that training one token requires approximately (6 imes) the number of parameters in FLOPs (forward + backward pass combined). This heuristic is widely used in practice.

Thus, for GPT-3 (175B parameters):

• FLOPs per token ≈ (6 imes 175 imes 10^9 = 1.05 imes 10^{12}) FLOPs per token.

Step 4: Total FLOPs for Training

Given GPT-3 was trained on approximately (300 ext{ billion tokens}):

[ ext{Total FLOPs} = ( ext{FLOPs per token}) imes ( ext{number of tokens}) ]

[ = (1.05 imes 10^{12}) imes (3.0 imes 10^{11}) ]

[ = 3.15 imes 10^{23} ext{ FLOPs} ]

Step 5: Final Approximation

Thus, the total number of FLOPs required to train GPT-3 is approximately:

[ oxed{3.15 imes 10^{23} ext{ FLOPs}} ]

Summary of Reasoning:

• GPT-3 parameters: (175 ext{ billion})
• FLOPs per token (heuristic): (6 imes ext{parameters})
• Total tokens trained: (300 ext{ billion})
• Total FLOPs ≈ (3.15 imes 10^{23})

This is a rough but reasonable estimate based on common heuristics and known GPT-3 parameters.