---
language:
- en
tags:
- pytorch
- causal-lm
license: apache-2.0
---

# Sparse GPT-J 6B

## Model Description
The sparse version of GPT-J 6B is a pruned variant derived from the original [GPT-J 6B](https://huggingface.co/EleutherAI/gpt-j-6b) model and the vast majority of linear layers maintain a 40% unstructured sparsity (except for the 'lm_head'). 


<figure>

| Hyperparameter       | Value      |
|----------------------|------------|
| \\(n_{parameters}\\) | 6053381344 |
| \\(n_{layers}\\)     | 28&ast;    |
| \\(d_{model}\\)      | 4096       |
| \\(d_{ff}\\)         | 16384      |
| \\(n_{heads}\\)      | 16         |
| \\(d_{head}\\)       | 256        |
| \\(n_{ctx}\\)        | 2048       |
| \\(n_{vocab}\\)      | 50257/50400&dagger; (same tokenizer as GPT-2/3) |
| Positional Encoding  | Rotary Position Embedding RoPE |
| RoPE Dimensions      | [64](https://github.com/kingoflolz/mesh-transformer-jax/blob/f2aa66e0925de6593dcbb70e72399b97b4130482/mesh_transformer/layers.py#L223) |
<figcaption><p><strong>&ast;</strong> Each layer consists of one feedforward block and one self attention block.</p>
<p><strong>&dagger;</strong> Although the embedding matrix has a size of 50400, only 50257 entries are used by the GPT-2 tokenizer.</p></figcaption></figure>

The model consists of 28 layers with a model dimension of 4096, and a feedforward dimension of 16384. The model
dimension is split into 16 heads, each with a dimension of 256. Rotary Position Embedding (RoPE) is applied to 64
dimensions of each head. The model is trained with a tokenization vocabulary of 50257, using the same set of BPEs as
GPT-2/GPT-3.



## Evaluation results
Evaluating the accuracy of the sparse model of gpt-j-6b using the lambada_openai dataset in lm_eval, providing the accuracy fluctuation under two precisions: FP32 and BF16.
<figure>

| Sparsity | Dataset | Precision | Dense Acc  ↑ | Sparse Acc ↑  | Acc fluctuations |
|------  |----------------   |-------   |-------   |--------   |------------------   |
| 40%    |Lambada_openai     | FP32     | 0.6831   | 0.6922     | +1.33%   |
| 40%    |Lambada_openai     | BF16     | 0.6771   | 0.6874     | +0.63%   |