MPT-7B is a decoder-style transformer pretrained from scratch on 1T tokens of English text and code.
This model was trained by MosaicML.
MPT-7B is part of the family of MosaicPretrainedTransformer (MPT) models, which use a modified transformer architecture optimized for efficient training and inference.
These architectural changes include performance-optimized layer implementations and the elimination of context length limits by replacing
positional embeddings with Attention with Linear Biases (ALiBi).
Thanks to these modifications, MPT models can be trained with high throughput efficiency and stable convergence.
MPT models can also be served efficiently with both standard HuggingFace pipelines and NVIDIA's FasterTransformer.
This model uses the MosaicML LLM codebase, which can be found in the llm-foundry repository. It was trained by MosaicML’s NLP team on the MosaicML platform for LLM pretraining, finetuning, and inference.
How is this model different?
MPT-7B is
Licensed for the possibility of commercial use (unlike LLaMA).
Trained on a large amount of data (1T tokens like LLaMA vs. 300B for Pythia, 300B for OpenLLaMA, and 800B for StableLM).
Prepared to handle extremely long inputs thanks to ALiBi (we finetuned MPT-7B-StoryWriter-65k+ on up to 65k inputs and can handle up to 84k vs. 2k-4k for other open source models).
MPT-7B-StoryWriter-65k+: a model designed to read and write fictional stories with super long context lengths.
Built by finetuning MPT-7B with a context length of 65k tokens on a filtered fiction subset of the books3 dataset.
At inference time, thanks to ALiBi, MPT-7B-StoryWriter-65k+ can extrapolate even beyond 65k tokens.
We demonstrate generations as long as 80k tokens on a single A100-80GB GPU in our blogpost.
Note: This model requires that trust_remote_code=True be passed to the from_pretrained method.
This is because we use a custom MPT model architecture that is not yet part of the Hugging Face transformers package.
MPT includes options for many training efficiency features such as FlashAttention, ALiBi, QK LayerNorm, and more.
To use the optimized triton implementation of FlashAttention, you can load the model on GPU (cuda:0) with attn_impl='triton' and with bfloat16 precision:
python
1import torch
2import transformers
34name ='mosaicml/mpt-7b'56config = transformers.AutoConfig.from_pretrained(name, trust_remote_code=True)7config.attn_config['attn_impl']='triton'8config.init_device ='cuda:0'# For fast initialization directly on GPU!910model = transformers.AutoModelForCausalLM.from_pretrained(11 name,12 config=config,13 torch_dtype=torch.bfloat16,# Load model weights in bfloat1614 trust_remote_code=True15)
Although the model was trained with a sequence length of 2048, ALiBi enables users to increase the maximum sequence length during finetuning and/or inference. For example:
python
1import transformers
23name ='mosaicml/mpt-7b'45config = transformers.AutoConfig.from_pretrained(name, trust_remote_code=True)6config.max_seq_len =4096# (input + output) tokens can now be up to 409678model = transformers.AutoModelForCausalLM.from_pretrained(9 name,10 config=config,11 trust_remote_code=True12)
The model can then be used, for example, within a text-generation pipeline.
Note: when running Torch modules in lower precision, it is best practice to use the torch.autocast context manager.
python
1from transformers import pipeline
23pipe = pipeline('text-generation', model=model, tokenizer=tokenizer, device='cuda:0')45with torch.autocast('cuda', dtype=torch.bfloat16):6print(7 pipe('Here is a recipe for vegan banana bread:\n',8 max_new_tokens=100,9 do_sample=True,10 use_cache=True))
Model Description
The architecture is a modification of a standard decoder-only transformer.
The model has been modified from a standard transformer in the following ways:
Data was formatted using the MosaicML StreamingDataset library to host our data in object storage and efficiently stream it to our compute cluster during training.
StreamingDataset obviates the need to download the whole dataset before starting training, and allows instant resumption of training from any point in the dataset.
Data Mix
The model was trained for 1T tokens (with batch size 1760 and sequence length 2048). It was trained on the following data mix:
Data Source
Number of Tokens in Source
Proportion
Effective Number of Tokens
Epochs
mC4 3.1.0 - English
417.99 B
0.33
330 B
0.14
C4 - English - SemDedup 80%
100.42 B
0.299
299 B
2.98
RedPajama - CommonCrawl
878.45 B
0.1
100 B
0.11
The Stack - Selected Languages
463.78 B
0.1
100 B
0.22
RedPajama - Wikipedia - En
4.87 B
0.04
40 B
8.21
The Stack - Markdown
107.07 B
0.035
35 B
0.33
S2ORC
48.85 B
0.033
33 B
0.68
RedPajama - Books
26.02 B
0.03
30B
1.15
RedPajama - arXiv
28.10 B
0.019
19 B
0.68
RedPajama - StackExchange
20.54 B
0.014
14 B
0.68
Samples for each batch were selected from one of the datasets with the probability specified above.
The examples were shuffled within each dataset, and each example was constructed from as many sequences from that dataset as were necessary to fill the 2048 sequence length.
The data was tokenized using the EleutherAI/gpt-neox-20b tokenizer. This BPE tokenizer has a number of desirable characteristics,
most of which are relevant for tokenizing code:
(1) It was trained on a diverse mix of data that includes code (The Pile)
(2) It applies consistent space delimitation, unlike the GPT2 tokenizer which tokenizes inconsistently depending on the presence of prefix spaces
(3) It contains tokens for repeated space characters, which allows superior compression of text with large amounts of repeated space characters.
The model vocabulary size of 50432 was set to be a multiple of 128 (as in MEGATRON-LM), model flop utilization (MFU) increased by up to four percentage points.
Training Configuration
This model was trained on 440 A100-40GBs for about 9.5 days using the MosaicML Platform.
The model was trained with sharded data parallelism using FSDP and used the LION optimizer.
MPT-7B (Base) is not intended for deployment without finetuning.
It should not be used for human-facing interactions without further guardrails and user consent.
MPT-7B can produce factually incorrect output, and should not be relied on to produce factually accurate information.
MPT-7B was trained on various public datasets.
While great efforts have been taken to clean the pretraining data, it is possible that this model could generate lewd, biased or otherwise offensive outputs.
The license on this model does not constitute legal advice. We are not responsible for the actions of third parties who use this model. Please cosult an attorney before using this model for commercial purposes.
Citation
Please cite this model using the following format:
@online{MosaicML2023Introducing,
author = {MosaicML NLP Team},
title = {Introducing MPT-7B: A New Standard for Open-Source,
Commercially Usable LLMs},
year = {2023},
url = {www.mosaicml.com/blog/mpt-7b},
note = {Accessed: 2023-05-05},
urldate = {2023-05-05}
}
