TinyMixtral v2

A 498M-parameter Mixture-of-Experts language model with a DeepSeek-style shared expert, trained from scratch on 4B tokens (FineWeb-Edu + Cosmopedia v2) and post-trained on 1B tokens (Wikipedia + Cosmopedia v2).

Quick Start

from transformers import AutoModelForCausalLM, AutoTokenizer

model = AutoModelForCausalLM.from_pretrained("mikecovlee/tinymixtral", trust_remote_code=True)
tokenizer = AutoTokenizer.from_pretrained("mikecovlee/tinymixtral")

text = "The capital of France is"
inputs = tokenizer(text, return_tensors="pt")
outputs = model.generate(**inputs, max_new_tokens=50, do_sample=True, temperature=0.7)
print(tokenizer.decode(outputs[0], skip_special_tokens=True))

Architecture

Parameter Value
hidden_size 896
num_layers 10
Attention GQA (16 heads / 4 KV heads, head_dim=56)
Experts 1 shared (always active) + 6 routed (top-2)
Expert FFN SwiGLU, intermediate = 2389
Vocab size 32,000 (TinyLlama SentencePiece)
Max position 2,048
Total params ~498M
Active params/token ~241M

The shared expert provides general-purpose features and is always computed. Routed experts specialize via top-2 gating with load-balancing auxiliary loss.

Training

Phase Data Tokens LR Schedule Time
Pretrain FineWeb-Edu (89%) + Cosmopedia v2 (11%) 4B 7e-4 WSD ~96h
Post-train Wikipedia (50%) + Cosmopedia v2 (50%) 1B 2e-5 WSD 24h
  • Hardware: single NVIDIA RTX A5000 24GB
  • Precision: bf16 (model + autocast)
  • Optimizer: AdamW (β=0.9,0.95, wd=0.1)
  • Batch: 22 × 1024 = 22,528 tokens/step
  • Gradient clipping: 1.0
  • Activation checkpointing: enabled

Results

Standard Benchmarks (lm-evaluation-harness, 0-shot)

Task Metric Score
HellaSwag acc_norm 0.326
PIQA acc 0.631
WinoGrande acc 0.506
ARC-Easy acc 0.474
ARC-Challenge acc_norm 0.272
OpenBookQA acc_norm 0.290
BoolQ acc 0.455
LAMBADA acc 0.224

Performance is comparable to SmolLM-360M on PIQA, ARC-C, and WinoGrande. HellaSwag and LAMBADA are weaker, reflecting limited next-token prediction capability at this scale.

GLUE (zero-shot, conditional log-likelihood)

Task Score
SST2 0.586
MRPC (F1) 0.809
QQP (F1) 0.519
QNLI 0.458
RTE 0.520
MNLI 0.348
MNLI-mm 0.368
Mean 0.515

Comparison with baseline (v1.1, 432M / 176M active)

Metric v1.1 v2 (this model)
GLUE Mean 0.513 0.515
ARC-C 0-shot 0.249 0.264
ARC-E 0-shot 0.365 0.388
SST2 0.568 0.586

v2 improves ARC (+1.5–2.3pp) and SST2 (+1.8pp) over v1.1, with GLUE mean roughly equivalent. The shared expert design increases knowledge capacity at the cost of slightly more parameters.

Limitations

  • At ~241M active parameters, performance on multi-step reasoning tasks (QNLI, MNLI, RTE) remains near random
  • Trained on English data only
  • Not instruction-tuned; best used as a base model or for text completion
  • 2048 token context window

Citation

@misc{tinymixtral2026,
  author = {Michael Lee},
  title = {TinyMixtral: Small-scale MoE Language Model Research},
  year = {2026},
  publisher = {GitHub},
  howpublished = {\url{https://github.com/mikecovlee/tinymixtral}}
}

License

MIT License. Copyright (C) 2026 Michael Lee (李登淳).

Downloads last month
21
Inference Providers NEW
This model isn't deployed by any Inference Provider. 🙋 Ask for provider support

Datasets used to train mikecovlee/tinymixtral-v2.0-beta

Collection including mikecovlee/tinymixtral-v2.0-beta