Gemma-4-125B-A12B

Gemma-4-125B-A12B is an expanded sparse Mixture-of-Experts language model based on google/gemma-4-26B-A4B-it. This release focuses on agentic coding, repository understanding, multi-turn tool use, explicit reasoning, and long-context software tasks.

The model is released in MXFP4 format for the expert weights, with shared and non-expert weights kept in BF16.

Model Summary

• Base lineage: google/gemma-4-26B-A4B-it
• Architecture: sparse Mixture-of-Experts language model
• Expert layout: 688 total experts
• Active experts per token: 50
• Total logical text parameters: approximately 125B
• Active parameter class: approximately A12B
• Weight format: MXFP4 experts with BF16 shared weights
• Intended serving mode: Gemma 4 chat, thinking, and tool-use template enabled
• Created on a two-GPU workstation

Expert Capacity

This checkpoint expands the Gemma 4 expert pool while preserving sparse inference. Each token activates a selected subset of experts rather than the full parameter set.

• Expert pool size: 688
• Active expert budget: 50 experts per token
• Active expert fraction per layer: approximately 7.27%
• Approximate logical active text size: 11.4B
• Approximate padded serving active size: 12.2B

Recommended Runtime

This model was created on a two-GPU workstation. The following command is the tested two-GPU serving configuration:

CUDA_VISIBLE_DEVICES=0,1 vllm serve /path/to/gemma-4-125b-a12b \
  --served-model-name vllm/doobee \
  --host 0.0.0.0 \
  --port 23333 \
  --dtype bfloat16 \
  --tensor-parallel-size 2 \
  --enable-expert-parallel \
  --max-model-len 200000 \
  --gpu-memory-utilization 0.96 \
  --trust-remote-code \
  --reasoning-parser gemma4 \
  --tool-call-parser gemma4 \
  --enable-auto-tool-choice \
  --default-chat-template-kwargs '{"enable_thinking": true}' \
  --language-model-only \
  --skip-mm-profiling \
  --max-num-seqs 1 \
  --max-num-batched-tokens 8192 \
  --enable-log-requests

Use a vLLM build with Gemma 4 MXFP4 MoE support. Long-context serving is memory-intensive; the command above is configured for a 200k token context on two high-memory GPUs.

Chat And Tool Use

The included chat template is intended to be used with thinking enabled. Tool calling should be exercised through native OpenAI-compatible tool-call paths rather than raw text parsing.

Recommended evaluation settings:

• Use temperature=0.0 for deterministic smoke tests.
• Use temperature=0.2 to 0.7 for normal agentic evaluation.
• Keep thinking enabled for the intended behavior profile.
• Use the included chat template and tokenizer files as shipped.

Intended Uses

• Agentic coding and software engineering tasks
• Repository exploration and codebase analysis
• Multi-turn tool-use workflows
• Long-context reasoning over technical material
• Patch planning, debugging, and implementation assistance

Limitations

• This is a large sparse MoE model and requires an inference stack that supports Gemma 4 MXFP4 MoE serving.
• The model is optimized for tool-oriented assistant workflows and may not be appropriate for all general-purpose chat settings.
• Long-context behavior depends heavily on serving configuration, GPU memory, and request batching.

Credits

Thanks to NVIDIA for providing a broad range of pretraining and post-training resources that helped make this work possible.