GLM-5.1-JANG_2S

744B-parameter Mixture-of-Experts at ~2.10 bits/weight — smallest 2-bit-family variant Created by Jinho Jang — eric@jangq.ai

⚠ EXPERIMENTAL

This is an early research release. Benchmarks (MMLU, HumanEval, GSM8K, etc.) are not yet finalized and will be uploaded in a follow-up revision.

🔬 Comparison model

JANG_2S is a smaller-floor variant of the same 2-bit-family family as GLM-5.1-JANG_1L. It uses the (6, 4, 2) bit tuple (critical=6, important=4, compress=2) vs JANG_1L's (8, 8, 2), trading ~5 GB of size for lower precision on the critical/important attention and routing tensors. For most users, JANG_1L is the recommended default. Use JANG_2S only if you want the smallest 2-bit-family variant for comparison or hardware where every GB matters.

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Requires MLX Studio

This model only runs on MLX Studio — Jinho Jang's native MLX inference app for Apple Silicon.

Standard mlx_lm will NOT work with this model. MLX Studio contains a patched deepseek_v32 runtime path that is required for coherent decode on quantized GLM-5.1 at bf16. Without the patched runtime, the model produces repetition loops during generation.

If you want to run this model and do not have MLX Studio, wait for the public release.

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Model summary

Field	Value
Base architecture	GLM-5.1 (ZhipuAI / THUDM) — MoE, 744B total params, 40B active, 256 routed experts top-8, 78 transformer layers + 1 MTP
Attention	MLA (Multi-head Latent Attention) with DSA (Dense Sparse Attention) indexer
Context window	202,752 tokens
Quantization method	JANG_2S — mixed-precision with (critical=6, important=4, compress=2) bits
Effective bits	2.10 bits/weight
On-disk size	228 GB
Active RAM during inference	~232 GB wired
Format	JANG v2 — MLX-native safetensors, instant mmap load
Source	Converted from the official GLM-5.1 FP8 release
Mode	Text-only

JANG_2S vs JANG_1L at a glance

	JANG_2S (this)	JANG_1L
Bit tuple (critical, important, compress)	(6, 4, 2)	(8, 8, 2)
Actual avg bits	2.10	2.15
On-disk size	228 GB	233 GB
gate (MoE router)	6-bit	8-bit
k_proj, q_proj, kv_a_proj_with_mqa, embed_tokens	4-bit	4–8-bit
lm_head	6-bit	6-bit
routed experts (gate/up/down_proj)	2-bit (97% of params)	2-bit (97% of params)
FAST-mode short answer accuracy (internal 10-prompt benchmark)	7/10	7/10
THINK-mode 500-tok reasoning coherence	7/10	7/10

Takeaway: the compress tier (routed experts, 97% of params) is identical between the two profiles. JANG_2S's savings come from lower precision on the critical/important attention path, which produces marginally different failure patterns on the same 10-prompt test but no measurable overall quality gain. Choose based on whether those 5 GB matter to your hardware.

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Running the model

Same as JANG_1L — see that model card for the recommended sampling config table. Short-form QA:

from mlx_studio import load, generate, make_sampler

model, tokenizer = load("GLM-5.1-JANG_2S")

messages = [{"role": "user", "content": "What is the capital of France? Answer in one word."}]
prompt = tokenizer.apply_chat_template(
    messages, add_generation_prompt=True, tokenize=False,
    enable_thinking=False,
)
print(generate(model, tokenizer, prompt=prompt, max_tokens=60,
               sampler=make_sampler(temp=0.0)))
# → "Paris"

Reasoning mode (needs max_tokens ≥ 1024 to reliably emit final answer):

tmpl = tokenizer.apply_chat_template(
    messages, add_generation_prompt=True, tokenize=False,
    enable_thinking=True,
)
print(generate(model, tokenizer, prompt=tmpl, max_tokens=1024,
               sampler=make_sampler(temp=0.0)))

Do NOT apply repetition penalty — GLM-5.1 penalizes correct-answer repetition on math.

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Performance snapshot (informal — full benchmarks TBD)

Tested on Apple M3 Ultra (256 GB unified memory) via MLX Studio.

Metric	Value
Cold load time (mmap)	~54 s
Short-form answer latency	<1 s after load
Reasoning generation speed	~5–7 tok/s
RAM footprint during generation	~232 GB wired

Qualitative coherence (10-prompt private benchmark, greedy)

Mode	Coherent
enable_thinking=False short-form	7/10
enable_thinking=True reasoning	7/10

Failure pattern differs from JANG_1L: JANG_2S gets to the "Paris" answer about 2× faster in THINK mode (15 s vs 32 s) but fails on fact_gold (the "Au" prompt) with a looping pattern JANG_1L doesn't exhibit.

Formal benchmarks (MMLU, GSM8K, HumanEval, BBH, GPQA, etc.) coming in a follow-up revision.

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Known limitations

1. Same reasoning budget requirement as JANG_1L — enable_thinking=True needs max_tokens ≥ 1024.
2. Code generation at 2-bit is rough — the model sometimes refuses with an essay rather than emitting code.
3. Memory requirement: requires ≥250 GB of GPU-wired memory. On Mac Studio, verify sysctl iogpu.wired_limit_mb returns 250000 or higher before loading.
4. MLX Studio only — see the notice at the top of this file.

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Credits

• Quantization & conversion — Jinho Jang, eric@jangq.ai
• Runtime — MLX Studio by Jinho Jang
• Base model — GLM-5.1 by ZhipuAI / THUDM / zai-org (see the original model card for training data, intended use, and safety information)

All JANG tooling and MLX Studio are commercial products of Jinho Jang. Please refer to the MLX Studio project page for licensing terms.

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Status

• Initial conversion + runtime validation on Apple M3 Ultra
• Short-form factual QA verified coherent
• Reasoning mode (enable_thinking=True) verified coherent through multi-step chains
• Formal benchmark sweep — MMLU, GSM8K, HumanEval, BBH, GPQA — uploading in a follow-up revision
• A true sub-2-bit variant (JANG_1S) is in active research — target: ~150 GB on disk via codebook quantization of routed experts

Questions or issues — contact eric@jangq.ai.