Calibrated 2-bit MLX quantization of poolside/Laguna-S-2.1
(118B total, 8B activated per token), produced with oMLX oQ at
level 2 enhanced — 2.70 bits/weight effective, 36 GB on disk. Data-driven mixed precision:
bits are allocated per tensor from an imatrix-calibrated sensitivity map, not a fixed rule.
For Apple Silicon.
36 GB on disk, down from 235 GB BF16
48 layers, 47 of them MoE with 256 routed experts + 1 shared, top-10 (L0 is a dense MLP);
interleaved attention (12 global with YaRN to 1M context, 36 sliding-window 512)
Peak memory in my tests: 34.4 GB at 1k context, 37.5 GB at 64k — fits a 48 GB Mac
Converted and tested on a Macbook Pro M5 Max 128GB 40 GPU
Requirements
mlx-lm doesn't support the laguna architecture yet — there's an open PR:
mlx-lm#1223. Until it lands, use mlx-vlm
(0.6.3+), which implements laguna as a text-only model:
oMLX serves it directly from 0.5.3 on — it vendors that PR and patches it into mlx-lm at
import, so no model setting is needed. On earlier builds, discovery decides between the mlx-lm and
mlx-vlm loaders by looking for a vision sub-config, and laguna has none — so it lands on mlx-lm and
fails with Model type laguna not supported. Set model_type_override: "vlm" in the model's
settings, then refresh discovery (omlx restart): the load failure is cached per entry until the
next discovery pass, so setting the override alone won't clear it.
Quantization
oQ2e allocates bits per tensor from an importance-matrix calibration pass over calibration data.
Here the split came out extreme: every non-expert tensor — attention, embeddings, lm_head,
routers, 386 in total — was boosted to 8 bits, leaving the 2-bit base to the experts alone. With
only 8B parameters active per token there's little margin in the dense spine, and the calibration
spent its entire budget protecting it. Output is standard MLX affine quantization — no custom
kernels or runtime required.
The measured sensitivity ranks L46, L24, L20 and L44 highest, and L0 lowest of the 48 by a wide
margin (0.0021), which tracks with L0 being the model's only mlp_only layer.
How it was quantized
oQ at level 2 enhanced — imatrix-calibrated, group size 128. I had to patch omlx to route laguna
through the mlx-vlm loader. At 235 GB the model doesn't fit in 128 GB of RAM, so calibration ran
against a uniform 4-bit proxy on disk rather than the FP weights, which shifts the bit allocation
slightly.
Unlike the upstream config, generation_config.json here ships repetition_penalty: 1.05: at this
bit-width the model can fall into verbatim repetition loops in long-form generation, and this is the
mildest setting that reliably broke them in my tests.
Conversion check
Smoke-tested after conversion with mlx_vlm.generate: coherent — solved 17 * 24 = 408, broke it
down by the distributive property and verified the result a second way, no repetition loop.
Performance
Measured with oMLX's benchmark harness on a Macbook Pro M5 Max 128GB 40 GPU, single request,
128 generated tokens:
prompt
gen tok/s
prefill tok/s
TTFT ms
peak GB
1k
61.5
1146.0
894
34.42
4k
61.2
1092.7
3750
34.57
8k
59.2
985.5
8314
34.76
16k
55.7
910.7
17992
35.12
32k
50.3
860.5
38080
35.91
64k
38.8
745.8
87879
37.54
Continuous batching at 1k prompt / 128 generated:
batch
tg tok/s
speedup
TTFT ms
E2E s
1
61.5
1.00x
894
2.98
2
90.4
1.47x
1874
4.71
4
127.0
2.07x
3332
7.44
8
165.5
2.69x
5328
11.78
Benchmarks & Variants
mmlu_pro, mathqa and winogrande, n=300 seeded samples each, thinking off, identical questions across
every variant. The bf16 row is the hosted API, measured the same way. Standard error at this n is
around 2.5 points, so oQ4e through oQ6e aren't separated by this run.
Accuracy vs bits per weight, three benchmarks, n=300
Treat this as a rough sighting, not a verdict. Three benchmarks at n=300 cover a narrow slice of what
the model does — no long-context work, no agentic loops, no real code — and at this sample size most
of the ladder above 3.6 bpw sits inside the error bars. I ran them to size the drop between levels,
not to rank the variants against each other. Test the one you're considering on your own workload
before trusting any of it.
Usage
bash
1# mlx-vlm — plain mlx-lm doesn't support the laguna architecture2uvx --from mlx-vlm mlx_vlm.generate --model mlx-community/Laguna-S-2.1-oQ2e \3 --prompt "Explain Bayes' theorem in two sentences." --max-tokens 30045# oMLX — discovers the model from the HF cache; set model_type_override: "vlm" first6omlx serve
License
OpenMDW-1.1, inherited from
the base model. Refer to the original model card for architecture, benchmarks, and intended use.