How it was produced
Starting from the author's asymmetric checkpoint, each expert projection was:
- Dequantized exactly to float32:
W = (q − zp)·s (original bf16 scale).
- Re-quantized symmetric about zero with fresh per-group scales:
s_new = amax(W, per 32-group) / 7.5 (stored bf16),
q = clamp(round(W / s_new), −8, 7), repacked 8 codes per int32.
- The zero-points were dropped and the config flipped to
symmetric: true, zp_dtype: null.
vLLM reconstructs each weight as (q − 8)·s_new. The cost is one extra
re-quantization step (~amax/15 per group) on top of the original AWQ
quantization. Everything non-quantized (BF16 vision tower, linear/full
attention, shared experts, norms, lm_head, embeddings, biases, A_log/
dt_bias/conv1d, and the full BF16 MTP head) is byte-identical to the
source. The conversion script is ornith_asym_to_sym.py (deterministic,
resumable, validates that no zero-points and no 3-D packed tensors remain).
Serve with vLLM
vllm serve /path/to/Ornith-1.5-35B-A3B-W4A16-SYM \
--tensor-parallel-size 2 \
--max-model-len 32768 \
--gpu-memory-utilization 0.90 \
--host 127.0.0.1 --port 9001 \
--limit-mm-per-prompt '{"image":1,"video":1}' \
--mm-processor-kwargs '{"max_pixels":401408}'
On two RTX 3090 (Ampere) it loads with
Using Marlin backend for WNA16 MoE (group_size=32, num_bits=4)
and serves at ~20 GB per GPU. Use
--kv-cache-dtype auto on Ampere (no fp8). The reasoning/tool parsers are
model-built-in for this first-serve config.
Quality
Verified against the release coherence gate on vLLM: multi-step arithmetic
(correct), syllogistic reasoning (correct), memoized Python (correct), and a
basic color image (correct dominant color). As with any 4-bit build, greedy
output diverges from BF16; this is a 4-bit model.
Provenance
- Base:
ornith-ai/Ornith-1.5-35B-A3B (MIT), a fine-tune of the Qwen3.6/3.5 A3B
MoE family.
- Source asym build:
ulkaa/Ornith-1.5-35B-A3B-AWQ-INT4 (MIT).
- Re-quantized by the Milner Team (MIRALABS) for local vLLM serving.
License
MIT, inherited from ornith-ai/Ornith-1.5-35B-A3B.