Why W8A8 on A100
The A100 has INT8 tensor cores (about twice its BF16 throughput) but no FP8. Weight-only 4-bit models (W4A16, e.g. AWQ) store small weights but still compute in BF16, so they do not speed up prompt processing. W8A8 runs the matrix multiplies in INT8; vLLM serves it with CutlassInt8ScaledMMLinearKernel.
About this quantization
- Base:
CMKL/MANGO1.5-Qwen3.5-9B (official BF16 weights)
- Tool: llm-compressor,
QuantizationModifier(targets="Linear", scheme="W8A8")
- Scheme: INT8 symmetric per-channel weights; INT8 dynamic per-token activations
- Calibration data: none (data-free: no dataset was used)
- Kept in BF16 (not quantized):
lm_head, the vision tower, the MTP head, and the small Gated-DeltaNet gate projections (in_proj_a, in_proj_b, in_proj_ba)
- MTP head: the 15
mtp.* tensors are copied unchanged (BF16) from the base checkpoint
- Format:
compressed-tensors (the quantization settings are in config.json)
Results (GreenMind Final test set, 1x A100-SXM4 40GB, vLLM 0.32.0)
Measured by the hackathon grader against the organizers' baseline (BF16 base model, default vllm serve):
- Best score 99.7 / 100; median 99.2 over 7 repeated Final runs with the configuration below
- Accuracy relative to the BF16 baseline (R): 0.998 to 1.053 across all our INT8 Final runs
- On-time requests per joule: up to 3.64x the baseline (164 J per request)
- MTP with 2 draft tokens: about 2.7 tokens accepted per decoding step
How to use (vLLM)
vllm serve PakornF/MANGO1.5-Qwen3.5-9B-W8A8-INT8-mtp \ --max-model-len 49152 \ --reasoning-parser qwen3 \ --enable-auto-tool-choice --tool-call-parser qwen3_coder \ --speculative-config '{"method":"mtp","num_speculative_tokens":2}'
The configuration we used for the scores above adds:
--gpu-memory-utilization 0.92 --enable-prefix-caching \ --max-num-seqs 64 --max-num-batched-tokens 2048 --long-prefill-token-threshold 1024 \ --scheduling-policy priority
with a small wrapper that gives shorter prompts a higher priority (see the GitHub repository).
License
Apache 2.0, inherited from the base model (Qwen3.5-9B license).
Credits