Quantization details
The checkpoint uses the standard EXL3 format with a target body bitrate of
3.0 bits per weight.
The target bitrate applies to the quantized body; not every tensor in the
checkpoint is stored at exactly 3 bits.
- EXL3 target body bitrate:
3.0 bpw
lm_head: 6-bit
- Vision component:
6-bit
- MTP component:
4-bit
- Calibration rows:
250
- Calibration context:
2048
- Codebook:
mul1
- Output scales:
always
- Shard size setting:
4096 MB
- Final output: four
safetensors shards
The four shards are the expected result of the 4096 MB shard-size setting
and do not indicate a missing or incomplete model.
The checkpoint metadata reports:
quant_method=exl3
version=1.5.0
bits=3.0
head_bits=6
vision_bits=6
mtp_bits=4
The conversion configuration was approximately:
python convert.py \ -i "$SRC" \ -o "$OUT" \ -w "$WORK" \ -b 3.0 \ -hb 6 \ -mb 4 \ -vb 6 \ -cr 250 \ -cc 2048 \ -cb mul1 \ --out_scales always \ -ss 4096 \ -cpi 120 \ -d 0
Runtime compatibility
This is a standard EXL3 checkpoint.
The model itself does not require the SM89 fork described below. The fork
is an optional runtime optimization for Ada SM89 GPUs and does not modify the
EXL3 checkpoint format.
Optional SM89 / Ada runtime optimization
I profiled ExLlamaV3 1.5.0 prefill performance on an
NVIDIA RTX 4060 Ti 16 GB (Ada SM89) and tested two small SM89-specific
runtime specializations.
These results are specific to the tested GPU, model shapes and runtime
configuration. Other Ada / SM89 GPUs and model shapes have not yet been
characterized to the same extent.
F16ACC GEMM specialization
The tested SM89 F16ACC layout is:
BM=128BN=64BK=644 warps (2x2)STAGES=2GROUP_M=16PAD=0
Matched cold-prefill server A/B results:
Table with columns: Context, Control, SM89 F16ACC, Uplift| Context | Control | SM89 F16ACC | Uplift |
|---|
| 16K | 727.38 tok/s | 761.64 tok/s | +4.710% |
| 32K | 652.37 tok/s | 679.31 tok/s | +4.129% |
| 64K | 535.73 tok/s | 554.60 tok/s | +3.522% |
Correctness was checked on all 16 F16ACC shapes observed in the real
workload using three deterministic seeds per shape.
Results:
max_abs = 0
mean_abs = 0
max_relative = 0
- no NaN
- no Inf
A per-shape oracle / dispatcher was also evaluated. It projected only about
1.8 tok/s beyond the simpler global SM89 configuration, so the global
configuration was retained.
The oracle number is a projection, not an additional end-to-end server
measurement.
Long-query paged attention
The second specialization targets the staged/cache-backed FP16 long-query
prefill path.
The direct packed quantized-cache path keeps the upstream behavior.
Tested configuration:
Control:BM64 / BN32 / W8 / S2SM89 candidate:BM64 / BN32 / W4 / S2
The key change is therefore:
The F16ACC specialization above was enabled in both A/B arms, so the
following experiment isolates the paged-attention change.
Formal cold-request server results:
Table with columns: Context, Control, SM89 optimized, Uplift| Context | Control | SM89 optimized | Uplift |
|---|
| 16K | 763.530 tok/s | 787.156 tok/s | +3.094% |
| 32K | 680.912 tok/s | 723.184 tok/s | +6.208% |
| 64K | 555.397 tok/s | 613.711 tok/s | +10.500% |
The formal requests used:
cached_tokens=0cached_pages=0
so these are cold-prefill measurements rather than prefix-cache reuse results.
Correctness gates at 16K, 32K and 64K all passed with:
No measured VRAM increase was observed.
Peak VRAM:
Table with columns: Context, Peak VRAM| Context | Peak VRAM |
|---|
| 16K | 14,488 MiB |
| 32K | 14,488 MiB |
| 64K | 14,608 MiB |
During the formal A/B runs there was no observed:
- OOM
- CUDA illegal-access error
- NVIDIA Xid
- server crash
Benchmark configuration
The reported runtime measurements used:
Table with columns: Setting, Value| Setting | Value |
|---|
| GPU | NVIDIA RTX 4060 Ti 16 GB |
| Architecture | Ada SM89 / compute capability 8.9 |
| ExLlamaV3 | 1.5.0 |
| Upstream base commit | 02aef45cd681b960a00afcd0749a4ab99e6c1bfe |
| Model | Qwen3.8-27B EXL3 3.0 bpw |
| KV cache | int4 |
| QC staging | EXL3_QC_STAGING=1 |
| Maximum prefill chunk |
Prefill throughput in the tables is the server's measured prefill timing,
rather than a client-side prompt-token / TTFT approximation.
These measurements should not be interpreted as a guarantee of identical
performance gains across every Ada GPU, model shape, batch size, cache mode or
context length.
The checkpoint retains the multimodal vision structure and its quantization
metadata reports vision_bits=6. Vision was disabled during these performance
benchmarks, so the results above should not be interpreted as a complete
vision-runtime compatibility test.
Runtime source and validation
The referenced GitHub Actions run completed successfully with:
This validates the source and wheel build matrix. It does not replace the
GPU correctness testing and server A/B measurements described above.
EXL3 runtime usage
For normal use, upstream ExLlamaV3 can be used directly:
https://github.com/turboderp-org/exllamav3
For the optional RTX 4060 Ti / SM89 optimized runtime:
git clone https://github.com/grimlee/exllamav3.gitcd exllamav3git checkout sm89-ada-optimizations
The SM89 branch is an experimental runtime optimization.
It is not required to load this model and does not introduce a different
model format.
Source model and usage considerations
This repository only provides an EXL3 quantization and the runtime benchmark
work documented above.
For information about:
- the original Qwen3.8 model,
- the abliteration procedure,
- model behavior,
- safety characteristics,
- previous source-model revisions,
- and source-model-specific usage instructions,
please refer to:
huihui-ai/Huihui-Qwen3.8-27B-abliterated
https://huggingface.co/huihui-ai/Huihui-Qwen3.8-27B-abliterated
This quantization does not introduce separate safety tuning beyond the source
model.