GLM-5.3-Flash W4A16 NVFP4-FP8

This checkpoint is a mixed-precision quantization of zai-org/GLM-5.3-Flash. It uses MSE-calibrated NVFP4 weights with BF16 inputs for routed experts in MoE layers 6 through 41. It uses 128x128 block-scaled FP8 weights for routed experts in edge MoE layers 3 through 5 and 42 through 44. Other quantized linear layers also use block-scaled FP8 weights. The checkpoint keeps their activation inputs unquantized. NVIDIA Model Optimizer produced the checkpoint.

The project release gate passed. Each test compares this checkpoint with the exact upstream FP8 revision in the same Transformers implementation. The saved-artifact test dequantizes the stored FP8 and NVFP4 weights to BF16 before reload. The gate is a project rule. It is not a published standard.

Source and format

Item Value
Upstream revision 04c4e9e95c5da8862dced7e5056455116f83a7e0
Upstream weight format native FP8
Interior routed expert weights NVFP4 E2M1, static FP8 scales, group size 16
Edge routed expert weights 128x128 block-scaled FP8 E4M3
NVFP4 routed expert inputs BF16
FP8 routed expert inputs Source precision
Other quantized linear weights 128x128 block-scaled FP8 E4M3
Other quantized linear inputs Source precision
KV cache Source precision
Export quantization method ModelOpt MIXED_PRECISION
ModelOpt build 0.0.1.dev1+g5db268251.d20260828
ModelOpt base commit 5db268251945b579d642bbd7449c63006cfa829f
PTQ container nvcr.io/nvidia/pytorch:26.08-py3
PTQ container image ID sha256:3becd068f49bd2ad38f90db5f9a4803019a76933a24e63d821376c44e7a9200a
PTQ Transformers 5.16.1
NVFP4 routed expert layer entries 36
FP8 routed expert layer entries 6
FP8 layer entries 468
Weight shards 21
Weight bytes 201,823,044,552
Total file bytes before this card 201,872,724,688
Chat template SHA-256 34d5ee66b12fa6446cdae131c352b8f68cd85369e0e6fda115583805fada3891

The embedding, LM head, routers, recurrent state controls, MTP block, and visual modules remain unquantized. The visual path was not evaluated.

Calibration

Item Value
Algorithm MSE with FP8 scale sweep for static NVFP4 interior expert weights
Data mix quotas OpenCodeReasoning 384, OpenMathReasoning 384, Nemotron-Science-v1 256
Dataset revisions 20a1ca19, d3d08664, 82e1af46
Packed rows 1,024
Tokens per row 1,024
Total calibration tokens 1,048,576
Batch size 4
Hardware 4 NVIDIA B200 GPUs
Peak calibration memory GPU 0: 119,350 MiB, GPU 1: 137,878 MiB, GPU 2: 137,938 MiB, GPU 3: 83,602 MiB

The loader collects 16 times each source quota, shuffles the combined source records with seed 0, then packs 1,024 rows. The code and math records use their source text fields. The science records use the upstream GLM chat template. Packing inserts EOS separators and fills each row to 1,024 tokens. The recipe directory contains the exact recipe, calibration manifest, ModelOpt base commit, local ModelOpt patch, PTQ command, and environment versions.

FP8 agreement

The reference uses the exact upstream FP8 checkpoint. The in-memory test and the saved-artifact reload use the same Transformers implementation and the same sequential device-map loader. The reload test reads the published packed weights, dequantizes them to BF16, and then runs the model. The temporary BF16 view is not part of this repository.

The sweep uses eight WikiText-2 samples, eight HumanEval samples, and eight GSM8K samples. It scores 6,507 held-out next-token positions. It also compares eight 48-token greedy generations. Sampling is disabled.

Runtime Top-1 token agreement Median first divergence Temp-0 repeats
In-memory ModelOpt fake quant 95.42% 49 3 / 3 identical: true
Saved checkpoint reload 95.24% 35 3 / 3 identical: true
Held-out source Tokens Reload agreements Agreement rate
WikiText-2 3,064 2,829 92.33%
GSM8K 1,226 1,171 95.51%
HumanEval 2,217 2,197 99.10%
Upstream FP8 margin Tokens Reload disagreements Disagreement rate
margin < 0.5 368 153 41.58%
margin 0.5 to < 2 847 136 16.06%
margin 2 to < 5 1,294 21 1.62%
margin >= 5 3,998 0 0.00%

The median first-divergence value is censored at 49 when a generation matches all 48 compared tokens. The observed comparison positions have median 35.

The release gate requires at least 92% overall agreement, at most 2% disagreement when the FP8 margin is 2 to 5, at most 0.5% disagreement when the margin is at least 5, median first divergence at or after token 24, and three identical temperature-0 repeats. Both the in-memory and saved-artifact paths must pass.

The in-memory to saved-artifact diagnostic is 97.40% across 6,507 positions.

Saved-artifact reload

Item Value
GPUs 4 NVIDIA B200, 183,359 MiB each
Runtime Transformers 5.16.1 with ModelOpt source loader
Device map sequential
GPU memory fraction 0.95
Packed-weight reload NVFP4 and block-FP8 dequantized to BF16
Model load time 2905.47 seconds
Agreement scoring time 20.59 seconds
Eight-generation time 89.21 seconds
Peak GPU memory GPU 0: 175,350 MiB, GPU 1: 179,764 MiB, GPU 2: 182,122 MiB, GPU 3: 145,748 MiB

The reload uses runtime/dequantize-modelopt-mixed-for-validation.py. It is an artifact integrity and quality test. It is not the recommended serving path.

Serving status

The pinned vLLM development build loaded the checkpoint on four B200 GPUs with pipeline split 15/9/9/12 and concurrency 1. The run was deterministic. Its cross-runtime top-1 agreement with the working Transformers FP8 control was 54.89%. The upstream vLLM control also produced invalid repeated token 1023 output. Therefore this card does not claim a validated vLLM serving recipe. The storage format and quality gate remain valid. A later vLLM GLM-5.3 integration can use the included runtime evidence.

Limits

  • The reference is upstream FP8, not BF16.
  • Interior routed expert weights are NVFP4. Six edge routed expert layers use block-scaled FP8. The saved-artifact gate dequantizes both formats to BF16 at load. It does not measure native FP4 kernel speed.
  • The agreement sweep is a stability test. It is not a task-accuracy score.
  • No HumanEval pass@1, agentic coding, long-context, or multimodal score is claimed.
  • The vLLM diagnostic uses context 1,024 and concurrency 1. It is not a passed serving gate.

License

The upstream checkpoint uses the MIT license. The upstream LICENSE file is included with this derivative.

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