The illegal memory access was not in `expand_sampling_params` at all, though that is where `CUDA_LAUNCH_BLOCKING` pointed. It was the metadata kernel leaving its output unwritten. `prepare_verification_metadata_tl` sized its second grid dimension from `num_steps`, i.e. `max_MTP_value`. With speculative decoding off that value is 0, and a zero-sized grid dimension launches nothing, so `row_to_req` -- a `torch.empty` buffer -- kept whatever the allocator handed out. `expand_sampling_params` then used those values as request indices, and the reads went off the end of the parameter arrays. The kernel now launches one program per request and loops the tiles at runtime, mirroring the TileLang version, so the row count comes from device memory and no host read is needed (which would have been rejected as a synchronising operation anyway). `num_steps` is accepted and ignored. The A/B case for this kernel is also fixed, in two ways that matter: - it used a fixed `total_q` while the request lengths were random, so it allocated more rows than were ever written and the comparison was meaningless; - it pre-filled the outputs with a sentinel but never required them to be overwritten, so both backends could write nothing and still agree with each other. The case now asserts every row was written, and covers `num_steps=0` plus a request longer than one tile. With that, `DEEPINFER_OPS_BACKEND=triton` runs end to end and produces exactly the same tokens as the pure TileLang run, `[17607, 2793, 3139, 666, 6127, 666, 320, 1]`, identical on all eight ranks. Fifteen of the required kernels are Triton; the remainder still come from TileLang through the fallback while they are ported. |
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| csrc | ||
| deep_cluster | ||
| deepinfer | ||
| doc | ||
| eval | ||
| examples | ||
| scripts | ||
| tests | ||
| vendor | ||
| .clang-format | ||
| .gitignore | ||
| .gitmodules | ||
| build.sh | ||
| CONTRIBUTING.md | ||
| H20-DEBUG-PLAN.md | ||
| H20-DRIFT-ANALYSIS.md | ||
| H20-PORTING-JOURNAL.md | ||
| H20-SM90-FINDINGS.md | ||
| H20-TRITON-PLAN.md | ||
| LICENSE | ||
| Makefile | ||
| pyproject.toml | ||
| README.md | ||
| requirements-ascend.txt | ||
| requirements-dev.txt | ||
| requirements-nvidia.txt | ||
| requirements.txt | ||
| setup.py | ||
DeepInfer
DeepInfer is the high-performance inference framework that powers DeepSeek's large-scale production services. This open-source release provides offline inference with the core features needed for serving at scale.
Supported models:
- DeepSeek-V4.1-Flash
Supported features:
- Optimized kernels, model and sampler runtime
- Parallelism: Attention DP / balanced CP, MoE EP + EPLB
- DSpark and confidence-scheduled verification
- SWA bounded replay
- Asynchronous scheduling (zero-overhead batch scheduler)
- Batch-invariant inference
- Deterministic sampling
- Structured outputs
Feature details and configuration
- Optimized kernels: FlashMLA, DeepGEMM, DeepEP, TileKernels, DeepSelect, and custom TileLang kernels.
- DSpark and confidence-scheduled verification: accelerate decoding with draft tokens and use confidence estimates to schedule verification. Set
DEEPINFER_ENABLE_MTP_VARLEN=1;DEEPINFER_USE_NEXTN_DECODEcontrols the maximum draft length (default: 5). - Decoder SWA bounded replay: reduce decoder prefill work by replaying only a bounded suffix. Set
DEEPINFER_YOCO_PREFILL_TRUNCATION_MODE=compactandDEEPINFER_YOCO_PREFILL_KEEP_TOKENS=140for the default V4.1 settings; the retained suffix must cover the SWA window plus the maximum backtracking length. - Asynchronous scheduling: overlap CPU batch scheduling with device execution. Enabled by default.
- Batch-invariant inference: keep model results identical across different batch compositions. Enable with
DEEPINFER_BATCH_INVARIANT=1(NVIDIA only). - Deterministic sampling: produce identical outputs for identical input tokens and sampling parameters. Set
DEEPINFER_BATCH_INVARIANT=1 DEEPINFER_ENABLE_MTP_VARLEN=0and pass a fixedseq_seedtoSamplingParams(NVIDIA only). - Structured outputs: constrain generation to a regex, JSON schema, or EBNF grammar. Pass
so_args={"schema_type": ..., "schema": ...}toSamplingParams; see examples.
Supported hardware:
- NVIDIA SM100 GPUs
- Huawei Ascend 950 NPUs
Required for a complete inference service (not included in this release):
- A KV cache system
- VE/Prefill/Decode disaggregation (most required engine functionality is already implemented)
- Load balancing across data-parallel replicas for both prefill and decode
Getting started
Prerequisites
- Linux
- GCC >= 13.0
- Python 3.12
- CUDA 13 (NVIDIA only)
- CANN 9.2 (Ascend only)
Build from source
Before building DeepInfer, please create and activate an empty Python 3.12 environment.
# Use `ascend` instead for the Ascend platform
# Keep it exported in the environment where you run DeepInfer
export DEEPINFER_ACCELERATOR=nvidia
./build.sh
Offline inference
The default checkpoint, deepseek-ai/DeepSeek-V4.1-Flash-1017, is
downloaded into the Hugging Face cache on the first run; set DEEPINFER_HF_MODEL_DIR=/path/to/DeepSeek-V4.1-Flash-1017 to
run from a local copy instead.
python examples/offline_inference.py
See examples for details.
Performance benchmarks
| Prefill | Decode |
|---|---|
![]() |
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Measured on 4 SM100 GPUs for prefill and 64 for decode — each within one scale-up domain. To reproduce the benchmarks, see run_sweep.sh.
Evaluation benchmarks
See eval/README.md.
License
DeepInfer is released under the Apache License 2.0. See LICENSE for details.
Acknowledgments
DeepInfer was originally built primarily on vLLM, with additional inspiration from SGLang and TensorRT-LLM. We thank their developers.
Citation
@misc{deepinfer2026,
title = {DeepInfer: High-performance, large-scale inference framework for DeepSeek models},
author = {DeepSeek-AI},
year = {2026},
publisher = {GitHub},
howpublished = {\url{https://github.com/deepseek-ai/DeepInfer}},
}

