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danielhanchen
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set_input_qsa asserted n_stream == 1, so llama-server could not serve this model with more than one slot unless -kvu was passed. With a non-unified cache each sequence owns its own cells, and a cell index means a different token in each stream, so a single shared mapping is wrong. - cell_blk, blk_cells and bias gain a stream dimension. At n_stream == 1 these collapse to the shapes they had, so the unified path is unchanged. - Scoring is now batched over streams. ggml_mul_mat matches ne[2] on both operands, so stream s's queries only ever meet stream s's blocks; without this sequences would score against each other's context. - set_input_qsa loops per stream and resolves cells through v_cells[seq_to_stream[seq_id]], following set_input_kq_mask_impl, instead of hardcoding v_cells[0]. - llama_kv_cache_context::get_n_stream() is added, mirroring the ns that get_k and get_v already derive from the slot info. build_attn_mask_top_k needed no change: it already expects [n_top_k, n_batch, 1, n_stream], so the top-k result is reshaped to meet it. set_input_qsa has exactly one caller, so the blast radius is qwen4exp only. Validation, UD-Q4_K_XL on one B200: - unified cache unchanged within noise: 1802.9/68.85 -> 1807.2/69.11 t/s at batch 1, 2262.5/192.43 -> 2270.1/193.75 at batch 4. - non-unified now runs at npl 1, 4, 16 where it previously aborted, and is 22% faster than the -kvu workaround at batch 16 (1205 vs 984 t/s total), since per-stream cells avoid the cross-sequence masking a unified cache pays for. - no cross-stream contamination: four concurrent sequences each carrying a distinct secret all recall their own and no other, on both cache modes. - test-llama-archs green on qwen4exp, deepseek2, gemma3n, qwen3next, llama. Note on testing: comparing concurrent output against solo output exactly is not a valid check. It failed 0/4 with no bug present, and the unified-cache control failed the same way, because batch composition changes the floating-point reduction order and near-tied tokens flip. The contamination test above is what the exit code gates on.
llama.cpp
LLM inference in C/C++
ggml / ops / maintainer PRs / dev stats / lib llama API / llama-server REST API
Quick start
A few options to get llama.cpp installed on your machine:
- Visit https://llama.app and follow the instructions
- Run with Docker - see our Docker documentation
- Download pre-built binaries from the releases page
- Build from source by cloning this repository - check out our build guide
Once installed:
# Download and run a model directly from Hugging Face
llama cli -hf ggml-org/Qwen3.5-0.8B-GGUF
# Launch OpenAI-compatible API server
llama serve -hf ggml-org/Qwen3.5-0.8B-GGUF
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Description
The main goal of llama.cpp is to enable LLM (and VLM) inference with minimal setup and state-of-the-art performance on
a wide range of hardware - locally and in the cloud.
- Plain C/C++ implementation without any dependencies
- Apple silicon is a first-class citizen - optimized via ARM NEON, Accelerate and Metal frameworks
- AVX, AVX2, AVX512 and AMX support for x86 architectures
- RVV, ZVFH, ZFH, ZICBOP and ZIHINTPAUSE support for RISC-V architectures
- 1.5-bit, 2-bit, 3-bit, 4-bit, 5-bit, 6-bit, and 8-bit integer quantization for faster inference and reduced memory use
- Custom CUDA kernels for running LLMs on NVIDIA GPUs (support for AMD GPUs via HIP and Moore Threads GPUs via MUSA)
- Vulkan and SYCL backend support
- CPU+GPU hybrid inference to partially accelerate models larger than the total VRAM capacity
The llama.cpp project is build on top of the ggml library.
Supported backends
| Backend | Target devices |
|---|---|
| BLAS | All |
| BLIS | All |
| CANN | Ascend NPU |
| CUDA | Nvidia GPU |
| HIP | AMD GPU |
| Hexagon [In Progress] | Snapdragon |
| IBM zDNN | IBM Z & LinuxONE |
| MUSA | Moore Threads GPU |
| Metal | Apple Silicon |
| OpenCL | Adreno GPU |
| OpenVINO [In Progress] | Intel CPUs, GPUs, and NPUs |
| RPC | All |
| SYCL | Intel GPU |
| VirtGPU | VirtGPU APIR |
| Vulkan | GPU |
| WebGPU | All |
| ZenDNN | AMD CPU |
Documentation
Tools
Development
- How to build
- Running on Docker
- Build on Android
- Multi-GPU usage
- Performance troubleshooting
- GGML tips & tricks
- XCFramework
- Completions
- Models
- Release process
Contributing
- Contributors can open PRs
- Collaborators will be invited based on contributions
- Maintainers can push to branches in the
llama.cpprepo and merge PRs into themasterbranch - Any help with managing issues, PRs and projects is very appreciated!
- Read the CONTRIBUTING.md for more information
Acknowledgements
- yhirose/cpp-httplib - Single-header HTTP server, used by
llama-server- MIT license - nothings/stb - Single-header image format decoder, used by multimodal subsystem - Public domain
- nlohmann/json - Single-header JSON library, used by various tools/examples - MIT License
- mackron/miniaudio - Single-header audio format decoder, used by multimodal subsystem - Public domain
- sheredom/subprocess.h - Single-header process launching solution for C and C++ - Public domain