Georgi Gerganov 631109b34d ggml : add alloc_buffer_n to buffer type interface (#23671)
* ggml : add `alloc_buffer_n` to buffer type interface

Add alloc_buffer_n method to ggml_backend_buffer_type_i
interface, with a public API ggml_backend_buft_alloc_buffer_n.

- Default implementation in ggml-backend.cpp handles multi-buffer
  splitting and tensor allocation via ggml_tallocr
- Meta buffer type provides custom implementation that creates
  per-device sub-contexts and delegates to simple buffer types
- ggml_backend_alloc_ctx_tensors_from_buft now collects tensors
  into a list and delegates to the new API
- Remove temporary ggml_backend_meta_alloc_ctx_tensors_from_buft
- Add NULL alloc_buffer_n to all existing buffer type
  interfaces (cpu, metal, openvino, hexagon, webgpu, zdnn, virtgpu, repack)

Assisted-by: llama.cpp:local pi

* cont : fix `cur_buf_size` init after flushing a buffer

* ggml : add TODO tag for shared buffer split logic

Assisted-by: pi:llama.cpp/DeepSeek-V4-Flash-Vision-Exp

* tests : add alloc_buffer_n coverage

Assisted-by: pi:llama.cpp/DeepSeek-V4-Flash-Vision-Exp

* cont : fix compile warnings

* tests : add descriptions for alloc_buffer_n tests

Assisted-by: pi:llama.cpp/Qwen3.8-27B

* ggml : address review comments on alloc_buffer_n

- restore GGML_LOG_ERROR on buffer alloc / tensor init failure in the
  default impl (name the failing tensor)
- check the malloc result and drop the _impl indirection in
  ggml_backend_alloc_ctx_tensors_from_buft
- remove comments that restate the code
- fix the TAG_ALLOC_SHARED_BUFFER_SPLIT typo

Assisted-by: pi:llama.cpp/Qwen3.8-27B

* ggml : add get_alloc_size_n to buffer type interface

- Add ggml_backend_buft_get_alloc_size_n public API
- Add optional get_alloc_size_n callback to ggml_backend_buffer_type_i
- Share tensor->buffer planning between alloc_buffer_n default and get_alloc_size_n default
- Replace unchecked realloc with std::vector in alloc_buffer_n default
- Make ggml_backend_alloc_ctx_tensors_from_buft_size use the new API
- Add test-alloc coverage for get_alloc_size_n

Assisted-by: pi:llama.cpp/DeepSeek-V4-Flash-Vision-Exp

* cont : report malloc failure
2026-10-02 11:08:08 +03:00
2026-10-01 14:13:27 +03:00
2026-10-02 09:12:25 +08:00
2026-06-12 15:53:26 +02:00
2026-02-02 08:38:55 +02:00
2026-09-09 15:56:27 +02:00

llama.cpp

llama

Quick start

A few options to get llama.cpp installed on your machine:

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
VLM session with `llama cli` VLM session with llama cli Built-in web UI against `llama serve` running Qwen 3.6 Built-in web UI against llama serve

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 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

Contributing

  • Contributors can open PRs
  • Collaborators will be invited based on contributions
  • Maintainers can push to branches in the llama.cpp repo and merge PRs into the master branch
  • 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
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