Piotr Wilkin (ilintar) f4e276a206 ggml-cuda : convert contiguous tensors four elements at a time (#29155)
convert_unary handles the contiguous case through the general strided kernel,
one element per thread: each lane reads 4 bytes and writes 2. Converting the
activations for a bf16 matrix multiplication that way moves 126 MB in 1021 us
on gfx1151, about 65% of what the memory system can do.

Give the contiguous path its own kernel that takes four elements per thread
through a vector type, so a warp loads 512 bytes at a time instead of 128. It
is used only when the element count is a multiple of four and both pointers
carry the alignment the vector type needs, and falls back to the strided
kernel otherwise.

Model level, Qwen3.8-Next-Flash IQ3_XXS on gfx1151, llama-bench -ub 2048 -r 6,
mean of the last 3 reps, ABBA counterbalanced:

    pp2048   688.0 680.0  ->  694.3 691.1   +1.26%
    tg128     24.8  24.8  ->   24.8  24.8   +0.14%

Every conversion in a prefill takes the new kernel (kernel trace: 1146
convert_unary_cont_vec4, no convert_unary). Output is bit identical; MUL_MAT,
MUL_MAT_ID, CPY, CONT, GET_ROWS and SET_ROWS pass.

Assisted-by: Claude Opus 5
2026-09-21 18:00:51 +02:00
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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