Pranesh Gonegandla 2b5621094e CUDA: adding switch points per HW and quant type to tune the mvq->MMQ decode crossover (#26079)
* CUDA: runtime GGML_CUDA_MMVQ_MAX to tune the mvq->MMQ decode crossover

Add a runtime override of the mul_mat_vec_q -> MMQ batch crossover
(default MMVQ_MAX_BATCH_SIZE). Lowering it routes batches above the
threshold from the CUDA-core vector kernel to the int8 MMQ tensor-core
path, which is faster once quantized decode becomes compute-bound at
B>1 (measured +23-41% at B=8 on RTX 5090 for Q4_K dense, no low-batch loss).

The value is parsed once and clamped to [1, MMVQ_MAX_BATCH_SIZE], since
mul_mat_vec_q asserts ncols_dst <= that; invalid input warns and falls
back to the default. The override is applied consistently in both the
mul_mat_vec_q and MUL_MAT_ID dispatch paths. Default behavior unchanged.

* Added Blackwell specific switch point, to reduce dependence on runtime env var.

* Add per-HW switch point values for DGX Spark and removing runtime env var

* Adding switch points for Ada, tested on RTX 4090

* Modifying DGX Spark numbers based on latest run and adding some comments and small functional changes relating to MoE

* Reverting an unnecessary conditional

* Update ggml/src/ggml-cuda/mmvq.cu

---------

Co-authored-by: praneshgo <227579474+praneshgo@users.noreply.github.com>
Co-authored-by: Oliver Simons <osimons@nvidia.com>
2026-08-20 14:36:21 +02:00
2026-08-18 11:30:03 +03:00
2026-06-12 15:53:26 +02:00
2026-02-02 08:38:55 +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 [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

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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