anujj 3466812d1f cuda: fuse MoE weighted expert reduction (#25952)
* cuda : fuse MoE weighted reduction (mul + view + add)

The MoE combine tail currently writes weighted expert outputs to
global memory before reducing them. That intermediate global-memory
traffic is the main cost. The production baseline generally runs two
physical fused kernels; this path runs one.

This change matches the full expert-weighting plus ordered-reduction
subgraph and replaces it with one weighted-reduction kernel.

Supported graphs:
- unscaled: experts * router_weights
- scaled:   (experts * expert_scale) * router_weights

k = 2..15 is handled by one runtime-k kernel.

Matching is structural: op sequence, shapes, strides, expert views,
and the left-to-right ADD chain. The fused kernel keeps that same
reduction order. Results are not claimed bit-identical; CUDA FP32
contraction can change rounding slightly.

Allocator integration uses add_alloc_dep from the graph-optimizer
API so experts, router weights, and optional expert scales stay live
until the fused destination is written. Memory ranges are rechecked
before the fused kernel runs.

Unrecognized or unsafe graphs are left alone and keep the existing
per-op path. Set GGML_CUDA_MOE_WEIGHTED_REDUCTION=0 to disable the
fusion.

test-backend-ops covers scaled/unscaled, aligned/unaligned, and
representative values across k=2..15, plus a k=16 case that must
stay on the per-op path.

* Pruned the test matrix from 15 to 6

* Addressed the aman and olivers review comments
2026-09-01 21:48:47 +02:00
2026-08-31 12:17:51 +02:00
2026-06-12 15:53:26 +02:00
2026-02-02 08:38:55 +02:00
2026-08-23 20:55:56 +03:00

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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