Hongqiang Wang c841aeeb8b opencl: use a better matmul path on two Adreno GPU generations (#27640)
* opencl: default the Adreno xmem F16xF32 GEMM on for X2E

kernel_mul_mm_f16_f32_l4_lm is the slowest matmul this backend has on Adreno: on
the X2-90 it runs the gpt-oss-20b attention projections at roughly a quarter of
what the tuned dense q4_0 GEMM reaches on the same device. That matters for any
model whose non-expert weights stay f16 -- the stock gpt-oss-20b release is
exactly that, and its prefill spends 40.8% of GPU time in that one kernel. The
xmem route already existed but was left opt-in, so nobody hit it.

Worth about 25% prefill on gpt-oss-20b on an Adreno X2-90. Gated to X2E: the
Adreno 840 measures neutral. Decode is untouched -- the dispatch gate needs
N >= 16. It is worth nothing on the q8attn variant, whose attention weights
already take the dp4a dense GEMM.

The env var was presence-tested before, so =0 previously enabled it; it is now
atoi()'d. MUL_MAT 963 OK / 0 FAIL on both arms.

* opencl: bypass the tiled f32 GEMM on the Adreno A7X

The A7X (E031.41) compiler executes kernel_mul_mm_f32_f32_l4_lm at roughly a
tenth of what the same silicon reaches in its own f16 and q4_K kernels. It
allocates 488 B/WI of private memory against 304 for the same source on the
following generation, i.e. the older register allocator spills in the K-loop.
Models with per-layer F32 projection pairs kept F32 by quantization policy land
on this kernel twice per layer, and it dominates their prefill on that part.

Route batched f32xf32 (ne11 > 8) around the tiled path on the A7X and let it
fall through to the per-row f32 kernel, which that compiler handles fine; small
batches keep the tiled path. Weights stay GPU-resident, so decode placement is
untouched -- declining the op in supports_op instead was measured first and
rejected, because the per-layer CPU round-trips cost more decode than the
prefill it gained.

Worth about 9% prefill on gemma-3n-E4B on an Adreno 740, with MUL_MAT counts
identical on and off. No other generation is affected. Override with
GGML_OPENCL_A7X_F32_LM_BYPASS=0.

* opencl: enable xmem GEMM for adreno by default

---------

Co-authored-by: Li He <lih@qti.qualcomm.com>
2026-08-29 10:46:27 -07:00
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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