Pascal 5262471615 vulkan: fix wrong results when a mul_mat reads a slice of a larger cache (#28956)
* vulkan: read the batch stride of an in place src0 from nb[2]

A dim01 contiguous tensor can still be a view whose batches are
strided by more than ne[1] rows, the first rows of a KV cache for
example. Both the mat-vec and the matrix paths read such a tensor in
place but passed ne00*ne01 as the batch stride, so every head past
the first read the wrong rows. The same applies to src1. The stride
now comes from nb[2] whenever the tensor is used in place; the value
is unchanged for a contiguous tensor.

test-backend-ops gets an m_v parameter on test_mul_mat, the number of
rows of a in memory, and two cases at the shapes of a decoder self
attention over a cache.

* vulkan: size the in place A and B ranges by their strided extent

The matrix path bound src0 and src1 to the shader with a range of
elements times type size, which ends before the batches of a strided
view. Pipelines with bounded access read zero past that range, so the
same view that the mat-vec path already handles gave wrong results
on Intel and on NVIDIA without coopmat2. The range now comes from
ggml_nbytes when the tensor is read in place.

* vulkan: address review from jeffbolznv

Bind the in place A and B of the matrix path with ggml_vk_subbuffer,
which spans to the end of the buffer, so a strided view is in range
without computing its extent.

mul_mat_id reads the batch stride of an in place src0 and src1 with
the same helper as mul_mat. test_mul_mat_id gets an m_v parameter,
the number of rows of as in memory, and a case whose experts are
strided by more rows than it uses.

* vulkan: read the batch stride of an in place src0 in mul_mat_vec_id

The single token path of mul_mat_id passed ne00*ne01 as the batch
stride of A, so a strided expert view read the wrong rows. The stride
now comes from ggml_vk_batch_stride like the other three paths, and
src1 follows the same rule.

test_mul_mat_id gets a single token case over the strided view.

* vulkan: address review from jeffbolznv

The batch stride of an in place tensor is taken from nb[2] as
nb[2] / type_size * block_size, which holds when nb[2] is padded and
not a multiple of nb[1]. A test_mul_mat case with a padded batch stride
covers it.

* vulkan: keep the A and B ranges exact in mul_mm

The quantized A loads of mul_mm carry no row bound and rely on the
descriptor range to read zeros past the last row of a partial tile.
Binding A and B up to the end of the buffer let those tiles read the
leftovers of a previous node and hung the NVFP4 mul_mm on NVIDIA
without coopmat2. The range is the strided extent of a tensor read in
place and the staged size otherwise.
2026-09-28 08:36:38 +02:00
2026-09-27 13:43:08 +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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