Katostrofik 9ed6e19b9d SYCL: fix multi-GPU system RAM exhaustion by using Level Zero allocations (#21597)
* SYCL: fix multi-GPU system RAM exhaustion by using Level Zero allocations

Replace sycl::malloc_device with zeMemAllocDevice for GPU memory allocation
in the SYCL backend. sycl::malloc_device triggers the xe kernel driver's
DMA-buf/TTM path which mirrors every VRAM allocation 1:1 in system RAM.
zeMemAllocDevice uses the SVM/P2P path with no host staging.

On a dual Intel Arc Pro B70 system (64GB VRAM, 64GB RAM), a 15.6 GiB model
consumed 60 GiB of system RAM via sycl::malloc_device, causing OOM crashes.
With zeMemAllocDevice, the same workload uses ~6.7 GiB of system RAM with
no performance regression.

All Level Zero calls include automatic fallback to the original SYCL
allocation path if Level Zero interop is unavailable.

* SYCL: address review feedback - remove try/catch, check device types, deduplicate

- Remove try/catch from malloc/free/memcpy helpers, check backend and
  device type upfront instead (ggml_sycl_is_level_zero, ggml_sycl_is_dgpu)
- Move shared helpers (is_level_zero, is_dgpu, free_device) to common.cpp
  and declare in common.hpp to eliminate code duplication
- Use SYCL_CHECK(CHECK_TRY_ERROR()) for fallback sycl::free calls
- Guard dev2dev_memcpy L0 path to dGPU-to-dGPU only, preserving the
  host-staged path for iGPU-to-dGPU transfers
- Add Windows Level Zero SDK path detection (LEVEL_ZERO_V1_SDK_PATH)
  in CMakeLists.txt (co-authored with @arthw)

* SYCL: add build/runtime flags for Level Zero, address review feedback

Implements the architecture suggested by @arthw: compile-time and runtime
flags to cleanly separate Level Zero and SYCL memory API paths.

- Add GGML_SYCL_SUPPORT_LEVEL_ZERO cmake option (default ON). All Level
  Zero code is wrapped in #ifdef so the build works on systems without
  the Level Zero SDK installed (e.g. CPU-only CI servers). Both the
  loader library and headers are checked before enabling.

- Add GGML_SYCL_ENABLE_LEVEL_ZERO runtime env var (default 1). Controls
  whether Level Zero or SYCL memory APIs are used. Only one API style is
  used per session, no mixing. If Level Zero is enabled but the devices
  don't support the Level Zero backend, it auto-disables with a warning.

- Remove Level Zero code from dpct_malloc. It was unused (dpct::device_memory
  is not called anywhere in the backend) and used try/catch for flow control.

- Update SYCL.md with documentation for both new parameters.

Tested on Intel Arc Pro B70 (32GB), single-GPU and dual-GPU, with both
GGML_SYCL_SUPPORT_LEVEL_ZERO=ON and OFF builds. AI-assisted development
(Claude). Code reviewed and tested on my hardware.

* SYCL: unify Level Zero malloc/free call sites, address review feedback

Move ggml_sycl_malloc_device to common.cpp alongside ggml_sycl_free_device.
Both functions are now unconditionally available — Level Zero code is
#ifdef'd inside the functions, not at call sites. All call sites use
uniform SYCL_CHECK(CHECK_TRY_ERROR()) wrapping with no #ifdef blocks.

Addresses arthw's review: wrap all malloc/free in SYCL_CHECK for stack
traces on failure, eliminate duplicated #ifdef/else patterns at 6 call
sites (-29 lines net).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* SYCL: add Level Zero SDK to CI, fix device check and missed alloc paths

Add Level Zero SDK installation to Ubuntu and Windows SYCL CI jobs
so the Level Zero code path is compiled and tested in CI.

Fix two bugs found during extended dual-GPU testing (no
ONEAPI_DEVICE_SELECTOR set):

- The Level Zero backend check was iterating all SYCL devices
  including CPU. The OpenCL CPU device caused Level Zero to be
  disabled for the GPUs, defeating the fix on multi-GPU systems.
  Added is_gpu() filter so only GPU devices are checked.

- sycl_ext_malloc_device/sycl_ext_free (tensor reorder temp buffers)
  were still calling sycl::malloc/sycl::free directly, bypassing the
  Level Zero path. Routed through ggml_sycl_malloc_device/free_device
  for consistency with the other device memory call sites.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* SYCL: address arthw review feedback on Level Zero memory API structure

- Move ggml_sycl_malloc_device to static function in ggml-sycl.cpp;
  only ggml_sycl_free_device (used by common.cpp) stays in common.cpp
- Switch both helpers to use g_ggml_sycl_enable_level_zero global
  instead of per-call queue backend checks
- Remove #ifdef wrapper from global definition; always declare at 0,
  add #else branch in init block so it stays 0 when L0 not compiled in
- Update init loop comment to explain GPU-only device check
- CMakeLists: message(STATUS) before the if block; align option wording

AI-assisted implementation. Reviewed and tested on dual Intel Arc Pro
B70 (32 GB each): test-backend-ops OK on both GPUs, single/dual-GPU
Q4_K_M and Q8_0 bench correct, zeMemAllocDevice GTT delta confirmed
<5 MiB per 4 GiB allocation (vs ~4 GiB shadow with sycl::malloc_device).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* SYCL: remove unused cstdio/cstdlib includes from common.cpp

Leftover from the deleted ggml_sycl_queue_supports_level_zero helper.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

* Apply suggestions from code review

Co-authored-by: Neo Zhang <zhang.jianyu@outlook.com>

* SYCL: preserve Level Zero allocation path during early malloc

* ci: fix Level Zero package conflict in Intel Docker build

* ci: find Level Zero loader in oneAPI package step

* ci: allow Windows SYCL package without Level Zero DLL

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Neo Zhang <zhang.jianyu@outlook.com>
2026-05-14 13:39:14 +08:00
2026-02-02 08:51:25 +02:00
2026-02-02 08:38:55 +02:00

llama.cpp

llama

License: MIT Release Server

Manifesto / ggml / ops

LLM inference in C/C++

Recent API changes

Hot topics


Quick start

Getting started with llama.cpp is straightforward. Here are several ways to install it on your machine:

Once installed, you'll need a model to work with. Head to the Obtaining and quantizing models section to learn more.

Example command:

# Use a local model file
llama-cli -m my_model.gguf

# Or download and run a model directly from Hugging Face
llama-cli -hf ggml-org/gemma-3-1b-it-GGUF

# Launch OpenAI-compatible API server
llama-server -hf ggml-org/gemma-3-1b-it-GGUF

Description

The main goal of llama.cpp is to enable LLM 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 the main playground for developing new features for the ggml library.

Models

Typically finetunes of the base models below are supported as well.

Instructions for adding support for new models: HOWTO-add-model.md

Text-only

Multimodal

Bindings
UIs

(to have a project listed here, it should clearly state that it depends on llama.cpp)

Tools
  • akx/ggify download PyTorch models from Hugging Face Hub and convert them to GGML
  • akx/ollama-dl download models from the Ollama library to be used directly with llama.cpp
  • crashr/gppm launch llama.cpp instances utilizing NVIDIA Tesla P40 or P100 GPUs with reduced idle power consumption
  • gpustack/gguf-parser - review/check the GGUF file and estimate the memory usage
  • Styled Lines (proprietary licensed, async wrapper of inference part for game development in Unity3d with pre-built Mobile and Web platform wrappers and a model example)
  • unslothai/unsloth 🦥 exports/saves fine-tuned and trained models to GGUF (Apache-2.0)
Infrastructure
  • Paddler - Open-source LLMOps platform for hosting and scaling AI in your own infrastructure
  • GPUStack - Manage GPU clusters for running LLMs
  • llama_cpp_canister - llama.cpp as a smart contract on the Internet Computer, using WebAssembly
  • llama-swap - transparent proxy that adds automatic model switching with llama-server
  • Kalavai - Crowdsource end to end LLM deployment at any scale
  • llmaz - ☸️ Easy, advanced inference platform for large language models on Kubernetes.
  • LLMKube - Kubernetes operator for llama.cpp with multi-GPU and Apple Silicon Metal support"
Games
  • Lucy's Labyrinth - A simple maze game where agents controlled by an AI model will try to trick you.

Supported backends

Backend Target devices
Metal Apple Silicon
BLAS All
BLIS All
SYCL Intel and Nvidia GPU
OpenVINO [In Progress] Intel CPUs, GPUs, and NPUs
MUSA Moore Threads GPU
CUDA Nvidia GPU
HIP AMD GPU
ZenDNN AMD CPU
Vulkan GPU
CANN Ascend NPU
OpenCL Adreno GPU
IBM zDNN IBM Z & LinuxONE
WebGPU [In Progress] All
RPC All
Hexagon [In Progress] Snapdragon
VirtGPU VirtGPU APIR

Obtaining and quantizing models

The Hugging Face platform hosts a number of LLMs compatible with llama.cpp:

You can either manually download the GGUF file or directly use any llama.cpp-compatible models from Hugging Face or other model hosting sites, by using this CLI argument: -hf <user>/<model>[:quant]. For example:

llama-cli -hf ggml-org/gemma-3-1b-it-GGUF

By default, the CLI would download from Hugging Face, you can switch to other options with the environment variable MODEL_ENDPOINT. The MODEL_ENDPOINT must point to a Hugging Face compatible API endpoint.

After downloading a model, use the CLI tools to run it locally - see below.

llama.cpp requires the model to be stored in the GGUF file format. Models in other data formats can be converted to GGUF using the convert_*.py Python scripts in this repo.

The Hugging Face platform provides a variety of online tools for converting, quantizing and hosting models with llama.cpp:

To learn more about model quantization, read this documentation

llama-cli

A CLI tool for accessing and experimenting with most of llama.cpp's functionality.

  • Run in conversation mode

    Models with a built-in chat template will automatically activate conversation mode. If this doesn't occur, you can manually enable it by adding -cnv and specifying a suitable chat template with --chat-template NAME

    llama-cli -m model.gguf
    
    # > hi, who are you?
    # Hi there! I'm your helpful assistant! I'm an AI-powered chatbot designed to assist and provide information to users like you. I'm here to help answer your questions, provide guidance, and offer support on a wide range of topics. I'm a friendly and knowledgeable AI, and I'm always happy to help with anything you need. What's on your mind, and how can I assist you today?
    #
    # > what is 1+1?
    # Easy peasy! The answer to 1+1 is... 2!
    
  • Run in conversation mode with custom chat template
    # use the "chatml" template (use -h to see the list of supported templates)
    llama-cli -m model.gguf -cnv --chat-template chatml
    
    # use a custom template
    llama-cli -m model.gguf -cnv --in-prefix 'User: ' --reverse-prompt 'User:'
    
  • Constrain the output with a custom grammar
    llama-cli -m model.gguf -n 256 --grammar-file grammars/json.gbnf -p 'Request: schedule a call at 8pm; Command:'
    
    # {"appointmentTime": "8pm", "appointmentDetails": "schedule a a call"}
    

    The grammars/ folder contains a handful of sample grammars. To write your own, check out the GBNF Guide.

    For authoring more complex JSON grammars, check out https://grammar.intrinsiclabs.ai/

llama-server

A lightweight, OpenAI API compatible, HTTP server for serving LLMs.

  • Start a local HTTP server with default configuration on port 8080
    llama-server -m model.gguf --port 8080
    
    # Basic web UI can be accessed via browser: http://localhost:8080
    # Chat completion endpoint: http://localhost:8080/v1/chat/completions
    
  • Support multiple-users and parallel decoding
    # up to 4 concurrent requests, each with 4096 max context
    llama-server -m model.gguf -c 16384 -np 4
    
  • Enable speculative decoding
    # the draft.gguf model should be a small variant of the target model.gguf
    llama-server -m model.gguf -md draft.gguf
    
  • Serve an embedding model
    # use the /embedding endpoint
    llama-server -m model.gguf --embedding --pooling cls -ub 8192
    
  • Serve a reranking model
    # use the /reranking endpoint
    llama-server -m model.gguf --reranking
    
  • Constrain all outputs with a grammar
    # custom grammar
    llama-server -m model.gguf --grammar-file grammar.gbnf
    
    # JSON
    llama-server -m model.gguf --grammar-file grammars/json.gbnf
    

llama-perplexity

A tool for measuring the perplexity 1 (and other quality metrics) of a model over a given text.

  • Measure the perplexity over a text file
    llama-perplexity -m model.gguf -f file.txt
    
    # [1]15.2701,[2]5.4007,[3]5.3073,[4]6.2965,[5]5.8940,[6]5.6096,[7]5.7942,[8]4.9297, ...
    # Final estimate: PPL = 5.4007 +/- 0.67339
    
  • Measure KL divergence
    # TODO
    

llama-bench

Benchmark the performance of the inference for various parameters.

  • Run default benchmark
    llama-bench -m model.gguf
    
    # Output:
    # | model               |       size |     params | backend    | threads |          test |                  t/s |
    # | ------------------- | ---------: | ---------: | ---------- | ------: | ------------: | -------------------: |
    # | qwen2 1.5B Q4_0     | 885.97 MiB |     1.54 B | Metal,BLAS |      16 |         pp512 |      5765.41 ± 20.55 |
    # | qwen2 1.5B Q4_0     | 885.97 MiB |     1.54 B | Metal,BLAS |      16 |         tg128 |        197.71 ± 0.81 |
    #
    # build: 3e0ba0e60 (4229)
    

llama-simple

A minimal example for implementing apps with llama.cpp. Useful for developers.

  • Basic text completion
    llama-simple -m model.gguf
    
    # Hello my name is Kaitlyn and I am a 16 year old girl. I am a junior in high school and I am currently taking a class called "The Art of
    

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!
  • See good first issues for tasks suitable for first contributions
  • Read the CONTRIBUTING.md for more information
  • Make sure to read this: Inference at the edge
  • A bit of backstory for those who are interested: Changelog podcast

Other documentation

Development documentation

Seminal papers and background on the models

If your issue is with model generation quality, then please at least scan the following links and papers to understand the limitations of LLaMA models. This is especially important when choosing an appropriate model size and appreciating both the significant and subtle differences between LLaMA models and ChatGPT:

XCFramework

The XCFramework is a precompiled version of the library for iOS, visionOS, tvOS, and macOS. It can be used in Swift projects without the need to compile the library from source. For example:

// swift-tools-version: 5.10
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
    name: "MyLlamaPackage",
    targets: [
        .executableTarget(
            name: "MyLlamaPackage",
            dependencies: [
                "LlamaFramework"
            ]),
        .binaryTarget(
            name: "LlamaFramework",
            url: "https://github.com/ggml-org/llama.cpp/releases/download/b5046/llama-b5046-xcframework.zip",
            checksum: "c19be78b5f00d8d29a25da41042cb7afa094cbf6280a225abe614b03b20029ab"
        )
    ]
)

The above example is using an intermediate build b5046 of the library. This can be modified to use a different version by changing the URL and checksum.

Completions

Command-line completion is available for some environments.

Bash Completion

$ build/bin/llama-cli --completion-bash > ~/.llama-completion.bash
$ source ~/.llama-completion.bash

Optionally this can be added to your .bashrc or .bash_profile to load it automatically. For example:

$ echo "source ~/.llama-completion.bash" >> ~/.bashrc

Dependencies

  • yhirose/cpp-httplib - Single-header HTTP server, used by llama-server - MIT license
  • stb-image - Single-header image format decoder, used by multimodal subsystem - Public domain
  • nlohmann/json - Single-header JSON library, used by various tools/examples - MIT License
  • miniaudio.h - Single-header audio format decoder, used by multimodal subsystem - Public domain
  • subprocess.h - Single-header process launching solution for C and C++ - Public domain
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