Copilot Instructions for llama.cpp

Repository Overview

llama.cpp is a large-scale C/C++ project for efficient LLM (Large Language Model) inference with minimal setup and dependencies. The project enables running language models on diverse hardware with state-of-the-art performance.

Key Facts:

• Primary language: C/C++ with Python utility scripts
• Size: ~200k+ lines of code across 1000+ files
• Architecture: Modular design with main library (libllama) and 40+ executable tools/examples
• Core dependency: ggml tensor library (vendored in ggml/ directory)
• Backends supported: CPU (AVX/NEON optimized), CUDA, Metal, Vulkan, SYCL, ROCm, MUSA
• License: MIT

Build Instructions

Prerequisites

• CMake 3.14+ (primary build system)
• C++17 compatible compiler (GCC 13.3+, Clang, MSVC)
• Optional: ccache for faster compilation

Basic Build (CPU-only)

ALWAYS run these commands in sequence:

cmake -B build
cmake --build build --config Release -j $(nproc)

Build time: ~10 minutes on 4-core system with ccache enabled, ~25 minutes without ccache.

Important Notes:

• The Makefile is deprecated - always use CMake
• ccache is automatically detected and used if available
• Built binaries are placed in build/bin/
• Parallel builds (-j) significantly reduce build time

Backend-Specific Builds

For CUDA support:

cmake -B build -DGGML_CUDA=ON
cmake --build build --config Release -j $(nproc)

For Metal (macOS):

cmake -B build -DGGML_METAL=ON
cmake --build build --config Release -j $(nproc)

Important Note: While all backends can be built as long as the correct requirements for that backend are installed, you will not be able to run them without the correct hardware. The only backend that can be run for testing and validation is the CPU backend.

Debug Builds

Single-config generators:

cmake -B build -DCMAKE_BUILD_TYPE=Debug
cmake --build build

Multi-config generators:

cmake -B build -G "Xcode"
cmake --build build --config Debug

Common Build Issues

• Issue: Network tests fail in isolated environments Solution: Expected behavior - core functionality tests will still pass

Testing

Running Tests

ctest --test-dir build --output-on-failure -j $(nproc)

Test suite: 38 tests covering tokenizers, grammar parsing, sampling, backends, and integration Expected failures: 2-3 tests may fail if network access is unavailable (they download models) Test time: ~30 seconds for passing tests

Server Unit Tests

Run server-specific unit tests after building the server:

# Build the server first
cmake --build build --target llama-server

# Navigate to server tests and run
cd tools/server/tests
source ../../../.venv/bin/activate
./tests.sh

Server test dependencies: The .venv environment includes the required dependencies for server unit tests (pytest, aiohttp, etc.). Tests can be run individually or with various options as documented in tools/server/tests/README.md.

Test Categories

• Tokenizer tests: Various model tokenizers (BERT, GPT-2, LLaMA, etc.)
• Grammar tests: GBNF parsing and validation
• Backend tests: Core ggml operations across different backends
• Integration tests: End-to-end workflows

Manual Testing Commands

# Test basic inference
./build/bin/llama-cli --version

# Test model loading (requires model file)
./build/bin/llama-cli -m path/to/model.gguf -p "Hello" -n 10

Code Quality and Linting

C++ Code Formatting

ALWAYS format C++ code before committing:

git clang-format

Configuration is in .clang-format with these key rules:

• 4-space indentation
• 120 column limit
• Braces on same line for functions
• Pointer alignment: void * ptr (middle)
• Reference alignment: int & ref (middle)

Python Code

ALWAYS activate the Python environment in .venv and use tools from that environment:

# Activate virtual environment
source .venv/bin/activate

Configuration files:

• .flake8: flake8 settings (max-line-length=125, excludes examples/tools)
• pyrightconfig.json: pyright type checking configuration

Pre-commit Hooks

Run before committing:

pre-commit run --all-files

Continuous Integration

GitHub Actions Workflows

Key workflows that run on every PR:

• .github/workflows/build.yml: Multi-platform builds
• .github/workflows/server.yml: Server functionality tests
• .github/workflows/python-lint.yml: Python code quality
• .github/workflows/python-type-check.yml: Python type checking

Local CI Validation

Run full CI locally before submitting PRs:

mkdir tmp

# CPU-only build
bash ./ci/run.sh ./tmp/results ./tmp/mnt

CI Runtime: 30-60 minutes depending on backend configuration

Triggering CI

Add ggml-ci to commit message to trigger heavy CI workloads on the custom CI infrastructure.

Project Layout and Architecture

Core Directories

• src/: Main llama library implementation (llama.cpp, llama-*.cpp)
• include/: Public API headers, primarily include/llama.h
• ggml/: Core tensor library (submodule with custom GGML framework)
• examples/: 30+ example applications and tools
• tools/: Additional development and utility tools (server benchmarks, tests)
• tests/: Comprehensive test suite with CTest integration
• docs/: Detailed documentation (build guides, API docs, etc.)
• scripts/: Utility scripts for CI, data processing, and automation
• common/: Shared utility code used across examples

Key Files

• CMakeLists.txt: Primary build configuration
• include/llama.h: Main C API header (~2000 lines)
• src/llama.cpp: Core library implementation (~8000 lines)
• CONTRIBUTING.md: Coding guidelines and PR requirements
• .clang-format: C++ formatting rules
• .pre-commit-config.yaml: Git hook configuration

Built Executables (in build/bin/)

Primary tools:

• llama-cli: Main inference tool
• llama-server: OpenAI-compatible HTTP server
• llama-quantize: Model quantization utility
• llama-perplexity: Model evaluation tool
• llama-bench: Performance benchmarking
• llama-convert-llama2c-to-ggml: Model conversion utilities

Configuration Files

• CMake: CMakeLists.txt, cmake/ directory
• Linting: .clang-format, .clang-tidy, .flake8
• CI: .github/workflows/, ci/run.sh
• Git: .gitignore (includes build artifacts, models, cache)

Dependencies

• System: OpenMP, libcurl (for model downloading)
• Optional: CUDA SDK, Metal framework, Vulkan SDK, Intel oneAPI
• Bundled: httplib, json (header-only libraries in vendored form)

Common Validation Steps

After Making Changes

1. Format code: git clang-format
2. Build: cmake --build build --config Release
3. Test: ctest --test-dir build --output-on-failure
4. Server tests (if modifying server): cd tools/server/tests && source ../../../.venv/bin/activate && ./tests.sh
5. Manual validation: Test relevant tools in build/bin/

Performance Validation

# Benchmark inference performance
./build/bin/llama-bench -m model.gguf

# Evaluate model perplexity
./build/bin/llama-perplexity -m model.gguf -f dataset.txt

Backend Validation

# Test backend operations
./build/bin/test-backend-ops

Environment Setup

Required Tools

• CMake 3.14+ (install via system package manager)
• Modern C++ compiler with C++17 support
• Git (for submodule management)
• Python 3.9+ with virtual environment (.venv is provided)

Optional but Recommended

• ccache: apt install ccache or brew install ccache
• clang-format 15+: Usually included with LLVM/Clang installation
• pre-commit: pip install pre-commit

Backend-Specific Requirements

• CUDA: NVIDIA CUDA Toolkit 11.2+
• Metal: Xcode command line tools (macOS only)
• Vulkan: Vulkan SDK
• SYCL: Intel oneAPI toolkit

Important Guidelines

Code Changes

• Minimal dependencies: Avoid adding new external dependencies
• Cross-platform compatibility: Test on Linux, macOS, Windows when possible
• Performance focus: This is a performance-critical inference library
• API stability: Changes to include/llama.h require careful consideration

Git Workflow

• Always create feature branches from master
• Never commit build artifacts (build/, .ccache/, *.o, *.gguf)
• Use descriptive commit messages following project conventions

Trust These Instructions

Only search for additional information if these instructions are incomplete or found to be incorrect. This document contains validated build and test procedures that work reliably across different environments.